DETERMINATION OF DEPTHS OF CLOSURE ALONG THE KELANTAN COAST NOR HISHAM BIN MOHD. GHAZALI UNIVERSITI TEKNOLOGI MALAYSIA iii In the name of Allah, the Compassionate, the Merciful Dedicated to my loving wife Noriah Abu Bakar for sharing my life and dreams, to my father and my mother for their relentless faith in me, and my sons Hazim, Nadim and Aqil Zuhair for their unconditional love. iv ACKNOWLEDGEMENT All praise be to Allah the Merciful, the Benevolent to Whom all will return and Whose knowledge is infinite, eternal. I would like to first thank my supervisor Associate Professor Dr. Ahmad Khairi Bin Abd Wahab whose guidance, counsel and support were critical to the direction, focus and completion of this thesis. I am indebted to my employer the Department of Irrigation and Drainage Malaysia and the Public Services Department Malaysia for providing me the opportunity and the financial means to pursue this study, and especially to Ir. Tan King Seng, Director of Coastal Engineering Division for his personal and professional support. My thanks extend to Khairol Azuan Bin Adam of the National Hydraulic Institute of Malaysia for his assistance, comments and advice on numerical modelling and the staff of the Coastal Engineering Division, Department of Irrigation and Drainage Malaysia for their immense support. And not in the least, my deepest and eternal gratitude to my wife Noriah Binti Abu Bakar whose strength, love and encouragement were beacons in all my pursuits. v ABSTRACT The design of beach-fill in beach nourishment works requires knowledge of the cross-shore sediment transport process. By the theory of equilibrium profiles, beachfill material will be redistributed across the shore profile up to a seaward limit known as the depth of closure or Dc. The determination of the depth of closure is a key component of beach-fill design and is measured in the field from the study of periodical surveys over the same beach profiles. The Hallermeier equation which relies on the incident pre-breaking wave height is the only analytical means to predict the depth of closure. This study has examined the applicability of the Hallermeier equation in predicting depth of closure for the coastline of Pantai Sabak, Kelantan using nearshore waves which were transformed from offshore waves through numerical modelling. The predicted depth of closure was compared against measured depth of closure at 13 profiles that were surveyed in 1998, 1999, 2000 and 2004. The widely-accepted Standard Deviation of Depth Change (SDDC) and Fixed Depth Change (FDC) methods to determine Dc were both explored and the Dc for monsoon, annual and 5-year events were investigated. The research found that along the study shoreline at Pantai Sabak, more than one closure point can occur across the same profile over the seasonal and annual period. Hallermeier’s equation overpredicts annual Dc by 43% and affirms previous findings that the predictive equation determines an upper limit value of Dc. Within the limitations of the survey data available, the annual depth of closure at Pantai Sabak can be equated to 1.5 times H0.137. vi ABSTRAK Pengetahuan mengenai proses pergerakan ampaian rentas pantai adalah penting dalam kerja-kerja merekabentuk penambakan pasir pantai. Berpandukan teori keseimbangan profil, pasir penambakan dijangka akan diangkut dan diendapkan ke seluruh profil pantai sehingga satu lokasi kedalaman yang dinamakan kedalaman tertutup atau Dc. Penentuan kedalaman tertutup merupakan salah satu komponen penting dalam rekabentuk penambakan pasir dan ianya diperolehi melalui kajian ke atas data ukur bersiri yang diperolehi daripada profil-profil pantai yang sama. Persamaan Hallermeier yang bergantung kepada keadaan ombak sebelum pecah merupakan satu-satunya kaedah analitikal yang ada untuk menentukan kedalaman tertutup. Kajian ini telah menguji kesesuaian persamaan Hallermeier ini dalam meramalkan kedalaman tertutup bagi Pantai Sabak, Kelantan dengan menggunakan ketinggian ombak di kawasan dekat pantai yang diperolehi melalui permodelan numerikal yang berasaskan ombak lepas pantai. Kedalaman tertutup yang dikira dengan menggunakan persamaan Hallermeier telah dibandingkan dengan kedalaman tertutup yang dianalisa di 13 profil pantai yang diukur dalam tahun 1998, 1999, 2000 and 2004. Kaedah Persisihan Piawai Perubahan Kedalaman dan Perubahan Kedalaman Tetap telah digunakan untuk menentukan Dc bagi keadaan tengkujuh atau monsun timur-laut, tempoh tahunan dan untuk tempoh 5 tahun. Penyiasatan ini telah mendapati bahawa lebih daripada satu kedalaman tertutup boleh wujud dalam profil yang sama. Ramalan Dc tahunan dengan menggunakan Persamaan Hallermeier didapati tinggi dengan lebihan purata 43% dan ini mengesahkan hasil kajian-kajian terdahulu yang menyatakan bahawa persamaan ini boleh menentukan nilai had teratas untuk Dc. Tertakluk kepada data ukur yang terhad di Pantai Sabak, kedalaman tertutup tahunan boleh disamakan dengan 1.5 kali ketinggian ombak H0.137. vii TABLE OF CONTENTS CHAPTER TITLE DECLARATION ii DEDICATION iii ACKNOWLEDGEMENT iv ABSTRACT v ABSTRAK vi TABLE OF CONTENTS vii LIST OF TABLES xii LIST OF FIGURES xiv LIST OF ABBREVIATIONS xix LIST OF SYMBOLS xx LIST OF APPENDICES 1 PAGE INTRODUCTION xxii 1 1.1 Introduction 1 1.2 Background of the Problem 2 1.2.1 Erosion Control and Beach Nourishment in Malaysia 2 1.2.2 Study Shoreline 3 1.2.3 5 Beach Nourishment Design and Depths of Closure 1.3 Objectives of the Study 7 1.4 Benefits of the Study 7 2 LITERATURE REVIEW 2.1 Introduction 2.2 Cross-shore Sediment Transport and Equilibrium 8 8 Beach Profiles 8 2.3 Definition of Depth of Closure 9 2.4 Methods of Determination 12 2.4.1 Predictive Methods 12 2.4.2 Depth of Closure from Profile Surveys 15 2.4.3 Depth Change Criterion 16 2.5 Application of Depth of Closure 18 2.6 Depth of Closure – Malaysian Context 19 2.7 Summary 21 3 RESEARCH METHODOLOGY 23 3.1 Introduction 23 3.2 Scope of the Research 24 3.3 Research Methodology 27 3.3.1 Data Sets 27 3.3.2 Primary Data Collection 28 3.3.3 Numerical Modelling 29 3.3.4 Analysis 30 3.4 4 3.3.5 Depths of Closure from Beach Profile Data 30 3.3.6 31 Depth of Closure from Empirical Formulae Summary FIELD DATA ANALYSIS 31 33 4.1 Introduction 33 4.2 Study Area 34 ix 4.3 Environmental and Climatic Conditions 35 4.4 Data Sets 36 4.5 Beach Profile Survey 36 4.5.1 Survey #1 - 1998 37 4.5.2 Survey #2 - 1999 37 4.5.3 Survey #3 - 2000 38 4.5.4 Survey #4 - 2004 38 4.5.5 Survey Data Selection 38 4.5.6 42 4.6 Sediment Data 42 4.7 Wave 44 4.7.1 UKMO Design Wave Analysis 45 4.7.2 Measured Waves 50 4.8 Tidal Heights 52 4.9 Wind 54 4.10 Summary 55 5 NUMERICAL MODELLING 57 5.1 Introduction 57 5.2 Model Description 57 5.3 Numerical Modelling 59 5.3.1 Model Area and Orientation 59 5.3.2 Wave Breaking Conditions 59 5.4 6 Survey Data Filtering 5.3.3 Calibration 61 5.3.4 66 Prediction of Nearshore Waves from Wave Model Summary 77 DETERMINATION OF DEPTHS OF CLOSURE 79 x 6.1 Introduction 79 6.2 Depth of Closure – Scope and Criteria 80 6.2.1 Definition 80 6.2.2 Algorithm for Determination of Dc from Profile Surveys 81 6.3 Predicted Depth of Closure, Dl,t 84 6.4 Monsoon Dc (1998-1999 surveys) 84 6.4.1 Profile Descriptions and Application of Algorithm 84 6.4.2 Monsoon Dc at Ch.3100 and Ch.2700 84 6.4.3 Monsoon Dc at Ch.2300 and Ch.1900 87 6.4.4 Monsoon Dc at Ch.1500, Ch.1200 and Ch.800 88 6.4.5 Monsoon Dc at Ch.400, Ch.200 and Ch.00 91 6.4.6 Monsoon Dc at Ch.-400, Ch.-900 and Ch.-1400 95 6.4.7 Summary for Monsoon Dc 97 6.5 Annual Dc (1999-2000) 100 6.5.1 Profile Description and Application of Algorithm 100 6.5.2 Annual Dc at Ch.3100 101 6.5.3 Annual Dc at Ch.2700 102 6.5.4 Annual Dc at Ch.1500 103 6.5.5 Annual Dc at Ch.1200 104 6.5.6 Annual Dc at Ch.800 105 6.5.7 Annual Dc at Ch.400 106 6.5.8 Annual Dc at Ch.200 107 6.5.9 Annual Dc at Ch.00 108 6.5.10 Annual Dc at Ch-400, Ch.-900 and Ch.-1400 109 6.6 Summary for Annual Dc (1999-2000) 111 6.7 Time-interval Dc (1999-2004) 113 6.7.1 Profile Description and Application of Algorithm 113 6.7.2 Five-year Dc at Ch.3100 114 6.7.3 Five-year Dc at Ch.2700 115 xi 6.7.4 Five-year Dc at Ch.1500 116 6.7.5 Five-year Dc at Ch.1200 117 6.7.6 Five-year Dc at Ch.800 118 6.7.7 Five-year Dc at Ch.400 119 6.7.8 Five-year Dc at Ch.200 120 6.7.9 Five-year Dc at Ch.00 121 6.7.10 Five-year Dc at Ch.-400, Ch.-900 and Ch.-1400 122 6.8 Summary of 5-year Dc (1999, 2000 and 2004) 124 6.9 Comparison of Event and Time-Interval Dc 126 6.10 Measured Dc vs. Hallermeier’s Equation 127 6.11 Simplified Dc Equations 129 6.12 Observation 131 CONCLUSIONS AND RECOMMENDATIONS 133 7.1 General Conclusions 133 7.2 Suggestions for Future Research 135 7 7.2.1 Dc Criteria and Survey Techniques 135 7.2.2 Wave Data 135 7.2.3 Profile Surveys and Bar Migration Phenomena 136 7.2.4 136 Determining a predictive formula for local Dc REFERENCES APPENDICES A - E 138 142-174 xii LIST OF TABLES TABLE NO. TITLE PAGE 4.1 Profile Survey Data Register 40 4.2 Starting And Ending Points Of Selected Survey Dataset (13 profile lines) off Pantai Sabak, Kelantan 41 4.3 Statistics of UKMO Wave Dataset 47 4.4 Tidal Levels Along Study Shoreline (meters, LSD) 53 4.6 Mean High Water (meters, LSD) 53 4.7 Difference between MSL and MLW at Study Coastline 54 4.8 Difference between MSL and MHW at Study Coastline 54 5.1 Results of Wave Model Calibration 63 5.2 Location of Offshore Points in Model Grid for Extraction of Wave Parameters Predicted Wave Heights At 10 M Depth Based On Offshore wave of H0.137 = 2.9 m and Tm = 6.3 secs 74 Predicted Wave Heights at 10 m depth Based On Offshore Wave of H0.027 = 3.13 m and Tm = 6.54 secs 75 6.1 Depths of Closure (SDDC) for Monsoon Event 1998-1999 99 6.2 Depths of Closure (FDC) for Monsoon Event 1998-1999 99 6.3 Annual Dc (May 1999 – May 2000) 111 6.4 Five-year Dc (1999, 2000, 2004 surveys) for beach-fill design 125 5.3 5.4 67 6.5 Outer Closure Depths Dco (MLW) from Profile Plots 127 6.6 Effective Dc and Predicted depth of closure, Dl,t , MLW 128 6.7 Dc from simplified equations compared with effective Dc 130 6.8 Dc from simplified equation compared to Dco 130 xiv LIST OF FIGURES NO. 1.1 TITLE PAGE Study Area - 4.5 km of Shoreline From Pantai Dasar Sabak to South of Kg. K.S.P. Besar (Sungai Pengkalan Datu) 4 Evolution of Beach-fill based on Theory of Equilibrium Profile 6 Zonation Of Seasonal Beach Profile (Hallermeier 1978, 1981); extracted from Rijkswaterstaat (1987) 10 3.1 Research Model 26 4.1 Location of Study Area 34 4.2 Close-up of Study Area from Kg. Pantai Dasar Sabak to Kg. Senok 35 4.3 Profile Lines At The Study Area 39 4.4 Distribution of sediments along Pantai Sabak 1998, 1999 and 2004 (d50 averaged across all chainages) 43 Distribution of bed sediments along Pantai Sabak 1998-1999. Negative chainages are south of the breakwater 43 4.6 Distribution of bed sediments along Pantai Sabak 2004 44 4.7 Location of Wavebuoy And UKMO Wavedata Source Relative to Kelantan Coast. 45 Offshore Significant Wave Heights at 6.39N 102.92E; 28/05/1999 – 30/07/2004 46 4.9 Histogram of UKMO Waves 47 4.10 Wave Height vs. Wave Period for UKMO Offshore Wave Records 1999 to 2004 48 1.2 2.1 4.5 4.8 xv 4.11 H0.137 Wave from 1999-2000 UKMO Wave Data 49 4.12 H0.027 Wave from 1999-2004 UKMO Wave Data 50 4.13 Wave Buoy Measurements at E19236.3 N33957 (Kelantan Cassini) off Pantai Sabak, Kelantan Coast; 30 June to 13 July 2004. 51 Comparison of Offshore (UKMO Data) and Nearshore Waves Measured at the -12 m LSD Contour 51 Location Of Water Level, Current and Wave Stations At Study Area. 52 Wind Rose for UKMO Offshore Wind Data (20 m Above MSL) 55 Orientation of rectangle model layout for the input (offshore) wave approach conditions N330o, N0o, N30o, N60o, N90o and N120o 58 Sensitivity of kN parameter and location of breaking wave based on waves in July 62 Water level measurements at Pantai Sabak during calibration period 64 Wave Model Calibration – Wave Heights (for offshore waves from 0 to 120 degrees) 64 Wave Model Calibration – Wave Directions (for offshore waves from 0 to 120 degrees) 65 5.6 Location of extraction points in wave model 67 5.7 Wave Refraction Diagram; H0.137 = 2.9, Tm = 6.3 sec; North approach. 68 Wave Refraction Diagram; H0.137 = 2.9, Tm = 6.3 secs; N30o approach. 69 Wave Refraction Diagram; H0.137 = 2.9 m, Tm = 6.3 secs; N60o approach. 69 Wave Refraction Diagram; H0.137 = 2.9 m, Tm = 6.3 secs; N90o approach. 70 Wave Refraction Diagram; H0.137 = 2.9 m, Tm = 6.3 secs; N120o approach. 70 4.14 4.15 4.16 5.1 5.2 5.3 5.4 5.5 5.8 5.9 5.10 5.11 xvi 5.12 Wave Refraction Diagram; H0.027 = 3.13 m, Tm = 6.54 secs; North approach. 71 Wave Refraction Diagram; H0.027 = 3.13 m, Tm = 6.54 secs; N30o approach. 71 Wave Refraction Diagram; H0.027 = 3.13 m, Tm = 6.54 secs; N60o approach. 72 Wave Refraction Diagram; H0.027 = 3.13 m, Tm = 6.54 secs; N90o approach. 72 Wave Refraction Diagram; H0.027 = 3.13 m, Tm = 6.54 secs; N120o approach. 73 Predicted Maximum Wave Heights at 10-m depth ACD contour along Pantai Sabak, Kelantan. 76 Predicted Wave Heights at 10-m depth (ACD) contour along Pantai Sabak, Kelantan averaged over all directions 77 6.1 Monsoon Dc at Ch.3100 85 6.2 Monsoon Dc at Ch.2700 86 6.3 Monsoon Dc at Ch.2300 87 6.4 Monsoon Dc at Ch.1900 88 6.5 Monsoon Dc at Ch.1500 89 6.6 Monsoon Dc at Ch.1200 90 6.7 Monsoon Dc at Ch.800 91 6.8 Monsoon Dc at Ch.400 92 6.9 Monsoon Dc at Ch.200 93 6.10 Monsoon Dc at Ch.00 94 6.11 Monsoon Dc at Ch.-400 95 6.12 Monsoon Dc at Ch.-900 (slope 1:400) 96 6.13 Monsoon Dc at Ch.-1400; closure is not defined with SDDC method at Ch.-1400 97 5.13 5.14 5.15 5.16 5.17 5.18 xvii 6.14 Comparison of SDDC and FDC methods in determining Monsoon Dc 100 6.15 Annual Dc at Ch.3100 101 6.16 Annual Dc at Ch.2700 102 6.17 Annual Dc at Ch.1500 103 6.18 Annual Dc at Ch.1200 104 6.19 Annual Dc at Ch.800 105 6.20 Annual Dc at Ch.400 106 6.21 Annual Dc at Ch.200 107 6.22 Annual Dc at Ch.00 108 6.23 Annual Dc at Ch.-400 109 6.24 Annual Dc at Ch. -900 110 6.25 Annual Dc at Ch.-1400 110 6.26 Radar Graph - Comparison between Dl,1-yr and measured Annual Dc 112 Variation in Dl,1-yr and measured Annual Dc along the study area 112 5-year Dc at Ch.3100 - Comparison of SDDC and mean of FDC between consecutive surveys at Ch.3100 114 6.29 5-year Dc at Ch.2700 115 6.30 5-year Dc at Ch.1500 116 6.31 5-year Dc at Ch.1200 117 6.32 5-year Dc at Ch.800 118 6.33 5-year Dc at Ch.400; three closure points were detected 119 6.34 5-year Dc at Ch.200 120 6.35 5-year Dc at Ch.00 121 6.36 5-year Dc at Ch.-400 122 6.27 6.28 xviii 6.37 5-year Dc at Ch.-900 123 6.38 5-year Dc at Ch.-1400 123 6.39 Comparison of 5-year Dc (effective Dc for beach-fill design), Dco (outermost Dc) and Dl,5-yr 125 Variation in 5-year Dc (effective Dc for beach-fill design), Dco (outermost Dc) and Dl,5-yr across the study area 126 6.41 Dc along Pantai Sabak, Kelantan 129 6.42 Dc based on different closure criteria 132 6.40 xix LIST OF ABBREVIATIONS CED Coastal Engineering Division CEM Coastal Engineering Manual cm centimeter DHI Danish Hydraulic Institute DID Department of Irrigation and Drainage Malaysia DSMM Department of Survey and Mapping Malaysia HAT Highest Astronomical Tide Kg. Kampung; village (malay) LAT Lowest Astronomical Tide LSD Land Survey Datum m meter mm millimeter MSL Mean Sea Level MHW Mean High Water MHHW Mean Higher High Water MLHW Mean Lower High Water MLW Mean Low Water MHLW Mean Higher Low Water MLLW Mean Lower Low Water Sg. Sungai; river (malay) SSMO Synoptic Shipboard Meteorological Observation UKMO United Kingdom Meteorological Office xx LIST OF SYMBOLS Dc depth of closure Dc,1-yr depth of closure over 1 year Dc,5-yr depth of closure over 5 years Dci depth of closure, innershore; from profile survey Dcm depth of closure, middleshore; from profile survey Dco depth of closure, outershore; from profile survey Dl predicted depth of closure; water depth at the seaward limit of significant sediment transport Dl,t predicted depth of closure over t years Dl,1-yr predicted depth of closure over 1 year Dl,5-yr predicted depth of closure over 5 years d water depth di lower limit of the shoal zone dl lower limit of the littoral zone d50 size of material of which 50% is finer g acceleration due to gravity H predicted depth of closure (Birkemeier's equation) hc predicted depth of closure (Hallermeier's equation) Hm0 energy-based wave height of the zeroth moment Hs significant wave height Hs50 median annual significant wave height Hl,t significant wave height exceeded 12 hours over t years H0.137 significant wave height exceeded 12 hours in a year H0.027 significant wave height exceeded 12 hours in t = 5 years He,t non-breaking significant wave height that is exceeded 12 hours per t years or (100/730t) % of the time kN Nikuradse's roughness parameter xxi s standard deviation t time T wave period associated with a particular wave height Te, t wave period corresponding to He,t Tm mean wave period Tp peak wave period Ub maximum horizontal wave-induced near-bed velocity xi measurement xm mean of all measurements n number of measurements σH annual standard deviation of significant wave height Φc sediment entrainment parameter γ’ ratio of the difference in density between sediment and fluid density γ1 wave breaking parameter which controls wave steepness condition γ2 wave breaking parameter which controls limiting water depth condition α adjustable constant in energy dissipation equation xxii LIST OF APPENDICES APPENDIX A TITLE Profile Surveys from the coastline of Pantai Sabak, Kelantan 1998, 1999, 2001 and 2004 B E 159 Summary of Grain Size Distribution from Pantai Sabak, Kelantan Surveys 1998, 1999, 2004 D 142 Description of United Kingdom Meteorological Office (UKMO) Dataset C PAGE 165 Tidal Data From Pantai Sabak, Kelantan; 2004 Survey 168 Model Wave Bathymetry 171 CHAPTER 1 INTRODUCTION 1.1 Introduction Beach nourishment is a preferred coastal protection measure for recreational beaches. The provision of a wider dry beach, by placing sand on the eroding shore that extends beyond the existing beach berm, is the main component of a beach nourishment scheme. A re-nourished beach presents a wider surface area that both dissipates wave energy impacting on the shoreline and creates more space for recreational activities. Sand re-nourished beaches remain as a part of the nearshore coastal system within which sediment can be moved freely by wave and tidal action. Inherent in the engineering design of beach nourishment is an element of prediction and projection based on the shoreline change trend of the concerned beach. Typical beach nourishment schemes may require annual refill as the nourished beach is exposed and continuously subjected to environmental forces. In Malaysia, beach nourishment schemes are expected to last 5 years before renourishment works are initiated again. In this approach, designs are based on a general rate of erosion for the beach and a five-year re-nourishment interval. An important aspect of beach nourishment design is the knowledge of the seaward limit to which the beach-fill is expected to move. This point is called the depth of closure and its determination involves the study of the nearshore profile over a period of time. 2 The beach nourishment projects conducted by the Department of Irrigation and Drainage Malaysia (DID) in the past did not have the benefit of sufficient periodical survey data needed to determine the depths of closure. Hence, the predictive formula of depth of closure introduced by Hallermeier (Hallermeier, 1981) and its simplified forms (US Army Corps Of Engineers, 1984) have been widely used. Since the completion of the beach nourishment projects, periodical monitoring surveys have been conducted on selected re-nourished shorelines. The situation now presents opportunities for further study and analysis of the depths of closure with the view of improving the design of sand-fill in beach nourishment for local conditions. This research determines and studies the depths of closure from periodical surveys of a stretch of shoreline in Kelantan and examines the applicability of existing predictive equations to the Kelantan shoreline. 1.2 Background of the Problem 1.2.1 Erosion Control and Beach Nourishment in Malaysia The National Coastal Erosion Study (Unit Perancang Ekonomi, 1985) determined that approximately 30% of Malaysia’s 4,809 km of coastline was eroding. It proceeded to recommend immediate coastal erosion protection measures on critical sites and led to the development of the Coastal Erosion Control Program under the DID. Under this program, revetment-type protection and beach nourishment schemes were constructed along Malaysia’s eroding coasts beginning in the late eighties. Among the major beach nourishment projects implemented by the Government of Malaysia under this program were: (i) Kuala Terengganu to Kuala Ibai, Terengganu (1993); (ii) Taman Robina, Seberang Perai Utara, Pulau Pinang (1994); 3 (iii) Pantai Kundur, Melaka (1995) (iv) Batu 4, Port Dickson, Negeri Sembilan (1996 and 2005) and; (v) Kg. Teritam to Kuala Sungai Pengkalan Datu, Kelantan (1997) Since the emergence of tourism as a dominant sector of the Malaysian economy, the need to preserve the quality and aesthetics of public beaches have become an important agenda under the Coastal Erosion Control Program. Therefore, the understanding of the evolution of re-nourished beaches must be enhanced so as to improve future planning and design works. 1.2.2 Study Shoreline The northeast coastline of Kelantan has been selected for this study due to its long-term erosion trend. This coastline is oriented along the northwest to southeast direction. Wind fetch lengths spanning over 1500 km across the South China Sea influence this stretch of coast. As a result, the long fetch and the predominant northeasterly winds during the northeast monsoon combine to generate high waves in the adjacent offshore area (Department of Irrigation and Drainage, 1993). Furthermore, there are no large islands off the Kelantan coast to offer any cover from the monsoonal waves. The study is limited to the coastline from Kg. Pantai Dasar to Kg. S.P. Besar, Kelantan which is shown in Figure 1.1. Locally known as Pantai Sabak, this coastline has experienced erosion at an average rate of exceeding 5 meters per year (Unit Perancang Ekonomi, 1985). The situation was later exacerbated by the construction of a breakwater at Sungai Pengkalan Datu which was completed in 1986 as part of a flood mitigation and agricultural drainage project. The breakwaters created a terminus to the littoral transport in the area and depleted the supply of 4 sediment to the adjacent shoreline of Pantai Sabak to the northwest. An erosion of 20 meters occurred within 7 months of the completion of the northern arm of the breakwaters and the completion of the southern arm 10 months after brought about an additional 60 meters of erosion in the following year (Lee, 1990). Studies by Universiti Teknologi Malaysia indicated that minor sediment bypassing of the Pengkalan Datu breakwaters in the northwest direction had begun within a few years of its completion (Ahmad Khairi Bin Abdul Wahab, 1989). Nevertheless, this was insufficient to reduce the erosion rate at Pantai Sabak. In 1996, the DID implemented a beach nourishment project which laid 1.2 million m3 of sand along a 2.1 km stretch within the study area. The constructed beach berms ranged from 70 m to 120 m. Whilst the study and design of the beach nourishment scheme took into account the reduction in sediment budget due to the breakwater, nearly 60% of the nourished volume was lost within a single monsoon (Jabatan Pengairan dan Saliran Malaysia, 2002). KELANTAN Study Area Study area Kelantan, MALAYSIA Figure 1.1: Study area - 4.5 km of shoreline from Pantai Dasar Sabak to South of Kg. K.S.P. Besar (Sungai Pengkalan Datu). (Source: Topo Maps #4068 [1985], #3968 [1991], Jabatan Ukur dan Pemetaan Malaysia) 5 1.2.3 Beach Nourishment Design and Depths of Closure The design of a beach nourishment scheme requires the same engineering parameters as other coastal protection solutions. Apart from the established wave, wind and tidal conditions, the design criteria for a typical DID beach nourishment includes: • a nourished beach slope as close as possible to the existing beach slope; • available funds to provide the widest beach berm possible based on a pre-determined re-nourishment interval of 5 years; • the availability of suitable sand-fill of grain size d50 greater than the native beach. From the Shore Protection Manual (US Army Corps Of Engineers, 1984), the design approach can be summarised as follows: (i) determination of the beach berm elevation and width (ii) determination of nourishment volume based on native and borrow composite material characteristics (iii) determination of post-project beach evolution. In practice, a pre-erosion shoreline is determined and the berm width is ‘overbuilt’ beyond the pre-erosion shoreline position based on local erosion rates and the expected interval of re-nourishment. Hence, if the local erosion rate is 5 meters per year and a re-nourishment is planned after every five years, the berm width will be built 25 meters beyond the desired shoreline. Artificial beach fills are created based on a construction cross-section. Over time and due to the action of waves and tides, the fill material forming the nourished profile of a constructed beach will be shaped by natural processes into a profile of generally concave upward shape called an equilibrium profile. This equilibrium profile concept was proposed by Bruun (1954) with further elaboration by Dean (1977) and is illustrated in Figure 1.2. In the application of this concept, it is assumed that there is a conservation of sediment 6 Evolved equilibrium profile Original nourished profile Original ground level Dc = depth of closure Figure 1.2: Evolution of beach-fill based on Theory of Equilibrium Profile volume across the profile and that a loss of sand volume from the upper profile of the beach is associated with a similar gain in volume in the lower profile. The seaward limit for the volume exchange process is the depth of closure. The depth of closure is effectively, the offshore limit of the active zone within which a nourished beach adjusts to equilibrium under the prevailing coastal conditions. Hence, a good estimate of the depth of closure is essential to a good estimate of the beach fill volume required. With respect to post-nourishment beach profiles, National Research Council (1995) refers to the depth of closure as a reference typically used by designers to estimate the limit of profile widening. These statements further confirm the importance of the depth of closure in beach nourishment design. Beach nourishment schemes have been built in Malaysia since 1992 but their evolution has not been extensively studied. Due to the lack or absence of periodical surveys then, the depth of closure has typically been predicted from empirical equations. With regards to this, a comparative study of the predictive and measured 7 depths of closure, in the writer’s opinion, would contribute to the understanding of the performance of beach nourishment schemes. In the Malaysian context, such detailed comparisons have, to date, yet to be done and this dearth of knowledge is the impetus to this research. 