Report on Coastal Zone Vulnerability and Adaptation Assessment, Aden Governorate, Republic of Yemen (As a part of Second National Communication) Prepared by: Coastal Zone Team, Mohammed M. Abubakr, (Team Leader), Mohammed Ali Al Saafani, Hisham M. Nagi, Ahmed Hajer, Adel M. Alhababy, Table of Contents 1. 1.1 1.2 1.3 1.4 1.5 2. 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 3. 3.1 3.2 3.3 3.4 3.5 3.6 4. 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8 4.9 4.10 4.11 4.12 5. 5.1 5.2 5.3 5.4 6. 6.1 6.2 7. Table of Contents………………………………………………………………….. List of Tables……………………………………………………………………..... List of Figures…………………………………………………………................... Abbreviations…………………………………………………………………….... Acknowledgments…………………………………………………………………. Executive Summary……………………………………………………………….. General Introduction……………………………………………………................. Introduction………………………………………………………………………... Research Context – Assessing Coastal Vulnerability……………………............... Current Approaches and Limitations……………………………………………… Research Purpose and Objectives…………………………………………………. Data Used………………………………………………………………….............. Study Area Characters…………………………………………………………... Coastal Physical Environment…………………………………………….............. Meteorology……………………………………………………………….............. Oceanography……………………………………………………………………… Study Area: Governorate of Aden…………………………………………………. Population and Administrative Divisions…………………………………………. Coastal and Marine Environment………………………………………………….. Review of SLR in Aden…………………………………………………………… Selection of Scenario………………………………………………………………. Potential Impacts of Sea Level Rise……………………………………............... Erosion……………………………………………………………………............... Inundation………………………………………………………………………….. Saltwater Intrusion………………………………………………………………… Increasing Flood Frequency Probability…………………………………………... Ecological Impacts………………………………………………………………... DIVA Model……………………………………………………………………….. Socioeconomic Impacts…………………………………………………............... Houses and Residential Area………………………………………………………. Land Value………………………………………………………………………… Saltpans Area………………………………………………………………………. Educational Structures……………………………………………………............... Health Structures…………………………………………………………............... Roads………………………………………………………………………………. Electricity………………………………………………………………….............. Water and Sanitation Networks……………………………………………………. Communications Network…………………………………………………………. Tourism Structures………………………………………………………………… Aden International Airport………………………………………………………… Other Constructions………………………………………………………............... Adaptation Strategies…………………………………………………….............. The Need for Adaptation…………………………………………………............... Adaptation to Climate Change…………………………………………….............. Adaptation Strategies and Plans…………………………………………………… Integration of the Adaptation into National Policy and Planning…………………. Conclusion and Recommendations……………………………………………… Conclusion…………………………………………………………………………. Recommendations…………………………………………………………………. References………………………………………………………………………… ii ii iii iii iv v vi 1 2 2 5 6 7 8 9 10 12 15 18 19 26 28 29 30 33 34 43 46 49 53 56 59 59 59 59 59 61 61 61 61 62 62 64 65 65 66 74 78 79 80 83 List of Tables 2.1 2.2 2.3 2.4 3.1 3.2 4.1 4.2 5.1 5.2 Plant species listed in Al Hiswah wetland………………………………………... List of common bird’s species associated with Aden wetlands…………………... Fishers and fishing boats numbers………………………………………………... Coastal areas recommended for special management in Aden due to their biological, environmental or recreational importance……………………………. Sea level rise scenarios for Aden Governorate…………………………………… Summary of well field production capacity and water level average drops up to the year 2001……………………………………………………………………… Areas which will be subjected to inundated in Aden Governorate……………….. Expected economic losses due to sea level rise (33cm) in Aden Governorate…… Adaptation measures in coastal areas to be highlighted in national communications of Yemen……………………………………………………….. The main biophysical effects of relative sea level rise, including examples of possible adaptation responses…………………………………………………….. 24 25 26 27 34 38 60 63 68 71 List of Figures 1.1 2.1 2.2 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9 4.1 4.2 4.3 4.4 Map of the study area……………………………………………………………... Schematic diagram showing the pattern of the mesoscale eddies in the surface circulation in the Gulf of Aden. The acronyms A and C represent anti-cyclonic and cyclonic eddies respectively………………………………………………….. Climatology of Air temperature in Aden, created from monthly values from 1992-2009………………………………………………………………………… Saltwater intrusion in a coastal aquifer…………………………………………… Base map of Delta Tuba and Delta Abyan………………………………………... Contour lines of saltwater intrusion in (a) Abyan delta, and (b) Tuban delta……. Resistivity cross-section: Line B Abyan delta……………………………………. Resistivity cross-section: Line D…………………………………………………. Resistivity along the eastern side of section E in Tuban delta……………………. Resistivity cross-section: Line G Tuban delta……………………………………. Khor Bir Ahmed shown in recent Google image, with compare with its situation in an aerial photography of 1975…………………………………………………. Output from DIVA model………………………………………………………… Map of important sectors in the Governorate of Aden…………………………… Map of Aden Governorate showing the expected inundated area due to the SLR of 33 and 60 cm…………………………………………………………………… Map of the most sensitive areas of the Governorate, which are vulnerable to inundation due to SLR of both 33 and 60 cm…………………………………….. 3D view of Aden Governorate shows the areas to be inundated by SLR of 33cm………………………………………………………………………………. iii 5 13 18 36 37 39 39 41 41 42 47 52 55 56 57 58 Abbreviations AR4 Fourth Assessment Report CD Chart Datum CZMS Coastal Zone Management Subgroup DIVA Dynamic Interactive Vulnerability Assessment EEZ Exclusive Economic Zone EPA Environment Protection Authority ERT Electric Resistivity Tomography EU DINAS-COAST GDP Dynamic and Interactive Assessment of national, regional and global vulnerability of Coastal Zones to Climate Change and Sea-level Rise Gross Domestic Product GIS Geographic Information Systems GVA Global Vulnerability Assessment HHT Highest High Tide ICZM Integrated Coastal Zone Management INC Initial National Communication IPCC Intergovernmental Panel of Climate Change MSL Mean Sea Level MSRRC Marine Science Research and Resource Center NAPA National Adaptation Programme of Action NE Northeast NGOs Non Governmental Organizations NWSA National Water Supply and Sanitation Authority PaR Population at Risk SC Specific conductance SLR Sea level Rise SNC Second National Communication SST Sea Surface Temperature SW Southwest SWL Scenario Water Level UNEP United Nations Environment Program UNFCCC United Nations Framework Convention on Climate Change iv Acknowledgment In the first place and for most, the coastal zone team would like to thank the Environment Protection Authority particularly eng. Mahmoud Shidiwah, Chair, for supporting the execution of this study. We warmly thank Mr. Anwar Noaman Head of Climate Change Unit, CDM-DNA Secretariat, for being critical as well as supportive, and whose suggestions, questions and patient eased and made our work enjoyable. Special thanks extend to the steering committee for their guidance & suggestion and to Mr. Faisal Al Sa’adi of the Climate Change Unit. Distinctive appreciations are due to Mr. Faisal Al Tha’alabi, Chair of EPA- Aden, Mr. Gameel Al Qadassi of Aden Governorate Office, Mr. Ahmed N. Al-Sarary and Munassar A. Hassan of the Geological Survey & Mineral Resource Board-Aden, Mr. Gamal Bawazeer of the Aden Wetland Project and to Mr. Mahfoud M. Qasem of the Maritime Authority. We also would like to thank Mr. Badr N. Al-Rosy and Ahmed Masheeb for their help during the field work. Finally, and not least important for us to express our gratitude to the hospitality, kindness, and openness of all interviewees and peoples met in Aden and Sana’a during the execution of this study. v Executive summary The Republic of Yemen is located at the southwestern edge of the Arabian Peninsula between 12o to 20o north and 41o to 54o east. The coastline of Yemen is more than 2300 kilometers long; the Gulf of Aden takes up about two thirds of this, with the remainder bordering the Red Sea. The Yemeni coastal line along Gulf of Aden and Arabian Sea is approximately 1400 km long, extending from Bab el Mandab at the west to Ras Darbat Ali at the east. The landmasses surrounding the