1.3 Objectives of the Study The purpose of this research is to determine the depths of closure of a 4.5 km stretch of sandy coast extending from north of Pantai Dasar Sabak to south of the Sungai Pengkalan Datu in the state of Kelantan. The study will analyse beach profile surveys, determine the depths of closure and to compare them against predicted values calculated from the Hallermeier equation. The research will examine the validity of this widely accepted equation for the Malaysian condition. 1.4 Benefits of the Study In general, the study is expected to contribute towards an improved understanding of cross-shore sediment transport and shore profile changes in the Malaysian coastal environment. Knowledge of profile trends and depths of closure will facilitate the design of coastal protection works primarily beach nourishment, revetments, groynes and breakwaters. It is envisaged that from the results of this research, engineers will be able to utilise a modified analytical method, specific to the local conditions, to predict depths of closure with greater confidence for areas where historical shore profile data is lacking. 8 CHAPTER 2 LITERATURE REVIEW 2.1 Introduction Coastlines change in response to the coastal processes that prevail. Coastal profiles develop due to the cross-shore sediment transport while the planform shapes are a result of longshore sediment transport. Sediment transport studies are an essential component of coastal protection works whereby its understanding contributes towards selection of the defence strategy and ultimately engineering design. The contribution of sediments from sources and their transportation and distribution alongshore is important in determining the length of shore-normal structures. Likewise, cross-shore transport is equally important particularly its seaward limit beyond which there is no significant sediment transport. This limit is often defined as the depth of closure whose concept, methods of determination, prediction and application will be the subject of this review. 2.2 Cross-shore Sediment Transport and Equilibrium Beach Profiles The depth of closure has its beginnings in the studies of cross-shore sediment transport. Cross-shore transport, the studies of which are relatively recent compared to longshore transport, involves both onshore and offshore transport which are associated with different modes and contrasting timescales (US Army Corps Of Engineers, 2003). The onshore sediment transport is related to mild wave conditions 9 while offshore sediment transport is due to wave activity during storms. Offshore sediment transport is of the greater concern to engineers due to its potential threat in the form of erosion of beach material and undermining the foundations of coastal structures. In applying the equilibrium beach profile concept to predict coastal profile change, most engineering methods assume that the volume of sand is conserved within the active profile i.e. erosion in the upper part of the profile is compensated by a corresponding deposition in the surf zone. In beach nourishment design, Dean (2003) described that nourished profiles are typically designed to be steeper than the equilibrium profile and they will then equilibrate to the closure depth. Although longshore transport plays a role in beach morphology, where significant longshore component exists, the movement of the profile is considered uniform across the elevation. The depth of closure is based on the observation that repeated nearshore profiles tend to show a reduction in vertical variability as depth increases (Nicholls et al, 1996). It is also a parameter which separates two distinct zones within the crossshore area with different levels of morphodynamic activity (Nicholls et al, 1998b). 2.3 Definition of Depth of Closure The concept of the depth of closure is credited to Hallermeier (1981) and his work in the zonation of coastal profiles. Hallermeier proposed that the coastal profile could be divided into offshore, shoal and littoral zone as shown in Figure 2.1. 10 Mean sea level dl di Variation in beach profile Mean sand level littoral zone offshore zone Figure 2.1: shoal zone Zonation of seasonal beach profile (Hallermeier 1978, 1981); extracted from Rijkswaterstaat (1987) In proposing a zonation for seasonal beach profiles, Hallermeier (1978, 1981; reviewed by Rijkswaterstaat, 1987) divides the beach into offshore, shoal and littoral zones. Hallermeier defined the shallower of the two depths, dl as the lower limit of the littoral zone while the depth di as the lower limit of the shoal zone. The littoral zone was defined by Hallermeier as a zone where there is significant alongshore transport and intensive onshore-offshore transport over a typical year. The shoal zone is one that is still subject to onshore-offshore sediment transport up to depth di while the offshore zone is where surface wave-effect on the bed is negligible. To facilitate volume calculations in beach-fill design, it is important to estimate a seaward limit or depth where the nourished profile is expected to develop. Yet, from Figure 2.1, it can be seen that the actual location to set a dimension for calculation depends on where one defines the limit of significant movement of sediment. Nicholls et al (1996) describes the depth of closure as a “fundamental morphodynamic boundary separating a landward active zone from a seaward less active zone over the period defined by the profile observations used to define closure” and emphasizes that the time scale of data is significant to the determination of the position of the depth of closure. Dean (2003) considers the shallower limit Dl as the more appropriate depth for beach nourishment design. 11 In the Manual on Artificial Beach Nourishment, the Rijkswaterstaat (1987) recommends that one assumes the active profile will develop seawards to the depth dl due to the action of waves despite the fact that onshore-offshore transport still occurs below this depth. Knudsen et al (2002) studied the coastal profiles in the Danish North Sea and proved that considerable erosion occurs outside the depth of closure. The thrust of this research however, requires the acceptance of a definition that serves the engineering purpose of determining the depth of closure. Kraus et al (1998) in the “Coastal Engineering Technical Note II-40 – Depth of Closure for Beach-fill Design” considered the various descriptions for this seaward limit and concluded that in order to apply to beach-fill design, the depth of closure should be defined as: “the most landward depth seaward of which there is no significant change in bottom elevation and no significant net sediment transport between the nearshore and the offshore” This definition is practical from an engineering viewpoint since it implies that bottom elevation and sediment transport can be measured. The adjective ‘significant’ is crucial to this definition as it alludes to the fact that this is not a terminal point in onshore-offshore sediment transport but merely one of reference. According to Kraus et al (1998), the definition as described above is intended for the design of fill or borrow material (also called beach-fill) in beach nourishment projects and is purported to be applicable to the open coast where the dominant mechanisms of sediment transport are nearshore waves and wave-induced currents. 12 2.4 Methods of Determination 2.4.1 Predictive Methods The only analytical method of estimating the depth of closure is one put forward by Hallermeier (1981). Hallermeier proposed that the annual depth of closure could be calculated as follows: Depth of closure hc = 2.28 H0.137 – 68.5 (H0.1372/gT2) (2.1) where, H0.137 = significant wave height exceeded 12 hours in a year T = wave period corresponding to H0.137 g = acceleration due to gravity Hallermeier predicted the depth of closure by associating it with the critical value of a sediment entrainment parameter, Φc, which is in the form of a Froude number. The threshold of sandbed agitation by wave action (Nicholls et al, 1996; Kraus et al, 1998) is given as follows, Φc = Ub2/(γ’gd) = 0.03 (2.2) where, Ub = maximum horizontal wave-induced near-bed velocity D = water depth G = acceleration due to gravity γ’ = ratio of the difference in density between sediment and fluid density In developing this predictive equation, Hallermeier used γ’= 1.6 for quartz sand in seawater and applied the linear wave theory. Validating against field 13 laboratory tests, Hallermeier found that it was insensitive to grain sizes of median diameter 0.16 mm to 0.42 mm which are typical of the nearshore area of sandy beaches (Kraus et al, 1998). Equation (2.1) is therefore valid only for grain sizes not greater than 0.42 mm. Depth of closure from Equation (2.1) is referenced to MLW to produce a conservative result acknowledging that tidal and wind-induced currents are capable of increasing near-bed flow velocities (Nicholls et al, 1998a). Hallermeier compared Equation (2.1) against annual predictions produced from survey data collected at the Gold Coast (Australia) and Avondale (Florida) and Torrey Pines (California) using a depth change criterion of 30 cm and found that the predicted values agree to within 10% of the observed values (Nicholls et al, 1998a). Birkemeier (1985) evaluated Equation (2.1) using the first two years of survey data obtained at Duck, North Carolina and found that it over-predicted the observed Dc by 25%. Specific to data from Duck, Birkemeier produced adjustments to the coefficients in Equation (2.1) and modified it as follows: hc = 1.75 Hs – 57.9 (H0.1372/gT2) (2.3) Equation (2.3), produced smaller (shallower) depths of closure than Equation (2.1) and demonstrated that Equation (2.1) can be refined for a specific stretch of coast if extensive survey data is available. Discussing Hallermeier’s earlier work, Nicholls et al (1996) reviewed and presented Equation (2.1) in a time dependent form:– Dl,t = 2.28 He,t – 68.5 (He,t2 / gTe,t2) (2.4) where, Dl,t = is the depth of closure predicted over t years referenced to MLW; He,t = non-breaking significant wave height that is exceeded 12 hours per t years or (100/730t) % of the time; Te,t = wave period corresponding to He,t ; g = acceleration due to gravity 14 Nicholls et al (1996) studied 12 years of repetitive beach profile data from Duck, North Carolina and validated Equation (2.4). This dataset comprised of surveys extending to depths of about 8 meters and wave observations at depths of up to 18 meters. These surveys were conducted every two weeks and also after storms. The Dl,t calculated with Equation (2.4) was tested against two scenarios:– i. event-dependent depth of closure whereby the beach profile change has occurred over a single event such as a major storm and; ii. time dependent depth of closure whereby the beach profile change has occurred due to an integrated response towards a range of driving conditions such as erosional and accretional waves and currents. Results from the two scenarios differed: time-dependent or time-interval depth of closure was, in general, found to be deeper than the largest event-dependent depth of closure for the same time-period of analysis. Time-interval depth of closure as predicted by Equation (2.4) also appeared to fail under accreting conditions as it predicted depth of closure values that were smaller than actually observed. Nicholls et al (1996) concluded that the application of Equation (2.4) requires an explicit consideration of time scales. The first term of Equations (2.1), (2.3) and (2.4) relate to the wave height while the second term provides an adjustment for wave steepness (Kraus et al, 1998). Hence, the selection of wave height is crucial to the prediction of the depth of closure. Hallermeier’s initial recommendations were to use the significant wave height exceeded 12 hours in a year which suggests extreme wave conditions. For time interval hc, or Dl,t the significant wave height exceeded 12 hours over the time interval is used. In any case, the offshore or deepwater wave should not be used as it will result in very conservative depth of closure values (Kraus et al, 1998). Kraus et al (1998) also recommends that a representative depth of closure should be based on wave conditions averaged over a period of years and states that the depth of closure can vary considerably with storm activity and wave conditions from year to year. Hence, Dl,t considers both erosional and accretional processes 15 that may happen over the period of wave data obtained. On the validity of Equation (2.1), Nicholls et al (1996, 1998b) notes that Equation (2.1) is invalid for rapidly accreting areas. Other derivations have been produced which simplify Hallermeier’s equation to the form: H = 1.57 Hs 0.137 (Birkemeier, 1985; cited in US Army Corps of Engineers[2003]) (2.5) where, H = Hs 0.137 = predicted depth of closure; extreme nearshore wave height exceeded 12 hours in a year Hallermeier also proposed a form of Equation (2.1) that did not include the associated wave period (US Army Corps of Engineers, 2003): hc = 2H + 11 σH (2.6) where, H = annual mean significant wave height; σH = standard deviation of wave height 2.4.2 Depth of Closure from Profile Surveys Numerous letters or symbols have been used to represent depth of closure in the literature. To avoid confusion, depth of closure in this study will be referred to as Dc. The most accurate method of determining the depth of closure is from studying profile surveys. Observed depth of closure can be empirically derived from the 16 observation of a series of profile surveys taken over a period of time. Dc corresponds to a pinch-out depth below which depth changes become small (Nicholls et al, 1996). The criterion for ‘small’ is usually equivalent to the accuracy of the survey measurements. The accuracy of field surveys invariably influences the analysis of profiles to determine the Dc. Topographical survey and hydrographic survey are the most common means of obtaining profile data. In conventional hydrographic survey using echo-sounders and where corrective algorithms have been applied to account for heave and other boat movements, the accepted accuracy is typically 30 cm. Detailed profile studies at Duck (Nicholls et al, 1998a; Kraus et al, 1998) used the Coastal Research Amphibious Buggy (CRAB) which has a survey accuracy standard deviation of up to ±2.5 cm. Another method recommended by Kraus et al (1998) for beach-fill projects is the sea-sled method which has an accuracy of 2.54 cm (1 inch). 2.4.3 Depth Change Criterion There are two widely used criteria in determining the depth of closure from profile measurements. The standard deviation of depth change (SDDC) method involves plotting the SDDC against distance seaward of the profile origin for each measured profile. The Dc is thus the point where the SDDC reduces to a constant, non-zero value. The SDDC method is useful in the sense that it avoids bias from outliers (Hinton and Nichols, 1998). The ‘standard deviation in depth’ method has been described by Kraus et al (1998) as one of the ways to estimate Dc from profile surveys. The limit of significant profile change is at the point where there is a sharp decrease of the standard deviation of depth to a small value. Statistically, the standard deviation of a set of measurements “is equal to the positive square root of the variance”. formula for variance is, The 17 s 2 = Σ ( xi – x m ) 2 (2.7) n–1 where, xi measurement xm mean of all measurements n number of measurements Therefore, the standard deviation is simply s. By this definition, and using the elevation of the bed at the same position over a period of surveys as the population, the standard deviation of significant depth change at any point can be determined. The second method is the fixed depth change (FDC) method (Nicholls et al, 1996) where the FDC is the absolute difference between the elevations of two consecutive surveys from the same profile line. The Dc is the depth where the variation in depth between the two profiles is equal or less than a pre-selected criterion usually associated with the accuracy of the profile survey. Hence, if a survey method has an accuracy of 30 cm, any absolute change exceeding 30 cm would be considered significant. Over a collection of surveys, the limit where significant change in depth can be estimated is the point where the mean of absolute change in depth does not exceed 30 cm. The average absolute change in depth is similar to SDDC but is more descriptive in deeper water (Larsen and Kraus, 1994). When testing Equation (2.1) against data from the Gold Coast, Florida and California, Hallermeier used a depth change criterion of 0.3 m which was the operational accuracy of the data (Nicholls et al, 1998b). Using profile data from Duck, North Carolina, Nicholls et al (1996) examined the variability of Dc using a fixed depth change (FDC) criteria of 6 cm, 10 cm and 15 cm as well as the standard deviation of depth change (SDDC) criteria. Different definitions of Dc were found to yield different depth estimates. Nevertheless, the SDDC method defined most of the annual Dc. 18 Hinton and Nicholls (1998) in their analysis of depth of closure for the Holland coast also used both methods which produced similar results. From their analysis, they found that the phenomena of profile closing, opening and re-closing occurs along the Dutch coast and were best depicted by the SDDC method. Hinton and Nicholls also used an FDC criteria of 0.25 m and 0.5 m and found that since FDC captures the largest depth variation it generally gave the more landward value of closure. The same study also found that profile re-opening is observed only over time-scales exceeding 10 years and at offshore distances of 1.5 km around the 12 m contour. 2.5 Application of Depth of Closure The depth of closure plays an important role in the determination of coastal sediment budgets and the design of erosion control solutions such as beach nourishment and offshore breakwaters. Considering the lifespan of such erosion control solutions, it is necessary for depth of closure determinations to be explicitly defined with a spatial and temporal scale. It has been stressed that the depth of closure is not an absolute cross-shore sediment transport boundary and that it is a morphological boundary that is highly dependent on the criteria of depth change and the period of profile observation (Nicholls et al, 1996; Nicholls et al, 1998a and 1998b). As described earlier, Equation (2.1) has been proven to be a robust definition of the seaward limit of significant cross-shore sediment transport for erosion or storm events up to the annual time-scale (Nicholls et al, 1996). Hinton and Nicholls (1998) studied closure depth behaviour based on the Large Scale Coastal Evolution Concept which distinguishes time scales as follows: Large scale: morphodynamic length scale of 10 km and time scale of decades; 19 Medium scale: morphodynamic length scale of 1 km and time scale of years; Small scale: morphodynamic length scale of 100 m and time scale of storms or seasons The large-scale analysis of data off the Dutch coast revealed that profile closure occurs on the shoreward side at depths of 5 m to 8 m and distance of 1 km from shore. Analysing 25 years of survey data, the profile closure then re-opens at middle/lower shore face locations at distances further than 1.5 km offshore. This phenomena is still being studied with possible influences being offshore sand bar formations as well as anthropogenic structures (Hinton and Nicholls, 1998). On the longshore variations of Dc using local wave climate, Francois et al (2004) reviewed Hallermeier’s equation and found that it “fails to reproduce” the longshore variations since a fixed offshore wave height is used. Francois et al (2004) focused on the use of local waves in the analysis which is a feature incorporated in this research. 2.6 Depth of Closure – Malaysian Context In 1986, the Kelantan coastline from Kuala Besar to Kuala Sungai Pengkalan Datu was the subject of a feasibility study for design of erosion control measures as part of the National Coastal Erosion Study (Unit Perancang Ekonomi, 1986). Under this study, an analysis of shore normal profiles was conducted based on a 1985 survey and revealed that the base of the shoreface becomes constant at a depth of 4.5 m. Referring to Hallermeier and for the case of quartz sand in seawater, the seaward limit, referred to as Dl, was also calculated using the following equation: Dl = 2Hs50 + 12σH where, (2.8) 20 Dl water depth at the seaward limit of significant sediment transport; Hs50 median annual significant wave height; σH annual standard deviation of significant wave height The report states that the Dl is roughly twice the extreme nearshore wave heights exceeded 12 hours per year which concurred with the existing data on observed seaward limits of sand transport. Using records from shipboard wave observations for the area known as Pantai Cinta Berahi (now Pantai Cahaya Bulan), the Hs50 and σH were both found to be 0.6 m which when substituted into Equation (2.8) produced a calculated Dl of 8.4 m. Nevertheless, due to the different results between calculated and measured Dl, the calculated value was dropped and the measured value of 4.5 m was chosen as the limit of significant sediment transport for the Kelantan coastline. Subsequently, it was recommended that sand extraction be prohibited from the region of the shoreface lesser than this depth. The report however, did not elaborate on the vertical datum reference for the depth. It also conceded that the σH which was calculated from the Synoptic Shipboard Meteorological Observation (SSMO) - the main source of offshore wave data available at the time - was the probable source of error which lead to the differences in Dl results. A key problem in local studies is the lack of long term, periodic survey data and concurrent measured wave data. On the other hand, it is noted that the defining works by Hallermeier (1981) and Birkemeier (1985) and later by Nichols et al (1996, 1998a and 1998b) reviewed above appear to have the benefit of detailed, medium to long-term survey data. Some of the profile surveys were obtained at fortnightly intervals and post-storm conditions complete with corresponding wave measurements. Nonetheless, with the availability of four profile survey datasets obtained in 1998, 1999, 2000 and 2004 on the Kelantan coastline, an independent research on the depth of closure for a Malaysian coast can now be conducted. 21 2.7 Summary This literature review has focused on the more recent work done on cross- shore sediment transport evident in the last decade with only one reference on the study of seaward limits of significant sediment transport done in 1986 for the Kelantan coastline. The work of Hallermeier and Birkemeier continue to be referred to in subsequent studies as more profile information is gathered by other researchers. In all cases, the Hallermeier equation is accepted as the equation that determines the seaward or upper limit of depth of closure. Of particular importance to this study are the findings of Hinton and Nicholls (1998) and Nicholls et al (1998a and 1998b). The former proved that the long-term behaviour of depths of closure could be achieved with large-scale analysis using profile survey that extends both in crossshore and longshore directions. Nicholls et al (1998b) critically examined the predictive capability of the Hallermeier equation comparing it against the measured depth of closure determined with several closure criterions. Several authors have mentioned the importance of the use of local wave conditions in the Hallermeier equation and Francois et al (2004) have focused on this in their work in studying the alongshore variations in Dc. Francois et al (2004) reports on the use of numerical modelling to predict the nearshore wave conditions which would be the more appropriate wave height for calculating Dc. The general conclusions of depth of closure studies are that Dc increases as more profile data is accumulated. Based on comparisons with measured profiles, the Hallermeier equation was found to be robust; it tends to over-predict the Dc and determines the upper boundary to the nearshore cross-shore morphological process. An important finding presented by Nicholls et al (1998b) was that Hallermeier’s equation is more accurate when predicting the Dc for an erosional event compared to an accretional one. This review also revealed that an initial study of the depth of closure has been conducted in 1985 along the Kelantan coastline from Kuala Besar to Kuala Sungai Pengkalan Datu albeit when the study of seaward limits of cross-shore transport was relatively in its infancy. The results however indicated that the calculated depth of closure was not consistent with measured profile data. Hence, the research work 22 proposed here is obviously relevant. A detailed investigation of depth of closure for the Kelantan coast, in the author’s opinion, would be of benefit to the local coastal engineering community. CHAPTER 3 RESEARCH METHODOLOGY 3.1 Introduction The pioneering studies on the depth of closure analysed the long-term profile measurement data obtained at the Field Research Facility operated by the Coastal Engineering Research Center (CERC) of the US Army Engineer Waterways Experiment Station at Duck, North Carolina (Birkemeier 1985, Nichols et al 1998a, Hinton and Nichols 1998). This research follows closely the approach and analysis used in those earlier works where there was a reliance on shore profile data extending to depths up to -8 meters. It is acknowledged however that the equipment used to obtain the profile measurements at Duck is more accurate than the conventional method of hydrographic survey. Nonetheless, the data used in this research would be from the conventional hydrographic survey method which is still widely accepted for engineering purposes. The methodology used in determining the depths of closure and investigating the analytical methods in determination of depth of closure is presented below. 24 3.2 Scope of the Research The depth of closure is a statistical concept hence its determination requires a rigorous treatment of survey data where reliability depends on the volume and extent of the series of surveys available. This research is founded on the analysis of a series of beach profile survey data made available to the author by the Coastal Engineering Division (CED) of the Department of Irrigation and Drainage Malaysia (DID). The main objective of this research is (i) to determine the depth of closure from a series of profile surveys for a certain stretch of Malaysian coastline and (ii) investigate the applicability of the Hallermeier equation in predicting the depth of closure based on local wave conditions. The data for the study was from the surveys obtained on the northeastern coastline of Kelantan where a shore monitoring programme was initiated by the DID following a trend of steady shoreline retreat since 1997. The research evolved along the following sequence of tasks: (i) Secondary Data Collection – a. Compilation of beach profile data of the study area; b. Compilation of meteorological and oceanographic (met-ocean) data including wind, wave, tides and bed sediment data; (ii) Primary Data Collection – Supplementation of survey and met-ocean data by hydrographic survey and sediment sampling off the northeast Kelantan coastline; (iii) Determination of the seaward limits of significant changes in bed elevation which corresponds to the depth of closure; a. Study and selection of criteria for determination of Dc b. Compiling, plotting and comparing survey data series; 25 (iv) Determination of depths of closure using analytical methods/predictive equations: a. Analysis of wave data to determine input data into numerical modelling; b. Conduct wave modelling using numerical modelling software to determine the nearshore wave heights and periods based on the offshore wave input parameters; c. Determination of Dc based on predictive equation introduced by Hallermeier (1981) using results from (iv) b; (v) Synthesizing of results and establishment of trends in beach profile and closure depths and introduction of site-specific adjustments to the Hallermeier equation; A model for the research is illustrated in Figure 3.1. 26 Beach Profile Water Levels Sediments Analysis of Profile Surveys Waves Bathymetry Numerical Modeling Predictive/ Analytical Equation Depths of Closure Modification to Predictive Equation Figure 3.3: Research model for the of depths of closure Figure 3.1:determination Research Model 27 3.3 Research Methodology 3.3.1 Data Sets 3.3.1.1 Beach Profile Survey For the purpose of this research, beach profile surveys were reduced to a single, common horizontal and vertical datum and this exercise would be critical to the accuracy of depths of closure estimates. Prior to analysis, cross-shore profiles that best represent the study shoreline were determined, selected and subjected to a quality check. 3.3.1.2 Wind and Wave The UK Meteorological Office has made available to public its offshore wave datasets that is generated by a global hindcast model. The data set also includes atmospheric wind data. Another source for local wind data is available with the Meteorological Services Department where the nearest recording station to the study site is at Pengkalan Chepa Airport, Kota Bharu, Kelantan. 3.3.1.3 Tidal Heights Tidal information is necessary to determine the local wave regime. Predicted tidal heights are obtainable from the Royal Malaysian Navy Tide Tables and the Malaysian Survey and Mapping Department Tide Tables. The nearest Standard Port to the study area is at Geting near the mouth of Sungai Golok (Malaysia-Thailand 28 border). Tidal data can also be derived from tidal measurements and can be used to determine the tidal heights in the study area. 3.3.1.4 Sediment The definition of depth of closure involves a study of sediment transport in the nearshore zone. Significant changes in sediment type, grain size or colour at a particular nearshore location over time infers that the depth of closure is further seaward. Sediment grain size affects its fall velocity and is also an indicator of its transportability. Hence, sediment data from borehole or grab (bed) sample records is essential to the research and data for the study coastline will be sourced from field surveys conducted or commissioned by the DID since 1998. Specifically, the required parameter is the mean particle size which can be determined through sieve and hydrometer analysis. 3.3.2 Primary Data Collection Additional data collection was conducted to complete the survey and beach profile datasets in 2004. This included nearshore bed sediment sampling and tidal measurements that were used to run the numerical model. New datasets were therefore obtained for profile survey, tidal heights and nearshore waves. 29 3.3.3 Numerical Modelling 3.3.3.1 Software and its Application Mike21-NSW is a nearshore spectral wind-wave wave model developed by the Danish Hydraulic Institute (DHI) which was used to model the propagation of offshore wave heights into the nearshore areas. The model is able to handle the following phenomena: • Shoaling and refraction • Wave breaking; based on expressions by Battjes and Janssen (1978) • Wave-current interaction • Bottom friction; using a formulation based on the quadratic friction law to represent bottom shear stress wave • Local wave generation or wind-forcing • Directional spreading Mike21-NSW does not include diffraction, reflection and non-linear effects such as wave-wave interaction. The model calculates the dependent variables using the Explicit Euler method over a rectangular grid for a number of discrete directions. The model was utilised to determine the nearshore wave climate along the study shoreline. The input into the model included a digitised bathymetry of the South China Sea extending into deep waters, offshore wave heights and their corresponding wave periods and directions. 30 3.3.3.2 Event and Scenarios for Modelling An important element in the numerical modelling would be the selection of the input data for the wave refraction model. In terms of modelling wave conditions, boundary data will comprise parameters of the offshore wave condition corresponding to an extreme event. As recommended by Hallermeier (1981), where depths of closure is calculated for a one-year interval, this would correspond to a wave height exceeded 12 consecutive hours of that year which is equivalent to 0.137%. This requires a statistical analysis of the offshore wave data. Since the study area is wave dominant, only a wave refraction model is proposed. The Mike21-NSW wave model will be utilised and the model will be run using Mean Higher High Water as the water level in the model. This would provide the setting for the furthest possible wave penetration into the nearshore area and the largest incident waves to occur in the model nearshore area. Nearshore wave heights will be extracted from the model nearshore area at the location of the 10 m ACD depth-contour. At 10 m depth, the waves are still considered unbroken as it is still beyond the offshore bar formations. The local wave values will be substituted into the analytical equations to predict the depth of closure. 3.3.4 Analysis 3.3.4.1 Depths of Closure from Beach Profile Data The study shoreline has been nourished in 1996 which created a new and unnatural post-construction shoreline. A series of monitoring surveys was conducted in 1998, 1999 and 2000 and will therefore be the primary dataset. The analysis of survey data involves making certain that the various datasets represent the same cross-shore profile locations with horizontal and vertical errors within tolerable limits. This quality check is also necessary to remove outliers or suspect readings. 31 A graphical analysis of beach profiles will be conducted to determine profile characteristics, envelope of changes and trends of bar migrations. Standard spreadsheet software will be used to tabulate profile measurement data and to calculate variations in the depths leading to the determination of the seaward limit of significant change in elevation. Both the standard deviation of depth change and fixed depth change criteria shall be explored. Following this, an algorithm will be established to facilitate the determination of closure points and the eventual Dc. Based on the available dataset, two scenarios for investigation of Dc analysis will be conducted on a pre and post monsoon as well as a time-dependent scenario. The pre and post monsoon datasets are expected to reveal the effect of an erosional event i.e. the northeast monsoon, on depths of closure. In the time dependent scenario, the Dc value represents an integrated effect of the various environmental forcings on the nearshore of the study profiles over the time span of the data. 3.3.4.2 Depth of Closure from Empirical Formulae The Hallermeier equation was used to calculate the depth of closure. Variables used as input were the transformed offshore waves in the nearshore area close to the seaward end of the profile dataset and their associated wave periods. These parameters were extracted from numerical modelling results. 3.4 Summary The research derives the depth of closure for the coastline of Kelantan. Its findings is expected to contribute towards a better understanding of beach profile changes in the area and its implications on the design of shoreline protection works. The seaward limit of profile change or the depth of closure has been defined by Kraus et al (1998) as (i) a depth seaward of which no significant change in bed 32 elevation occurs over time and (ii) a depth seaward of which no significant net sediment transport occurs. The research involved the analysis of surveys, beach profile and sediment data over the study shoreline to determine the depth of closure. This was compared with depth of closure values calculated using the Hallermeier equation. The research was later directed at producing local adjustments to the predictive equation and establishing a definitive depth of closure for the north-eastern shoreline of Kelantan encompassing the rapidly eroding stretch from Pantai Dasar Sabak to Kuala Sg. Pengkalan Datu. CHAPTER 4 FIELD DATA ANALYSIS 4.1 Introduction The data compiled and collected for this study on the depths of closure is designed to fulfill two main objectives (i) to enable the study of variations in bed elevation and (ii) the establishment of the nearshore wave conditions that feed into the mathematical equations that will be used to calculate Dc. The required data thus comprises hydrographic survey, meteorological and ocean wave data and sediment properties. This research is based on four profile survey exercises conducted in the study area in the state of Kelantan in 1998, 1999, 2000 and 2004 (Jabatan Pengairan dan Saliran Malaysia, 1999a, 1999b, 2000 and 2004). All surveys were conducted by licensed surveyors and hydrographers appointed by the Coastal Engineering Division, Department of Irrigation and Drainage Malaysia. The purpose of the first three surveys was essentially to capture the changes of the nearshore profile over the northeast monsoon when erosion is expected to occur. The fourth survey was obtained to facilitate detailed design of coastal protection works. This chapter describes the study area followed by each dataset as to their form, extent, accuracy and limitations in relation to the determination of the depths of closure. This is followed by an explanation of the processes conducted to produce both the measured depth of closure and the calculated depth of closure. 34 4.2 Study Area The study area lies in the state of Kelantan which is located in the northeast of Peninsular Malaysia and south of the Thailand-Malaysia border. The study area is the coastline of Kg. Pantai Dasar Sabak to Kg. Senok and encompasses a once famous public beach known as Pantai Sabak. The shoreline is part of Kelantan’s dynamic northeast coast which is generally sandy and void of headlands, rock outcrops and offshore islands. This coastal region has developed from the alluvial deposits originating from Sungai Kelantan to the northwest. Figures 4.1 and 4.2 show the general and specific location of the study area. Study Area Figure 4.1: Location of study area The bathymetry in the nearshore of the study area is generally parallel to the coastline. The shore profile gradient is gentle and comprises of single or multiple alongshore bars. The general direction of the littoral drift here is in the northwest direction (from the Pengkalan Datu rivermouth towards Kuala Besar). N 35 Kuala Besar Sungai Pengkalan Datu rivermouth breakwaters Pantai Dasar Sabak (CH2700 to 3100) KELANTAN Figure 4.2: 4.3 Kg. Kemerok (CH1900) Kg. S.P. Besar, Kg. Senok (CH-400 to 1400) Kg. Tanjung Kuala (CH400 to 00) Close-up of Study Area from Kg. Pantai Dasar Sabak to Kg. Senok Environmental and Climatic Conditions The northeast monsoon produces the strongest winds in this area with speeds as high as 35 m/s. Nonetheless, these winds are gusty and with low duration. The southwest monsoon produces milder wind conditions with maximum speeds of 14 m/s. The tide along the study coastline is diurnal with a maximum range of 1.77 m based on the tidal heights at Geting from the tide tables (Royal Malaysian Navy, 2005). Fetch lengths affecting this coastline extend up to 1480 km into the South China Sea and 660 km into the Gulf of Siam. Based on these fetch lengths, offshore wave heights established through wave hindcasting in the National Coastal Erosion Study (Unit Perancang Ekonomi, 1985) range from 3.6 m to 5.3 m. 36 4.4 Data Sets The data available for the study comprises the following: • profile survey data • bathymetric data • wave data • tidal data • bed sediment (from grab samples) The profile survey data was used to establish the depth of closure by analysing the variation in elevation change. The wave, tidal, sediment and bathymetric data was used as input into a numerical model to establish the local wave heights and periods that were subsequently used in the depth of closure equations. 4.5 Beach Profile Survey Three sets of beach profile survey data taken in 1998, 1999 and 2000 were initially chosen for this study. An additional set from the “Detailed Design for Coastal Protection of Pantai Sabak” in 2004 completes the survey data required for the analysis. These surveys were undertaken using the conventional survey technique: profile measurements were taken using a combination of land-based topographical survey and hydrographic survey techniques. Measurements up to MLW were taken using total stations and staff-mounted prisms. Beyond MLW, depth measurements were taken using boat-mounted, dual frequency echo sounders. Echo-sounders were calibrated prior to and after each survey session. The accepted accuracy of plotted surveys using this technique is 30 cm. A common problem with this conventional survey method however is at and just beyond MLW where the water is often too deep for land survey methods but still too shallow for survey boats. 37 At this location, due to turbulence caused by breaking waves, excessive vessel movements make it difficult to survey accurately. The dates of the surveys are listed below: i. Survey #1: 3rd October to 14th October 1998 ii. Survey #2: 4th May to 27th May, 1999 iii. Survey #3: 20th May to 31st May 2000 iv. Survey #4: 1st June to 30th July 2004 4.5.1 Survey #1 - 1998 The first of three monitoring surveys was conducted at Pantai Sabak from 3rd to 14th October 1998 and established the control points and baseline for subsequent surveys in 1999 and 2000. This survey was completed prior to the onset of the northeast monsoon that typically produces the highest waves on the east coast of Peninsular Malaysia. The survey straddled the Sungai Pangkalan Datu Breakwaters and covered a shoreline length of 5.1 km southwards and 6.1 km northwards from the breakwaters. The cross-shore profiling survey extended seawards to a depth of about 8 to 9 meters LSD for the northern section and 10 meters LSD for the southern section. 4.5.2 Survey #2 - 1999 The second survey dataset was obtained from a survey conducted between 4th and 27th May, 1999. east coast. This coincided with the end of the northeast monsoon in the The bathymetric survey extended seawards to the 10 meter contour. The shoreline length covered by this survey was similar to that covered in the permonsoon survey (survey #1). 38 4.5.3 Survey #3 - 2000 The third survey dataset was obtained from a survey conducted from 20th May to 31st May 2000). Some difficulties were encountered with the data from this survey since there were no x-y coordinates recorded for each point along the profile line. The documentation nevertheless referred the chainage to the temporary benchmarks established by the 1998 and 1999 surveys. 4.5.4 Survey #4 – 2004 Between 2000 and 2004, serious erosion had occurred along the study shoreline causing a shoreline retreat of at least 20 meters. The fourth survey in this dataset conducted from 1st June to 30th July 2004 was based on an entirely new baseline. Original profile lines produced by this survey did not coincide with those established in the 1998 survey. Hence, the profile lines had to be re-created from the 2004 survey data points. The software Mike InfoCoast which automates profile line creation from 3-dimensional survey data (x-y coordinates and z-elevation) was used to extract the 2004 profile lines based on the starting and ending points of the 1998 and 1999 survey. 4.5.5 Survey Data Selection The survey data obtained at Pantai Sabak under the DID monitoring survey conducted in 1998, 1999 and 2000 covered a distance of 11.2 km and produced a total of 29 profile lines. The surveys began at Ch.00 which is next to the northern arm of the Sungai Pengkalan Datu breakwater to Ch.6100 at Pantai Cahaya Bulan. From Ch.00 to Ch.2300, profiles were measured at intervals of 200 meters. The shoreline stretch between Ch.3100 and Ch.00 generally experienced the worse 39 erosion. From Ch.2300 to Ch.3100, three profiles were captured at intervals of 400 meters. The surveys also extended southwards from the breakwaters to Ch. -5100 at intervals of 400 meters. The chainages with the most data were noted and following the starting and ending coordinates of the 1998 and 1999 dataset, new profile data was generated from the 2004 survey. In the final analysis, profiles from 13 chainages as shown in Table 4.1 were selected. Chainage basepoint wavebuoy Figure 4.3: Profile lines at the study area Based on the data set, three consecutive years of profile survey data were captured for thirteen profiles while only the baseline survey was done for 15 profiles. Two surveys, one each in 1998 and 1999, were recorded for Ch.6100. From the above, annual depths of closure can be determined from the 13 profiles that had three survey datasets. Those with less were ignored in this study. Table 4.2 shows the starting and ending points of the selected survey datasets and the profile lines are illustrated in Figure 4.3. It can be seen that the seaward limits of the survey lie at depths ranging from -8.0 m LSD to -12.0 m LSD. 40 Table 4.1: Profile Survey Data Register No. Chainage 1 CH-400 1998 Data Availability 1999 2000 2004 √ √ √ √ √ √ √ √ √ √ √ √ √ √ √ √ √ √ √ √ 12 CH00 √ √ √ √ 13 14 15 16 17 18 CH200 CH400 CH600 CH800 CH1000 CH1200 √ √ √ √ √ √ √ √ √ √ √ √ √ √ √ √ √ √ 19 CH1400 √ 20 CH1500 21 CH1700 22 CH1900 √ √ √ √ √ √ √ √ √ 23 CH2100 √ 24 25 26 27 28 29 √ √ √ √ √ √ √ √ √ √ √ √ √ √ √ 2 3 4 5 6 7 8 9 10 11 CH-900 CH-1400 CH-1900 CH-2400 CH-2900 CH-3400 CH-3900 CH-4400 CH-4900 CH-5100 CH2300 CH2700 CH3100 CH4100 CH5100 CH6100 √ Notes 4 years; at southern breakwater 4 years 4 years 1 year 1 year 1 year 1 year 1 year 1 year 1 year 1 year 4 years; at northern breakwater 4 years 4 years 1 year 4 years 1 year 4 years 1 year; Surau Insaniah, Kg. Kemerok 4 years 1 year 4 years 1 year; bend at Sungai Raja Gali 4 years 4 years 4 years 1 year 1 year 2 years 41 Table 4.2: Starting and ending points of selected survey dataset (13 profile lines) off Pantai Sabak, Kelantan Profile Start Point No. Chainage (Cassini) 1 2 3 4 5 6 7 8 9 10 11 12 13 CH00 CH200 CH400 CH800 CH1200 CH1500 CH1900 CH2300 CH2700 CH3100 CH-400 CH-900 CH-1400 Depth at profile end (m) Profile End Point (Cassini) Easting Northing Easting Northing 18259. 93 18111. 50 17947. 90 17658. 80 17364. 62 17124. 31 16780. 26 16430. 05 16092. 04 15709. 49 18614. 95 18991. 55 19280. 08 30046. 62 30182. 11 30300. 59 30578. 63 30853. 18 31032. 77 31239. 08 31440. 15 31607. 06 31726. 16 30036. 20 29689. 44 29282. 12 20112. 40 19967. 30 19805. 10 19523. 60 19176. 70 18915. 80 18772. 40 18457. 60 16873. 10 16507. 60 21568. 30 22048. 50 22513. 70 32534. 90 32658. 20 32787. 30 33087. 50 33261. 90 33432. 30 33922. 00 34152. 30 33678. 50 33862. 90 32103. 40 31847. 90 31547. 30 -9. 75 -9. 62 -9. 71 -10. 27 -10. 14 -10. 31 -11. 65 -11. 66 -8. 27 -8. 53 -11. 04 -10. 98 -11. 54 The three survey datasets made available for this research enables a comparison only for a single erosional event and a three-year temporal condition. The period from October 1998 to April 1999 coincides with the northeast monsoon in the east coast of Malaysia within which the severest wind and wave conditions have been known to occur. Most major erosion incidents in the study area have been associated with the northeast monsoon. The 12-month period between surveys #2 and #3 that is from May 1999 to May 2000 covers both the typically swelldominated and accretional south west monsoon (May to September) and the wavedominated erosive northeast monsoon. The final data set obtained in 2004 allows an examination of depths of closure over a period of six years. presented in Appendix A. The survey data is 42 4.5.6 Survey Data Filtering Profile survey data from 1998, 1999 and 2000 in digital format were compiled based on their respective survey chainage. The raw data was then checked for abnormalities and errors. For consistency, the profile data for each chainage was reproduced at seaward intervals of 50 meters up to approximately 3 km offshore based on the start points and end points shown in Table 4.2. After analysis, the survey provided 13 cross-shore profiles for the three years of survey. From hydrographic sounding data, the depth elevation data were reproduced for specific intervals by linear interpolation. Minimal smoothing was done on the 2004 dataset using the moving average method. The 2004 coastline is at least 20 meters behind the 2000 coastline hence it must be noted that the zero position in the profile plots for the 2004 dataset does not necessarily lie on dry beach. 4.6 Sediment Data Bed samples were successfully collected along 11 profile survey lines corresponding to the locations of the 2 m, 5 m and 8 m to 10 m depth contours. These samples were taken during the 1998, 1999 and 2004 survey. Grain size analysis was conducted on these samples according to BS1377 and plotted. Hydrometer analysis was not conducted hence, graphical plots did not capture particle sizes of less than 0. 063 mm (the lower limit for fine sand). From the 1998 and 1999 survey, the grain size of sediments sampled at depths from 2 m to 10 m ranged from 0.06 mm to 1.75 mm with a mean of 0.5 mm. Additonal samples were taken concurrent with the 2004 survey at depths of 4 m to 11 m. These provided a material d50 range of 0.07 mm to 0.7 mm and averaged at 0.3 mm. The summary of sediment data from the study area is shown in Appendix C. Typically, beach sediments are expected to be naturally sorted with the coarser sediments being deposited on the upper parts of the beach while finer sediments get 43 deposited further seawards. The study area data however shows that on the average, coarser sediments are located offshore for the 1999 and 2004 data as shown in Figure 4.4. Figures 4.5 and 4.6 illustrate the sediment distribution trends of relevant profiles where data was available. Sediment Distribution at Pantai Sabak 1.6 1.4 1.2 1 1998 1999 2004 0.8 0.6 0.4 0.2 0 0 2 4 6 8 10 12 Depth, m (approximate) Figure 4.4: Distribution of sediments along Pantai Sabak 1998, 1999 and 2004 (d50 averaged across all chainages) Distribution of Bed Sediments at Pantai Sabak 2 1.8 1.6 Ch.1900 1998 Ch.1200 1998 Ch.00 1998 Ch.-400 1998 Ch.00 1999 Ch.1900 1999 Ch.-400 1999 Ch.1200 1999 1.4 1.2 1 0.8 0.6 0.4 0.2 0 0 2 4 6 8 Depth, m (approximate) Figure 4.5: Distribution of bed sediments along Pantai Sabak 1998-1999. Negative chainages are south of the breakwater 44 Sediment distribution at Pantai Sabak 2004 0.8 0.7 0.6 North of breakwater 1 North of breakwater 2 At breakwater area 1 At breakwater area 2 South of breakwater 1 South of breakwater 2 0.5 0.4 0.3 0.2 0.1 0 0 2 4 6 8 10 12 Depth, m (approximate) Figure 4.6: Distribution of bed sediments along Pantai Sabak 2004 4.7 Wave Earlier studies and reports on Kelantan utilised the SSMO wave data which was the only data available at the time. Wave data used in this study was obtained from the United Kingdom Meteorological Office (UKMO). The UKMO dataset is produced from a Global Wave Model which analysed fields of wind and 1dimensional spectra which represents the energy within each spectral band and the mean direction for that band. The data is archived at 6-hour intervals in a spatial resolution of approximately 60 km (grid spacing). The model assumes that depth is fixed at 200 m with grid points in latitude and longitude. The model is depthdependent and includes shallow water physics, namely bottom friction, refraction and shoaling. Output at each time-step consists of wind speed, direction and the conventional integrated variables derived from the spectrum – the significant wave height, period and direction for both wind-sea and swell together with the resultant height and period. The wind data is taken from the lowest level of the Atmospheric Model and represent conditions approximately 20 meters above mean sea level. The UKMO data documentation is presented in Appendix B. 45 4.7.1 UKMO Design Wave Analysis The UKMO data procured for this study was referred to a single point approximately 70 km offshore in the South China Sea with coordinates 6.39o N 102. 92o E as illustrated in Figure 4.7. A total of 8500 records were examined beginning from 28th May, 1999 to 1st January 2005. From this population, 7459 records coincided with the temporal range of the available profile surveys which is 28th May 1999 to 31st July 2004 as can be seen in Figure 4.8. It is noted that the first wave record is dated 28th May, 1999 which means there are no wave data available to associate with the 1998-1999 profile change dataset. The water depth at this UKMO data point is reported as 52 m. Wavebuoy @ 6.2o N 102.35o E Study Area UKMO wave data point @ 6.39o N 102.92o E South China Sea KELANTAN Distances TERENGGANU Wavebuoy to UKMO point = 66 km Wavebuoy to coastline = 3.6 km Figure 4.7: Location of wavebuoy and UKMO wavedata source relative to Kelantan coast. There is limited UKMO ocean wave data in the South China Sea and cost limitations permitted only a single location dataset to be purchased. The above location was selected since it is close to the study shoreline and is expected to represent all waves from the northeast approach window. 