Gulf of Aden are characterized by hot and dry climates with little vegetation. Strong winds blowing across these areas often carry sand and dust. The Gulf of Aden coast is dominated by the Indian Ocean monsoon system. Winter monsoon continue from November to March with northeasterly wind. The Second National communication (SNC) (present study) conducted taking into consideration the good practice and lessons learnt from the INC and other climatechange related projects. The coastal zone sector was studied and identified under the National Adaptation Programme of Action (NAPA), as one of the most vulnerable areas to climate change in Yemen. NAPA process focuses on the national and shortterm implications of climate change on (i) water resources, (ii) agriculture, and (iii) coastal zones. SNC works at the level of specific geographical hotspots, addresses long-term climate risks and adaptation on these three sectors. The priority area, targeted by the SNC coastal zones team, is the coastal zone of Aden Governorate, as a new area of study. This study describes the vulnerability assessment of the impact of sea level rise (SLR) on the coastal area of the Governorate of Aden, and discussed the possible adaptation options. With the identification of the scenarios for accelerated sea level rise, the study identified the possible impacts on both the coastal habitats and socio-economic. This includes identification of biophysical impact of SLR on the coastal area and the socioeconomic impacts. The study approach to assess climate change impacts was designed by adopting a range of assessment methods including stakeholders involvement, and the use of expert judgment. The stakeholders were involved in the assessment by discussions and responses to a questionnaire about the vulnerability and adaptation to sea level vi rise in Aden Governorate. Other tools were also used, such as geographic information systems (GIS) and Dynamic Interactive Vulnerability Assessment (DIVA). Regarding the modelling, DIVA model was used to give preliminary idea about the vulnerability of the coastal area to climate change and sea level rise. Two plausible future sea-level rise scenarios for the Governorate of Aden coastal region are adopted. Values are in meters above main sea level (MSL), which is 1.4 m above CD (Chart Datum) for Aden. Scenarios are based on (i) observed rates for Aden mean sea-level rise, 3.3 mm/yr, and (ii) extreme sea-level rise rate of 5.9 mm/yr at highest high tide (HHT) is included for an extreme scenario. Scenarios of 0.33m, and 0.60m SLR over this century were assumed. Bruun rule used to estimate the erosion along the coastal area of the governorate due to SLR based on the parameters of the study area. The recession of the shoreline was estimated at about 23 m and 41 m along the eastern part of the study area (Khormaksar till Al Alam), for rise in sea level of 0.33 m and 0.6 m, respectively, and about 18 m and 33 m, respectively, along the western shoreline (Foqm Bay). This was translated to a potential land loss along the entire shoreline of the pilot area (length 23 km) about 48 and 86 ha, respectively. This loss of the sandy beaches will affect the tourism and recreation activities in coastal communities, especially along Khormaksar, Glod Moor, Foqm Bay Beaches, and the rest of the sandy beaches. The total land area that would be inundated under the various climate change scenarios is substantial. With the proposed sea level rise of 33 cm, the percentage of the inundated area is 43 Km2, which represents 5.7% of the total area of Aden Governorate (about 750 km2). The inundated area would increase to about 45 km2 (6%) for SLR of 60 cm. Inundation will unevenly affect Aden Governorate coastal area. Khormaksar, Al Tawahi Bay, the coastal beach between Khormaksar and Al Alam (Abyan Coastal Beach), Aden lagoons and wetlands are the most affected regions. About 3.90 km2 will be inundated in the dens populated area of Khormaksar, Al Mansoora, and Al Mua’alla Districts for SLR of 33 cm, while 4.35 km2 would be inundated for SLR of 60 cm. The saltwater intrusion into Delta Abyan, extends to a distance of 4 km of the southeastern portion of the delta. It appears that the further inland position of the vii shallow portion of the saltwater intrusion front on the east side of the Abyan area is related to incursion of saltwater along unconsolidated, more permeable sediments. The extent of the saltwater intrusion will extend further inland by rising sea level, for the proposed scenarios of 0.33 and 0.6 m. The interface between the saltwater and freshwater will extend 160 m and 240 m inland and 16m and 24 m upward, respectively, affecting the fresh water aquifer in that region. In Tuban Delta, the contours of saltwater intrusion are approximately parallel to the coastline, about 10 km inland on the eastern side of the delta. Bir Nasser well field is located along the eastern side of the delta, where possible brackish water deeper than 150 m is threatening the water quality of this water field. With the rising sea level of 0.6 m, the level of the intrusion could rise to the well depth and affect the main source of ground water of Aden Governorate. Along the section of Bir Ahmed well field, the first 3000 m from the shoreline are characterized by a saltwater intrusion. The saltwater intrusion front dips northward. Bir Ahmed well field produces groundwater at a maximum depth of 64 m. The layer deeper than that may contain brackish water as indicated from low resistivity. Increased conductivity over time may reflect increasing intrusion of saline water from the ocean, or up-coning if a wedge of saline water has intruded under the well field. This increasing in conductivity will be accelerated due to sea level rise. Sea-level rise and changes in coastal population are unconstrained. In all scenarios, there are large potential increases in coastal population, which is reinforced by the assumption of coastal attraction of population. The current population of Aden Governorate according to the 2004 Census is 598,419, and by 2030, it would increase to 1.5 million (considering a growth rate of 3.53% for Aden population). Relative sea level rise simply displaces the extreme water levels upwards. Following the GVA steps, risk is measured using the average number of people flooded per year. For the first scenario the future storm surge will be 2.81 m above the MSL, resulting in the height of the maximum flood level of 4.24 m for the first scenario and 4.50 m for the second scenario above CD. Accordingly, the flood prone area, the area contained between the coastline and the maximum flood level would be vulnerable to storm surge flooding, which could cover most of the coastal plain of Aden Governorate, including Khormaksar, Al Mansoorah, Al Mua’alla, Al Buraiqah, the beach between viii Ras Umran and Foqm. This would effects about 50% of the populated area of Aden Governorate, where the present average population density considering that the population is equally distributed, is 800/km2. The population density is expected to increase to 2100/km2 in 2030, considering growth rate of 3.53%. DIVA model was used to investigate the effect of sea level rise in the costal area of the Gulf of Aden as an integral way. The output from DIVA was compared with the vulnerability assessment approach used in this study. The output from the model shows underestimated result compare with the output of the vulnerability analysis. The under estimation of the impacts by DIVA model was due to the coarse resolution of the input data and also due to the fact that the division of the coastal region into coastal segments was not representing the actual situation. In despite of the underestimation of the impact by DIVA model, it also show the risk of the sea level rise on the coastal area of Aden Governorate. The total socio-economic loose include loss in the infrastructures, livelihoods. Total of the houses at risk of inundation under the first scenario are about 11462 houses, which represent about 11.88% of the total number of houses in the governorate. The number of families liven in these houses represents about 11.5% of the total families of the governorate with about 68843 people will be affected. This represents about 12% of the total population of the governorate according to 2004 census. It has been found that the grand total economic losses due to sea level rise by 33cm and 60cm are equal to 410,233 and 459,461 