46 UKMO waves 1999-2004 3.5 3 Wave height, m 2.5 2 1.5 1 0.5 0 7/24/1998 0:00 12/6/1999 0:00 4/19/2001 0:00 9/1/2002 0:00 1/14/2004 0:00 5/28/2005 0:00 Date-time Figure 4.8: Offshore Significant Wave Heights at 6.39N 102.92E; 28/05/1999 – 30/07/2004 Although referred to a single geographical coordinate, the UKMO offshore waves dataset represents a 60 km grid in the ocean model. The offshore waves are probably conservative since the location is partly sheltered by Indo-China (Vietnam and Cambodia). 47 Histogram UKMO waves 1999-2004 2500 2295 2280 Frequency 2000 1500 1058 1000 504 500 340 277 247 184 118 73 40 18 13 9 2 1 2.3 2.5 2.7 2.9 3.1 3.3 0 0.3 0.5 0.7 0.9 1.1 1.3 1.5 1.7 1.9 2.1 Wave Height, m Figure 4.9: Histogram of UKMO waves The maximum significant wave height from this dataset was 3.3 m corresponding to a wave period of 6.8 seconds recorded on 22 December 1999. From the histogram of offshore waves shown in Figure 4.9, the dominant wave heights are in the 0.5 m to 0.7 m range. The statistics associated with the UKMO wave dataset are shown in Table 4.3. Table 4.3: Statistics of UKMO wave dataset Statistical parameter 1999-2000 1999-2004 Mean 0.81 0.76 Std. Dev. 0.45 0.4 Median 0.7 0.6 Max 3.3 3.3 Min 0.2 0.2 Figure 4.10 illustrates a plot of wave height against wave period for the resultant wave. A regression line is then obtained where it is observed that a linear relationship apparently exists between the two parameters and represented by the following equation, 48 Y = 0.9526x + 3.5464 (4.1) Applying the statistical correlation test onto the pairs of wave height and wave period, the correlation coefficient r between the wave height and the wave period was found to be 0.744 (R2 is 0.5537). This indicates a moderately strong positive linear relationship between the offshore significant wave height and wave period values. From this relationship, it is clear that the larger waves are associated with longer periods. Resultant Wave Height vs. Wave Period (1999-2004) 8 7 6 5 4 y = 0.9526x + 3.5464 3 R2 = 0.5537 2 1 0 0 0.5 1 1.5 2 2.5 3 3.5 Wave Height, m Figure 4.4: Wave Height vs. Wave Period for UKMO offshore wave records 1999 to 2004 The calculation of Dc using Hallermeier’s equation required the significant wave height exceeded 12 hours in a year equivalent to an exceedance probability of 0.137%. This wave height is determined from a plot of cumulative percentage against significant wave height as in Figure 4.11. From this graph, the H0.137 wave was determined to be 2.9 m with a corresponding wave period of 6.3 sec. From the UKMO dataset, the H0.137 wave was registered on 23 December 1999 at 0600 hours. For time-dependent Dc, the design wave height would be the significant wave height exceeded only 12 hours over a period of t years or (100/730t)% of the time (Nichols et al, 1996). Considering the 5-year period from May 1999 to May 2004, the 49 exceedance probability of this wave is 0.027%. From Figure 4.12, this wave, H0.027, is 3.13 m with an associated wave period of 6.53 sec. The H0.027 wave actually occurred on 08/03/2004 (3.13 m) and 22/12/1999 (3.3 m). Cumulative Percentage vs Offshore Wave Heights 1999-2000 3.5 H0.137 = 2.9 m Offshore Wave Height, m 3 2.5 2 1.5 1 0.5 0 0.01% 0.10% 1.00% 10.00% 100.00% Cumulative Percentage Figure 4.11: H0.137 wave from 1999-2000 UKMO wave data It was also noted that from the UKMO dataset, the offshore waves reached 2.9 – 3.3 meters on 5 occasions between 1999 and 2004 and all occurred during the northeast monsoon period. 50 Cumulative Percentage vs Offshore Wave Heights (1999-2004) 3.5 H0.027 = 3.13 m Offshore Wave Heights 3 2.5 2 1.5 1 0.5 0 0.01% 0.10% 1.00% 10.00% 100.00% Cumulative Percentage Figure 4.12: H0.027 wave from 1999-2004 UKMO wave data 4.7.2 Measured Waves Nearshore wave data was also obtained from a Datawell MKII Directional Waverider Buoy from 30 June to 13 July 2004 at 30-minute intervals as part of the 2004 data collection campaign. The wave buoy was positioned at the 12 m LSD depth-contour at coordinates N33957 E19236.3 (Kelantan Cassini) 3.6 km north of the Sg. Pengkalan Datu breakwaters (refer to Figure 4.4). The recorded wave heights are as shown in Figure 4.13. Figure 4.14 is a plot of both the measured waves and the offshore waves from the UKMO dataset. The peaks in both these wave time-series are seen to coincide which infers that a relationship exists between the offshore UKMO dataset and the concurrent recorded nearshore waves. Hence, both datasets could be safely used to model the wave conditions in this study. 51 MEASURED WAVES 90 80 70 Wave ht (Hs), cm 60 50 40 30 20 10 0 7/2/2004 0:00 7/4/2004 0:00 7/6/2004 0:00 7/8/2004 0:00 7/10/2004 0:00 7/12/2004 0:00 7/14/2004 0:00 Date-time Figure 4.13: Wave Buoy Measurements at E19236.3 N33957 (Kelantan Cassini) off Pantai Sabak, Kelantan Coast; 30 June to 13 July 2004. Wave Heights off Kelantan Coast measured waves UKMO offshore waves 0.8 0.7 Wave Height, m 0.6 0.5 0.4 0.3 0.2 0.1 0 02/07/2004 00:00 04/07/2004 00:00 06/07/2004 00:00 08/07/2004 00:00 10/07/2004 00:00 12/07/2004 00:00 14/07/2004 00:00 Date Time Figure 4.14: Comparison of offshore (UKMO data) and nearshore waves measured at the -12 m LSD contour 52 4.8 Tidal Heights Tidal information is necessary to determine the vertical references of depth. From the 2004 survey, three water level stations were set-up simultaneously at Pantai Sabak, Sungai Pangkalan Datu and off Pantai Perupuk (see Figure 4.15). Continuous measurements were taken from 3rd June to 14th July 2004 and the tidal constituents were extracted. Tidal heights were then established. The MLW level is of importance because it is the reference to depth of closure in the original definition (Hallermeier, 1981). Water levels have a direct influence on wave refraction and breaking in the nearshore zone. Larger waves typically occur during the northeast monsoon when water levels are higher due to greater wind set-up. Department of Irrigation and Drainage (1993) determined that MSL during the northeast monsoon period is 0.3 m higher than during the south-west monsoon period. Kg. Pantai Dasar Pantai Sabak Kg. Senok Sg. Pengkalan Datu breakwaters Pantai Perupuk WL = water level Wavebuoy = wave station CM = current meter Figure 4.15: Location of water level, current and wave stations at study area. Table 4.4, 4.5 and 4.6 shows the tidal heights established at Pantai Sabak and Sungai Pangkalan Datu from the 2004 survey. The tidal range along this shoreline averaged from the three stations is 0.95 m signifying a clearly micro-tidal shoreline (tide range < 2.0 meters). Pantai Perupuk (WL3) is located much further south of 53 the study area and considered to be of less influence. Subsequent analysis was done using only the Pantai Sabak (WL2) and Sungai Pangkalan Datu (WL4) stations (Appendix D). It can be observed that the MLLW level ranges from -0.56 m to -0.43 m LSD and average at 0.5 m LSD. MHHW was found to range from 0.37 m to 0.45 m LSD and average at 0.44 m. Averaging values between the two stations, MHW for the study shoreline is calculated to be 0.18 m LSD whilst MLW is -0.36 m LSD (see Tables 4.7 and 4.8). Table 4.4: Tidal Levels Along Study Shoreline (meters, LSD) Tidal Level H.A.T. Mean Higher-High Water Mean Lower-High Water Mean Sea Level Mean Higher-Low Water Mean Lower-Low Water L.A.T. Sungai Pengkalan Datu Pantai Perupuk 0.88 0.87 1.06 0.37 0.45 0.51 -0.11 -0.16 0.00 -0.04 -0.01 -0.07 -0.30 -0.16 -0.20 -0.56 -0.91 -0.43 -0.80 -0.53 -0.97 Pantai Sabak Table 4.5: Mean Low Water (meters, LSD) Station Pantai Sabak Pengkalan Datu Average MHLW MLLW MLW -0.30 -0.56 -0.43 -0.16 -0.43 -0.30 -0.22 -0.51 -0.36 Table 4.6: Mean High Water (meters, LSD) Station Pantai Sabak Pengkalan Datu Average MLHW MHHW MHW -0.11 0.37 0.13 0.00 0.45 0.23 -0.04 0.44 0.18 54 Table 4.7: Difference between MSL and MLW at Study Coastline Station MSL MLW Pantai Sabak -0.16 -0.43 0.27 Pengkalan Datu -0.04 -0.30 0.26 -0.10 -0.36 0.26 Average MSL - MLW Table 4.8: Difference between MSL and MHW at Study Coastline 4.9 Station MHW MSL MHW - MSL Pantai Sabak Pengkalan Datu Average 0.13 0.23 0.2 -0.16 -0.04 -0.09 0.29 0.27 0.28 Wind Wind data from the UKMO dataset is associated with the same point as the wave data and is the result extracted from an atmospheric model in about the same way as the waves (see description in Appendix B). Hence, the wind speeds actually represent the wind speed inside the wave model at a height of 20 m above sea level. The records indicate an average wind speed of 7 knots (3.6 m/s) with a maximum of 25 knots (12.86 m/s) with the strongest winds predominantly coming from the 45 – 120 degree sector. Based on the Beaufort scale, the strongest wind can be described as a moderate breeze. The wind rose is shown in Figure 4.16. 55 Radial units are in % occurrence Knots Figure 4.16: Wind rose representing UKMO offshore data point (20 m above MSL) at coordinates 6.39o N 102. 92o E 4.10 Summary The data set obtained for this study is limited to beach and nearshore profile surveys with an accepted accuracy of 30 cm. The three surveys completed in October 1998, May 1999 and May 2000 can be used to determine the variation of depth of closure for two erosional events between October 1998 and May 1999, and May 1999 to May 2000. When the 2004 survey is included, the depth of closure for a temporal scale of 6 years (1998 to 2004) where changes in the depth of closure due to an integrated effect of erosional and accretional events and can be determined. However, to directly compare calculated Dc using Hallermeier’s equation with 56 measured Dc from survey data, the period of surveys and the wave dataset selected must be concurrent. Therefore, the dataset from 1999 to 2004 will be used in the analysis. The UKMO dataset was used exclusively in this analysis. Based on a global hind-cast model, this time-series offshore dataset provides the complete wave parameters (wave height, period and direction) necessary for input into the wave model to generate the nearshore wave parameters needed to predict the depth of closure. The UKMO dataset also included wind speeds from the same point as the waves. From the 1998 and 1999 surveys, sediment size d50 at the study shoreline ranged from 0.06 mm to 1.75 mm with a mean of 0.5 mm. This grain size is slightly larger than the d50 range for valid application of Hallermeier’s equation which is between 0.16 mm to 0.42 mm. However, the mean d50 for the 2004 samples is 0.3 mm which falls within the accepted range. The d50 for the sediments in the study area can be summarised as being marginally higher than the accepted range. How they affect the results of this study will eventually become evident. The analysis also determined MLW at -0.36 m LSD which will be significant in the subsequent calculations of Dc. Since Hallermeier’s equation refers the calculated Dc to MLW and all surveys were referred to LSD, this difference must therefore be adjusted before comparisons are made between the two. CHAPTER 5 NUMERICAL MODELLING 5.1 Introduction One of the terms in the Hallermeier equation represents the wave condition at the depth of closure. To establish the nearshore wave climate, the UKMO offshore wave data for the periods 1999-2004 has been transformed to 13 points along the 10m depth contour nearest to the offshore endpoints of the 13 cross-sections analysed in this study. The significant wave height Hs exceeded 12 hours in a year or H0.137 has been determined as the minimum wave height that causes significant movement in bed sediments. This wave and its corresponding wave period, is required to compute the annual Dc using the empirical equations by Hallermeier. For the 5-year Dc, the 12-hour exceedence Hs over the 5 years or H0.027 is used. This chapter explains the wave refraction modelling that was conducted to produce the nearshore wave parameters. 5.2 Model Description A wave refraction model is a static wind-wave model which calculates the wave height and direction at each grid point within the model grid lay-out based on a set of input wave parameters entered at one end of the grid. The software Mike21NSW was used to model the wave refraction in this study. The Mike21 NSW is a 58 stationary spectral wave model that handles wave-breaking phenomena including shoaling, refraction and energy dissipation due to bottom friction. It however, does not simulate diffraction, reflection or wave-wave interaction effects. Since there are no large islands off the Kelantan coast, there is no risk of the model diffracting waves around islands. Mike21 NSW requires that the offshore wave parameters be entered at the left water boundary of the model. Wave directions are referred to in degrees from north. Initially working with the offshore waves from N330o to N120o, it was necessary to create up to 6 model layouts in order to transform offshore waves into the nearshore area and produce the required wave heights and periods to calculate the depth of closure. The overall description of the modelling is shown in Figure 5.1 Figure 5.1: Orientation of rectangle model layout for the input (offshore) wave approach conditions N330o, N0o, N30o, N60o, N90o and N120o. 59 Subsequently, only the waves approaching from N0o to N120o were modelled. Due to the orientation of the study shoreline, it is assumed that N330o waves would not be critical since it would have been refracted at least 90o to reach the study area. The model study therefore focuses on the waves approaching from the northeast sector. 5.3 Numerical Modelling The numerical modelling work is described below. 5.3.1 Model Area and Orientation The Mike21-NSW module uses a calculation grid where the spacing along the x-axis is 4 times that of the y-axis. The offshore wave parameters are entered at the left (open) boundary. The module’s numerical scheme also requires that the maximum deviation between the propagating waves and the x-axis to be around 4060 degrees. Hence, five wave approach windows were created for N0o, N30o, N60o, N90o and N120o approach directions (see Appendix E). Offshore bathymetries were found to be fairly parallel to the coastline and no islands are present offshore of Kelantan. 5.3.2 Wave Breaking Conditions Mike21-NSW applies wave breaking based on the formulation by Battjes and Janssen (1978) whereby the rate of energy dissipation is expressed by: 60 dE = dt - α_ . Qb . ω . Hm2 8π and, 1 - Qb = - Hrms 2 ln (Qb) Hm where, E total energy ω frequency Hrms root-mean square of Hm Hm maximum allowable wave height Qb fraction of breaking waves α adjustable constant Hm = γ1 . k -1 . tanh (γ2 . kd/ γ1) where, k wave number d water depth γ1 wave breaking parameter that controls steepness condition γ2 wave breaking parameter that controls limiting water depth The user is able to directly control the parameters γ1, γ2 and α. The model also includes bottom dissipation which is controlled by the Nikuradse’s roughness parameter. 61 5.3.3 Calibration Numerical wave models need to be calibrated against actual wave measurements whenever data is available. In this study, the only measured wave data available was captured by a solitary wave buoy installed at a depth of -12 m LSD. This wave measurement was conducted over a period of 14 days in July 2004 (see 4.7.2). It is important to note that this measurement period does not coincide with the north-east monsoon within which the H0.137 and H0.027 waves occur. It is therefore not appropriate to calibrate the wave model using this dataset. Nonetheless, the following exercise was carried out in order to demonstrate how wave Mike21 NSW transforms the offshore waves. For this purpose, offshore wave heights from the UKMO data point corresponding to the period 3/7/2004 to 13/7/2004 were separated into their respective directions and averaged. The approach between N345o and N15o therefore represents N0o (north) and similar grouping was carried out for the rest of the dataset. Upon analysis, it was found that the selected wave dataset contained waves from N0o, N90o, N120o and N150o only. Since wave measurements were obtained during the southwest monsoon in July 2004, the northeasters were low in height. The sea was dominated by waves from the N120o and N150o. Input data was determined from an analysis of offshore waves corresponding in time with the available wave buoy measurements. The mean wave height or Hm0 and corresponding wave period for N0o, N90o and N120o were calculated from the UKMO offshore data. The N150o waves were not considered in the analysis because these waves are essentially propagating parallel and away from the Kelantan coast. Typically, Mike21NSW can be calibrated using a single parameter which is the Nikuradse’s roughness parameter that controls bottom dissipation. Other values such as wave breaking parameters are usually kept at model default values. 62 The input parameters for Mike21-NSW module as used in the attempted calibration process were as follows: • Model water level: the water level records along the length of the study shoreline indicate that the mean water level during the period of calibration was calculated at -0.07 m LSD (see Figure 5.3). A model water level of 0 m LSD was used during the calibration of the model; • Bottom dissipation: this is represented by the Nikuradse’s roughness parameter kN. DHI recommends that a kN value equal to 2.5 times d50 (of the bed sediments) is used for bottom dissipation. Based on a mean d50 of 0.7 mm at depths greater than -10 m ACD (see Appendix C), the kN value is calculated to be 0.002 m. The effect of bottom dissipation on mean wave period is included; • Wave breaking parameters were kept at constant (default) values: γ1 = 1.0, γ2 = 0.8 and α = 1.0. The effect of wave breaking on mean wave period was excluded since the area of concern is before the surf zone. N90-K02 N90-K0002 Bathymetry 15 0.55 0.5 10 0.45 0.35 0 0.3 -5 0.25 -10 0.2 0.15 Bathymetry [m] 5 0.4 -15 0.1 -20 0.05 0 -25 0 25 50 75 100 125 150 175 200 225 250 275 300 Grid Spacing [40 meter] Figure 5.2: Sensitivity of kN parameter and location of breaking wave based on waves in July 63 A sensitivity analysis was done on the kN value by comparing the wave heights produced by kN = 0.002 m and kN = 0.2 m. From Figure 5.2, the following was observed for the waves in July (south-west monsoon): • Offshore waves decrease significantly at a depth immediately after -10 m ACD indicating that this is the start of the surf zone; • there is no significant change to the wave heights prior to -10 m ACD when different kN values are used. The results of the model runs based on kN of 0.002 m are shown in Table 5.1, Figure 5.4 and Figure 5.5. Based on the analysis above, the nearshore wave extraction point from the wave model was located at the -10 m ACD contour to capture the non-breaking condition. Table 5.1: Results of wave model calibration Direction Model input (Offshore) Model output (nearshore) Measured (nearshore) Significant Wave Height & Mean Wave Period Hm0 (m) Tm (sec) Hm0 (m) Tm (sec) Direction Hs (m) mean Tz (sec) mean Direction N0o N90o N120o 0.4 4.1 0.39 4.1 0.37 0.31 4.54 358.6 0.50 4 0.48 4 87.9 0.42 6.55 90.5 0.45 4.1 0.36 4.1 110 0.28 3.36 197.25 64 Tidal Heights at Pantai Sabak 1.2 1 0.8 0.6 0.4 0.2 0 -0.2 -0.4 -0.6 -0.8 -1 6/30/04 0:00 7/2/04 0:00 7/4/04 0:00 7/6/04 0:00 7/8/04 0:00 7/10/04 0:00 7/12/04 0:00 7/14/04 0:00 Date-time Figure 5.3: Water level measurements at Pantai Sabak during calibration period Predicted Wave Height, m Wave Model Calibration: Measured vs. Model-predicted Wave heights 0.60 0.50 0.40 y = 1.1798x + 0.0098 2 R = 0.992 0.30 0.20 0.10 0.00 0.00 0.10 0.20 0.30 0.40 0.50 Measured Wave Height, m Figure 5.4: Wave Model Calibration – Wave Heights (for offshore waves from 0 to 120 degrees) 65 Predicted Wave Direction, degrees Wave Model Calibration: Measured vs. Model-predicted Wave Directions 400 350 300 250 200 150 100 50 0 y = 1.001x + 2.5823 2 R = 0.9984 0 50 100 150 200 250 300 350 400 Measured Wave Direction, degrees Figure 5.5: Wave Model Calibration – Wave Directions (for offshore waves from 0 to 120 degrees) From the graph plotted in Figure 5.4, the wave heights from the model were found to be slightly higher than the measured wave data for the corresponding period. There were no waves from the N30o and N60o directions during the particular period of calibration therefore the analysis were based on results using the N0o, N90o and N120o offshore wave approach angles. The model was found to be generally over-predicting the measured wave heights at the calibration point by about 20%. It is noted that the measured waves are given as Hs which is assumed to be equivalent to H1/3 and by definition smaller than H0.137. According to US Army Corps of Engineers (2003): (i) Hm0 is a good estimate of Hs in deep water (ii) near breaking, Hs is 1.1 Hm0 and (iii) Hs can be 10% lower than Hm0 after breaking. Since, the measured wave heights from the wave recorder in section 4.7.2 are given in Hs, and the model-predicted Hm0 values are larger than Hs, the model predicted waves would actually be closer to H0.137. Hence, it is assumed that the wave heights at -10 m ACD predicted by the model, following this calibration, would be a reasonable approximation of the transformed offshore H0.137 and H0.027 waves. It is also observed that the predominant wind direction is blowing from the 110 degrees to 157 degrees sector during the calibration period. Including the wind forcings would therefore not contribute to a more accurate model of the wave 66 propagating towards the Kelantan coast. Furthermore, the runs without wind forcings have already overpredicted the Hs. 5.3.4 Prediction of Nearshore Waves from Wave Model 5.3.4.1 Input Data In order to predict the nearshore wave, the input wave at the offshore boundary must correspond to the accepted wave definitions for calculation of the Dc . For the annual Dc , the wave height exceeded for only 12 hours in a year or H0.137 (Hallermeier, 1981; Nichols et al, 1998a) was determined using statistical analysis. For the temporal depth of closure or Dl , the wave height exceedence percentage equivalent to 100/730t where t equals the period of data in years was used. From the analysis of UKMO wave data (see 4.7.1) the H0.137 wave (for the purpose of annual depth of closure calculations) was determined to be 2.9 m with a corresponding period (Tm) of 6.3 seconds. For the 5-year wave record from 1999-2004 (100/730t, where t = 5), the H0.027 wave was calculated to be 3.13 m with a wave period of 6.54 seconds. A matrix of offshore wave data was prepared for the model for approaches from N0o, N30o, N60o, N90o and N120o. Model water level was set at 0.4 m to account for storm surges during the monsoon. Following completion of the model runs for the parameter sets in the matrix, wave heights were extracted from the model nearshore area at 13 locations along the 10 m ACD depth contour nearest to the offshore limit of each profile line. The coordinates of these offshore points are shown in Table 5.2. 67 Table 5.2: Location of Offshore Points in Model Grid for Extraction of Wave Parameters Profile End Point (Geographical Coordinates) o 6 6o 6o 6o 6o 6o 6o 6o 6o 6o 6o 6o 6o 11’ 11’ 11’ 11’ 11’ 11’ 12’ 12’ 11’ 12’ 11’ 10’ 10’ Latitude 17.1742” 21.1898” 25.3945” 35.1705” 40.8520” 46.4016” 2.3454” 9.8459” 54.4382” 0.4449” 3.11” 54.7863” 44.9948” o 102 102o 102o 102o 102o 102o 102o 102o 102o 102o 102o 102o 102o 21’ 21’ 21’ 21’ 21’ 20’ 20’ 20’ 19’ 19’ 22’ 22’ 22’ Longitude 32.5251” 27.8063” 22.5314” 1 3.3778” 2.0953” 53.61” 48.9503” 38.7123” 47.1632” 35.2752” 19.8794” 35.4967” 50.6253” Figure 5.6: Location of extraction points in wave model 68 5.3.4.2 Wave Modelling Results The results of the wave modelling are given in Tables 5.3 and 5.4 based on the respective offshore extreme wave conditions H0.137 and H0.027. Figures 5.7 through 5.16 illustrate the refraction patterns from the wave model using the H0.137 and H0.027. The series of dots represent points where nearshore wave parameters were extracted which are near the 10 m ACD-depth contour (see Figure 5.6). The transformed wave heights predicted at nearshore were found to be generally smaller than the offshore waves. Another significant finding is that the offshore waves close to the seaward limits of profiles CH.00 to CH.3100 were slightly higher than those at CH.-400 to CH.-900 which are to the southeast of CH.00. For the H0.137 condition, predicted near shore wave heights range from 1.61 m to 2.61 m. The model predicted higher waves for the H0.027 condition and these range from 1.77 m to 2.81 m. In terms of maximum wave heights, the model indicated that these were produced by offshore waves from the N30o. Study Area Kilometers Figure 5.7: Wave Refraction Diagram; H0.137 = 2.9, Tm = 6.3 sec; North approach. 69 Study Area Figure 5.8: Wave Refraction Diagram; H0.137 = 2.9, Tm = 6.3 secs; N30o approach. Study Area Figure 5.9: Wave Refraction Diagram; H0.137 = 2.9 m, Tm = 6.3 secs; N60o approach. 70 Study Area Figure 5.10: Wave Refraction Diagram; H0.137 = 2.9 m, Tm = 6.3 secs; N90o approach. Study Area Figure 5.11: Wave Refraction Diagram; H0.137 = 2.9 m, Tm = 6.3 secs; N120o approach. 71 Study Area Kilometers Figure 5.12: Wave Refraction Diagram; H0.027 = 3.13 m, Tm = 6.54 secs; North approach. Study Area Figure 5.13: Wave Refraction Diagram; H0.027 = 3.13 m, Tm = 6.54 secs; N30o approach. 72 Study Area Figure 5.14: Wave Refraction Diagram; H0.027 = 3.13 m, Tm = 6.54 secs; N60o approach. Study Area Figure 5.15: Wave Refraction Diagram; H0.027 = 3.13 m, Tm = 6.54 secs; N90o approach. 73 Study Area Figure 5.16: Wave Refraction Diagram; H0.027 = 3.13 m, Tm = 6.54 secs; N120o approach. Table 5.3: Predicted wave heights at 10 m depth based on offshore wave of H0.137 = 2.9 m and Tm = 6.3 secs WAVE DIRECTION CH2700 2.55 6.09 4.05 CH2300 2.52 6.08 4.59 CH1900 2.52 6.07 5.10 CH1500 2.52 6.07 4.56 CH1200 2.52 6.07 4.15 CH800 2.53 6.06 4.20 CH400 2.53 6.06 3.52 CH200 2.54 6.05 3.48 CH00 2.56 6.06 3.38 CH -400 2.53 6.04 4.26 CH -900 2.54 6.03 4.44 CH -1400 2.53 6.03 4.46 North Hm0 (m) Tm (s) MWD (deg) CH3100 2.58 6.10 3.87 N30 Hm0 (m) Tm (s) MWD (deg) 2.58 6.09 28.37 2.58 6.08 28.47 2.59 6.07 28.60 2.61 6.06 29.10 2.58 6.06 28.39 2.58 6.06 28.12 2.59 6.05 28.20 2.60 6.05 27.84 2.60 6.05 27.90 2.61 6.05 28.11 2.59 6.06 28.74 2.55 6.03 28.64 2.53 6.02 28.44 N60 Hm0 (m) Tm (s) MWD (deg) 2.50 6.03 52.21 2.53 6.03 52.54 2.52 6.02 52.72 2.50 6.01 52.99 2.48 6.01 52.25 2.50 6.01 52.32 2.49 6.00 52.49 2.54 6.00 52.70 2.54 5.99 52.62 2.55 6.00 53.10 2.55 5.99 52.87 2.52 5.99 53.17 2.53 5.98 53.16 N90 Hm0 (m) Tm (s) MWD (deg) 2.16 5.93 73.65 2.17 5.93 73.96 2.18 5.92 74.07 2.15 5.91 73.53 2.19 5.91 72.70 2.20 5.91 73.16 2.22 5.90 73.14 2.21 5.90 73.40 2.19 5.90 73.00 2.19 5.90 73.55 2.23 5.89 74.57 2.23 5.89 74.94 2.28 5.88 75.32 N120 Hm0 (m) Tm (s) MWD (deg) 1.61 5.72 90.15 1.62 5.71 90.68 1.64 5.70 91.34 1.62 5.68 90.54 1.66 5.67 90.15 1.68 5.67 91.00 1.70 5.66 91.35 1.74 5.65 92.66 1.75 5.64 92.51 1.78 5.65 93.04 1.92 5.63 95.06 1.97 5.63 95.75 2.02 5.62 96.48 2.29 5.97 2.58 2.29 5.97 2.58 2.29 5.96 2.59 2.28 5.94 2.61 2.29 5.94 2.58 2.30 5.94 2.58 2.31 5.94 2.59 2.32 5.93 2.60 2.32 5.93 2.60 2.34 5.93 2.61 2.36 5.92 2.59 2.36 5.91 2.55 2.38 5.90 2.53 6.09 6.08 6.07 6.06 6.06 6.06 6.05 6.05 6.05 6.05 6.06 6.03 6.03 Mean Wave Ht. Mean Wave Period Max Hm0 Corresponding Tm 74 Table 5.4 Predicted Wave Heights at 10 m depth based on offshore wave of H0.027 = 3.13 m and Tm = 6.54 secs WAVE DIRECTION North Hm0 (m) Tm (s) MWD (deg) CH3100 2.78 6.28 4.09 CH2700 2.74 6.28 4.27 CH2300 2.72 6.26 4.83 CH1900 2.71 6.25 5.35 CH1500 2.71 6.25 4.79 CH1200 2.71 6.25 4.36 CH800 2.72 6.24 4.39 CH400 2.73 6.24 3.69 CH200 2.73 6.24 3.64 CH00 2.75 6.24 3.55 CH 400 2.72 6.22 4.49 CH900 2.73 6.21 4.67 CH1400 2.72 6.20 4.69 N30 Hm0 (m) Tm (s) MWD (deg) 2.78 6.27 28.17 2.78 6.26 28.27 2.79 6.25 28.40 2.81 6.24 28.93 2.78 6.24 28.20 2.78 6.24 27.92 2.79 6.23 28.00 2.80 6.23 27.62 2.80 6.22 27.69 2.81 6.23 27.91 2.79 6.25 28.57 2.75 6.21 28.49 2.72 6.20 28.28 N60 Hm0 (m) Tm (s) MWD (deg) 2.69 6.21 51.62 2.72 6.20 51.98 2.71 6.19 52.16 2.69 6.18 52.45 2.67 6.18 51.69 2.69 6.18 51.76 2.68 6.17 51.92 2.73 6.17 52.16 2.74 6.16 52.10 2.74 6.17 52.61 2.75 6.16 52.37 2.71 6.16 52.67 2.73 6.14 52.64 N90 Hm0 (m) Tm (s) MWD (deg) 2.31 6.09 72.81 2.32 6.09 73.12 2.34 6.08 73.22 2.30 6.07 72.69 2.34 6.06 71.80 2.36 6.07 72.27 2.38 6.06 72.26 2.37 6.06 72.49 2.34 6.06 72.06 2.34 6.06 72.62 2.38 6.05 73.64 2.38 6.05 74.01 2.44 6.04 74.41 N120 Hm0 (m) Tm (s) MWD (deg) 1.79 5.89 87.69 1.80 5.88 88.24 1.81 5.86 88.98 1.77 5.84 88.33 1.82 5.84 87.94 1.84 5.83 88.80 1.85 5.82 89.17 1.88 5.81 90.54 1.89 5.80 90.44 1.92 5.80 91.00 2.06 5.78 93.17 2.11 5.78 93.92 2.15 5.77 94.66 Mean Hm0 Mean Tm Max Hm0 2.47 6.15 2.78 2.47 6.14 2.78 2.47 6.13 2.79 2.46 6.11 2.81 2.46 6.11 2.78 2.47 6.11 2.78 2.49 6.11 2.79 2.50 6.10 2.80 2.50 6.10 2.80 2.51 6.10 2.81 2.54 6.09 2.79 2.54 6.08 2.75 2.55 6.07 2.73 Corresponding Tm 6.27 6.26 6.25 6.24 6.24 6.24 6.23 6.23 6.22 6.23 6.25 6.21 6.14 75 Figure 5.17 illustrates the maximum wave conditions that were produced by the offshore wave from N30o. It can be observed that there is very slight alongshore variation in the transformed wave heights. Nonetheless, lower waves are noted at Ch.-900 and Ch.-1400. MODEL-PREDICTED MAXIMUM WAVE HEIGHT AT -10 M ACD H0.137 Wave (1999-2000) H0.027 Wave (1999-2004) 2.85 2.80 2.75 2.70 2.65 2.60 2.55 2.50 2.45 2.40 2.35 CH3100 CH2700 CH2300 CH1900 CH1500 CH1200 CH800 CH400 CH200 CH00 CH-400 CH-900 CH-1400 Chainage Figure 5.17: Predicted Maximum Wave Heights at 10-m depth ACD contour along Pantai Sabak, Kelantan. In the case of mean wave heights, a more definite pattern has developed as illustrated in Figure 5.18. The local wave heights decrease as one moves from Ch.1400 to Ch.1200 however the percentage changes are insignificant. 77 MODEL-PREDICTED MEAN WAVE HEIGHTS AT -10M ACD H0.137 Wave (1999-2000) H0.027 Wave (1999-2004) 2.60 2.55 2.50 2.45 2.40 2.35 2.30 2.25 2.20 2.15 2.10 CH3100 CH2700 CH2300 CH1900 CH1500 CH1200 CH800 CH400 CH200 CH00 CH-400 CH-900 CH-1400 Chainage Figure 5.18: Predicted Wave Heights at 10-m depth (ACD) contour along Pantai Sabak, Kelantan averaged over all directions 5.4 Summary The purpose of wave modelling is to transform the offshore wave heights to their nearshore equivalents which will be subsequently applied in the equation to predict Dc. The software Mike21-NSW is used for this purpose. Two major assumptions at this point in this study are that (i) model-predicted Hm0 is greater than Hs at the -10 m ACD depth contour and is a good approximation of H0.137 and H0.027 (ii) the kN value of 0.002 m applied for the model which used data from the calmer conditions and swell-dominated wave climate of the south-west monsoon, is valid for predicting nearshore wave conditions for the more severe north-east monsoon. Though not preferred, in the absence of measurements during the northeast monsoon, this dataset offers the only means of calibrating the wave model. Fundamentally, the laws applying to shoaling, refraction and breaking incorporated in the model hold for all meteorological conditions. With the benefit of only a single and limited set of field data, the attempted calibration conducted in this study succeeded only to describe that the model overpredicts the inshore wave height by 20% during the south-west monsoon (July). Refining the calibration using the July dataset would 78 therefore not be beneficial if the runs are to be done for the north-east monsoon. A validated model using north-east monsoon data would add confidence to the predicted results. The UKMO wave data set obtained for this study for the years 1999-2004 corresponds to the periods of surveys available for the analysis of Dc. The 12-hour per t year exceedence waves essential to the predicted Dc calculations were derived from the 1999-2000 dataset for the annual condition (H0.137), and the 1999-2004 dataset for the ‘t = 5 years’ case (or H0.027), respectively. The highest waves were observed to be from N30o. Two scenarios of resultant waves were produced from the numerical model – the mean and maximum transformed wave heights for the H0.137 and H0.027 offshore wave conditions. The results from the wave modelling indicate that maximum wave heights at -10 m ACD for the annual or H0.137 condition is 2.61 meters while for the 5 year or H0.027 condition is 2.81 meters. CHAPTER 6 DETERMINATION OF DEPTHS OF CLOSURE 6.1 Introduction The depth of closure is a morphological limit of sediment transport which can be determined in the field from a series of profile data. In designing beach nourishment schemes, the depth of closure is an important parameter which signifies the seaward limit where the beach-fill will move. In the following, the depth of closure is determined for the purpose of beach-fill design. Determination of the depth of closure always requires an association with a criteria and time frame. When considering the depth of closure in relation to beach nourishment projects, it is important to be able to differentiate between offshore sand transport processes and the nearshore processes which are most likely to affect the shoreline position or the beach-fill. This chapter describes the Dc analysis done on the selected chainages of periodical survey data based on a chosen criteria and time frames. The known methods of analysis, the standard deviation of depth change (SDDC) and fixed depth change (FDC) method, are both applied for determination of an effective Dc on the study area and examined against Hallermeier’s predictive formula for selected cases. 6.2 Depth of Closure – Scope and Criteria 6.2.1 Definition There are two definitions of depth of closure being addressed in the following discussion. Firstly, Dc is regarded as the seaward limit of foreshore morphological changes. Hence, this would be the furthest point from the shoreline where significant bed elevation changes occur which in turn is linked to the highest prebreaking wave conditions. Secondly, considering that this analysis is to improve beach-fill design, the definition by Kraus et al (1998) whereby the Dc is the most landward depth seawards of which, there is no significant change in bottom elevation and no significant net sediment transport between the nearshore and the offshore, also applies. This infers a closure point nearest to the shoreline that will serve as a limit for beach-fill placement. 6.2.1.1 Event-dependent Dc Event-dependent Dc in this analysis attempts at determining an event- dependent Dc (Nicholls et al, 1998) where the event is the northeast monsoon. Generally, shoreline erosion occurs along the east coast of Peninsular Malaysia during the northeast monsoon which is from November to April (Unit Perancang Ekonomi, 1985). A monsoon Dc can be determined from the changes between the October 1998 and May 1999 surveys which exactly envelopes the northeast monsoon period. 6.2.1.2 Depth of Closure from Empirical Formulae (Dl,t ) The predicted depth of closure has been presented by Nicholls et al (1998) as Dl,t to indicate its association to the selected period of analysis. The 12-hour exceeded wave height for the annual (H0.137) and 5-year (H0.027) cases have been 81 transformed to their nearshore equivalents using the software Mike21 NSW. Dl,t is referred to MLW following Hallermeier’s original definition. 6.2.1.3 Time-interval Dc Time-interval Dc is determined from surveys taken from 1999 to 2004. It encompasses the erosion events over the northeast monsoon and the accretion phase that happens over the southwest monsoon (May through September). Two timeinterval Dc scenarios are investigated:1. Annual Dc – determined from the changes between two post-monsoon surveys i.e. the May 1999 and May 2000 surveys which are exactly 12 months apart; 2. 5-year Dc – determined from the May 1999, October 2000 and July 2004 surveys. 6.2.2 Algorithm for Determination of Dc from Profile Surveys Depths of closure from surveys are determined from the SDDC or FDC method. For SDDC, where the plot of the standard deviation of the selected series of surveys down-crosses below 0.3 m and tails off, a limit to the nearshore profile change i.e. the depth of closure, has been reached. Similarly, when the FDC plot down-crosses and remains below 0.3 m, the first point after the down-cross is deemed as the depth of closure. The algorithm is as follows: 1. Determine and plot envelope of bed elevations over series of surveys (distance shorewards as x-axis; bed elevation as y-axis); alternatively, and to clearly show profile changes over two consecutive surveys, each profile survey may be plotted; 82 2. Plot SDDC/FDC criteria line of 0.3 m (plotted on secondary y-axis); 3. Determine:• standard deviation of depth change between a series of surveys and; 4. • fixed depth change between consecutive surveys; • Determine opening and closing points along each profile: Beginning from shoreline where the shoreline is 0 m LSD, assuming that SDDC /FDC plot starts above the criteria line, the first point where the SDDC/FDC graph down-crosses the criteria line is deemed a closure point. If the SDDC/FDC line at the shoreline starts below the criteria line, the first up-crossing point is recorded as an opening point and the analysis proceeds from there; 5. From a closure point and continuing seawards, the point when SDDC/FDC graph next up-crosses the criteria line is recorded as a reopening point; 6. Identify morphological zones:• Closure zones – profile regions where the SDDC/FDC graph down-crosses and remains below the criteria line for a series of profile points. For this research, a zone is decided if the SDDC/ FDC line remains below the criteria line for at least 300 m ; • Reopening zones – when the SDDC/FDC graph up-crosses and remains above the criteria line; 83 • Multiple closure points are thus expected across a profile and these would be designated as: • Dci - for the starting point of the first closure zone that occurs (expected at innershore locations); • Dcm - for the starting point of a subsequent closure point that occurs seawards of Dci (expected at middleshore locations); • Dco – for the starting of a closure zone occurring in the outershore and seawards of Dcm . • Reopening zones are zones of significant cross-shore sediment transport. When the SDDC/FDC graph up-crosses and downcrosses the criteria line alternately along the profile, the length of this recurring phenomena is considered an area of significant sediment transport activity. 7. Determine effective Dc for beach fill design – the depth of closure is the depth where there is a clear tailing-off of the SDDC/FDC graph below the criteria line which is related to a change in the shoreline and foreshore but unrelated with offshore sediment transport phenomena. A tailing-off zone (closure zone) occurring between two zones of significant bed elevation change indicates that their processes differ from one another. In multi-barred profiles, there is a tendency for double or triple contours to occur. If a closure depth occurs twice along the same profile, the outermost point is chosen. 84 6.3 Predicted Depth of Closure, Dl,t The predicted depth of closure or Dl,t was determined for the annual and 5- year period (hence, Dl,1-yr and Dl,5-yr) . The application of Hallermeier’s equation requires the determination of the 12-hour exceeded significant wave height over the period of study resulting in a design wave exceedance of 0.137% (H0.137 ) for the annual case and 0.027% (H0.027) for the 5-year case. These wave conditions and their associated periods have been determined in Chapter 5. 6.4 Monsoon Dc (1998-1999 surveys) 6.4.1 Profile Descriptions and Application of Algorithm The criteria line for both SDDC and FDC methods applied herein is 0.3 m which corresponds to the accuracy of hydrographic surveys. Figures of representative profiles are presented for better appreciation of the analysis. The discussion is presented beginning from the updrift to downdrift locations (starting from Ch.3100 and ending at Ch.-1400). It is useful to note that a breakwater situated between Ch.-400 and Ch.00 interrupts the littoral drift. 6.4.2 Monsoon Dc at Ch.3100 and Ch.2700 Ch.3100 and Ch.2700 are 3-bar profiles with the bar systems occurring between 300 m and 800 m from the baseline. These profiles appear to be part of a stable region of the study coastline where the shoreline was essentially unchanged over the monsoon period. 85 6.4.2.1 Monsoon Dc Ch.3100 Bed elevation changes are insignificant at Ch.3100 especially in the innershore area. The SDDC method does not produce a closure. The FDC method however shows a Dcm of -3.64 m LSD and a Dco of -7.1 m LSD at 400 m and 1750 m from the baseline (Figure 6.1). The FDC method shows no change in shoreline position but an inshore reopening zone is noted at the inshore bar between 250 m and 350 m from the baseline before closing at 400 m. Significant bed elevation changes also occur at the outershore bar at 1300 m from the baseline. The effective Dc is -3.64 m LSD. Depth of Closure: Ch 3100; 1998-1999 Min envelope SDDC Max envelope Criteria line MLW FDC Mean depth 3 1 FDC Dcm = Dc = -3.64 m @ 400 m 2 1 0.9 0 FDC Dco = -7.1 m @ 1450 m -2 -3 0.7 0.6 -4 0.5 -5 -6 0.4 -7 0.3 -8 -9 0.2 -10 0.1 -11 -12 0 0 500 1000 1500 Distance Offshore, m Figure 6.1: Monsoon Dc at Ch.3100 2000 FDC/SDDC, m 0.8 -1 86 6.4.2.2 Monsoon Dc Ch.2700 At Ch.2700, the SDDC plot exceeds the 0.3 m-criteria line above MLW and closes 150 m from the baseline. The effective SDDC Dc for Ch.2700 is thus the first closure point -1.82 m LSD and 150 m from the baseline. Using the FDC method, Ch.2700 registered slight profile changes above MLW, and an innershore closure point coinciding with a bar location at -1.82 m LSD from the baseline (Figure 6.2). In the outershore, a reopening zone exists beyond the outershore bar between 1350 m and 1700 m from the baseline before closing again at -7.46 m LSD (1750 m from the baseline) near the offshore limit of the survey. The FDC Dc of Ch.2700 is determined to be -1.82 m LSD as the innershore bar does not contribute to the shoreline changes. Depth of Closure: Ch. 2700; 1998-1999 Mean bed elevation SDDC Min envelope Criteria line Max envelope FDC MLW 2.4 4 SDDC, FDC Dci = Dc = -1.82 m @ 150 m 2 2.1 1.5 -2 FDC Dco = -7.46 m @ 1750 m 1.2 -4 0.9 -6 Change criteria, m 1.8 0 0.6 -8 0.3 -10 0 0 500 1000 1500 2000 Distance offshore, m Figure 6.2: Monsoon Dc at Ch.2700 6.4.3 Monsoon Dc at Ch.2300 and Ch.1900 Ch.2300 and Ch.1900 are 2-bar profiles with the outer bars located significantly further offshore at 1300 m and 1700 m respectively. The comparison of the 1998 and 1999 plots show a growth and shoreward movement of the innershore 87 bar but with a flat middleshore. At Ch.1900, the shoreline is seen to have eroded over this monsoon corresponding to a growth in the innershore bar. 6.4.3.1 Monsoon Dc at Ch.2300 Applying the SDDC method, a closure zone is observed at Ch.2300 from 100 m to 400 m until the first reopening point appeared at the innershore bar 450 m from the baseline (Figure 6.3). The FDC Dc for Ch.2300 is found to be the same as the SDDC case. The effective Dc for Ch.2300 is -2.17 m LSD which lies 100 m from the shoreline. Depth of Closure: Ch.2300; 1998-1999 Mean bed elevation MLW FDC Profile 1998 SDDC Profile 1999 Criteria line 1 4 3 2 1 0 -1 -2 -3 -4 -5 -6 -7 -8 -9 -10 -11 -12 0.9 SDDC, FDC Dc = -2.17 m @ 100 m 0.8 0.6 0.5 0.4 0.3 0.2 0.1 0 0 500 1000 1500 2000 2500 Distance offshore, m Figure 6.3: Monsoon Dc at Ch.2300 3000 SDDC/FDC, m 0.7 88 6.4.3.2 Monsoon Dc at Ch.1900 No significant bed change occurred between 100 m to 750 m from the baseline at Ch.1900 (Figure 6.4). SDDC Dc for Ch.1900 is -1.8 m LSD and located at 100 m from the baseline. From the FDC analysis, triple contours occur for the depth corresponding to the innershore closure point of -2.75 m LSD at 250 m from the baseline. Depth of Closure: Ch.1900; 1998-1999 Mean bed elevation SDDC Min envelope Criteria line Max envelope FDC MLW 2.1 4 SDDC Dc = -1.80 m @ 100 m 3 2 1.8 1 FDC Dc = -2.75 m @ 250 m 1.5 -2 1.2 -3 -4 -5 0.9 -6 -7 SDDC/FDC, m 0 -1 0.6 -8 -9 0.3 -10 -11 -12 0 0 500 1000 1500 2000 2500 3000 3500 Distance Offshore, m Figure 6.4: Monsoon Dc at Ch.1900 6.4.4 Monsoon Dc at Ch.1500, Ch.1200 and Ch.800 The 1999 profile shows that a 3-bar profile has developed at Ch.1500, Ch.1200 and Ch.800 with outer bars at 1250 m to 1400 m from the baseline and inner-shore bars at 200 m to 400 m from the baseline. The Ch.1500 and Ch.1200 shoreline positions do not appear to change over this monsoon however a distinct lowering of the middleshore and seawards migration of the offshore bar can be 89 observed. Due to the proximity of the two innershore bars, they are both affected by erosion of the shoreline and by each other. 6.4.4.1 Monsoon Dc at Ch.1500 The SDDC Dc for Ch.1500 (Figure 6.5) is at -1.86 m LSD (250 m from baseline). Using the FDC method, a Dci for Ch.1500 is determined at -3.51 m LSD. The profile envelope separates at the outershore bar and Dco of -2.49 m LSD appears at 950 m offshore. The shallower Dco is due to the bar formation. The FDC Dc is therefore -3.51 m LSD at 550 m away from the shoreline. Depth of Closure: Ch. 1500; 1998-1999 Mean SDDC Min envelope criteria line Max envelope FDC MLW 3 1.2 SDDC Dci = Dc = -1.86 m @ 250 m 2 1 FDC Dci = Dc = -3.51 m @ 550 m 0 SDDC, FDC Dco = -2.49 m @ 950 m -2 -3 -4 0.6 -5 -6 -7 0.3 -8 -9 -10 0 -11 0 500 1000 1500 2000 Distance offshore, m Figure 6.5: Monsoon Dc at Ch.1500 2500 3000 SDDC/FDC, m 0.9 -1 90 6.4.4.2 Monsoon Dc at Ch.1200 At Ch.1200 (Figure 6.6), both the SDDC and FDC Dc coincide at -3.0 m (500 m from baseline). A reopening zone appears between 1200 m and 1450 m from the baseline. The effective Dc for Ch.1200 is therefore -3.0 m LSD. Depth of Closure: Ch.1200; 1998-1999 Min envelope Max envelope MWL SDDC Criteria line FDC mean 4 SDDC, FDC Dci = Dc = -3.0 m @ 500 m 2 0 0.9 -2 0.6 -4 Closure zone -6 0.3 -8 -10 -12 0 0 500 1000 1500 2000 Distance offshore, m Figure 6.6: Monsoon Dc at Ch.1200 2500 3000 SDDC/FDC, m FDC Dco = -3.53 m @ 1500 m 91 6.4.4.3 Monsoon Dc at Ch.800 SDDC Dc for Ch.800 (Figure 6.7) is located at -1.3 m LSD (100 m from baseline). A reopening zone appears at 1300 m to 1500 m from the baseline. Applying the FDC method on Ch.800, the reopening is at 1250 m and 1550 m from the baseline. The FDC Dc for Ch.800 is -2.77 m LSD. Depth of Closure: Ch.800; 1998-1999 5 Min envelope Max envelope MLW SDDC Criteria line FDC SDDC Dci = Dc = -1.30 m @ 100 m 3 Mean 2.1 FDC Dci = Dc = -2.77 m @ 550 m 1.8 1 SDDC, FDC Dco = -4.1 m @ 1550 m -3 1.2 -5 0.9 -7 Closure zone -9 SDDC/FDC, m 1.5 -1 0.6 -11 0.3 -13 -15 0 0 500 1000 1500 2000 2500 3000 Distance offshore, m Figure 6.7: Monsoon Dc at Ch.800 6.4.5 Monsoon Dc at Ch.400, Ch.200 and Ch.00 At these chainages, the innershore bars are located furthest from the baseline at 450 to 600 m. The outershore bars are at distances of 1300 m to 1500 m. Ch.00 is located next to the northern arm of the Sungai Pengkalan Datu breakwaters. The Ch.00 innershore bars experienced 1.0 m change in elevation over the monsoon making it a very active section of this coastline. 92 6.4.5.1 Monsoon Dc at Ch.400 Both Ch.400 (Figure 6.8) and Ch.200 (Figure 6.9) show their SDDC graph spiking over the criteria line at the innershore bars but further offshore the SDDC plots do not up-cross the criteria line. There was some doubt whether closure within 50 m of the baseline is accurate since this is the region where gaps in survey data often exist. Hence, the Dci for Ch.400 is placed at -2.59 m LSD located 550 m from the baseline. The FDC analysis reveals more significant changes at the bar. However, the Dc location is the same at -2.59 m LSD. Depth of Closure: Ch. 400, 1998-1999 Min envelope MLW SDDC Criteria line FDC 4 3 2 1 0 -1 -2 -3 -4 -5 -6 -7 -8 -9 -10 -11 Mean depth SDDC, FDC Dc = -2.59 m @ 550 m 0.9 0.6 0.3 0 0 500 1000 1500 2000 2500 Distance offshore, m Figure 6.8: Monsoon Dc at Ch.400 3000 SDDC/FDC, m Max envelope 93 6.4.5.2 Monsoon Dc at Ch.200 Ch.200 (Figure 6.9) has a very uniform slope with 4 visible bars at nearly regular intervals. Following the same arguments as in Ch.400, the SDDC Dc for Ch.200 is at -1.05 m LSD at 100 m from the baseline where a closure zone of 300 m wide begins. By the FDC method, the Dci is also -1.05 m LSD at Ch.200. Both the SDDC and FDC method produce the same Dco at -2.89 m. Depth of Closure: Ch.200; 1998-1999 Min envelope Max envelope MWL SDDC Criteria line FDC Mean depth 6 1.8 SDDC, FDC Dci = Dc = -1.05 m LSD @ 100 m 2 1.6 SDDC, FDC Dco = -2.89 m LSD @ 650 m 0 1.4 1.2 -2 1 -4 0.8 -6 0.6 -8 0.4 -10 0.2 -12 0 0 500 1000 1500 2000 2500 Distance Offshore, m Figure 6.9: Monsoon Dc at Ch.200 3000 SDDC/FDC, m 4 94 6.4.5.3 Monsoon Dc at Ch.00 At Ch.00 (Figure 6.10), no significant bed elevation changes occured between the shoreline and the innershore bar. However, distinct zones of reopening are noted at 600 m to 850 m and 1300 m to 1650 m. Hence, the Dci and Dco are determined to be at depths of -2.07 m and -5.44 m LSD respectively. By the FDC method, the Ch.00 profile is essentially unchanged until a reopening occurs at 300 m from the baseline. The profile envelope later converges at 900 m from the shore just beyond the innershore bars where the depth is -3.04 m LSD and qualifies as the Dc. Depth of Closure: Ch.00; 1998-1999 Mean bed elevation MWL FDC 4.0 SDDC Dci = Dc = -2.07 m @ 850 m 3.0 2.0 Min envelope SDDC Max envelope Criteria line FDC Dci = Dc = -3.04 m @ 900 m 2.4 SDDC Dco = -5.44 m @ 1700 m 2.1 1.0 FDC Dco = -6.21 m @ 2000 m -2.0 -3.0 -4.0 -5.0 1.5 1.2 0.9 -6.0 -7.0 0.6 -8.0 -9.0 0.3 -10.0 -11.0 0 500 1000 1500 2000 Distance offshore, m Figure 6.10: Monsoon Dc at Ch.00 2500 0 3000 SDDC/FDC, m 1.8 0.0 -1.0 95 Monsoon Dc at Ch.-400, Ch.-900 and Ch.-1400 6.4.6 Ch.-400, Ch.-900 and Ch.-1400 represent the shoreline updrift of the Sungai Pengkalan Datu breakwaters and characterised by a smooth nearshore gradient. This section of the shoreline is observed to be accreting as a result of the interruption of the northwest bound littoral supply by the breakwaters. 6.4.6.1 Monsoon Dc at Ch.-400 Referring to Figure 6.11, up-crossing of the SDDC graph occurred only at Ch.-400 at the location of the innershore bar 500 m from the baseline and closed at 550 m. The effective Dc is placed at -3.07 m LSD. The FDC method when applied to Ch.-400 establishes a zone of high sediment transport up to 500 m from the baseline. The Dc is registered at -3.07 m LSD. Depth of Closure: Ch. -400; 1998-1999 Min envelope Max envelope MLW SDDC Criteria line FDC Mean depth 1.5 4 SDDC, FDC Dc = -3.07 m @ 550 m 2 1.2 -2 0.9 -4 0.6 -6 -8 0.3 -10 -12 0 500 1000 1500 2000 2500 Distance Offshore, m Figure 6.11: Monsoon Dc at Ch.-400 3000 0 3500 SDDC/FDC, m 0 96 6.4.6.2 Monsoon Dc at Ch.-900 From Figure 6.12, the SDDC Dc is not defined For Ch.-900 but the FDC Dci which defines Dc is located at -3.3 m LSD (300 m from the shoreline). Dco is located at -4.04 m LSD which is 850 m from the baseline and just seawards of the innershore bar. Depth of Closure: Ch. -900; 1998-1999 4 Min envelope Max envelope MLW SDDC criteria line FDC Mean 1.5 FDC Dci = Dc = -3.3 m @ 300 m 3 2 1 1.2 -1 -2 0.9 -3 -4 -5 0.6 -6 -7 -8 0.3 -9 -10 -11 -12 0 500 1000 1500 2000 2500 3000 Distance Offshore, m Figure 6.12: Monsoon Dc at Ch.-900 (slope 1:400) 0 3500 SDDC/FDC, m FDC Dco = -4.04 m @ 850 m 0 97 6.4.6.3 Monsoon Dc at Ch.-1400 SDDC Dc is also not defined in Ch-1400 but FDC Dci is -4.18 m LSD and Dco is -7.59 m. The effective Dc is therefore -4.18 m LSD which is 600 m from the baseline (Figure 6.13). Depth of Closure: Ch.-1400; 1998-1999 Min envelope Max envelope MLW SDDC Criteria line FDC Mean depth 6 1.8 4 1.5 FDC Dc = -4.18 m @ 600 m 0 1.2 -2 0.9 -4 -6 0.6 SDDC/FDC, m 2 -8 0.3 -10 -12 0 0 500 1000 1500 2000 2500 3000 3500 Distance Offshore, m Figure 6.13: Monsoon Dc at Ch.-1400; closure is not defined with SDDC method at Ch.-1400 6.4.7 Summary for Monsoon Dc 6.4.7.1 Profile Evolution and Dc over a Monsoon The Dc from the October 1998 and May 1999 surveys define the monsoon Dc typically associated with an erosional event in the east coast of peninsular Malaysia. By the interpretion that a distance of about 300 m of insignificant bed change constitutes a closure zone, zones can be differentiated from points of significant bed elevation change and simplifies the analysis. Dc could be determined at all 13 profiles using the FDC method but was observed in 10 out of 13 profiles analysed 98 using the SDDC method. FDC being based on absolute change between elevations may however suffer from survey errors. The results from both methods indicate that profile envelopes typically separate over the bars. Closures occur at least at two locations across the profiles separated by closure and reopening zones. Over the 1998-1999 monsoon, bar movement was very active and there is a tendency for the innershore bars to move shorewards while the outershore bars shift seawards. The offshore migration of the outershore bars proves that the monsoon is an erosive event. 