million YR, respectively. As the average annual growth of different establishments in Aden Governorate is increasing by 1.5%, the expecting economic losses in 2050 are expected to reach approximately 767,136 million YR Identification of adaptation options was carried out by designing and administering a questionnaire based on direct communication with stakeholders in vulnerable areas. An adaptation decision matrix approach based on cost effectiveness of adaptation measures was also evaluated. The following attributes were found to be the most important: expenses, net benefits, environmental impacts, robustness and flexibility, chance of success, feasibility, and fairness. Each adaptation option was evaluated based on the above-mentioned attributes. ix The protection option consists of hard and soft technologies: dikes, revetment as a hard one and beach nourishment, wetland restoration as a soft one. This includes: set back, full Protection, beach nourishment and managed retreat and accommodation. Accordingly, the coastline of the governorate was divided into six regions depending on the adaptation options and the topographic nature of that region. x Chapter 1 General Introduction 1.1 Introduction This report documents the approach, methods, and key findings of the coastal zone team on Coastal Zone Vulnerability and Adaptation Assessment, Aden Governorate, Republic of Yemen, as a part of the Second National Communication, EPA Project No. 00044077. This study was funded by GEF. The document contains several sub-sections that present: 1) The research context, objectives and approach, 2) Study area characteristics, 3) Potential impact of sea level rise (SLR), 4) Socio-economic impact of the sea level rise, 5) Adaptation measures and strategies, and 6) Conclusion and recommendations. Following this, a list of references and appendixes of supplemental materials. A list of acronyms and symbols used throughout this report is also provided following the list of Tables. 1.2 Research Context – Assessing Coastal Vulnerability Human population is attracted, to a greater extent, to coastal zones than to other regions. Urbanization and rapid growth of coastal cities have therefore been a dominant population trend over the last decades, leading to the development of numerous mega cities in all coastal regions around the world. In 1990, it was estimated that at least 200 million people live in the coastal floodplain (in the area inundated by a 1 in 1000 year flood), and it is likely that their number increases to 600 million by the year 2100 (Nicholls and Mimura, 1998). Collectively, this would results in growing demands on coastal resources, as well as increasing people’s exposure to coastal hazards. Global climate changes are affecting coastal communities around the world, many of which are already considered vulnerable to ongoing climatic variability impacts (IPCC, 2007). One of the more certain consequences of global climate change is accelerated global sea-level rise, which will intensify the stress on many coastal zones, particularly those where human activities have diminished natural and socio-economic adaptive capacities. In addition, the impacts of climate change will include possible increases to sea surface temperatures, greater variability in the patterns of rainfall and runoff, possible changes to wave climate, changes to the frequency, intensity and duration of storms, and changes to ocean chemistry. In light of this, the coast is regarded as one of the most vulnerable areas on 2 the planet and is increasingly the focus for assessments of vulnerability and adaptation to climate change. Estimates for the 20th century show that global average sea level rose at a rate of about 1.7 mm/yr. Satellite observations available since the early 1990s provide more accurate sea level data with nearly global coverage. This decade-long satellite altimetry data set shows that since 1993, sea level has been rising at a rate of around 3 mm/yr, significantly higher than the average during the previous half century. Coastal tide gauge measurements confirm this observation, and indicate that similar rates have occurred in some earlier decades. Sea level is projected to rise at an even greater rate in this century. The two major causes of global sea level rise are thermal expansion of the oceans (water expands as it warms), and the loss of land-based ice due to increased melting. Until recently, scientists assumed that thermal expansion dominated contemporary SLR (Houghton et al., 2001). Recent progress has changed that perception, and it now appears that mass contributions from glaciers and ice sheets dominate, with the latter comprising at least half of total SLR over the past decade (Nerem et al., 2006). The greatest source of uncertainty for predicting future SLR is how large ice sheets will behave in the future as warming proceeds (Alley et al., 2005; Gregory and Huybrechts, 2006; IPCC, 2007). Sea level rise can lead to increased coastal flooding, accelerated erosion, rising water tables, increased saltwater intrusion, and a suite of ecological changes. These biophysical changes result in various socio-economic impacts including loss of land, increasing damage and maintenance costs of coastal infrastructure, changing quantity and quality of coastal resources, as well as declines in associated economic, ecological, cultural, and subsistence values (Klein and Nicholls, 1999). According to the Intergovernmental Panel of Climate Change (IPCC), Fourth Assessment Report (AR4), global temperature is projected to rise by 1.1 to 6.4°C, while global mean sea level is projected to rise by 18 to 59 cm, over 1990 levels by around 2100, based on future scenarios of varying global emission levels (Bindoff et al., 2007). The most recent evidence suggests that sea-level rise could reach 1m or more during this century (Rahmstorf, 2007; Dasgupta, et al., 2009). 3 In the context of coastal zones, the goal of vulnerability analysis for sea-level rise (and other coastal implications of climate change) is to assess the potential impacts on coastal populations and the related protection systems and coastal resources, including the ability to adapt to these changes. A range of methods for such analyses has been developed and these have been extensively applied at the national and sub-national levels (e.g. IPCC-CZMS, 1992; Klein and Nicholls, 1999). The analysis of the coastal vulnerability starts with some concepts of the natural system’s potential to be affected by the different bio-geophysical effects of sea level rise (erosion, inundation, flooding, salt-water intrusion, coastal hazards, and rising water tables), and its natural capacity to cope with these effects (resilience and resistance). Climate change impacts on Yemen's coastal communities through gradual effects of accelerated sea-level rise, and more immediate risks of extreme events including increased storm surge flooding, accelerated coastal erosion, contamination of coastal aquifers, and various ecological changes. These biophysical changes create risks of land loss, coastal infrastructure damage, coastal resource changes, and shifts in related economic, social and cultural values (Klein and Nicholls, 1999). Climate change impacts are, and will continue to be, unevenly distributed among coastal communities due to different local exposures and vulnerabilities (Clark et al.,1998; Dolan and Walker 2006). Yemen considered one of the top five most vulnerable low-income countries, with more than 50% of their coastal areas at risk, for exposed populations, and more than 50% of coastal urban areas lie within the potential impact zones (Dasgupta et al., 2009). The first assessment of Yemen’s climate vulnerability and adaptation options was carried out during the year 2000, as a part of Yemen Initial National Communication (INC), which covered a small part of Yemen’s coastal area, along the Red Sea coast (Hodiedah city (Al Subbary et al., 2000)). The Second National communication (SNC) (present study) conducted taking into consideration the good practice and lessons learnt from the INC and other climate-change related projects. The coastal zone sector was studied and identified under the National Adaptation Programme of Action (NAPA), as one of the most vulnerable areas to climate change in Yemen. While the NAPA process focuses on the national and short-term implications of climate change on (i) water resources, (ii) agriculture, and (iii) coastal zones, the SNC 4 works at the level of specific geographical hotspots, addresses long-term climate risks and adaptation on these three sectors. The priority area, targeted by the SNC coastal zones team, is the coastal zone of Aden Governorate, as a new area of study (Figure 1.1). Figure 1.1. Map of the study area. This project describes a general overview of national coastal conditions and trends, and conducting vulnerability assessment to the impacts of sea-level rise on the coastal zone of Aden Governorate. Conceivable response strategies and adaptation technologies discussed. 