6.4.7.2 Monsoon Dc for Beach-fill Design The effective Dc for beach-fill design will indicate the location of where the toe of a beach-fill should be situated. Hence, the most landward closure which is separated from the offshore bar processes is assumed to be the effective Dc. From Table 6.1 and 6.2, it is observed that the effective SDDC Dc ranges from -1.05 m LSD to -3.07 m LSD and the effective FDC Dc is from -1.05 m LSD to -4.24 m LSD. These depths are located very close to the innershore bars and the FDC generally produces more seaward Dc values. Figure 6.14 presents a comparison of the Monsoon Dc for the two methods. It can be seen that in clearly eroding areas of Ch.200, Ch.400 and Ch.800, the SDDC and FDC method both concur on Dc. The FDC method to determine Dc would be recommended for beach-fill design since it captures more significant changes and regularly produces deeper Dc than the SDDC method. Another observation is that Dci occurs at distances of 600 m or less from the shoreline which encompasses the inner bars. Dco on the other hand was detected between 650 m and 2300 m offshore towards the limit of the survey data. Since this occurs over a single monsoon, the results are indicative of a highly active shoreface. 99 Table 6.1: Depths of Closure (SDDC) for Monsoon Event 1998-1999 Chainage Hm0 CH00 CH200 CH400 CH800 CH1200 CH1500 CH1900 CH2300 CH2700 CH3100 CH-400 CH-900 CH-1400 Average 2.61 2.60 2.60 2.59 2.58 2.58 2.61 2.59 2.58 2.58 2.59 2.55 2.53 2.58 Mean Profile Gradient 0.0030 0.0028 0.0027 0.0027 0.0025 0.0024 0.0029 0.0031 0.0038 0.0035 0.0031 0.0028 0.0026 0.0029 SDDC Dc (1998-1999) Dci , m LSD Dco m, LSD Dc m, LSD Dc, m MLW Distance offshore, m -2.07 -1.05 -2.59 -1.3 -3.00 -1.86 -1.80 -2.17 -1.82 na -3.07 na na -2.28 -5.44 -2.89 -2.59 -4.09 na -2.49 na na na na na na na -3.75 -2.07 -1.05 -2.59 -2.77 -3.00 -2.49 -1.80 -2.17 -1.82 na -3.07 na na -2.28 -1.71 -0.69 -2.23 -2.41 -2.64 -2.13 -1.44 -1.81 -1.46 na -2.71 na na -1.92 850 100 550 550 500 950 100 100 150 na 550 na na 440 Dci = innershore closure; Dcm = middleshore closure; Dco = outershore closure; Dc = effective closure Table 6.2: Depths of Closure (FDC) for Monsoon Event 1998-1999 Mean Profile Gradient FDC Dc (1998-1999) Dci, Distance Dco, Dc, m Dc , m offshore, m m LSD MLW m LSD LSD CH00 2.61 0.003 -3.04 -6.21 -3.04 -2.68 900 CH200 2.60 0.0028 -1.05 -2.89 -1.05 -0.69 650 CH400 2.60 0.0027 -2.59 na -2.59 -2.23 550 CH800 2.59 0.0027 -2.77 -4.09 -2.77 -2.41 550 CH1200 2.58 0.0025 -3.00 -3.53 -3.00 -2.64 1500 CH1500 2.58 0.0024 -3.51 -2.49 -3.51 -3.15 550 CH1900 2.61 0.0029 -2.75 na -2.75 -2.39 250 CH2300 2.59 0.0031 -2.17 na -2.17 -1.81 100 CH2700 2.58 0.0038 -1.82 -7.46 -1.82 -1.46 150 CH3100 2.58 0.0035 -3.64 -7.1 -3.64 -3.28 400 CH-400 2.59 0.0031 -3.07 na -3.07 -2.71 550 CH-900 2.55 0.0028 -3.3 -4.04 -3.3 -2.94 300 CH-1400 2.53 0.0026 -4.18 na -4.18 -3.82 600 Average 2.58 0.0029 -2.84 -4.73 -2.84 -2.48 542 Dci = innershore closure; Dcm = middleshore closure; Dco = outershore closure; Dc = effective closure; MLW = -0.36 m LSD Chainage Hm0 100 Monsoon Dc (1998-1999) from MLW (LSD - 0.36 m) CH3100 4.0 CH-1400 3.5 CH2700 3.0 2.5 CH-900 CH2300 2.0 1.5 1.0 CH-400 CH1900 0.5 0.0 CH00 CH1500 CH200 CH1200 CH400 FDC Dc CH800 SDDC Dc Figure 6.14: Comparison of SDDC and FDC methods in determining Monsoon Dc 6.5 Annual Dc (1999-2000) 6.5.1 Profile Description and Application of Algorithm Applying the same algorithm to the 1999-2000 surveys, the depth of closure for exactly one-year interval between surveys was determined for the study area and presented in the following sections. The similarity in results using both the SDDC and FDC method is illustrated for Ch.3100. For subsequent chainages, the FDC method is used and the absolute bed change along the same profile over the two surveys is plotted. The application of the algorithm is described below for selected profiles which represent the study shoreline. Ch.2300 and Ch.1900 were excluded due to irregularities in the profile dataset. 101 Annual Dc at Ch.3100 6.5.2 A shoreward migration of the innershore bars can be seen at Ch.3100 (Figure 6.15). The SDDC and FDC methods produce similar Dc of -3.70 m LSD at Ch.3100 but at slightly different locations. Depth of Closure (FDC): Ch.3100; 1999-2000 Profile 1999 FDC 4 Profile 2000 FDC criteria (0.3m) MLW SDDC Mean depth 1.6 SDDC Dc = -3.70 m @ 300 m 3 1.4 2 1 FDC Dc = -3.70 m @ 550 m 0 1.2 -1 0.8 -3 -4 0.6 -5 -6 0.4 -7 -8 0.2 -9 -10 0 500 1000 1500 Distance Offshore, m Figure 6.15: Annual Dc at Ch.3100 2000 0 2500 FDC, 1 -2 102 Annual Dc at Ch.2700 6.5.3 A shoreline retreat of almost 40 m has occurred at the baseline with closure achieved before the nearshore bars. Dc is -2.0 m at 150 m from the baseline with no signs of offshore reopening (Figure 6.16). Depth of Closure (FDC): Ch.2700; 1999-2000 Profile 1999 Profile 2000 MLW Mean Depth FDC FDC criteria (0.3m) 4 3 Dc = -2.0 m @ 150 m 2 3 1 0 2.4 -1 -3 1.8 -4 -5 -6 1.2 -7 -8 -9 0.6 -10 -11 -12 0 500 1000 1500 Distance offshore, m Figure 6.16: Annual Dc at Ch.2700 2000 0 2500 FDC, m -2 103 Annual Dc at Ch.1500 6.5.4 Significant bed elevation changes can be seen at the shoreline, and across the nearshore and offshore bars. Dci is -2.48 m LSD and located at 300 m from the baseline for Ch.1500 just seawards of the innershore bar. The profile envelope closes again at the depth of -3.32 m LSD at 1300 m offshore. The Dci is the effective annual Dc since it is separated from the outer bar by a closure zone (Figure 6.17). Depth of Closure: Ch. 1500; 1999-2000 Profile 1999 Profile 2000 MLW Mean Depth FDC FDC criteria (0.3m) 3 1.4 2 Dci = Dc = -2.48 m @ 300 m 0 -1 1.2 Dco = -3.32 m @ 1300 m -2 -3 1 0.8 -4 -5 0.6 -6 -7 0.4 -8 -9 0.2 -10 -11 0 500 1000 1500 2000 Distance offshore, m Figure 6.17: Annual Dc at Ch.1500 2500 0 3000 FDC, m 1 104 Annual Dc at Ch.1200 6.5.5 At Ch.1200, the outershore bar has migrated seawards while the innershore bar has reduced in height and moved shorewards indicating that they are influenced by different factors. The Dc is therefore the Dci at -2.02 m LSD and located 400 m offshore (Figure 6.18). Depth of Closure (FDC): Ch.1200; 1999-2000 Profile 2000 Profile 1999 Mean depth MLW FDC FDC criteria (0.3m) 3 2.4 Dci = Dc = -2.02 m @ 400 m 2 1 Dco = -3.07 m @ 1450 m 0 2.1 1.8 -1 -2 -4 1.2 -5 0.9 -6 -7 0.6 -8 -9 0.3 -10 -11 0 0 500 1000 1500 2000 2500 Distance offshore, m Figure 6.18: Annual Dc at Ch.1200 3000 FDC, m 1.5 -3 105 Annual Dc at Ch.800 6.5.6 The 1999 and 2000 profile envelope first closes at -0.61 m LSD merely 50 m from the baseline but immediately separates at the innershore bar (Figure 6.19). Another closure, point is detected at -2.39 m LSD at 350 m from the shoreline marking the beginning of a long closure zone before the offshore bar is reached. The profile envelope separates at the offshore bar but closes again at -4.13 m LSD. The most landward closure is -0.61 m LSD yet it is maintained that closures within 50 m of the shoreline should be disregarded due to possible survey inaccuracies and also because there is significant bed activity at the innershore bar. Dc is hence the location of Dcm where the depth is -2.39 m LSD. Depth of Closure (FDC): Ch.800; 1999-2000 Profile 1999 Mean Profile 2000 FDC MLW FDC criteria (0.3m) 1.8 5 Dcm = Dc = -2.39 m @ 350 m 3 1.5 1 -1 Dco = -4.13 m @ 1550 m 1.2 -5 0.9 -7 0.6 -9 -11 0.3 -13 -15 0 0 500 1000 1500 2000 Distance offshore, m Figure 6.19: Annual Dc at Ch.800 2500 3000 FDC, m -3 106 Annual Dc at Ch.400 6.5.7 A 500 m zone of insignificant bed elevation change exists at the shoreline hence, the Dc is established at a depth of -2.56 m LSD (Figure 6.20). From a beach nourishment aspect, the toe of the beach-fill may be placed in this zone. Depth of Closure (FDC): Ch.400; 1999-2000 Profile 1999 4 Profile 2000 Mean depth MLW FDC FDC criteria line 1.6 Dci = Dc = -2.56 m @ 550 m 2 1.4 1.2 Dco = -3.83 @ 1550 m -2 1 -4 0.8 -6 0.6 -8 0.4 -10 0.2 -12 0 0 500 1000 1500 2000 2500 Distance offshore, m Figure 6.20: Annual Dc at Ch.400 3000 FDC, m 0 107 Annual Dc at Ch.200 6.5.8 Significant sediment transport occurs at the bar of this profile as shown in Figure 6.21. A 500 m zone of insignificant bed elevation change exists at the shoreline hence, the Dc is established at a depth of -3.42 m LSD. Depth of Closure (FDC): Ch.200; 1999-2000 Min envelope MLW Max envelope FDC Mean depth FDC Criteria (0.3m) 4 1.8 2 Dc = -3.42 m @ 1150 m 0 1.2 FDC, m -2 -4 -6 0.6 -8 -10 -12 0 -14 0 500 1000 1500 2000 2500 Distance offshore, m Figure 6.21: Annual Dc at Ch.200 3000 108 Annual Dc at Ch.00 6.5.9 Based on the FDC criteria of 0.3 m, the Ch.00 profile appears as very active over the annual period (Figure 6.22). The plots indicate a seaward movement of the outershore bar but accreting innershore bars. Three closure points are found along the profile: Dci at -2.24 m LSD, Dcm at -3.81 m LSD and Dco at -6.19 m LSD which is situated 1900 m from the shoreline. The significant cross-shore sediment transport occurring offshore can be attributed to the discharge at the mouth of the breakwaters. Hence, this makes the Dci the selected Dc. Depth of Closure (FDC): Ch. 00; 1999-2000 FDC criteria (0.5m) MLW FDC Criteria (0.3m) Profile 1999 Mean depth Profile 2000 FDC 4 1.8 Dci = Dc = -2.24 m @ 850 m 2 Dcm = -3.8 m @ 1100 m 0 1.2 Dco = -6.19 m @ 1900 m FDC, m -2 -4 -6 0.6 -8 -10 0 -12 0 500 1000 1500 2000 Distance offshore, m Figure 6.22: Annual Dc at Ch.00. 2500 3000 109 6.5.10 Annual Dc at Ch-400, Ch.-900 and Ch.-1400 These three chainages updrift of the breakwaters have similar characteristics of gentle sloping nearshore and the absence of offshore bars (Figure 6.23, 6.24 and 6.25 respectively). The annual Dc at Ch.-400, Ch.-900 and Ch.-1400 are -4.37 m LSD, -3.35 m LSD and -4.59 m LSD respectively. Depth of Closure (FDC): Ch. - 400; 1999-2000 Profile 1999 Profile 2000 MLW Mean depth FDC FDC criteria (0.3m) 3 2 2 1.8 1 0 1.6 -1 1.4 Dc = -4.37 m @ 950 m -3 1.2 -4 1 -5 -6 0.8 -7 0.6 -8 -9 0.4 -10 0.2 -11 -12 0 500 1000 1500 2000 2500 Distance Offshore, m Figure 6.23: Annual Dc at Ch.-400 3000 0 3500 FDC, m -2 110 Depth of Closure (FDC): Ch.- 900; 1999-2000 Profile 1999 Profile 2000 Mean MLW FDC FDC criteria (0.3m) 6 1.4 Dc = -3.35 m @ 650 m 4 1.2 2 0 -2 0.8 -4 FDC, m 1 0.6 -6 0.4 -8 0.2 -10 -12 0 0 500 1000 1500 2000 2500 3000 3500 Distance Offshore, m Figure 6.24: Annual Dc at Ch. -900 Depth of Closure (FDC): Ch. - 1400; 1999-2000 Profile 1999 Profile 2000 MLW Mean Depth FDC FDC criteria (0.3m) 6 3 Dc = -4.59 m @ 700 m 4 2 2.4 1.8 -2 -4 1.2 -6 -8 0.6 -10 -12 0 0 500 1000 1500 2000 2500 Distance Offshore, m Figure 6.25: Annual Dc at Ch.-1400 3000 3500 FDC, m 0 111 6.6 Summary for Annual Dc (1999-2000) The analysis for annual Dc revealed that multiple closure and reopening zones develop across the profile producing two or three closure points (see Table 6.3). The Dco was consistently situated just beyond the outershore bars while Dc varied between 150 m to 900 m. To enable comparison with calculated Dl,t from Hallermeier’s equation, the measured values were reduced to MLW which has been established to be -0.36 m below LSD. The comparison between Dl,1-year and the effective Dc is illustrated using both a radar chart in Figure 6.26 and a line graph as in Figure 6.27. Dl,1-year is found to be greater than the measured Dc. The selection of local wave height from the model could be the reason for this overprediction. The outer bars alter both the wave height and direction in its lee creating a different wave condition. The examination of the effect of using waves from various parts of the crossshore on Dl,t is however outside the scope of this study. Table 6.3: Annual Dc (May 1999 – May 2000) FDC, m LSD FDC, m MLW Chainage Dci Dcm Dco Dci Dcm Dco Dc Dl, 1-year CH00 -2.24 -3.80 -6.19 -1.88 -3.44 -5.83 -1.88 -4.65 CH200* na na -3.42 na na -3.06 -3.06 -4.64 CH400 -2.56 na -3.83 -2.20 na -3.47 -2.20 -4.64 CH800 na -2.39 -4.13 na -2.03 -3.77 -2.03 -4.62 CH1200 -2.02 na -3.07 -1.66 na -2.71 -1.66 -4.62 CH1500 -2.48 na -3.32 -2.12 na -2.96 -2.12 -4.61 CH2700 -2.00 na na -1.64 na na -1.64 -4.61 CH3100* na -3.70 na na -3.34 na -3.34 -4.63 CH-400* na na -4.37 na na -4.01 -4.01 -4.63 CH-900* na -3.35 na na -2.99 na -2.99 -4.56 CH-1400* na na -4.59 na na -4.23 -4.23 -4.53 Average -2.05 -3.10 -4.00 -1.74 -2.74 -3.64 -3.01 -4.61 Dci = innershore closure; Dcm = middleshore closure; Dco = outershore closure; Dc = effective closure na = not applicable; * the location designation (Dci, Dcm or Dco) is estimated 112 FDC Annual Depth of Closure (1999-2000), m LSD CH3100 5.00 CH-1400 CH2700 4.00 3.00 CH-900 CH1500 2.00 1.00 0.00 CH-400 CH1200 CH00 CH800 CH200 CH400 Calculated Dc Annual FDC Dc Figure 6.26: Radar Graph - Comparison between Dl, 1-yr and measured Annual Dc Annual FDC Dc (1999-2000) in meters below ML 5.0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0.0 3100 2700 1500 1200 800 400 200 0 -400 -900 -1400 Chainage Annual Dc Calculated Dc Figure 6.27: Variation in Dl, 1-yr and measured Annual Dc along the study area 113 6.7 Time-interval Dc (1999-2004) 6.7.1 Profile Description and Application of Algorithm The profiles off Pantai Sabak over the period 1999 to 2004 have undergone erosion. Offshore bars can be seen to have eroded and some have totally disappeared. Zones of closure are identified as areas where the FDC line dips below the criteria line and remains for at least 200 m. The time-interval Dc for the period 1999-2004 was determined based on the 1999, 2000 and 2004 surveys using the mean absolute FDC method. The FDC method applied in this case is by finding the mean of the FDC in bed elevation between the 1999-2000 and 2000-2004 surveys. Due to the gaps in annual surveys from 2001 to 2003, the profile envelope established from three surveys representing 5 years may not necessarily mean that the actual maximum bed elevation change has been captured. It would be desirable to have such surveys in order for better understanding of the profile changes over annual periods. 114 Five-year Dc at Ch.3100 6.7.2 The application of different methods or criteria for determination of Dc may produce different results. In this section, this variability in Dc is demonstrated by using both the SDDC and FDC method for Ch.3100 (Figure 6.28). Both the SDDC and mean FDC method produce nearly identical results in the case of Ch.3100. Dc is placed at -3.48 m LSD. The FDC method has been reported by Larsen and Kraus (1994a) to be more descriptive in deeper water. This is demonstrated at Ch.3100 where the mean FDC method detects a change in bed elevation at 2000 m offshore not registered by the SDDC method. Depth of Closure: Ch. 3100; 1999-200 Min envelope FDC criteria (0.3m) Max envelope Mean FDC MLW SDDC Mean depth 3 2 2.4 Dc = -3.48 m @ 550 m 1 -1 1.8 -2 -3 -4 1.2 -5 -6 -7 0.6 -8 -9 -10 0 0 500 1000 1500 2000 2500 Distance Offshore, m Figure 6.28: 5-year Dc at Ch.3100 - Comparison of SDDC and mean of FDC between consecutive surveys at Ch.3100 SDDC/FDC, m 0 115 6.7.3 Five-year Dc at Ch.2700 From Figure 6.29, a closure zone appears to exist between 150 m to 350 m from the baseline but it is also part of the innershore bar system. To place a closure point here would be judgemental. A less controversial location would be at -4.14 m LSD where a tailing off of the FDC line occurs. Depth of Closure (FDC): Ch.2700; 1999-2004 Min envelope Mean depth Max envelope FDC criteria (0.3m) MLW Mean FDC 4 6 3 5.4 2 4.8 Dc = -4.14 m @ 700 m 0 4.2 -1 3.6 -2 3 -3 -4 2.4 -5 1.8 -6 1.2 -7 0.6 -8 -9 0 0 500 1000 1500 Distance offshore, m Figure 6.29: 5-year Dc at Ch.2700 2000 FDC, m 1 116 Five-year Dc at Ch.1500 6.7.4 Ch.1500 is addressed in Figure 6.30. A distinct closure zone can be seen between 350 m and 900 m offshore separating the shoreline changes from the outer bar evolution. Therefore the Dci of -2.92 m LSD is selected as the Dc. Depth of Closure (FDC): Ch. 1500; 1999-2004 Min envelope Max envelope MLW Mean depth FDC criteria (0.3m) Mean FDC 2.4 4 3 Dc = Dci = -2.92 m @ 350 m 2 1 2.1 Dco = -3.99 m @ 1450 m 0 1.8 1.5 -2 -3 1.2 -4 -5 0.9 -6 -7 0.6 -8 -9 -10 0.3 -11 -12 0 0 500 1000 1500 2000 Distance offshore, m Figure 6.30: 5-year Dc at Ch.1500 2500 3000 FDC, m -1 117 6.7.5 Five-year Dc at Ch.1200 From Figure 6.31, there are similarities between Ch.1200 and Ch.1500 in terms of the closure zone in the nearshore area. The Dci at -2.06 m LSD is selected as the Dc. Depth of Closure (FDC): Ch.1200; 1999-2004 3 Min envelope Max envelope Mean depth MLW Mean FDC FDC criteria (0.3m) 2.4 Dc = Dci = -2.06 m @ 400 m 2 2.1 1 0 Dco = -3.9 m @ 1600 m -1 1.8 -2 -4 1.2 -5 -6 0.9 -7 -8 0.6 -9 -10 0.3 -11 0 -12 0 500 1000 1500 2000 2500 Distance offshore, m Figure 6.31: 5-year Dc at Ch.1200 3000 FDC, m 1.5 -3 118 Five-year Dc at Ch.800 6.7.6 Ch.800 is described in Figure 6.32. The innershore bar processes are clearly separated from the outershore bar processes at Ch.800 and a Dc of -2.56 m LSD is chosen. The offshore deepens quite suddenly immediately after the outershore bar. Depth of Closure (FDC): Ch.800; 1999-2004 Max envelope Min envelope MLW Mean Depth FDC criteria (0.3m) Mean FDC 3.6 4 3 3.3 Dc = Dci = -2.56 m @ 500 m 2 3 1 2.7 -1 2.4 -2 2.1 -3 1.8 -4 -5 1.5 -6 1.2 -7 0.9 -8 0.6 -9 0.3 -10 -11 0 0 500 1000 1500 2000 Distance offshore, m Figure 6.32: 5-year Dc at Ch.800 2500 3000 FDC, m Dco = -4.75 m @ 1700 m 0 119 Five-year Dc at Ch.400 6.7.7 Ch.400 (Figure 6.33) presents an overall active profile but spikes and dips of the FDC graph pose uncertainties in determining the closure points. By strictly following the algorithm and assuming that a closure zone exists if the graph remains below the criteria line for more than 300 m, three closure points can be isolated. The Dcm of -3.65 m LSD is selected as the effective Dc as a conservative measure. Depth of Closure (FDC): Ch.400; 1999-2004 Max envelope Mean depth Min envelope FDC Criteria line (0.3m) MLW Mean FDC 4 2.4 Dci = -1.86 m @ 150 m 2 Dc = Dcm = -3.65 m @ 800 m 1.8 Dco = -4.65 m @ 1650 m -2 1.5 -4 1.2 -6 0.9 -8 0.6 -10 0.3 -12 0 0 500 1000 1500 2000 2500 3000 Distance offshore, m Figure 6.33: 5-year Dc at Ch.400; three closure points were detected FDC, m 0 2.1 120 6.7.8 Five-year Dc at Ch.200 Ch.200 (Figure 6.34) presents a similar situation as Ch.400 and again using the same argument, the Dco is selected as the Dc. The FDC line indicates a very active profile at this chainage and following the criteria, innershore closures could not be defined. Depth of Closure (FDC): Ch.200; 1999-2004 Min envelope MLW Max envelope FDC criteria (0.3m) Mean depth FDC 6 3 Dc = Dco = -6.13 m @ 2000 m 4 2 2.7 2.4 1.8 -2 1.5 -4 1.2 -6 0.9 -8 0.6 -10 0.3 -12 0 0 500 1000 1500 2000 2500 Distance Offshore, m Figure 6.34: 5-year Dc at Ch.200 3000 FDC, m 2.1 0 121 Five-year Dc at Ch.00 6.7.9 At Ch.00 (Figure 6.35), a closure zone extends seawards of the offshore bar but caution has been applied here due to the presence of the breakwater. The discharge from the mouth of the breakwater would influence the bar formation but this phenomena is outside the scope of this study. The Dcm of -3.74 m LSD which is the beginning of a 300 m closure zone in the middleshore area is selected as the Dc. Depth of Closure (FDC): Ch.00; 1999-2004 Min envelope Max envelope MLW Mean depth FDC Criteria line (0.3m) Mean FDC 4 Dci = -1.50 m @ 300 m 2 Dc = Dcm = -3.74 m @ 1050 m 3.6 3 -2 Dco = -6.33 m @ 2000 m 2.4 -4 1.8 -6 1.2 -8 0.6 -10 -12 0 0 500 1000 1500 2000 Distance Offshore, m Figure 6.35: 5-year Dc at Ch.00 2500 3000 FDC, m 0 122 6.7.10 Five-year Dc at Ch.-400, Ch.-900 and Ch.-1400 The 5-year Dc at these chainages were easily determined due to their smooth and regular offshore gradients. As shown in Figures 6.36 to 6.38, this accreting portion of the Pengkalan Datu shoreline have Dc located at less than 1 km from the shoreline. The Dc for Ch.-400, ch.-900 and Ch.-1400 are thus -3.63 m LSD, 4.19 m LSD and -4.65 m LSD respectively. Depth of Closure (FDC): Ch. - 400; 1999-2004 Min envelope Max envelope Mean profile MLW FDC criteria (0.3m) Mean FDC 2.4 4 3 2 1 0 1.8 Dc = -3.63 m @ 750 m -1 -3 1.2 -4 -5 -6 -7 0.6 -8 -9 -10 -11 0 -12 0 500 1000 1500 2000 2500 Distance Offshore, m Figure 6.36: 5-year Dc at Ch.-400 3000 3500 FDC, m -2 123 Depth of Closure (FDC): Ch.- 900; 1999-2004 Min envelope MLW Max envelope FDC Mean depth FDC criteria (0.3m) 6 2.4 4 2.2 Dc = Dci = -4.19 m @ 900 m 2 2 1.8 0 1.4 -2 Dco = -8.59 m @ 2700 m -4 1.2 FDC, m 1.6 1 -6 0.8 -8 0.6 0.4 -10 0.2 -12 0 500 1000 1500 2000 2500 3000 3500 0 4000 Distance Offshore, m Figure 6.37: 5-year Dc at Ch.-900 Depth of Closure (FDC): Ch. - 1400; 1999-2004 Max envelope Min envelope Mean depth MLW Mean FDC FDC criteria (0.3m) 6 3 4 2.4 2 1.8 -2 -4 1.2 -6 -8 0.6 -10 -12 0 0 500 1000 1500 2000 2500 Distance Offshore, m Figure 6.38: 5-year Dc at Ch.-1400 3000 3500 FDC, m Dc = -4.65m @ 700 m 0 124 6.8 Summary of 5-year Dc (1999, 2000 and 2004) The detailed results from the 5-year Dc analysis describing the prominent closure points along each profile is as shown in Table 6.4. The effective Dc for beach-fill design at the study shoreline of Pantai Sabak is in the range of -1.70 m to -4.29 m MLW and average at -3.36 m MLW. It follows that the Dl,5-yr predicted the upper boundary of the depths of closure as displayed in Figure 6.39 hence affirming earlier studies that: Dl,t > Dc In the foregoing analysis, the Dc has been selected from two or three closure points following the algorithm explained earlier. The Dc is hence subjective and a change in criteria or interpretation can shift the position of Dc. In most instances, the outer closure point Dco is not the selected Dc since it is often located at the outershore bars therefore far removed from innershore processes that effect the shoreline position. However, the Dco being a significant point of bed elevation change would be closely related to the pre-breaking wave and its relationship will also be discussed vis-à-vis Dl,t . Studying Figure 6.39, Ch.-900, Ch.00 and Ch.200 are exceptions to the norm whereby their Dco is greater than Dl,5-yr which may be explained by: • Ch.00 and Ch.200 are immediately downdrift of the breakwaters and the mouth of the breakwaters discharges at a location 500 m from the baseline of both the profiles and; • Ch.-900 is updrift of the breakwater and the profile is accreting. In such cases Hallermeier’s equation has been known to fail (Nicholls et al, 1996). 125 Table 6.4: Five-year Dc (1999, 2000, 2004 surveys) for beach-fill design FDC, m LSD Chainage Dcm Dci FDC, m MLW (-0.36 m LSD) Dco Dci Dcm Dco Dc Dl, 5-yr CH00 -1.50 -3.74 -6.33 -1.14 -3.38 -5.97 -3.38 CH200 na -6.13 na na -5.77 -5.77 na CH400 -1.86 -3.65 -4.65 -1.50 -3.29 -4.29 -3.29 CH800 -2.56 na -4.75 -2.20 na -4.39 -2.20 CH1200 -2.06 na -3.90 -1.70 na -3.54 -1.70 CH1500 -2.92 na -3.99 -2.56 na -3.63 -2.56 CH2700 -2.03 na -4.14 -1.67 na -3.78 -3.78 CH3100 na na -3.68 na na -3.32 -3.32 CH-400 na na -3.63 na na -3.27 -3.27 CH-900 -4.19 na -8.59 -3.83 na -8.23 -3.83 CH-1400 na na -4.65 na na -4.29 -4.29 Average -2.98 -3.81 -5.48 -2.62 -3.45 -5.12 -3.36 Dci = innershore closure; Dcm = middleshore closure; Dco = outershore closure; Dc = effective closure; Dl,5-yr = predicted Dc for period of analysis -4.97 -4.96 -4.96 -4.95 -4.94 -4.94 -4.95 -4.96 -4.96 -4.89 -4.85 -4.94 5-year Depth of Closure (1999-2004), m below MWL Dc, 5-yr (measured) Dl, 5-yr (predicted) Dco, 5-yr (measured) CH3100 CH-1400 CH-900 9 8 7 6 5 4 3 2 1 0 CH2700 CH1500 CH-400 CH1200 CH00 CH800 CH200 CH400 Figure 6.39: Comparison of 5-year Dc (effective Dc for beach-fill design), Dco (outermost Dc) and Dl,5-yr 126 5-year Depth of Closure (1999-2004), m below MWL Dc, 5-yr (measured) Dl, 5-yr (predicted) Dco, 5-yr (measured) 9 8 7 6 5 4 3 2 1 0 3100 2700 1500 1200 800 400 200 0 -400 -900 -1400 Chainage Figure 6.40: Variation in 5-year Dc (effective Dc for beach-fill design), Dco (outermost Dc) and Dl,5-yr across the study area 6.9 Comparison of Event and Time-Interval Dc The summary of Dco and Dc over the monsoon, annual and 5 year period is shown in Table 6.5 and 6.6. From the 1-year and 5-year results, it can be seen that with increasing years, the outer closure depth Dco generally increases. Exceptions to this trend occurred only at Ch.200 downdrift of the breakwater and in the accreting shoreline south of the breakwater. The same trend is noted in the effective Dc for beach-fill design. The monsoon Dc is presented here for completeness but should be excluded from the analysis because it has a base year of 1998 while the annual and 5year Dc analysis used a base year of 1999. Notwithstanding the above, Dco for the 1998-1999 monsoon event (6 months) was found to be deeper than Dl,5-yr at only 2 out of the 13 profiles examined (Table 6.5). 127 Table 6.5: Outer Closure Depths Dco (MLW) from Profile Plots Chainage Measured Outer Closure Points, Dco Dco 6 Predicted Dl,t Dco 1 yr Dco 5 yr Dl, 1-yr Dl, 5-yr -4.65 -4.64 -4.64 -4.62 -4.62 -4.61 -4.61 -4.63 -4.63 -4.56 -4.53 -4.61 -4.97 -4.96 -4.96 -4.95 -4.94 -4.94 -4.95 -4.96 -4.96 -4.89 -4.85 -4.94 mths CH00 -5.85 -5.83 -5.97 CH200 -2.53 -3.06 -5.77 CH400 na -3.47 -4.29 CH800 -3.73 -3.77 -4.39 CH1200 -3.17 -2.71 -3.54 CH1500 -2.13 -2.96 -3.63 na na -3.78 na na -3.32 -3.27 CH2700 CH3100 CH-400 -7.1 -4.01 CH-900 -6.74 na -8.23 CH-1400 na -4.23 -4.29 Average -4.46 -3.64 -4.59 6.10 % Diff. % Diff. Dco and Dco and Dl,t for Dl,t for 1-yr 5-yr -ve indicates overprediction 25.38% 20.12% -34.05% 16.33% -25.22% -13.51% -18.40% -11.31% -41.34% -28.34% -35.79% -26.52% na -23.64% na -33.06% -13.39% -34.07% na 68.30% -6.62% -11.55% -21.04% -7.02% Measured Dc vs. Hallermeier’s Equation Hallermeier’s equation has been applied using local wave conditions to produce the predicted annual and the time-interval depths of closure Dl,1-yr and Dl,5-yr. Alongshore variability of both Dl,1-yr and Dl,5-yr is not discernible from these results since the bathymetry is essentially parallel to the coastline. The results have proven that Hallermeier’s equation remains valid and typically produces the upper limit to Dc. It overpredicts the measured effective Dc values by an average 42.5% for the 1-year case and 34.8% for the 5-year case. In comparison, for the outermost depths of closure Dco, Hallermeier’s equation overpredicts Dco by 21% for the annual case and 7% for the 5-year case. The distribution along the coastline is shown in Figure 6.41. These findings reveal a trend of increasing accuracy of Dl,t in estimating actual Dc with an increase in number of surveys and time. The case of predicting the 5-year Dco is encouraging 128 since the accuracy improved by 10% with a singular addition of the 2004 survey to the earlier 1999 and 2000 survey data. The study area was a re-nourished area and it has been mentioned earlier that based on 1998-1999 bed samples, the mean d50 for the bed material in the study area is 0.5 mm thereby exceeding the suggested range of material d50 valid for Hallermeier’s equation which is 0.16 mm to 0.42 mm. The results however do not invalidate Hallermeier’s equation as providing the upper limit to Dc on micro-tidal coasts. This is perhaps mitigated by the fact that the 2004 samples have produced a mean d50 of 0.3 mm thereby falling within the permissable range. Table 6.6: Effective Dc and Predicted depth of closure, Dl,t , MLW Predicted Dl,t Chainage CH00 (Measured) Dc 5-yr Monsoon 1-yr Dc Dc -Dc -2.68 -1.88 -3.38 % % Diff. Diff. 15-yr yr -ve indicates overprediction Dl, 1-yr Dl, 5-yr -4.65 -4.97 -59.6% -32.0% CH200 -0.69 -3.06 -3.42 -4.64 -4.96 -34.1% -31.0% CH400 -2.23 -2.20 -3.29 -4.64 -4.96 -52.6% -33.7% CH800 -2.41 -2.03 -2.2 -4.62 -4.95 -56.1% -55.6% CH1200 -2.64 -1.66 -1.7 -4.62 -4.94 -64.1% -65.6% CH1500 -3.15 -2.12 -2.92 -4.61 -4.94 -54.0% -40.9% CH2700 -1.46 -1.64 -3.78 -4.61 -4.95 -64.4% -23.6% CH3100 -3.28 -3.34 -3.32 -4.63 -4.96 -27.9% -33.1% CH-400 -2.71 -4.01 -3.27 -4.63 -4.96 -13.4% -34.1% CH-900 -2.94 -2.99 -3.83 -4.56 -4.89 -34.4% -21.7% CH-1400 -3.88 -4.23 -4.29 -4.53 -4.85 -6.6% -11.5% Average -2.55 -2.65 -3.36 -4.61 -4.94 -42.5% -34.8% 129 Depths of Closure at Pantai Sabak, Kelantan 1-yr Dc 5-yr Dc Dl, 1-yr Dl, 5-yr Baseline elev. MLW -8 -6 -4 -2 breakwater 0 2 4 3000 2500 2000 1500 1000 500 0 -500 -1000 -1500 Chainage, m Figure 6.41: Dc along Pantai Sabak, Kelantan 6.11 Simplified Dc Equations The simplified forms of the Hallermeier equation as described in Section 2.4.1 do not carry the wave period term within them and are therefore convenient in providing quick estimates of Dc. Equations 2.5, 2.6 and 2.8 are of such nature and are reproduced below: H = 1.57 Hs 0.137 (2.5) hc = 2H + 11 σH (2.6) Dl = 2Hs50 + 12σH (2.8) Where, 130 H, hc and Dl = depth of closure H, Hs = mean annual significant wave height Hs 0.137 = significant wave height exceeded 12-hours a year Hs50 = median significant wave height σH = standard deviation of mean Hs The following have been determined from the UKMO dataset (in meters MLW) and comparing against Ch.1500 which is eroding and far away from the influence of the breakwater (see Tables 6.7 and 6.8): Table 6.7: Dc from simplified equations compared with effective Dc H Predicted Dc Ch. 1500 Dc -1 yr Hs50 σH - - - 4.55 2.12 114.6% - 0.812 - 0.446 6.53 2.12 208.0% - - 0.7 0.446 6.75 2.12 218.4% Equation Hs 0.137 1.57 Hs 0.137 2.9 2H + 11σH 2Hs50 + 12σH % diff. Table 6.8: Dc from simplified equation compared to Dco Equation Hs 0.137 1.57 Hs 0.137 2.9 2H + 11σH 2Hs50 + 12σH H - - 0.812 - Hs50 σH - - 4.55 Ch. 1500 Dco -1 yr 2.96 - 0.446 6.53 2.96 120.6% 0.7 0.446 6.75 2.96 128.0% Predicted Dc % diff. 53.7% 131 Tables 6.7 and 6.8 above reveal that Dc from simplified equations also overpredict the effective Dc values. Equation 2.8 was tested by Unit Perancang Ekonomi (1986) on the Kelantan coast and produced wave heights of 8.4 m. Within the limits of the Pantai Sabak data, the lowest measured annual Dc or Dl,1-yr based on the algorithm used above was found to be -4.23 m MLW at Ch.-1400. A simple relationship can thus be formed between this and the UKMO offshore wave, H0.137: Dc,1-yr / H0.137 = 4.23 / 2.9 = 1.45 therefore, equating the above to Dl.1-yr say, 6.12 Dl.1-yr = 1.45 H0.137 Dl.1-yr = 1.5 H0.137 (6.1) Observation The annual Dc analysis has revealed that when the pre-breaking wave condition is applied, Hallermeier’s equation tends to predict the outer closure depths (Dco) which are associated with the outer bar changes and not the beach-shoreline area. A cursory view of the wave heights in the middleshore area (Figures 5.7 to 5.16) landwards of the offshore bar indicates that they are smaller than the prebreaking waves at the -10 m depth contour which were the basis of the predictive equation and could produce shallower Dc values. Francois et al (2004) commented that Hallermeier did not specify at what depth of ‘local’ wave heights should be used in the Hallermeier equation. The results of the depth for closure analysis above has shown that predicted Dc or Dl,t based on waves at -10 m depth consistently overpredicts the measured values over the annual period and 5-year period. Predicted values from simplified equations overpredict Dc since these are essentially calculated using offshore waves. 132 Comparatively, the Hallermeier equation is a better choice as the percentage difference averages around 42% and improves with more data avalaibility. The use of an algorithm to estimate Dc is designed to produce consistency. The selection of a criteria value, in this case 0.3 m, is based on commonly acccepted accuracy of survey. It is noted that if a lower criteria of 0.2 m is used, the area of ‘significant’ bed elevation could possibly encompass the entire foreshore from MLW to the innershore bar as shown in Figure 6.42. Consequently, a different Dc could result. Depth of Closure (FDC): Ch.400; 1999-2000 Profile 1999 Profile 2000 Mean depth MLW FDC FDC criteria line criteria-2 4 1.6 Dc = -2.56 m based on 0.3 m criteria 2 Dc = -3.7 m based on 0.2 m criteria 1.4 1.2 -2 1 -4 0.8 -6 0.6 -8 0.4 -10 0.2 -12 0 0 500 1000 1500 2000 2500 Distance offshore, m Figure 6.42: Dc based on different closure criteria 3000 FDC, m 0 133 CHAPTER 7 CONCLUSIONS AND RECOMMENDATIONS 7.1 General Conclusions The determination of the depths of closure requires a definition of the depth of closure and the determination of a criteria to pinpoint the depth of closure. Hence, depth of closure studies include an element of the subjective. Nevertheless, Dc is an important parameter in cross-shore transport studies as it separates the nearshore into the respective zones of shoreline and offshore morphology. Knowing the depth and location of Dc facilitates the design of beach-fill in beach nourishment projects. Determining the position of depth of closure requires an analysis of a series of overlapping profile surveys. Such data is not always available hence, predictive equations based primarily on nearshore wave height conditions are often used. In this study, the depths of closure for the shoreline of Pantai Sabak, Kelantan were determined by analysing 4 sets of profile surveys. The depths of closure were also calculated using the Hallermeier equation and both results were compared. The findings have re-affirmed that Hallermeier’s equation is robust in predicting the upper boundary of depth of closure and its applicability to wave-dominated microtidal coasts. In the case of Pantai Sabak, the prediction exceeds the measured value of effective annual Dc by 42.5%. Exceptions to this general conclusion nonetheless have manifested in profiles that were (i) close to coastal structures specifically, a rivermouth breakwater in the study area and (ii) accreting stretches of the studied 134 shoreline. To summarise, the following relationships hold true in the case of the Kelantan shoreline: Dl,t > Dc (for beach fill design) Dl,t > Dco Dl,5-yr > Dl,1-yr Referring to the results in Chapter 6, the following relationship for the Pantai Sabak coast has been observed: Dl,1-yr = 1.5 H0.137 The commonly used methods of standard deviation of depth change (SDDC) and the Fixed Depth Change (FDC) were both utilised in the analysis and both yielded results consistent with each other. This research has determined that in the multi-barred profiles of the Kelantan coast, cross-shore profiles typically close around the innershore bars, re-open before the outershore bars and close again beyond the outershore bars revealing zones of closure and reopening as wide as 500 meters. This phenomenon can be observed from pre and post-monsoon surveys (northeast monsoon). Due to this, it was necessary to add new definitions such as Dci, Dcm and Dco to the terminology to describe the innershore, middleshore and outershore closure points. From these points, an effective depth of closure for the purpose of beach-fill design, Dc, was chosen. Outer closure points Dco are often unrelated to the inshore and shoreline processes that produce Dci and in some instances Dcm. Hence, the Dci and Dcm would be the best representative Dc for beachfill design purposes. 135 7.2 Suggestions for Future Research This study has benefited from a periodical survey program initiated in 1998. Similar type of programs will add more avenues for research in the field of crossshore transport and beach-fill design. Some suggestions are added below for consideration as future research areas. 7.2.1 Dc Criteria and Survey Techniques The analysis above has used only a 30 cm closure criterion associated with hydrographic survey accuracy. Other criteria can be applied if more improved measurement techniques are used. This will allow for a redefinition of the term ‘significant’ when applied to Dc studies. 7.2.2 Wave Data One of the key limitations of this study was the absence of wave data over the erosional northeast monsoon period. As a result, the calibration of the wave model was done based on the wave data recorded over the weaker southwest monsoon which is dominated by low swells. Wave data collection over the northeast monsoon period would provide the more appropriate dataset for verification of the wave model. Such collection has been attempted by many parties with little success. There is generally very little measured wave data available throughout the country which hinders the progress of coastal research. 136 7.2.3 Profile Surveys and Bar Migration Phenomena The profile surveys in this analysis extended over 3000 m from the study shoreline and provided sufficient hydrographic information. In some profiles, when using the FDC method, there were indications of re-opening well beyond the outershore bars suggesting further cross-shore transport activities. Though prohibitive cost-wise, detailed surveys should be attempted beyond 3500 meters from the shoreline to ascertain if the profiles do re-open in deeper waters. A key observation in this research was that the innershore and offshore bars migrated in opposite direction over the same monsoon period. This suggests that different processes take place at different locations along the same profile. One way to study this further is by establishing a periodical survey program supplemented with post-storm surveys. The results of this research have also pointed that the Pengkalan Datu breakwaters have a distinct effect on the Dc results on the adjacent profiles. It is inferred that with both Ch.00 and Ch.200 being immediately on the downdrift side of the breakwater, the alongshore drift would have been eliminated and that the profile formations at both these locations would be predominantly driven by cross-shore process. However, other hitherto uninvestigated factors such as wave reflection off the northern breakwater begs further study. 7.2.4 Determining a predictive formula for local Dc This research has established the major profile trends and the results have pointed to an over-estimation of the Dc by the Hallermeier equation. It is therefore possible to follow the footsteps of Birkemeier and produce a local equation for predicting Dc provided long-term nearshore wave measurements are available to validate the wave numerical model. A simplified relationship between H0.137 and Dl,1-yr (Equation 6.1) has been proposed which establishes an upper limit to the 137 Pantai Sabak Dc based on the criteria applied. It however, cannot be claimed to be applicable to other Malaysian coasts as yet. 138 REFERENCES Ahmad Khairi Bin Abd Wahab (1989); Rivermouth Siltation at Sungai Pengkalan Datu, Kelantan. Universiti Teknologi Malaysia; Master thesis. Battjes, J.A. and Janssen, J.P.F.M. (1978). Energy Loss And Setup Due to Breaking of Random Waves. Proceedings of the 16th Coastal Engineering Conference, American Society of Civil Engineers, pp. 569-587. Birkemeier. W.A. (1985). Field data on seaward limit of profile change. Journal of Waterway, Port, Coastal and Ocean Engineering 11 1(3), 598-602 Bruun, P. (1954). Coast Erosion And The Development of Beach Profiles. US Army Corps of Engineers, Beach Erosion Board, Tech. Memo No. 44 Dean, R.G. (1977). Equilibrium Beach Profiles: U.S. Atlantic and the Gulf Coasts, Department of Civil Engineering, Ocean Engineering Report No. 12, University of Delaware, Newark, DE. Dean, R.G. (2003). Beach Nourishment Theory and Practice, Advanced Series on Ocean Engineering – Volume 18; World Scientific Publishing Co., pp. 34-37 Department of Irrigation and Drainage (1993). Feasibility Study and Detailed Design of Coastal Protection Works at Pengkalan Datu-Kuala Besar, Kelantan, Kampung Buntal, Sarawak and Tanjung Aru-Sungai Kinarut, Sabah; Part 1 – Feasibility Study Final Report Volume 1: Pengkalan Datu – Kuala Besar, 139 Kelantan. Study conducted by Ranhill Bersekutu in association with Unit Penyelidikan dan Perundingan, UTM. June 1993. Francois, S., Stive, M.J.F., Pons, F. (2004). Longshore Variation of Depth of Closure on a Micro-tidal Wave-dominated Coast. In Proc. 29th Coastal Engineering Conference, ASCE (2004). Hallermeier, R. J. (1978). Uses for a calculated limit depth to beach erosion. Proceedings 16th Coastal Engineering Conference, ASCE, 1493-1512 Hallermeier, R.J. (1981). A profile zonation for seasonal sand beaches from wave climate. Coastal Engineering 4, pp. 253–277 Hinton, C. and Nicholls, R.J. (1998). Spatial and temporal behaviour of depth of closure along the Holland coast. In: Proc. 26th Coastal Engineering Conference, ASCE, pp. 2913–2925 Jabatan Pengairan dan Saliran Malaysia (1999). Kerja-kerja Ukur di Pengkalan Datu, Kelantan (Pre-monsoon). Kontrak No. JPS(PP)/PT/1/98. Laporan disediakan oleh Jurukur Nik Hisham & Tung Sdn. Bhd. Jabatan Pengairan dan Saliran Malaysia (1999). Kerja-kerja Ukur di Pengkalan Datu, Kelantan (Post-monsoon). Kontrak No. JPS(PP)/PT/1/98. Laporan disediakan oleh Jurukur Nik Hisham & Tung Sdn. Bhd. Jabatan Pengairan dan Saliran Malaysia (2000). Proposed Survey Work at Pengkalan Datu, Kelantan 26th July, 2000. Report prepared by Kumpulan Ukur Petanah. Jabatan Pengairan dan Saliran Malaysia ( 2002). Internal report on erosion at Pantai Sabak. Jabatan Pengairan dan Saliran Malaysia (2004). Kerja-kerja ukur untuk ‘Nearshore Area from Kuala Besar to Kuala Kemasin (Pantai Sabak)’, Kota Bharu, 140 Kelantan Darul Naim. Report prepared by Wira Ukur Consultant and Jurukur Wibawa. Knudsen, S.B., Laustrup, C., Madsen, H. T., Christensen, E.D. (2002). Sediment transport in the outer part of the coastal profile. In: Proc. 28th Coastal Engineering Conference, ASCE, pp. 2453-2465 Kraus, N.A., Larson, M. and Wise, R. (1998). Depth of Closure in Beach-fill Design; Coastal Engineering Technical Note – II-40 Larsen, M. and Kraus, N.C. (1994a). Temporal and Spatial Scales of Beach Profile Change, Duck, North Carolina. In: Marine Geology 117 (1994), pp.75-94. Larson, M. and Kraus, N. M. (1994b). Prediction of cross-shore sediment transport at different spatial and temporal scales. In: Marine Geology 126 (1995), pp. 111-127. Lee, S.C. (1990). “Stabilisation of River Mouths – The Pengkalan Datu Seaworks Experience”; Department of Irrigation and Drainage Malaysia Senior Engineers’ Conference, Kuantan, Pahang 1990. National Research Council (1995). Beach Nourishment and Protection. National Academies Press, Washington D.C. Nicholls, R.J., Birkemeier, W.A. and Hallermeier, R.J. (1996). Application of the depth of closure concept. In: Proc. 25th Coastal Engineering Conference, ASCE (1996), pp. 3874–3887. Nicholls, R.J., Birkemeier, W.A. and Lee, G. (1998a). Evaluation of depth of closure using data from Duck, NC, USA. Marine Geology 148 (1998), pp. 179– 202. Nicholls, R.J., Capobianco, M., Larson, M. & Birkemeier, W.A. (1998b). Depth of Closure: Improving understanding and prediction. Proceedings 26th 141 International Conference on Coastal Engineering, Copenhagen, ASCE New York, pp. 2888-2901 Rijkswaterstaat (Dutch Public Works Department) (1987). Manual on Artificial Beach Nourishment. Delft Hydraulics Laboratory, The Netherlands. Royal Malaysian Navy (2005). Tide Tables Malaysia 2005. Hydrographic Department, Royal Malaysian Navy US Army Corps of Engineers (1984). Shore Protection Manual, 4th ed. 2 Vol., US Army Engineer Waterways Experiment Station, US Govt. printing office, Washington D.C. US Army Corps of Engineers (2003). Coastal Engineering Manual; Coastal and Hydraulic Laboratory, US Army Corps of Engineers. Unit Perancang Ekonomi (1985). National Coastal Erosion Study Final Report (Volume 1 and 2). Prepared by Stanley Consultants, Moffat and Nichol Engineers and Jurutera Konsultant (SEA) Sdn. Bhd. for Unit Perancang Ekonomi, Jabatan Perdana Menteri Malaysia; August 1985. Unit Perancang Ekonomi (1986). National Coastal Erosion Study Phase II Feasibility Studies Final Report Volume I - Kelantan. Prepared by Stanley Consultants, Moffat and Nichol Engneers and Jurutera Konsultant (SEA) Sdn. Bhd. for Unit Perancang Ekonomi, Jabatan Perdana Menteri Malaysia; January 1986. 142 APPENDIX A PROFILE SURVEYS FROM COASTLINE OF PANTAI SABAK, KELANTAN 1998, 1999, 2000 AND 2004 CH-1400 Distance 0 50 100 150 200 250 300 350 400 450 500 550 600 650 700 750 800 850 900 950 1000 1050 1100 1150 1200 1250 1300 1350 1400 1450 1500 1550 1600 1650 1700 1750 1800 1850 1900 1950 2000 2050 2100 2150 2200 2250 2300 Profile 1998 3.76 2.74 -0.26 -1.28 -1.96 -2.64 -3.18 -3.46 -3.71 -3.6 -3.99 -4.19 -4.24 -4.26 -4.49 -4.6 -4.66 -4.67 -4.77 -5 -4.42 -4.3 -4.66 -4.81 -4.81 -5.02 -5.08 -5.31 -5.34 -5.63 -5.64 -5.69 -5.86 -5.94 -6.14 -6.1 -6.12 -6.41 -6.29 -6.5 -6.5 -6.56 -6.79 -7.14 -7.25 -7.31 -7.54 All levels in m LSD Profile Profile 1999 2000 3.76 3.99 2.78 3.26 0.1 -0.46 -1.14 -1.19 -2.14 -2.23 -2.79 -3.05 -3.06 -3.38 -3.25 -3.49 -3.36 -3.8 -3.92 -4.13 -3.93 -4.3 -3.86 -4 -4.11 -3.8 -4.5 -4.06 -4.66 -4.52 -4.72 -4.92 -4.91 -4.8 -4.91 -4.84 -4.98 -4.73 -4.82 -4.55 -4.48 -4.54 -4.49 -4.73 -4.81 -4.81 -4.88 -4.85 -4.98 -4.95 -5.18 -5.02 -5.33 -5.24 -5.56 -5.36 -5.6 -5.5 -5.73 -5.65 -5.89 -5.76 -5.97 -5.88 -5.98 -6.01 -6.23 -6.15 -6.23 -6.32 -6.41 -6.21 -6.21 -6.16 -6.43 -6.34 -6.47 -6.36 -6.61 -6.44 -6.8 -6.76 -6.96 -6.97 -7.17 -7.11 -7.31 -7.3 -7.46 -7.51 -7.63 -7.57 -7.64 -7.67 Profile 2004 3.67 3 1.85 -0.17 -2.19 -2.95 -4.03 -4.22 -4.24 -4.31 -4.34 -4.56 -4.86 -4.68 -4.78 -5.18 -4.97 -4.7 -4.44 -4.4 -4.56 -4.85 -4.99 -4.16 -4.64 -5.17 -5.31 -5.31 -5.32 -5.67 -5.89 -6 -5.95 -6.03 -6.26 -6.27 -6.24 -6.31 -6.36 -6.42 -6.6 -6.66 -6.65 -6.75 -6.92 -7.02 -7.14 143 CH-1400 Distance 2350 2400 2450 2500 2550 2600 2650 2700 2750 2800 2850 2900 2950 3000 3050 3100 3150 3200 3250 3300 3350 3400 3450 3500 3550 3600 3650 3700 3750 3800 3850 3900 3950 Profile 1998 -7.63 -7.63 -7.79 -7.83 -7.89 -8.03 -8.2 -8.22 -8.44 -8.5 -8.73 -8.92 -9.01 -9.09 -9.15 -9.49 -9.45 -9.72 -9.81 -10.04 -10.13 -10.32 -10.46 -10.55 -10.72 -10.76 -10.86 -10.88 -11.08 -11.18 -11.39 -11.39 0 CH.-900 Distance 0 50 100 150 200 250 300 350 400 450 500 550 600 650 700 Profile 1998 3.19 2.57 2.85 -0.27 -1.21 -2.66 -3.44 -3.58 -3.05 -3.35 -3.72 -3.63 -3.28 -3.44 -3.5 All levels in m LSD Profile Profile 1999 2000 -7.74 -7.69 -7.92 -7.83 -7.95 -7.83 -7.97 -7.97 -8.08 -8.08 -8.15 -8.24 -8.36 -8.34 -8.38 -8.48 -8.44 -8.53 -8.6 -8.69 -8.71 -8.82 -8.99 -8.95 -9.13 -9.09 -9.19 -9.23 -9.36 -9.35 -9.55 -9.48 -9.81 -9.56 -9.88 -9.66 -9.98 -9.79 -10.07 -9.83 -10.26 -9.95 -10.2 -10.06 -10.42 -10.21 -10.54 -10.33 0 -10.51 0 -10.59 0 -10.72 0 -10.87 0 -10.93 0 -11.06 0 -11.12 0 -11.23 0 -11.22 All levels in m LSD Profile 1999 Profile 2000 3.19 3.39 2.83 2.74 3.19 3.09 -0.1 -0.94 -1.62 -1.87 -2.33 -2.75 -3.15 -3.34 -3.59 -3.4 -2.82 -2.6 -3.22 -2.75 -3.89 -3.66 -3.94 -3.61 -3.71 -3.27 -3.3 -3.41 -3.16 -3.45 Profile 2004 -7.24 -7.37 -7.47 -7.48 -7.56 -7.83 -7.93 -7.94 -8.19 -8.26 -8.47 -8.53 -8.7 -8.87 -9.03 -9.08 -9.24 -9.31 -9.53 -9.43 -9.72 -10.02 -9.99 -10.1 -10.23 -10.46 -10.5 -10.7 -10.74 -10.89 -11.03 -11.19 0 Profile 2004 0 2.58 2.93 0.58 -0.69 -2.11 -2.97 -3.69 -3.93 -3.75 -4.05 -4.05 -4.03 -3.51 -3.79 144 CH.-900 Distance 750 800 850 900 950 1000 1050 1100 1150 1200 1250 1300 1350 1400 1450 1500 1550 1600 1650 1700 1750 1800 1850 1900 1950 2000 2050 2100 2150 2200 2250 2300 2350 2400 2450 2500 2550 2600 2650 2700 2750 2800 2850 2900 2950 3000 3050 3100 3150 3200 3250 3300 3350 3400 Profile 1998 -3.46 -3.63 -3.92 -4.04 -4.31 -4.48 -4.71 -4.85 -4.97 -5.05 -5.2 -5.34 -5.57 -5.54 -5.63 -5.73 -5.76 -5.9 -6.07 -6.17 -6.3 -6.4 -6.54 -6.33 -6.69 -6.87 -7.24 -7.29 -7.5 -7.51 -7.39 -7.5 -7.6 -7.74 -7.9 -8.03 -8.28 -8.38 -8.52 -8.61 -8.75 -8.86 -9.01 -9.05 -9.26 -9.43 -9.5 -9.63 -9.72 -9.99 -10.11 -10.13 -10.37 -10.51 All levels in m LSD Profile 1999 Profile 2000 -3.75 -3.63 -3.97 -3.73 -4.15 -3.84 -4.22 -4.14 -4.31 -4.33 -4.5 -4.49 -4.75 -4.61 -4.91 -4.81 -4.99 -4.98 -5.2 -5.21 -5.27 -5.33 -5.43 -5.4 -5.54 -5.47 -5.58 -5.58 -5.69 -5.66 -5.8 -5.69 -5.93 -5.81 -6.09 -5.9 -6.11 -5.94 -6.1 -6.11 -6.36 -6.38 -6.48 -6.55 -6.53 -6.71 -6.68 -6.8 -6.82 -6.8 -7.07 -7.05 -7.15 -7.21 -7.28 -7.24 -7.39 -7.34 -7.46 -7.43 -7.56 -7.56 -7.68 -7.67 -7.78 -7.73 -7.95 -7.84 -8 -7.99 -8.13 -8.06 -8.24 -8.28 -8.35 -8.33 -8.56 -8.46 -8.72 -8.59 -8.79 -8.72 -8.93 -8.89 -9.14 -9.03 -9.22 -9.11 -9.41 -9.28 -9.47 -9.4 -9.73 -9.54 -9.69 -9.62 -9.85 -9.77 -9.98 -9.9 -10.06 -10.01 -10.14 -10.08 -10.33 -10.18 -10.41 -10.31 Profile 2004 -4.34 -3.46 -3.73 -4.21 -4.57 -4.79 -4.96 -5.07 -5.27 -5.21 -5.37 -5.58 -5.49 -5.63 -5.76 -5.92 -5.99 -6.01 -6.04 -6.23 -6.1 -6.27 -6.36 -6.57 -6.58 -6.76 -6.77 -6.76 -6.82 -7.01 -7.07 -7.42 -7.34 -7.44 -7.51 -7.68 -7.55 -8.24 -8.23 -8.45 -8.79 -8.75 -9 -9 -9.17 -9.24 -9.53 -9.88 -9.83 -9.96 -9.73 -10.26 -10.45 -10.53 145 CH.-900 Distance 3450 3500 3550 3600 3650 3700 3750 Profile 1998 -10.66 -10.75 -10.74 -10.94 -10.99 -11.18 0 CH.-400 Distance 0 50 100 150 200 250 300 350 400 450 500 550 600 650 700 750 800 850 900 950 1000 1050 1100 1150 1200 1250 1300 1350 1400 1450 1500 1550 1600 1650 1700 1750 1800 1850 1900 1950 2000 Profile 1998 2.39 2.4 2.23 1.71 -0.97 -1.93 -2.86 -3.16 -2.78 -2.82 -2.48 -3.05 -3.27 -3.41 -3.66 -3.57 -3.58 -3.81 -3.95 -4.24 -4.36 -4.36 -4.57 -4.7 -5.02 -5.04 -5.07 -5.28 -5.47 -5.53 -5.9 -6.03 -6.07 -6.13 -6.26 -6.43 -6.65 -6.63 -6.87 -6.78 -6.96 All levels in m LSD Profile 1999 Profile 2000 -10.54 -10.47 -10.66 -10.57 -10.66 -10.7 -10.8 -10.84 0 -10.99 0 -11.08 0 -11.21 All levels ini m LSD Profile Profile 1999 2000 2.4 2.36 2.38 2.79 2.19 2.42 1.38 1.62 -1.09 -1.21 -2.29 -2.61 -3.21 -3.16 -3.61 -3.1 -2.91 -2.19 -2.45 -2.51 -3.01 -3.29 -3.08 -3.48 -3.19 -3.17 -3.48 -2.88 -3.79 -3.09 -3.8 -3.46 -3.75 -3.85 -3.82 -4.11 -3.97 -4.3 -4.25 -4.49 -4.65 -4.61 -4.65 -4.61 -4.84 -4.71 -4.97 -4.91 -5.2 -5.12 -5.33 -5.2 -5.4 -5.27 -5.49 -5.39 -5.68 -5.53 -5.72 -5.66 -5.96 -5.9 -6.18 -6.02 -6.14 -6.14 -6.31 -6.24 -6.41 -6.35 -6.49 -6.5 -6.58 -6.58 -6.71 -6.73 -6.78 -6.78 -6.86 -6.89 -7.11 -7.03 Profile 2004 -10.53 -10.65 -10.84 -10.86 -11.06 -11.35 -11.03 Profile 2004 -0.71 -1.31 1.42 2.51 0.55 -1.44 -2.68 -3.34 -3.68 -3.05 -2.5 -2.54 -3.11 -3.38 -3.5 -3.62 -3.75 -3.95 -4.16 -4.43 -4.67 -4.84 -5.06 -5.2 -5.29 -5.29 -5.39 -5.46 -5.57 -5.7 -5.79 -5.89 -5.97 -6.04 -6.1 -6.23 -6.3 -6.47 -6.57 -6.66 -6.78 146 CH.-400 Distance 2050 2100 2150 2200 2250 2300 2350 2400 2450 2500 2550 2600 2650 2700 2750 2800 2850 2900 2950 3000 3050 3100 3150 3200 3250 3300 3350 3400 3450 Profile 1998 -7.05 -7.19 -7.26 -7.49 -7.5 -7.84 -7.78 -8.04 -8.07 -8.2 -8.47 -8.66 -8.76 -8.84 -8.97 -9.13 -9.33 -9.37 -9.61 -9.62 -9.93 -9.96 -10.12 -10.31 -10.52 -10.66 -10.81 -11.01 -11.07 All levels ini m LSD Profile Profile 1999 2000 -7.26 -7.14 -7.4 -7.24 -7.57 -7.38 -7.61 -7.58 -7.63 -7.66 -7.94 -7.84 -7.98 -7.88 -8.17 -8.13 -8.35 -8.23 -8.56 -8.3 -8.59 -8.43 -8.75 -8.63 -8.88 -8.73 -8.94 -9.03 -9.1 -9.21 -9.2 -9.3 -9.26 -9.46 -9.54 -9.62 -9.61 -9.77 -9.78 -9.94 -9.99 -10.14 -10.05 -10.28 -10.29 -10.43 -10.35 -10.53 -10.51 -10.56 -10.56 -10.56 -10.86 -10.7 -10.98 -10.86 -11.01 -10.99 CH.00 Distance 0 50 100 150 200 250 300 350 400 450 500 550 600 650 700 750 800 850 900 Profile1998 2.35 3.04 -1.06 -1.09 -1.31 -1.56 -1.76 -1.53 -1.88 -2.4 -2.66 -2.17 -2.35 -1.84 -2.81 -3.23 -2.91 -2.7 -3.02 All levels in m LSD Profile 1999 Profile 2000 2.56 2.6 3.09 2.91 -0.99 -1.1 -0.89 -1.11 -1.4 -1.6 -1.79 -1.87 -1.42 -1.53 -1.91 -1.93 -2.22 -2.26 -2.64 -2.83 -2.67 -2.88 -1.89 -1.92 -1.87 -1.45 -3.04 -2.72 -3.56 -3.74 -3.85 -4.1 -3.62 -3.14 -2.34 -2.15 -3.06 -2.93 Profile 2004 -6.93 -7.09 -7.2 -7.36 -7.54 -7.69 -7.88 -8.08 -8.33 -8.45 -8.6 -8.77 -8.9 -9.09 -9.25 -9.37 -9.5 -9.62 -9.78 -9.88 -10.05 -10.22 -10.28 -10.51 -10.66 -10.8 -10.89 -11.11 -11.24 Profile 2004 2.45 1.37 0.98 -0.82 -0.8 0.36 -1.56 -1.99 -2.33 -2.92 -3.13 -1.95 -1.93 -2.52 -3.71 -3.73 -2.98 -3 -3.06 147 CH.00 Distance 950 1000 1050 1100 1150 1200 1250 1300 1350 1400 1450 1500 1550 1600 1650 1700 1750 1800 1850 1900 1950 2000 2050 2100 2150 2200 2250 2300 2350 2400 2450 2500 2550 2600 2650 2700 2750 2800 2850 2900 2950 3000 CH.200 Distance 0 50 100 150 200 250 300 Profile1998 -3.53 -3.82 -3.93 -3.79 -4.01 -4.22 -4.08 -3.22 -3.12 -3.85 -4.49 -4.7 -4.72 -4.76 -5.04 -5.39 -5.47 -5.54 -5.69 -5.69 -5.88 -6.07 -6.42 -6.52 -6.62 -6.77 -6.85 -6.85 -6.94 -7.1 -7.31 -7.61 -7.85 -7.97 -8.17 -8.42 -8.52 -8.7 -9.08 -9.4 -9.66 Profile 1998 1.25 -0.86 -1.01 -1.39 -1.59 -1.78 -1.86 All levels in m LSD Profile 1999 Profile 2000 -3.6 -3.82 -3.87 -4.14 -4 -3.63 -3.79 -3.81 -3.97 -4.03 -4.2 -4.28 -4.44 -4.52 -4.17 -4.47 -4 -4.3 -3.55 -4.1 -3.63 -4 -4.27 -4.12 -4.98 -4.63 -5.27 -5.51 -5.46 -5.77 -5.49 -5.9 -5.55 -6 -5.67 -6.09 -5.86 -6.25 -6.1 -6.28 -6.22 -6.47 -6.35 -6.48 -6.52 -6.52 -6.53 -6.6 -6.64 -6.68 -6.74 -6.76 -6.84 -6.96 -6.99 -7.03 -7.08 -7.07 -7.14 -7.26 -7.32 -7.64 -7.72 -7.84 -7.88 -7.94 -8.04 -8.25 -8.24 -8.37 -8.35 -8.48 -8.5 -8.66 -8.81 -8.87 -9.08 -9.28 -9.47 -9.53 -9.64 -9.72 -9.84 -9.94 All levels in m LSD Profile 1999 Profile 2000 0.95 1.28 -1.35 -1.21 -1.09 -1.3 -1.38 -1.61 -1.64 -1.77 -1.74 -1.86 -1.87 -2.07 Profile 2004 -3.08 -3.44 -3.6 -3.77 -3.96 -4.19 -4.14 -4.5 -4.41 -4.81 -4.79 -4.88 -5.15 -5.25 -5.54 -5.47 -5.63 -5.71 -5.97 -5.9 -6.05 -6.16 -6.21 -6.42 -6.49 -6.75 -6.64 -6.85 -7 -7.45 -7.72 -7.82 -8.21 -8.12 -8.12 -8.32 -8.92 -9.08 -9.49 -9.47 -9.7 -10.22 Profile 2004 -1.44 -1.49 -1.55 -1.7 -1.83 -1.98 -2.02 148 CH.200 Distance 350 400 450 500 550 600 650 700 750 800 850 900 950 1000 1050 1100 1150 1200 1250 1300 1350 1400 1450 1500 1550 1600 1650 1700 1750 1800 1850 1900 1950 2000 2050 2100 2150 2200 2250 2300 2350 2400 2450 2500 2550 2600 2650 2700 2750 2800 2850 2900 2950 3000 Profile 1998 -2.16 -2.42 -2.43 -2.26 -1.46 -1.75 -2.91 -3.31 -3.22 -2.57 -2.86 -3.37 -3.67 -3.67 -3.06 -2.99 -3.66 -4.01 -4.22 -4.5 -4.42 -3.75 -3.75 -3.99 -4.37 -4.92 -5.09 -5.05 -5.09 -5.25 -5.37 -5.58 -5.86 -6.05 -6.16 -6.29 -6.39 -6.44 -6.63 -6.82 -6.91 -7.11 -7.48 -7.73 -7.84 -7.98 -8.19 -8.36 -8.38 -8.57 -8.95 -9.34 -9.5 -9.56 All levels in m LSD Profile 1999 Profile 2000 -2.06 -2.33 -2.65 -2.7 -2.79 -2.68 -1.95 -2.14 -1.73 -1.62 -2.48 -1.97 -2.87 -2.72 -3.38 -3.63 -3.35 -3.8 -2.49 -3.18 -3.06 -2.19 -3.44 -3.43 -3.81 -4.11 -3.95 -4.08 -3.29 -3.29 -2.65 -3.13 -3.37 -3.48 -3.97 -3.98 -4.24 -4.21 -4.49 -4.42 -4.64 -4.49 -4.14 -4.28 -4 -4.28 -3.86 -4.1 -4.24 -4.37 -4.7 -4.77 -5.02 -5.04 -5.25 -5.17 -5.22 -5.23 -5.35 -5.31 -5.36 -5.29 -5.44 -5.28 -5.89 -5.66 -6.05 -6.06 -6.22 -6.24 -6.44 -6.31 -6.51 -6.48 -6.69 -6.63 -6.78 -6.75 -6.92 -6.85 -7.05 -7.2 -7.37 -7.43 -7.65 -7.7 -7.9 -7.83 -7.89 -7.92 -8.14 -8.06 -8.23 -8.14 -8.36 -8.36 -8.36 -8.46 -8.56 -8.73 -9.1 -9.13 -9.4 -9.38 -9.53 -9.59 -9.63 -9.74 Profile 2004 -2.14 -2.51 -1.96 -1.82 -1.7 -2.6 -3.26 -3.78 -2.99 -2.16 -2.46 -3.18 -3.61 -3.65 -3.62 -4 -4.12 -4.13 -4.25 -4.49 -4.42 -4 -3.95 -4.28 -4.65 -5.14 -5.42 -5.55 -5.7 -5.79 -5.92 -6.02 -6.14 -6.27 -6.39 -6.45 -6.56 -6.84 -6.91 -7.04 -7.1 -7.41 -7.55 -7.71 -7.88 -8.03 -8.33 -8.65 -8.9 -9.19 -9.39 -9.57 -9.63 -9.83 149 CH.400 Distance 0 50 100 150 200 250 300 350 400 450 500 550 600 650 700 750 800 850 900 950 1000 1050 1100 1150 1200 1250 1300 1350 1400 1450 1500 1550 1600 1650 1700 1750 1800 1850 1900 1950 2000 2050 2100 2150 2200 2250 2300 2350 2400 2450 2500 2550 Profile 1998 2.14 -0.96 -1.24 -1.59 -1.89 -2.17 -2.41 -2.49 -2.28 -1.89 -2.02 -2.56 -2.79 -2.99 -3.3 -3.48 -3.47 -3.39 -3.38 -3.83 -3.7 -3.15 -3.07 -3.61 -4.05 -4.2 -4.07 -4.23 -4.05 -3.77 -3.67 -3.81 -4.13 -4.69 -5.06 -5.37 -5.47 -5.63 -5.81 -5.87 -6.1 -6.1 -6.23 -6.36 -6.55 -6.67 -6.77 -6.92 -7.15 -7.37 -7.58 -7.7 All levels in m LSD Profile 1999 Profile 2000 2.65 2.39 -1.02 -1.15 -1.5 -1.65 -1.8 -1.93 -1.91 -2.17 -2.06 -2.32 -2.47 -2.45 -2.8 -2.65 -2.57 -2.42 -1.79 -1.66 -2.54 -1.77 -2.61 -2.51 -2.76 -2.76 -2.94 -3.21 -3.27 -3.42 -3.49 -3.76 -3.65 -3.78 -3.35 -3.22 -3.63 -3.62 -3.92 -3.98 -3.78 -3.8 -3.24 -3.12 -3.32 -3.46 -3.72 -3.58 -3.98 -3.7 -4.21 -4.14 -4.45 -4.59 -4.26 -4.61 -3.87 -3.51 -3.82 -3.39 -3.58 -3.93 -3.71 -3.94 -4.1 -3.92 -4.74 -4.6 -5.11 -4.81 -5.01 -5.28 -5.44 -5.22 -5.51 -5.56 -5.67 -5.52 -5.76 -5.63 -5.91 -5.85 -6.02 -5.99 -6.26 -6.18 -6.42 -6.36 -6.58 -6.47 -6.59 -6.62 -6.81 -6.82 -6.95 -6.87 -7.14 -7.18 -7.43 -7.29 -7.55 -7.56 -7.69 -7.72 Profile 2004 -0.54 -0.65 -0.75 -1.84 -2 -2.01 -2.22 -2.42 -2.6 -2.61 -1.57 -1.4 -2.56 -3.06 -2.93 -2.95 -3.54 -3.64 -3.47 -3.78 -3.97 -3.68 -3.19 -3.16 -3.46 -3.86 -4.1 -4.32 -4.54 -4.59 -4.2 -4.21 -4.46 -4.61 -4.82 -4.84 -4.86 -5.28 -5.61 -5.74 -5.98 -6.14 -6.28 -6.39 -6.48 -6.75 -6.98 -7.18 -7.36 -7.45 -7.59 -7.79 150 CH.400 Distance 2600 2650 2700 2750 2800 2850 2900 2950 3000 CH.800 Distance 0 50 100 150 200 250 300 350 400 450 500 550 600 650 700 750 800 850 900 950 1000 1050 1100 1150 1200 1250 1300 1350 1400 1450 1500 1550 1600 1650 1700 1750 1800 1850 1900 1950 2000 Profile 1998 -7.89 -8.02 -8.24 -8.45 -8.65 -8.78 -9.1 -9.33 -9.68 All levels in m LSD Profile 1999 Profile 2000 -7.95 -7.92 -8.06 -8.1 -8.27 -8.25 -8.48 -8.43 -8.65 -8.6 -8.64 -8.76 -8.99 -8.9 -9.29 -9.3 -9.57 -9.59 Profile 2004 -8.02 -8.18 -8.38 -8.47 -8.68 -8.96 -9.14 -9.37 -9.69 Profile 1998 1.82 0.05 -1.12 -1.93 -2.19 -1.89 -1.35 -2.17 -2.77 -2.99 -2.13 -2.67 -3.02 -3.25 -3.37 -3.5 -3.62 -3.8 -3.54 -3.46 -3.4 -3.62 -3.72 -3.68 -3.57 -3.43 -3.45 -2.94 -2.76 -3.41 -3.94 -4.08 -4.32 -4.57 -4.85 -4.95 -5.18 -5.34 -5.46 -5.61 -5.74 All levels in m LSD Profile 1999 Profile 2000 1.82 2.41 -0.61 -0.57 -1.47 -1.38 -2.23 -1.95 -2.43 -2.34 -2.33 -1.85 -1.55 -2.14 -2.44 -2.33 -2.81 -2.51 -2.8 -2.59 -2.75 -2.68 -2.86 -2.77 -3.04 -3.01 -3.25 -3.26 -3.39 -3.51 -3.61 -3.61 -3.67 -3.76 -3.9 -3.78 -3.74 -3.81 -3.57 -3.71 -3.7 -3.78 -3.73 -3.86 -3.77 -3.57 -3.51 -3.43 -3.59 -3.48 -3.71 -3.83 -4.05 -4.68 -3.8 -3.83 -3.15 -2.39 -2.76 -2.86 -3.43 -3.75 -4.1 -4.16 -4.43 -4.44 -4.76 -4.68 -4.93 -4.93 -5.1 -5.14 -5.29 -5.29 -5.53 -5.37 -5.54 -5.58 -5.77 -5.75 -6.05 -5.72 Profile 2004 0.47 0.26 -1.22 -2.04 -2.29 -2.47 -2.68 -2.82 -1.98 -1.73 -2.26 -2.47 -2.78 -3.13 -3.37 -3.7 -3.88 -4.02 -3.9 -3.82 -4.1 -4.04 -3.19 -2.94 -3.62 -3.93 -4.15 -4.25 -4.17 -3.91 -3.33 -3.74 -3.72 -3.96 -4.4 -4.95 -5.44 -5.69 -5.73 -5.78 -5.95 151 CH.800 Distance 2050 2100 2150 2200 2250 2300 2350 2400 2450 2500 2550 2600 2650 2700 2750 2800 2850 2900 2950 3000 CH.1200 Distance 0 50 100 150 200 250 300 350 400 450 500 550 600 650 700 750 800 850 900 950 1000 1050 1100 1150 1200 1250 1300 1350 1400 Profile 1998 -5.9 -6.01 -6.17 -6.38 -6.52 -6.66 -6.86 -6.98 -7.29 -7.6 -7.95 -8.17 -8.4 -8.5 -8.72 -8.94 -9.08 -9.32 -9.71 -10.13 Profile 1998 1.35 1.86 -0.82 -1.53 -1.2 -2.02 -2.46 -2.51 -1.61 -2.08 -3.04 -3.26 -3.23 -3.4 -3.66 -3.77 -3.68 -3.67 -3.7 -3.34 -3.3 -3.48 -3.35 -2.95 -2.23 -2.02 -3.05 -3.6 -3.46 All levels in m LSD Profile 1999 Profile 2000 -6.06 -5.88 -6.18 -6.09 -6.26 -6.18 -6.48 -6.38 -6.61 -6.4 -6.86 -6.46 -7.06 -6.97 -7.31 -7.25 -7.47 -7.38 -7.75 -7.78 -8.13 -8 -8.29 -8.16 -8.5 -8.32 -8.66 -8.57 -8.9 -8.73 -9.04 -8.94 -9.2 -9.15 -9.47 -9.43 -9.79 -9.62 -9.95 -9.87 All levels in m LSD Profile 1999 Profile 2000 1.35 1.53 1.98 2.25 -0.9 -1.23 -1.46 -1.56 -1.43 -1.73 -1.98 -2.14 -2.57 -2.6 -2.77 -2.13 -1.88 -2.17 -2.53 -2.65 -2.87 -2.89 -3.17 -3.07 -3.31 -3.21 -3.44 -3.42 -3.61 -3.54 -3.7 -3.6 -3.76 -3.67 -3.72 -3.66 -3.81 -3.78 -3.56 -3.52 -3.4 -3.2 -3.24 -3.29 -3.42 -3.47 -3.04 -3.21 -2.58 -2.78 -2.36 -3.28 -2.82 -2.96 -3.19 -2.35 -3.17 -2.49 Profile 2004 -6.15 -6.26 -6.33 -6.5 -6.65 -6.95 -7.17 -7.49 -7.7 -7.94 -8.25 -8.42 -8.67 -8.73 -8.95 -9.17 -9.55 -9.8 -9.91 -10.11 Profile 2004 1.61 0.52 -1.47 -2.66 -2.77 -2.3 -1.69 -1.53 -2.12 -2.49 -2.98 -3.19 -3.34 -3.53 -3.7 -3.77 -3.78 -3.82 -3.75 -3.43 -3.18 -3.36 -3.58 -3.63 -3.59 -3.46 -3.51 -3.51 -2.96 152 CH.1200 Distance 1450 1500 1550 1600 1650 1700 1750 1800 1850 1900 1950 2000 2050 2100 2150 2200 2250 2300 2350 2400 2450 2500 2550 2600 2650 2700 2750 2800 2850 2900 2950 3000 CH.1500 Distance 0 50 100 150 200 250 300 350 400 450 500 550 600 650 700 750 800 Profile 1998 -3.47 -3.62 -3.8 -4.04 -4.26 -4.27 -4.28 -4.20 -4.28 -4.37 -4.49 -4.65 -4.85 -5.01 -5.08 -5.21 -5.36 -5.45 -5.57 -5.82 -6.12 -6.49 -7.03 -7.49 -7.74 -8.09 -8.49 -8.91 -9.4 -9.87 -10.08 -10.13 Profile 1998 1.32 1.88 -1.27 -2.03 -1.95 -1.98 -2.48 -2.64 -2.79 -3.08 -3.18 -3.5 -3.65 -3.76 -3.84 -3.86 -3.45 All levels in m LSD Profile 1999 Profile 2000 -3.13 -3.01 -3.43 -3.39 -3.82 -3.66 -4.13 -3.83 -4.21 -4 -4.29 -4.03 -4.41 -4.02 -4.27 -4.1 -4.33 -4.15 -4.39 -4.24 -4.6 -4.35 -4.67 -4.53 -4.84 -4.71 -4.99 -4.86 -5.15 -5 -5.3 -5.11 -5.48 -5.2 -5.52 -5.29 -5.65 -5.44 -5.87 -5.67 -6.14 -5.96 -6.62 -6.45 -7.13 -6.95 -7.5 -7.41 -7.85 -7.69 -8.18 -8 -8.57 -8.44 -8.93 -8.86 -9.38 -9.39 -9.82 -9.85 -9.94 -10 -10.03 -10.19 All levels in m LSD Profile 1999 Profile 2000 1.32 1.61 1.87 0.54 -1.33 -1.28 -2.21 -2.27 -2.51 -2.1 -1.74 -2.37 -2.34 -2.61 -2.98 -2.99 -3.15 -3.12 -3.43 -3.37 -3.6 -3.49 -3.51 -3.61 -3.76 -3.66 -3.76 -3.83 -3.88 -3.9 -3.88 -3.84 -3.74 -3.87 Profile 2004 -2.14 -2.12 -3.2 -3.73 -3.72 -3.77 -3.94 -3.97 -4.01 -4.11 -4.4 -4.69 -4.73 -4.8 -4.94 -5.21 -5.3 -5.24 -5.49 -5.79 -6.05 -6.55 -6.98 -7.41 -7.79 -8.26 -8.6 -9.08 -9.52 -10.09 -10.32 -10.54 Profile 2004 3.39 -0.23 -2.42 -2.46 -2.37 -2.16 -2.23 -2.8 -3.19 -3.53 -3.68 -3.83 -3.81 -3.87 -3.88 -4.05 -4.03 153 CH.1500 Distance 850 900 950 1000 1050 1100 1150 1200 1250 1300 1350 1400 1450 1500 1550 1600 1650 1700 1750 1800 1850 1900 1950 2000 2050 2100 2150 2200 2250 2300 2350 2400 2450 2500 2550 2600 2650 2700 2750 2800 2850 2900 2950 3000 CH.1900 Distance 0 50 100 150 200 Profile 1998 -2.93 -2.58 -2.38 -2.8 -3.08 -3.42 -3.85 -3.85 -3.54 -3.37 -3.58 -3.77 -3.97 -4.04 -4.04 -4.08 -4.06 -4.15 -4.15 -4.18 -4.28 -4.28 -4.28 -4.34 -4.4 -4.56 -4.63 -4.82 -4.94 -5.07 -5.38 -5.63 -5.99 -6.42 -7.06 -7.76 -8.33 -8.67 -9.12 -9.69 -9.88 -9.98 -10.18 All levels in m LSD Profile 1999 Profile 2000 -3.48 -3.89 -3.18 -3.46 -2.59 -2.43 -2.52 -2.78 -3.2 -3.31 -3.61 -3.24 -3.89 -3.78 -4.03 -4.2 -3.84 -3.42 -3.46 -3.18 -3.51 -3.64 -3.74 -3.97 -3.99 -4.13 -4.11 -4.16 -4.23 -4.15 -4.11 -4.19 -4.02 -4.11 -4.07 -4.05 -4.16 -4.08 -4.19 -4.05 -4.21 -4.15 -4.24 -4.15 -4.32 -4.27 -4.42 -4.34 -4.49 -4.48 -4.55 -4.62 -4.77 -4.72 -4.75 -4.8 -4.92 -5 -5.17 -5.2 -5.42 -5.35 -5.69 -5.61 -6.1 -6.05 -6.49 -6.46 -7.12 -7.09 -7.85 -7.74 -8.32 -8.4 -8.69 -8.79 -9.26 -9.33 -9.82 -9.82 -9.93 -10.04 -10.09 -10.2 -10.5 Profile 1998 2.42 -0.17 -1.64 -2 -2.22 All levels in m LSD Profile 1999 Profile 2004 2.42 -2.42 -1.29 -2.86 -2.01 -3.02 -2.2 -3.16 -2.54 -3.1 Profile 2004 -3.86 -3.83 -3.61 -3.33 -3.54 -4.05 -4.24 -4.31 -3.61 -2.57 -2.48 -3.11 -3.84 -4.2 -4.25 -4.26 -4.25 -4.22 -4.18 -4.19 -4.17 -4.16 -4.22 -4.43 -4.48 -4.67 -4.95 -4.97 -5.12 -5.27 -5.52 -5.75 -6.06 -6.47 -7.12 -7.69 -8.15 -8.67 -9.39 -9.97 -10.3 -10.5 -10.62 -10.79 154 CH.1900 Distance 250 300 350 400 450 500 550 600 650 700 750 800 850 900 950 1000 1050 1100 1150 1200 1250 1300 1350 1400 1450 1500 1550 1600 1650 1700 1750 1800 1850 1900 1950 2000 2050 2100 2150 2200 2250 2300 2350 2400 2450 2500 2550 2600 2650 2700 2750 2800 2850 2900 Profile 1998 -2.74 -3.07 -3.29 -3.5 -3.68 -3.57 -3.66 -3.96 -4.04 -4.18 -3.14 -2.8 -3.28 -3.75 -3.93 -4.05 -4.11 -4.25 -4.17 -4.29 -4.49 -4.53 -4.52 -4.45 -4.21 -3.96 -3.86 -3.47 -3.23 -2.74 -3.05 -3.25 -3.66 -4.07 -4.21 -4.45 -4.86 -5.26 -5.53 -6.04 -6.44 -6.86 -7.19 -7.81 -8.15 -8.62 -8.92 -9.24 -9.61 -9.69 -9.9 -9.96 -10.15 -10.25 All levels in m LSD Profile 1999 Profile 2004 -2.76 -2.84 -3.09 -3.03 -3.31 -3.33 -3.53 -3.62 -3.69 -3.84 -3.82 -4.02 -3.82 -4.15 -3.92 -4.27 -4.07 -4.22 -4.3 -4.3 -2.73 -4.07 -2.34 -3.17 -2.87 -3.12 -3.63 -3.67 -3.9 -4.29 -4.11 -4.64 -4.08 -4.32 -4.11 -3.45 -4.34 -3.33 -4.41 -3.62 -4.61 -4.03 -4.76 -4.4 -4.48 -4.5 -4.4 -4.59 -4.27 -4.69 -4.1 -4.58 -3.82 -4.22 -3.38 -3.9 -3.14 -3.54 -3.01 -3.45 -2.93 -3.45 -3.18 -3.57 -3.59 -3.69 -3.88 -3.91 -4.23 -4.17 -4.46 -4.48 -4.78 -4.84 -5.27 -5.18 -5.57 -5.48 -5.98 -5.94 -6.38 -6.37 -6.88 -6.77 -7.17 -7.21 -7.75 -7.71 -8.11 -8.14 -8.58 -8.51 -8.86 -8.92 -9.24 -9.44 -9.59 -9.77 -9.74 -9.94 -9.86 -10.08 -10.12 -10.24 -10.24 -10.43 -10.42 -10.53 155 CH.1900 Distance 2950 3000 3050 3100 3150 3200 3250 3300 3350 Profile 1998 -10.41 -10.64 -10.64 -10.87 -11.03 -11.23 -11.31 -11.41 CH.2300 Distance 0 50 100 150 200 250 300 350 400 450 500 550 600 650 700 750 800 850 900 950 1000 1050 1100 1150 1200 1250 1300 1350 1400 1450 1500 1550 1600 1650 1700 1750 1800 1850 1900 1950 2000 Profile 1998 2.71 -1.33 -2.23 -2.58 -2.97 -3.17 -3.32 -3.44 -3.67 -3.4 -3.05 -3.63 -3.89 -3.94 -3.99 -3.88 -3.96 -3.82 -3.84 -3.76 -3.79 -3.99 -4.21 -4.43 -3.86 -3.31 -2.98 -3.15 -3.46 -3.72 -4.03 -4.2 -4.63 -5.01 -5.38 -6 -6.59 -6.91 -7.07 -7.24 -7.41 All levels in m LSD Profile 1999 Profile 2004 -10.55 -10.7 -10.58 -10.81 -10.58 -10.91 -10.78 -11.08 -10.97 -11.19 -10.96 -11.36 -11.29 -11.5 -11.65 -11.84 All levels in m LSD Profile 1999 Profile 2004 1.96 -2.61 -1.6 -2.63 -2.11 -2.14 -2.36 -2.34 -2.82 -2.88 -3.07 -3.05 -3.29 -3.29 -3.44 -3.48 -3.59 -3.62 -2.88 -3.74 -3.03 -3.89 -3.51 -4.1 -3.68 -3.54 -3.79 -2.58 -3.88 -2.92 -3.9 -3.65 -4.01 -4.09 -3.8 -4.09 -3.9 -3.6 -3.87 -3.29 -3.78 -3.6 -3.98 -3.82 -4.28 -4.09 -4.35 -4.21 -3.92 -4.04 -3.37 -3.4 -3.06 -3.13 -3.15 -3.28 -3.35 -3.52 -3.61 -3.67 -4.03 -3.87 -4.3 -4.08 -4.6 -4.43 -5.03 -5.26 -5.49 -5.96 -6.13 -6.44 -6.81 -6.67 -7.07 -6.84 -7.19 -7.09 -7.32 -7.24 -7.51 -7.49 156 CH.2300 Distance 2050 2100 2150 2200 2250 2300 2350 2400 2450 2500 2550 2600 2650 2700 2750 2800 2850 2900 2950 3000 3050 3100 3150 3200 3250 3300 3350 3400 Profile 1998 -7.5 -7.75 -7.99 -8.19 -8.43 -8.56 -8.71 -8.79 -9.06 -9.09 -9.25 -9.43 -9.69 -9.85 -10.14 -10.3 -10.37 -10.51 -10.58 -10.77 -10.84 -11.15 -11.46 -11.44 -11.46 0 CH.2700 Distance 0 50 100 150 200 250 300 350 400 450 500 550 600 650 700 750 800 850 All levels in m LSD Profile 1999 Profile 2004 -7.62 -7.64 -7.77 -7.83 -8.04 -7.97 -8.23 -8.12 -8.24 -8.33 -8.44 -8.43 -8.7 -8.57 -8.89 -8.71 -8.98 -8.85 -9.06 -9 -9.23 -9.13 -9.5 -9.38 -9.85 -9.5 -9.95 -9.65 -10.09 -9.81 -10.17 -9.96 -10.3 -10.14 -10.45 -10.33 -10.52 -10.57 -10.73 -10.75 -10.89 -10.92 -10.99 -11.11 -11.26 -11.43 -11.59 -11.78 -11.88 All levels in m LSD Profile 1998 2.09 2.72 -0.8 -1.72 -2.36 -2.79 -3.27 -2.81 -2.41 -3.1 -3.71 -3.93 -3.35 -3.56 -4.16 -3.71 -3.18 -3.34 Profile 1999 2.09 1.82 -1.4 -1.92 -2.12 -2.68 -3.1 -2.54 -2.07 -3.28 -3.57 -3.72 -3.51 -3.68 -4.24 -3.52 -3.12 -3.41 Profile 2000 2.53 -1.37 -2.14 -2.07 -2.17 -2.63 -3.1 -2.71 -2.23 -3.09 -3.46 -3.54 -3.55 -3.98 -3.99 -3.34 -3.4 -3.6 Profile 2004 -0.01 -1.29 -2.45 -2.1 -2.34 -2.91 -3.21 -3.09 -3.34 -3.58 -3.47 -2.76 -3.55 -4.42 -4.18 -3.35 -3.29 -3.56 157 CH.2700 Distance 900 950 1000 1050 1100 1150 1200 1250 1300 1350 1400 1450 1500 1550 1600 1650 1700 1750 1800 1850 1900 1950 2000 2050 2100 2150 2200 2250 All levels in m LSD Profile 1998 -3.64 -4.05 -4.37 -4.8 -5.19 -5.62 -5.94 -6.14 -6.33 -6.47 -6.64 -6.72 -6.83 -6.89 -7.07 -7.21 -7.22 -7.33 -7.48 -7.56 -7.69 -7.8 -7.87 -8.01 -8.13 -8.21 Profile 1999 -3.69 -4.11 -4.52 -4.84 -5.17 -5.65 -6.06 -6.42 -6.62 -6.79 -6.98 -7.11 -7.19 -7.31 -7.31 -7.51 -7.57 -7.6 -7.74 -7.77 -7.84 -7.92 -8.01 -8.01 -8.01 -8.12 -8.18 -8.25 CH.3100 Distance 0 50 100 150 200 250 300 350 400 450 500 550 600 650 700 750 800 850 Profile 2000 -3.65 -4.25 -4.6 -4.96 -5.24 -5.87 -6.33 -6.44 -6.61 -6.75 -6.88 -6.97 -7.08 -7.18 -7.27 -7.32 -7.43 -7.49 -7.6 -7.72 -7.78 -7.84 -7.94 -8.05 -8.16 -8.3 -8.39 Profile 2004 -3.91 -4.18 -4.51 -4.92 -5.36 -5.76 -5.97 -6.11 -6.3 -6.39 -6.49 -6.64 -6.72 -6.83 -6.95 -6.99 -7.09 -7.22 -7.28 -7.34 -7.51 -7.59 -7.7 -7.7 -7.8 -7.89 -8 -8.07 All levels in m LSD Profile 1998 1.71 -1.56 -1.87 -2.36 -3.04 -3.09 -2.19 -2.8 -3.6 -3.35 -2.89 -3.75 -4.02 -4.28 -4.21 -3.3 -3.16 -3.54 Profile 1999 1.9 -1.58 -1.82 -2.45 -3.08 -2.77 -2.5 -3.22 -3.69 -3.07 -2.92 -3.71 -3.88 -4.06 -4.12 -3.13 -3.33 -3.71 Profile 2000 0.53 -1.71 -1.93 -2.46 -2.98 -2.24 -3.02 -3.67 -3.44 -2.71 -3.27 -3.68 -3.94 -4.23 -3.81 -3.26 -3.28 -3.69 Profile 2004 -0.22 -0.5 -2.11 -2.65 -2.91 -3.35 -3.65 -3.56 -3.29 -2.77 -2.66 -3.64 -4.29 -4.58 -3.71 -3.3 -3.49 -3.81 158 CH.3100 Distance 900 950 1000 1050 1100 1150 1200 1250 1300 1350 1400 1450 1500 1550 1600 1650 1700 1750 1800 1850 1900 1950 2000 2050 2100 2150 2200 2250 2300 2350 2400 2450 2500 All levels in m LSD Profile 1998 -4.02 -4.47 -4.96 -5.42 -5.91 -6.13 -6.28 -6.5 -6.58 -6.79 -6.84 -7.03 -7.08 -7.25 -7.3 -7.43 -7.5 -7.65 -7.75 -7.9 -7.9 -8.01 -8.04 -8.23 -8.19 -8.33 -8.44 0 0 0 0 0 0 Profile 1999 -4.14 -4.53 -5.08 -5.51 -5.93 -6.39 -6.6 -6.75 -6.97 -7.05 -7.14 -7.2 -7.3 -7.4 -7.46 -7.51 -7.62 -7.66 -7.83 -7.81 -7.89 -7.9 -8.05 -8.05 -8.18 -8.31 -8.37 -8.54 -8.63 0 0 0 0 Profile 2000 -4.09 -4.52 -5.01 -5.43 -5.85 -6.3 -6.53 -6.65 -6.75 -6.95 -6.99 -7.04 -7.18 -7.24 -7.33 -7.37 -7.49 -7.56 -7.62 -7.75 -7.84 -8.03 -8.12 -8.23 -8.35 -8.37 -8.45 -8.57 -8.68 -8.75 -8.89 -9.01 -9.2 Profile 2004 -4.1 -4.51 -5.14 -5.58 -5.88 -6.04 -6.19 -6.27 -6.4 -6.57 -6.63 -6.72 -6.84 -7.01 -7.04 -7.11 -7.25 -7.36 -7.46 -7.57 -7.63 -7.75 -7.82 -7.96 -8.02 -8.12 -8.23 -8.35 -8.47 -8.55 -8.61 -8.78 0 159 APPENDIX B DESCRIPTION OF UNITED KINGDOM METEOROLOGICAL OFFICE (UKMO) DATASET 160 APPENDIX B.1 QUALITY STATEMENT: UK Met Office Wave Model archive The Met Office Wave Model Archive consists of the hindcast fields of winds and waves produced during the operation of the atmospheric and wave model forecast suite. To produce the best possible analysis of surface wind, all available reports of surface pressure, wind speed and direction (from ships, buoys, platforms and land stations) are subjected to a range of consistency checks before being assimilated into the model's analysis. The resulting wind field is then used to modify the wave field derived from earlier timesteps. For each of the 16 directional and 13 frequency bands, the changes in wave energy are computed at each gridpoint, using the local wind as energy input, and allowing for propagation, dissipation and transfer between spectral bands. The model is a so-called ‘Second Generation' model, where the spectral shape is empirically defined, rather than being calculated at run time; this latter process is too expensive of computing time for an operational model of this resolution. For further details see Golding (1983) and Francis (1985). There are two versions of the wave model, both in operation since 1986 - one covers the Global oceans and the other European waters. The Global Wave Model The analysed fields of wind and 1-dimensional spectra (i.e. energy within each spectral band, plus a mean direction for that band) have been archived, initially at 12-hour intervals and subsequently (since June 1988) at 6-hour intervals. The spatial resolution was initially 150km (approx.) (13.8k gridpoints), this was improved in June 1991, to a resolution of 85km (approx.) (37.3k gridpoints). Both versions of the model operated with an assumed fixed depth (200m) on a lat/long grid. In May 1999, a higher resolution Global Model was brought into operational use with 60km (approx.) grid spacing. The model is depth-dependent and includes shallow water physics, namely bottom friction, refraction and shoaling. Nested within the Global Wave Model, and taking boundary conditions from it, is a European Waters Wave Model. This is a depth-dependent second-generation model operating on a lat/long grid with spacing approx. 25km (8.5k gridpoints). The model covers West European waters to 14degW between 30.5N and 66.7N and also covers the Mediterranean and Baltic Seas; the Black Sea was added in 1993. Wind and wave hindcast values were archived initially at 6-hour intervals and since June 1988 at 3-hour intervals. Output at each timestep consists of wind speed and direction, plus either: 1-dimensional spectrum (energy and mean direction in each of the 13 spectral bands) or the conventional integrated variables derived from the spectrum (i.e. significant wave height, period and direction for both windsea and swell, together with resultant height and period). Since the winds are taken from the lowest level of the Atmospheric Model, they represent conditions approx. 20m above mean sea level. As with any operational model, there have been many small-scale improvements incorporated over the years. Most of these are introduced for computational reasons, to improve the efficiency of the calculations, but some are more fundamental, including the assimilation of wave height data from the ERS-1 (from June 1993) and ERS-2 satellites into the Global Wave model analysis (see Foreman et al, 1994). Further detail (and dates) of the more significant changes to the model's operation are available on request. Over the years, there have been occasional interruptions to the operational routine due to mainframe malfunction. Consequently, there are some periods of missing data in the archive, most of them of 12 hours duration or less. 161 References Foreman, SJ, Holt, MW & Kelsall, S Francis, P E (1994) (1985) Golding, B (1983) Holt, M W (1993) Preliminary assessment and use of ERS-1 altimeter wave data J Atmos & Ocean Tech 11 pp1370-1380 Sea surface wave and storm surge models Meteorol Mag 114 pp 234-241 A wave prediction system for real-time sea state forecasting Q J R Meteorol Soc 109 pp393-416 Modelling Ocean Waves Meteorol Mag 122 pp238-247 March 2002 162 APPENDIX B.2 Changes to UK Met Office Wave Models since 1986 Any operational model is subject to small-scale modifications over time, to deal with minor problems which are detected in day-to-day usage of the model products. It should also be recognised that changes in the formulation of the atmospheric models' winds will have some effect on the wave model results. Many of these changes are minor, and will have little impact on the wave model output for most practical applications. Listed below are the more significant changes which have been made to the formulation of either Atmospheric or Wave model since 1986. Because of the inherent month-to-month variability in winds and waves over many parts of the globe, it is difficult in most cases to detect and quantify changes in the archived data as a result of these modifications. Jul 1986 Global and European lat/long grids introduced on CYBER mainframe computer. Global:1.5deg lat x 1.875deg long European: 0.25deg lat x 0.4deg long Oct 1986 Archiving begins of wave model hindcasts from Global (12-hour intervals) and European (6-hour intervals) models. Apr 1987 Revised physics introduced for Global Wave Model, including improved GreatCircle turning for swell. Feb 1988 Ice edge now updated (approx weekly) for Global Model. Jun 1988 Global Model now archived at 6-hourly intervals and European Model at 3-hour intervals. Nov 1988 Analysis-correction (AC) scheme introduced to assimilate data into Atmospheric Model. Apr 1990 Coastal point depths in European model amended to correct erroneous swell directions near coasts. Jun 1991 Unified (Atmospheric) Model introduced on CRAY computer. Global Wave Model resolution changed to match Atmospheric Model's grid (now 0.833deg lat x 1.25deg long – approx 90km) European Wave Model grid unchanged. Oct 1992 Wave Model physics revised to improve retention of swell. Apr 1993 European Wave Model extended to cover Black Sea. Jun 1993 Wave height data derived from ERS-1 altimeter assimilated into Global model analysis. Aug 1993 ERS-1 scatterometer winds assimilated into Global Atmospheric Model analysis. Nov 1993 Bottom friction increased in European wave model. Nov 1994 Wave Model revised to improve waves at low windspeeds and reduce swell dissipation. Jan 1995 New version of Gravity Wave Drag implemented in atmospheric models, resulting in improved surface pressure fields and directions of low-level winds. Jan 1996 Change of orographic roughness, giving improvement to low-level winds. Apr 1996 Improved assimilation of temperature profiles from satellite soundings, giving lower wind field errors, especially in the tropics. Also, ERS-1 altimeter data superseded by data from ERS-2,further reducing bias against wave measurements. Nov 1996 Improvements to Convective Momentum Transport, Gravity wave Drag and satellite humidity assimilation, resulting in lower RMS errors in winds and pressures. Jan 1998 Global atmospheric model resolution increased from 90km to approx 60km. (26 Feb 1999-21 July 1999: Global wave model assimilation of ERS-2 wave data switched off.) May 1999 Global wave model spatial resolution increased to 60km and depth-dependency introduced. 163 Oct 1999 April 2000 New surface wind data from Special Sensor Microwave Imager (SSMI) on board the DMSP F13 satellite and further data from F15 from early 2000, resulted in further improvements to wind fields. Operational implementation of new Mesoscale (UK Waters) wave model, covering coast of Denmark to approx 15deg W, 47.5N to 61N (on same grid as surge model). Includes wave-current interactions, and uses Mesoscale atmosphere model winds. Resolution is approx 12km, giving better treatment of coastlines. Currently running in parallel with the (unchanged) European wave model. March 2002 164 APPENDIX B.3 MET OFFICE WAVE MODEL GRIDPOINT DATA INTEGRATED FORMAT (FROM OCTOBER 1986) Layout of data record Byte No. Parameter 1-2 4-5 7-8 10-13 16-20 21-21 23-28 29-29 31-31 33-35 37-37 39-42 HOUR (GMT/UTC) DAY MONTH YEAR LATITUDE LATITUDE (N OR S) LONGITUDE LONGITUDE (E OR W) WIND INDICATOR WATER DEPTH SEA INDICATOR WIND SPEED 44-46 48-51 53-56 58-60 62-65 67-70 72-74 76-79 81-84 86-88 WIND DIRECTION RESULTANT WAVE HEIGHT RESULTANT WAVE PERIOD RESULTANT WAVE DIRECTION WIND-SEA HEIGHT WIND-SEA PERIOD WIND-SEA DIRECTION SWELL HEIGHT SWELL PERIOD SWELL DIRECTION Units degrees degrees metres knots ms-1 degrees true metres seconds degrees true metres seconds degrees true metres seconds degrees true Data Type I2 I2 I2 I4 F5.2 A1 F6.2 A1 I1 I3 I1 I4 F4.1 I3 F4.1 F4.1 I3 F4.1 F4.1 I3 F4.1 F4.1 I3 Notes: WIND INDICATOR: 1 - Wind speed in ms-1 2 - Wind speed in knots SEA INDICATOR: 1 - Open Sea Point 2 - Coastal Point (N.B. Coastal points should be treated with caution. Please contact Met Office for further details). For each gridpoint, there is one record per timestep. March 2002 165 APPENDIX C SUMMARY OF SEDIMENT GRAIN SIZE DISTRIBUTION FROM PANTAI SABAK, KELANTAN SURVEYS 1998, 1999, 2004 Depth Depth APPENDIX C.1: SUMMARY OF GRAIN SIZE DISTRIBUTION FROM 1998, 1999 AND 2004 SURVEYS 1998 2m 5m > 7m CH 3100 Na 0.35 Na CH 2700 0.44 0.36 na CH 2300 0.12 0.7 na CH 1900 0.12 0.38 na CH 1500 0.35 na na CH 1200 0.18 0.62 0.43 CH 800 0.6 Na 0.35 CH 400 0.07 na 0.3 CH 200 na na na CH 00 0.15 0.62 0.28 CH -400 0.68 na 0.38 CH900 na na na CH1400 0.16 na na MIN 0.07 0.35 0.28 MAX 0.68 0.7 0.43 MEAN 0.287 0.505 0.348 1999 2m 5m > 7m CH 3100 Na 0.56 Na CH 2700 na 0.34 na CH 2300 na 0.62 na CH 1900 0.06 0.43 na CH 1500 0.21 0.58 0.3 CH 1200 na 0.47 1.75 CH 800 Na Na Na CH 400 na na 1.6 CH 200 na na na CH 00 0.26 na 1.6 CH400 0.2 na 1.6 CH900 na na na CH1400 0.26 na na MIN 0.06 0.34 0.3 MAX 0.26 0.62 1.75 MEAN 0.198 0.5 1.37 SUMMARY FOR 2004 SURVEYS DEPTH 2-5 m depth >5 - 7 m depth >= 10 m depth MEAN MAX MIN 0.19 0.35 0.70 0.30 2.46 0.70 0.09 0.07 0.7 166 APPENDIX C.2 Area A Date 6/9/04 Area B BED SEDIMENT SAMPLES AND GRAIN N SIZE DISTRIBUTION FROM 2004 SURVEY NORTH OF BREAKWATERS Time 11:58 11:49 Line 17 17 12:23 41 11:20 41 BREAKWATER AREA Tide 1.0m 0.95m Water Depth 4.0m 7.0m Samples No. AA17D A17E Fix No. 12 11 1.0m 0.85m 4.4m 6.9m AA41D A41E 13 10 Coordinates Samples N 34704.5m E 9071.8m N 35309.9m E 9470.6m Remarks Find Sand (Black) Soft Mud Brown D50 0.12 0.32 N 32985.4m N 33653.4m Sand Soft Mud Brown 0.3 0.55 E 13605.4m E 13917.4m Date Time Line Tide Water Depth Samples No. Fix No. 6/9/04 12:40 10:58 23 23 1.1m 0.8m 4.3m 6.9m BB23D BB23E 14 9 N 32073.9m N 32982.5m E 15790.8m E 16643.1m Remarks Muddy & Fine Sand Soft Sand 12:56 10:27 10:39 89 89 89 1.1m 0.7m 0.8m 4.4m 7.1m 10.9m BB89D BB89E BB89F 15 7 8 N 31424.5m N 32915.3m N 33390.7m E 17372.4m E 18883.2m E 19057.7m Muddy & Fine Sand Coarse Sand Muddy & Shell 0.6m 0.7m 3.6m 6.8m BB177D BB177E 1 6 N 30380.1m N 31267.4m E 19401.4m E 20206.9m Sandy Black Muddy Area C Date 6/9/04 8:49 177 10:14 177 SOUTH OF BREAKWATERS Time 9:05 9:50 Line 12 12 Tide 0.6m 0.7m Water Depth 3.8m 6.7m Samples No. CC12D C12E Fix No. 2 5 9:20 9:30 25 25 0.65m 0.65m 3.9m 6.8m CC25D C25E 3 4 Coordinates Samples D50 0.3 0.09 0.12 0.65 0.7 0.07 Coordinates Samples N 27755.0m E 20821.2m N 28831.6m E 22337.6m Remarks Muddy Soft Muddy & Sand D50 0.09 0.7 N 25652.4m N 26278.6m Muddy & Fine Sand Muddy Black 0.2 0.08 E 22308.5m E 23209.3m 167 168 APPENDIX D TIDAL DATA FROM PANTAI SABAK, KELANTAN; 2004 SURVEY APPENDIX D.1: Time Series Plot of Tidal Heights at WL2,Pantai Sabak 1.20 WL2 - Pantai Sabak Tide(m)LSD 1.00 0.80 0.60 0.40 0.20 0.00 -0.20 -0.40 -0.60 -0.80 -1.00 7/3/04 14:00 7/4/04 0:00 7/4/04 10:00 7/4/04 20:00 7/5/04 6:00 7/5/04 16:00 7/6/04 2:00 7/6/04 12:00 7/6/04 22:00 7/7/04 8:00 7/7/04 18:00 7/8/04 4:00 7/8/04 14:00 7/9/04 0:00 7/9/04 10:00 7/9/04 7/10/04 7/10/04 7/11/04 7/11/04 7/11/04 7/12/04 7/12/04 7/13/04 20:00 6:00 16:00 2:00 12:00 22:00 8:00 18:00 4:00 169 APPENDIX D.2: Time series Plot of tidal heights at WL4 Sg. Pengkalan Datu WL4 - Sg Pgkl Datu Tide(m) LSD 1.00 0.80 0.60 0.40 0.20 0.00 -0.20 -0.40 -0.60 -0.80 7/3/04 13:30 7/4/04 1:30 7/4/04 13:30 7/5/04 1:30 7/5/04 13:30 7/6/04 1:30 7/6/04 13:30 7/7/04 1:30 7/7/04 13:30 7/8/04 1:30 7/8/04 13:30 7/9/04 1:30 7/9/04 13:30 7/10/04 1:30 7/10/04 13:30 7/11/04 1:30 7/11/04 13:30 7/12/04 1:30 7/12/04 13:30 7/13/04 1:30 170 171 APPENDIX E WAVE MODEL BATHYMETRY 172 WAVE MODEL BATHYMETRY Model orientation for waves from North Model orientation for waves from N30 173 Model orientation for waves from N60 Model orientation for waves from N90 174 Model orientation for waves from N120o