1.3 Current Approaches and Limitations Vulnerability assessment includes the susceptibility of the coastal zone to physical changes resulting from climate change, the anticipated impacts on socio-economic and ecological systems, and available adaptation options (Harvey et al., 1999). Coastal zone vulnerability assessment work has been driven largely by IPCC via its Coastal Zone Management Subgroup (CZMS) (IPCC-CZMS, 1992), the IPCC Technical Guidelines for Assessing Climate Change Impacts and Adaptations (Carter et al., 1994), and the United Nations Environment Program (UNEP) Handbook on Methods for Climate Change Impact Assessment and Adaptation Strategies (UNEP, 5 1998). Sharples (2004) provides a GIS based framework that includes first-pass indicative mapping at large scale, and more detailed local and site-specific scale methods. This ‘Smart line’ approach is a cheap and effective method of producing a geomorphic sensitivity map that may have far reaching applications, especially at a continental scale. Presently most vulnerability assessments do not yield results sufficient for widespread, day-to-day application for local coastal zone management (Klein and Nicholls, 1999). The study approach to assess climate change impacts was designed by adopting range of assessment methods, including stakeholders’ involvement, and the use of expert judgment. The stakeholders were involved in the assessment by discussions and responses to the questionnaire about the vulnerability and adaptation to sea level rise in Aden Governorate. Other tools were also used, such as geographic information systems (GIS) programs. Regarding the modelling, the team explored the use of Dynamic Interactive Vulnerability Assessment (DIVA) model to give preliminary idea about the vulnerability of the coastal area to climate change and sea level rise. DIVA is a tool for integrated assessment of coastal zones produced by the EU-funded DINAS-Coast consortium (2006). It is specifically designed to explore the vulnerability of coastal areas to sea-level rise. Its limitation with application at a national scale does not give particularly insightful perspectives on vulnerability of the coast to climate change. 1.4 Research Purpose and Objectives 1.4.1 Purpose Develop a chapter on the vulnerability and adaptation to be submitted as a part of the SNC of Yemen that; - Develop and enhance national capacities, and facilitate the process of mainstreaming climate change issues into national planning and policy, thus enabling the country to deal with climate change and consider it not only as environmental issue but also as an issue of sustainable development. - Enable Yemen to prepare and submit its SNC to the UNFCCC and meet its Convention obligations. 6 1.4.2 Objectives - Assess current vulnerability of climate and sectors under the priority area. - Assess future climate risk and adaptation measures for the priority area. - Develop a policy framework for adaptation for the selected areas. 1.5 Data Used Data used in this study includes: climatological data of 18 years, monthly air temperature, wind speed, and sea level pressure, for the period from 1992 tell 2009; historical tide gauge data for about 60 years, from 1880 tell 1969 with some gaps; topographical maps of D38-114 and D38-115 covering Aden Governorate with scale of 1:100,000; socio-economic data, etc. 7 Chapter 2 Study Area Characters 8 The following sections describe the coastal and marine physical environments along the coast of Aden. 2.1 Coastal Physical Environment Yemen coast is characterized by a narrow coastal plain between the Gulf of Aden and the mountain range that parallels the shoreline. This coastal plain interspersed with volcanic intrusions right to the sea shore extending along the Gulf of Aden. The land rises steeply inland from the coastal plain to elevations of several thousand meters in the western part of the country. This range averages 1,070 m in height and influences the local weather, especially wind. Further east, towards Omani border, the elevations are not as great. Gulf of Aden is bounded on the north by the Yemeni coastline, and on the south it is bounded by the Somali Peninsula. The Yemeni coastal line along Gulf of Aden and Arabian Sea is approximately 1400 km long, extending from Bab el Mandab at the west to Ras Darbat Ali at the east. The landmasses surrounding the Gulf of Aden and Arabian Sea are characterized by hot and dry climates with little vegetation. Strong winds blowing across these areas often carry sand and dust. 2.1.1 Coastal Geomorphology The Gulf of Aden is a young ocean basin formed by the rifting of Asia (Arabia) from Africa (Somalia) (Girdler et al., 1980). It has a well-defined continental margin, small oceanic basin, and an active mid-ocean ridge (Sheba Ridge) in the center, characterized by a rift valley and fracture zones (Matthews et al., 1967; Bosworth et al., 2005). The rifting of the Arabian Peninsula was accompanied by violent movements in the earth’s crust, creating one of the world’s largest volcanic zone along the western and southern borders of the Arabian Peninsula. The Gulf of Aden coastline is characterized by sedimentary strata interbreeds of limestone, sandstone and shale with volcanic intrusions and extrusions. The old sedimentary strata are primarily marine sediments of Jurassic and Cretaceous periods (Mesozoic), whereas the coastal plains are often more recent alluvial and marine sediments (Al-Hubaishi et al., 1984). Most of the coastline exhibits signs of block faulting, raised beaches, pediments, wadi mouths, headlands, escarpments and dunes. Volcanic pyroclastics (fragmented material from explosive volcanic processes) from 9 some shore areas are sometimes complex because they exhibit raised beaches with wave cut platforms and pediments, erosional features common to deserts. Most geo-morphological (tectonic, erosional and depositional) events, which have formed the present day coastline, took place in relatively recent, geological time, primarily during the quaternary period of the Cenozoic Era. The quaternary period and Pleistocene epoch are coincidental, occurring within the past three million years (before present). The Pleistocene epoch covers the time of most recent glacial and interglacial activity. 2.2 Meteorology The coastal region of Yemen is influenced by two distinct monsoon seasons. The southwest (SW) monsoon of the Indian Ocean occurs between the months of May and September, while the northeast (NE) monsoon prevails between October and April. The months of April, May and October are transitional months as global pressure patterns re-adjust to the changing incoming solar energy (Al Saafani, 2008). The air temperatures recorded in this area are among the highest of any coastal regions in the world (Red Sea and Gulf of Aden pilot, 1987). Mean daily maximum temperatures exceed 30C at Aden for seven months of the year, while mean daily minimum temperature only drops bellow 20C in January (Canadian Occidental Petroleum, 1992). Relative humidity is generally higher during the SW monsoon than during the NE monsoon although the seasonal differences are not large. In addition, three extreme weather conditions also occur in the Gulf of Aden. These are locally known as (i) Belat, a strong sand storm, during the winter monsoon in midDecember (it generally persists for one to three days), (ii) Khamasin, hot dry north wind that blows across the Gulf of Aden during the summer monsoon that occurs for three to four times a year lasting for 3–4 hours, and (iii) Shamal, also occurring during the summer monsoon, blows mostly from the north for a few successive days (Canadian Occidental Petroleum, 1993). 2.2.1 Solar Radiation & Day Length The annual path of the sun crosses Yemeni coast twice annually, on April 25th and August 8th, as the sun first moves northward to the summer solstice and again as it 10 retreats to the autumnal equinox. Therefore, the peak energy flux of incoming solar radiation through a clear sky at local noon has a bimodal peak (Al-Motawakel et al., 1983). Being close to the equator, the length of the day varies little from twelve hours. The range in day length from summer solstice (12.87 hours) to the winter solstice (11.13 hours) is 1.74 hours. 2.2.2 Precipitation Although the term “monsoon” generally implies heavy seasonal rain, both monsoons are dry in the study area. The climate of Yemeni coast and nearby waters is dominated by hot and extremely arid conditions characteristic of North Africa and Arabian Peninsula (Howe et al., 1968). Precipitation in the region falls infrequently, especially along the western Gulf of Aden coast and accumulation is light. The data available from the rain gauge stations in Yemen (Aden and Mukalla) indicates that most of the precipitation occurs during the winter monsoon. However, at Salalah, along the southern coast of Oman, most of the rainfall occurs during the summer monsoon (Canadian Occidental Petroleum, 1993). 2.2.3 Storms According to National Climate Data Center, the most frequent storms affecting the area are thunderstorms and blowing sand and dust. The monthly frequencies of such storms observed offshore range from 0 to 1.7% (Canadian Occidental Petroleum, 1993). Tropical cyclones may influence the region. Occasionally, a tropical cyclone originating in the north of the Arabian Sea moves into the Gulf of Aden (Murty, 1984). The greatest chance of encountering a cyclone in the area is in November (Naval Oceanography Command Detachment, 1982). The eastern Arabian Sea is one of the tropical cyclone genesis regions of the world (Murty, 1984). These storms generally form in the transitional seasons between monsoons off southwest coast of India. During the period from 1891 to 1960, a total number of 165 cyclonic disturbances were formed in the Arabian Sea, half of which intensified into storms (winds greater than 32 knots). The months of October and November have recorded the most storms (17 and 21, respectively), while May and June have had 13 storms each. Forty-eight severe cyclones (wind greater than 56 11 knots) were recorded in the Arabian Sea during the period of 1891 - 1960 (Canadian Occidental Petroleum, 1993). The annual probability of a tropical cyclone (maximum sustained winds > 32 knots) in the western Gulf of Aden is 6.7% and 13.3% in the eastern part (where 50 E latitude separates west from east) (Canadian Occidental Petroleum, 1993). These probabilities translate to an average of one tropical cyclone every 15 years in the west, and one every 7.5 years in the east. Severe cyclone, however, in the Gulf of Aden are much less frequent. During the periods 1943 - 1967 and 1972 - 1982, a total of only eight severe storms entered the Gulf of Aden (Pedgley, 1969; Canadian Occidental Petroleum, 1992). No cyclones reached hurricane intensity (wind speeds of 65 knots) or greater in the Gulf of Aden during the period 1971 - 1979 (Canadian Occidental Petroleum, 1993). 2.3 Oceanography The oceanographic conditions for the Gulf of Aden are also influenced by the monsoon reversal. The Sea surface temperature (SST) and surface current show seasonal variability following the air temperature and wind pattern. The most important phenomena is the seasonal upwelling along the eastern part of Yemeni coastal line, which enrich the coastal marine ecosystem with the necessary nutrients for the primary production, making this region one of the most productive of the world oceans. 2.3.1 Sea surface temperature (SST) The surface layer showed strong seasonal variations in its characteristics. The SST was about 24–25ºC during winter (November–February). It increased to reach a maximum (31ºC) in May. During summer (June–August), the SST decreased along the northern side due to upwelling. The upwelling temperature along Yemeni coast reaches a minimum of 17ºC (Pichura and Sobaih, 1986), it started in the eastern side during June and extended towards the west during July–August. In September, the SST started to rise again soon after the weakening of summer monsoon winds over the gulf to ~ 30ºC. Similarly, the mixed layer depth decreased from ~ 80m during winter to ~ 20m during summer (Al Saafani, 2008). 12 2.3.2 Currents The recent studies show that the circulation in the Gulf of Aden is not simple as thought earlier. It is influence by mesoscale eddies that propagate from the Arabian Sea (Fratantoni et al., 2006, Al Saafani et al., 2007). The net flows at the surface were westward during October–April and maximum during November to February. This westward flow would transport water from the Gulf of Aden into the Red Sea. During summer, the flow is reverse to flow eastward during June to August. The eastward flow in the western end of the gulf during this season is a continuation of the outward flow from the Red Sea in the surface layer. This pattern of flow is modified with mesoscale eddies propagating towards west into the Gulf of Aden (Figure 2.1). These eddies influence the circulation from the surface to depth of ~ 1000 m (Bower et al., 2002; Al Saafani, 2008). Figure 2.1. Schematic diagram showing the pattern of the mesoscale eddies in the surface circulation in the Gulf of Aden. The acronyms A and C represent anticyclonic and cyclonic eddies respectively. 13 2.3.3 Sea Level The attempts made to understand the sea level variations in the Gulf of Aden are very limited (Morcos, 1990). Patzert (1974) presented the sea level changes at Aden and Perim (Myuun) Island, and concluded that these changes resulted from the reversal of circulation, which is closely associated with the reversals in the monsoon winds acting on the sea surface. The sea level at Aden rises between September and May, and falls during June–July to reach the minimum in August. The seasonal oscillations in the mean sea level can arise due to astronomical effects, evaporation effect, precipitation and wadies discharge, atmospheric pressure, and steric sea-level effects. The effects of purely astronomical conditions (long-period tides) are not significant; they do not exceed 12 mm at these latitudes (Pattullo et al., 1955). Because rainfall is very low and no large rivers are discharging into the Gulf of Aden, these two factors can be ignored. Maximum evaporation over the gulf occurs during winter when the sea level is highest (Privett, 1959). Since the sea level variations are completely out of phase with the variations in evaporation, evaporation also does not appear to control the seasonal oscillations of mean sea level. The isostatic adjustment of the ocean surface to changing atmospheric pressure requires that the sea surface rise (fall) by 1 cm for every 1 mbar decrease (increase) in pressure. Patzert (1974) noted that the atmospheric pressure at mean sea-level is highest during January and lowest during July at Aden with a range of ~ 10 mbar. Corrections to the monthly mean sea-level curves for the pressure variations results in an increase in the range of mean sea level. Thus, the observed variations in mean sea level do not appear to be due to the effect of atmospheric pressure change. A variation of the density within a water column, from which the steric sea level is calculated, depends on the thermohaline variations within the column. It is high when water is warm and/or less saline and low when water is cold and/or more saline. In the upper 300 m of the water column near Aden, the steric variations have the same phase and similar range as the sea level at Aden, though the range of the steric variations is larger by approximately 8 cm (Patzert, 1974). This variation in density of the upper 300 m of the water column is due to the upwelling of cool, low-salinity water that occurs in the northern coast of Gulf of Aden during the southeastern monsoon. 14 2.3.4 Astronomical Tides The tides in the Gulf of Aden are mixed diurnal and semi-diurnal type. There are two low waters and two high waters per day but these are generally different. The tidal range exceeds 2m, and the tidal currents are reportedly weak. Along the coast of Yemen, the flood current apparently sets southeast (Defense Mapping Agency, 1990) and ebb current flows in the opposite direction. 2.3.5 Upwelling Understanding the process of upwelling is important since the Gulf of Aden has been regarded as one of the most productive areas (Kabanova, 1968; Krey and Babenard, 1976; Currie et al., 1973). Piechura and Sobaih (1986) showed that the upwelling develops first in the far eastern parts of the Yemeni coastal waters in May, and subsequently, progresses further towards the west. Mostly, the upwelling appears in separated patches similar to those appear in the coastal waters elsewhere (Boje and Tomczak, 1978). Awad and Kolli (1992) studied the upwelling process in the Gulf of Aden by analyzing the hydrographic data collected during 1984–85. They described the distribution of hydrographic properties and estimated the strength of upwelling. The most conspicuous feature is the cooling of near surface layer by more than 8ºC. 2.4 Study Area: Governorate of Aden Governorate of Aden is one of the important governorates in Yemen, where the main harbor of Yemen, Aden Harbor, is located only 4km from the international navigation rout. It is one of the largest natural harbors in the world with an area of about 70 km2 of sheltered water surrounded by Shamsan Mountain, Khormaksar, and the shore, which extends to the hills of Little Aden. The governorate extends between 12º 40 to 12 º 58 N and 44 º 25 to 45 º 7 E with an area of 750 km2. The geological structure of the governorate of Aden is an integral part of the composition of Yemen and the Arabian Peninsula. In the time period between the Miocene and Paleocene, six volcanoes were created along the southern coast of the Arabian Peninsula, stretching from Perim Island, Gabal Karaz, Ras Umran, Little Aden Peninsula and Aden (Crater). The last three volcanoes are located in the coastal area of Aden governorate. Rock formation is of volcanic nature, and the subsequent 15 impact of erosion and weathering, which are still ongoing, has earned a prominent terrain features. Aden consists of two parts, The Mountainous region and the Coastal Plateau. The southern part consists of two peninsulas, Aden and Little Aden, and an intervening stretch of the mainland. The two peninsulas of Aden are connected by sandy and muddy encircling Gulf of Al Tawahi. The volcanic rock formation of Ras Umran and the island of Jabal Aziz is similar in structures and formation to that of Aden and Little Aden, although erosion great impact had been aggravated from the marine side. Aden Governorate has 21 islands and rocky heads mainly found around Little Aden and Ras Umran and Gulf of Al Tawahi, in addition to Perim Island in Bab el Mandab, which follow the Aden governorate administrative. Offshore islands around Aden is a rocky islands supporting a scattered coral reefs and are mostly fishing areas in addition to many other activities. Following are the discretions of the two peninsulas: 2.4.1 Aden Peninsula Aden Peninsula is an oval-shaped rock formations centered with a six km in diameter crater. These formations extended westerly to form Shamsan Mountain with a range as high as 531 m above sea level. At Ras Tarchin the rock formation split towards the east and south to form Al Mandar Mount at the east and Mount Aidaroos at south, and terminated in the south east at the head of Ras Ma’asheeq. At the southeast side of the crater, a series of branched sub-mountains Alta’akor, Al Mansuri and Al Akdar mount formed. Another extension of the rocky mountain extends toward the northwest and ends at Hadeed Mount. The rigid configurations slope sharply into the sea to form a number of heads and bays. The most important of which are Ras Ma’asheeq, Ras Antouk, Ras Tarsheen, Ras Marbat, Serah Bay, Hakat Bay, Fishermen Bay, Gold Moor Bay, etc., are formed at the meeting points of the mounts and the water. 16 2.4.2 Little Aden Peninsula Little Aden peninsula is a range of hills interspersed with sandy depressions most vulnerable to erosion. Most forms of terrain is Almzalghem Mount, Mount Ihssan and a number of mountain peaks known as Albrouj, where the highest high of 350 m above sea level. Little Aden Peninsula, is surrounded by a number of rocky headlands and bays. The most prominent head lands are Ras Khesa, Ras Abu Kyamah, Ras Mjelb Hadi, Ras Ulagah, Ras Foqm. A number of bays with sandy beaches stuck between these headlands such as Khesa Bay, Bay of Darbah, and Bay of Bandar Sheikh. 2.4.3 The Coastal Plateau The Coastal Plateau is located in the northern part of Aden, which starts by linking the two peninsulas to the mainland, then ascends gradually towards the north. This Plateau is flat, mostly covered with sand dunes and includes two wadies (Wadi Al Kabeer and Wadi Al Sageer). The two wadies are considered as extensions of Tuban Wadi, which is located in Lahj Governorate, and include Tuban Delta in between. These two wadies are terminated at Al Tawahi Bay. Aden Governorate’s coastal area extends from Qa'awa in the west to Al Alam in the east. As mentioned above, Aden as a part of Gulf of Aden is influenced by the monsoonal variations. Using monthly values for air temperature for the period from March 1992 to December 2009, monthly climatology of air temperature for Aden was created (Figure 2.2). The annual mean air temperature is about 30 ºC. Whereas the highest monthly mean is 33.8 ºC during June, the lowest monthly mean is 26.5 ºC, which occurs during January. The relative humidity is between 66 – 75%, and the amount of precipitation is only 50 mm per year, since Aden is a part of the arid region. There are periodic rainy seasons with cycles of 12-15 yeas (EPAG, 2009). Mean annual temperature has increased by 1.8°C since 1960, a rate of around 0.39°C per decade. The rate of increase is most rapid in summer (June, July, August), with increases at an average rate of 0.56°C per decade and slower in winter (December, January, February) at a rate 0.21°C per decade. The rate of warming in Yemen is more rapid than the global average. There is insufficient daily temperature data available to determine trends in the frequency of hot and cold days and nights. Mean 17 rainfall over Yemen has decreased since 1960, at a rate of 1.2mm per month (~9%) per decade. These decreases generally affect the drier seasons. There is insufficient daily precipitation data available to determine trends in heavy rainfall events (McSweeney et al., 2007). 34.00 Temperature (C) 32.00 30.00 28.00 26.00 24.00 22.00 20.00 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Months Figure 2.2. Climatology of Air temperature in Aden, created from monthly values from 1992-2009. The topographic structure of the coastal plain of Aden comprises of three classes as described by MEP (1995). The rocky sub-littoral coasts, this includes Crater and Buraiqah, medium energy sandy coastal plains with fine sands, this type mainly located from Khormaksar east to Shuqra, and the same from Ras Umran to Qa’awa. The third type is also fine substrates of low energy of mud/fine sands, this type is located along the sheltered Al Tawahi Bay between the headlands of Little Aden and Crater, as well as the sheltered sandy bay to the west of Ras Foqm. The second and third classes are more vulnerable to sea level rise and climate change as the coastal slope is less the 5º. 2.5 Population and Administrative Divisions According to the 2004 Census, the population of Aden Governorate is 598,419, of which 53.2% is male. This population composes about 3% of total the Yemen population with a growth rate of 3.53%. The average number of families of Aden Governorate is 90,667, and number of dwellings is 97,408 households. From the population and number of families and dwellings, it can be found that the average 18 numbers of family members is 6.5 persons, and number of residents per household is 6.1 persons. Aden Governorate population is distributed along its eight administrative divisions (districts), which are Buraiqah (or Little Aden), Al Tawahi, Al Shiekh Othman, Al Mua’alla, Al Mansoorah, Khormaksar, Dar Sa’ad and Seerah. Aden peninsula contains most of the city's population and is divided into a number of districts. Little Aden peninsula contains the city's main industrial district and is the site of a large oil refinery. However, Aden with its harbor together with Al Shiekh Othman, hold most of the commercial and administrative activities. 2.6 Coastal and Marine Environment Gulf of Aden’s marine and coastal ecology has received little attention, particularly that of Aden city. However, the few studies and surveys conducted by the Marine Science Research and Resource Center (MSRRC) were focused on the fisheries aspects, and covered the near and offshore areas of the Gulf of Aden (20-500m) (MEP, 1995). CEMP (1985) had conducted a survey of the main habitats and species in the Yemen southern coastal region. The study highlighted the sites of special interest. In Aden Governorate the following locations were recommended to be of ecological importance: Sites Ras Umran Importance Coral reef, seagrass beds, turtle nesting Ras Abu Quijara Rocky shores, submarine hard bottom communities, coral reef Shallow bay, rich fishing ground Mud flats, bird & high productivity Mud flats, bird & high productivity Exposed sandy beach Bandar Foqm Farisi Lagoon Aden Inner Harbour Khormaksar Beach Reference Ehrenfield1981; CEMP,1985 MEP,1996 CEMP,1985 CEMP,1985 CEMP,1985 CEMP,1985 Preliminary work has been under taken on coastal zone between Bab el Mandab and Ras Darbat Ali, including comprehensive surveys of ecosystems (MEP, 1995). This survey covered eleven locations along 150 km of Aden coastal area and described their topographic and ecological characters. 19 The geomorphologic structure and composition of Aden coastal area have contributed directly to the type and conditions of its environment, and helped to form a number of distinguished marine and coastal habitats. The formation of rock heads and mountains, which extend into the sea, have led to the creation of a number of bays and hard substratum which form the suitable conditions for coral growth in the vicinity of Aden (Crater) and little Aden Peninsulas. Meanwhile, the processes of erosion and alluvial sediments (Mud) prevailed during a long period of time have contributed to the formation of sand plains, marshes and mud flats. These created favorable conditions for growth and reproduction of many species of plants and animals (marine and terrestrial). Consequently, the following marine and coastal environments form the main features of Aden Governorate coastal area: 1. Coral reefs. 2. Sea grass beds. 3. Turtle nesting sandy beaches. 4. Wet lands. 5. Rocky shores. 6. Birds (local and Migratory). 7. Mud flats. 8. Fresh & salt water vegetations. 2.6.1 Rock shores Rocky shores of Aden are mainly occurring in Crater, Little Aden and Umran, and surrounding islands in the form of steeply sloping volcanic mountainous intrusions and extrusions, and wave cut platforms. The coral and coral fauna forms a veneer over steeply sloping volcanic rocks and boulders down to 8 m depth, where a gently sloping sandy bottom prevents further colonization. Many of the marine and climatic features have helped the growth and prosperity of the coral reefs in some areas, including water clarity and the absence of 20 wadies, as well as the warm temperatures and water currents. Corals are found as patchy and fringing reef. Live coral cover is high on average (30 - 50 %), although it reaches 100 % in some places. Massive growth forms of Porites colonies dominate, with at least 20 other genera, including large colonies of Lobophyllia, Galaxea, the solitary coral Fungia spp. and Turbinaria spp. in deeper water. Rosen (1971) reports a total of 32 genera for the Aden area. Reefs in Aden support good coral communities of reef fishes, such as parrot fishes, butterfly fishes and surgeon fishes. Rock lobster and other marine invertebrates and algae are found in extensively numbers reflecting the high productivity of Aden reef community. Artisanal fishers depend greatly on fish and lobster resource of this area. Studies of Kemp and Benzoni (2000) had confirmed the presence of highly dense and divers coral communities in Aden waters around the sub-tidal rocky substrate. The presence of corals around Seerah is sparse and consisting of small colonies of branching species (Stylophora sp, Pistilata sp, and Acropora sp). In little Aden, corals are scattered parallel to the rocky shores with 50 to 150m in length, and down to 6 meters. Corals of this region are solid and massive forms and mainly massive Porites sp, Gonipora sp, Siderastrea sp, Platygera sp, Galaxea sp, and few of the branching coral Acropora sp, Stylophora sp and Pistilata sp. Most coral reefs in these locations is poorly evaluated and are under pressure due to a high concentration of fishing activates, anchoring, messing nets and pollution. 2.6.2 Sandy Shores A medium energy sandy shores, mainly located on the long stretched, exposed shores (Khormaksar) and between headlands, forming coarse to medium sandy bays (little Aden). Khormaksar intertidal and supra-littoral fringe harbor many mollusks and crabs, and support important bird’s populations. The sandy shores bounded by igneous mountains in Crater and Little Aden such as the Gold Moor, Elephant Bay, Wreck Bay, Sapper Bay, Round Island Bay, Bandar Daras, Hokat Bay, refinery recreational bay, Ghadeer Bay, and Bandar Foqm, are formed 21 from medium to coarse sandy beaches and some are mixed with calcareous shells fragments. All the shores are used as recreational beaches, and are under threat from intensive development along its supra-littoral fringe. Foqm village’s sandy beach forms the landing site of the biggest artisanal fisheries in Aden. The sandy beach west of Ras Umran is formed from flat plain and desert dunes inland that gently descent to coarse sand with pebble and many fragmented shells supra-littoral shore. Seagrass beds located in Umran Bay and Tawahi bay in scattered locations. There are two types of seagrass beds in the inner harbor Halodule uninervis, Halophila ovalis, (MEP 1996, Golder and Associates 1998). Seagrass beds is one of the important habitats of highly productive ecosystems forming a feeding areas for many of the benthic, fish, turtles and nursery areas for many of the neighborhoods most important economic fishes and crustaceans. Halophila ovalis, Cymodocea sp. and Haloddule uninervis are also reported from Umran Bay, and Khor Bir Ahmed. The southern coastal of Yemen is ranked as one of the most important regions in the world for turtle nesting and breeding of green turtles. Reports indicated that the area of Jabal Aziz should be given priority in the maintenance of turtles (UNEP, 1985). Sandy beaches of Aden regions are important for nesting of two endangered species (green turtles Chelonia mydas and Hawksbill Turtles Eretomchelys imbricata), which today may be less abundant than it was in the past, due to increased human activity in the coastal zone area. 2.6.3 Muddy shores Muddy shores in Aden present in enclosed inlets of Aden inner harbour, where wave action and other movements are of low energy. This enables the suspended mud to settle down to form mud flats or wetlands. Aden wetlands consists of Aden inner harbour east of the cause way (Aden Lagoons), salt pans and extend to little Aden including Aden marsh, which form a large area of marsh and Dom palm, created by a long established sewage outflow at Al Hiswah. They also found to the west of Ras Foqm and the back side area of Abyan beach. Al Gadeer semi-enclosed beach is mainly formed from silt materials and retain some of the muddy environments. The great productivity of the wetland at Al Hiswah sustains a unique diversity of flora and fauna. A fairly numbers of plant species recorded are listed in table 2.1. 22 The wetland vegetation supports a number of wildlife species, especially migratory and domestic birds, which considered a safe haven for many of them and for a large number of wild animals such as rabbits, foxes, reptiles, scorpions and bats. Despite the high salinity of Aden saltpans, a number of plants species appear to tolerate and adapt the high concentrations of the dried salts. These plants include Tamarix spp, Prosopis juliflora, Sueada monoica, Sueada fruticosa, Typha elephant aiodes, Cyprus laevigatus, Sporbulus spicatus, and Odyssia mucronata. Aden lagoons are located in the innermost recess of Aden inner harbor were resulted from the construction of the causeway across the Bay of Aden in shallow waters. One main gate and secondary pipes situated under the road to feed three main lagoon bonds. Behind the three main ponds, the salt pans are existed. Water quality is unknown but high salinities might be expected, resulting from shallow waters and intense evaporation. Bottoms are sandy near the sea shore but turn gradually to mud in all parts of the lagoons. These lagoons are important for their environmental and bio-diversity nature, and role as feeding ground of many species of birds in addition to the presence of many plants and marine organisms. They own an aesthetic dimension as a coastal park to the Tourism of Aden and economic assets. They provide a natural protection for the builtup areas and economic activities of the nearby areas from tidal waves. It is also home to many sea grass species such as Halophila stipulacea , Cymodocea searulata , and Kalodule uninervis. The importance of seagrass beds appear, in the settling of the seabed soil erosion and deposition and accumulation of organic materials and inorganic. Seagrass beds form a habitat for a wide range of marine flora and fauna and a direct source of food for the animals that live on it, such as crustaceans, sea urchins, herbivorous fish, mollusks, and birds. On the boarder of the lagoons some coastal plants are nourished, such as Sporobulus spicatus, Odyssia mucronata, Sueada fruticosa, and Sueada monoica. The Lagoons supports many types of marine fauna such as fish (latycephalide and Mugilidae), crustaceans, (Penaeidae and crabs) and mollusks (Stromdidae). There high productivity is considered as important feeding, nursery and proliferation place 23 Table 2.1. Plant species listed in Al Hiswah wetland. Forest Plants Cultivated Plants Grazing plants Echoinchloa colona Inga deluce Echiocnloa colona ((L)) Lank Sporopulus spicatus Conocarpus lancifolius Cynadon dactylon Panicum antiditole Catharanthus rosus Eluropis lagopoides Lasiurus hirsutus Nerium oleander Sporobulus spicatus Cynadon dacylon Casuarina equisitifolai Cyperus laevigatus Aeluropis lagopoides Prosopis cinerria Lasiurus hirsutus Chloris barbata Prosopis juliflora Odyssia mucronata Odyssa mucronata Acaica nilotica Chloris barbata Cyperus laevigatus Prosopis chiliensis Panicum antiditole Cyperus conglomartus Azidrachta indica Prosopis juliflora Pheonix dactylifera Prosopis chiliensis Pennisitum spp Sueada fruticosa Syzigium cuminii Sueada monica Hyphaene thebica Halopeplis perfoliata Cormulaca amblycanthus Calotropis procera Leptadeia puyrothecnica Euphorbia granulata Hyphaene thebaica Pheonix dacytlifera Typha elephataiodes Tamarix aphylla Ziziphus spina – christi Acacia tortilis Balanites eagyptiaca Acacia ernheber giana Auphorpia granuata Halopyrum mucronatum Sevada schimperi 24 for a large number of fish species and marine invertebrates. They also provide a suitable environment for a large numbers of migratory and endemic water birds and other water fowl. The wetlands of Aden (saltpans, freshwater wetland and lagoons) form an important staging and wintering areas for a wide variety of migratory waterfowl, notably shorebirds, gulls (including Larus leucophthalmus) and terns, with at least six species occurring in numbers exceeding 1 % of the regional population (Table 2.2). Accordingly, Aden wetland has identified as an important bird area by Bird Life International. It is considered amongst the most important wetlands in Yemen and Arabia. Table 2.2. List of common bird’s species associated with Aden wetlands. Name Cattle Egret, Bubulcus ibis Imperial Eagle, Aquila heliaca Western Reef Heron, Egretta gularis Moorhen, Little Egret, Egretta garzetta Black-winged stilt, Himantopus himantopus Black Egret Pied avocet, Recurvirostra avosetta Grey Heron, Ardea cinerea Pacific Golden Plover, Black-headed Heron, Ardea melanocephala Little Stint, Calidris minuta Sacred Ibis, Threskiornis aethiopicus Temminck's Stint, Calidris temminckii Glossy Ibis, Plegadis falcinellus Ruff, Philomachus pugnax African Spoonbill, Platalea alba Black-tailed Godwit, Limosa limosa Greater Flamingo, Phoenicopterus roseus Curlew sandpiper, Calidris ferruginea Lesser Flamingo, Phoenicopterus minor Spotted redshank, Tringa erythropus Pintail, Anas sp. Common greenshank, Tringa nebularia Garganey, Anas querquedula Common Sandpiper, Actitis hypoleucos Northern shoveler, Anas clypeata Gull-billed Tern, Sterna nilotica Black Kite, Milvus migrans Chestnut-bellied Sandgrouse, Pterocles exustus Greater Spotted Eagle, Aquila clanga Alaemon Alaudipes Galerida Cristata Streptopelia Rosegrisea Pycononotus Xanthopygos Streptopelia Semitorquata Anthreptes Metallicus Streptopelia Seneglensis Corvus Splendens Oena capensis Passer Domesticus Centropus Superciliosus Ploceus Galbula Upupa Epops long-legged buzzar, Buteo rufinus Dark chanting goshawk, Melierax metabatus Esprey, Pundion haliaetus Sriffon vulture, Gyps fulvus Egyptian Vulture Neophron percnopterus Lanner falcon, Falco biarmicus Sparrow gawk, Accipiter nisus Osprey, Pandion haliaetus White-eyed Gull, Larus leucophthalmus 25 Artisanal fisheries is the main traditional livelihood in Aden and the traditional fishermen is the main fish producing sectors, which covers the needs of Aden and surrounding governorates. The main fishing and landing villages are Qa’awa, Ras Umran, Foqm, Khesa, Seerah (Table 2.3). Table 2.3. Fishers and fishing boats numbers (MFW, 1998). location No of Fishers Qa’awa Ras Umran Foqom Keisah Seerah 255 Fishers family no. 1000 No & Type of fishing boats 777 4000 105 140 4 249 4 245 636 600 400 5000 8000 2000 58 60 5 85 200 275 1 - 144 260 280 1 144 260 280 Wooden 28 Fiberglass 50 sambouk 1 total 79 No & Type of engines Internal External 1 78 Aden is characterized by being one of the major fishing areas along the southern coast of Yemen. Coastal waters rich with fish as well as crustaceans and mollusks of commercial value. Fishing locations are concentrated in coastal areas near deep and varies from 5 to 30 meters and using deferent catching gears. Total annual production of fish and marine life in the province has increased from 4,135 tons in 1990 to 24.545 tons in 1999, with absolute growth rate of 593%. Recent development activities have accelerated the nature of the threats to biodiversity and natural habitats. Table (2.4) lists the coastal area in need of special management for their importance, economically and environmentally. 2.7 Review of SLR in Aden As mentioned above, the IPCC fourth assessment report suggested rise in sea level globally by 18-59cm by the end of this century. Regionally, Unnikrishnan and Shankar (2007), using stations from the northern Indian Ocean, showed that the sea level at Aden rises by about 2 mm/yr, which is similar to that of the global estimate. Woodworth et al. (2009) showed that the sea level rise at Aden is similar to that of 26 Table 2.4. Coastal areas recommended for special management in Aden due to their biological, environmental or recreational importance. Location Habitat Species Fishing 1 Ras Qa’awa Ras Umran Is. AL Guhub Is. Gabal al GaziraRas Abu Qiama Habban Is. Birds, Turtles feeding Turtle nesting Birds + 2 Seagrass, Coral reef, Sandy beach Sea grass, Coral reef Coral reef 3 4 5 6 Khor Bir Ahmed 7 Al Hiswa 8 Inner Aden Port Caltex Swamp 9 Recreation Sci* Impact Source + + 4 + Sandy beach + Fishing 1, 2, 4 + Snorkkeling + Fishing 4 Fishing Swimming Snorkeling + Oil pollution Land filling 3, 4 + Urban Fishing 4 + Urban Fishing 2, 4 Urban (free zone) Urban (free zone) Grazing 4 Coral reef, Rocky shores Coral reef Fishes + Seagrass, Coral reef Birds + Seagrass, Coral reef, Silt, Mud flat Sand beach, Palm trees Seagrass, Coral reef, Mud flats Swamp(sewage) Birds + Birds + Birds + Sandy beach Fishing Fishing + + Birds 10 Aden Lagoons Wetlands Birds + Fishing + 11 Fishermen Bay Turtle nesting Birds + + 12 Khormaksar Beach Sand beach Birds + Swimming, Sandy beach Fishing Swimming Fishing Sandy beach + 2) CEMP1985 27 3,4 Urban ,Fishing, Land filling ,Oil pollution. Hunting of turtles 4 Urban filling Oil pollution, Sewage 2, 3, 4 * Scientific importance Sources: 1) Ehrenfield 1981 4) Current Study 2, 3, 4 3) MEP 1995,MEP1996 4 other places in the globe. These studies confirm that sea level is rising at Aden and will continue in future. Most of Aden sandy coasts are lowlands (like Khormaksar), and hence, the Governorate of Aden is considered as a sensitive site, and will be affected by global climate change and accelerated sea level rise. This in turn would lead to the destruction of residential and industrial areas, commercial and natural resources, coastal erosion, destruction of marine habitats, natural reserves, and the bulldozing of the soil and the elimination of the coastal wetlands in low-lying areas (PERSGA, 2001). 2.8 Selection of Scenario Two possible future sea-level rise scenarios for Governorate of Aden coastal region are adopted. Values are in meters above main sea level (MSL), which is 1.4 m above CD (Chart Datum) for Aden. Scenarios are based on (i) observed rates for Aden mean sea-level rise, 3.3 mm/yr (Woodworth et al., 2009), and (ii) extreme sea-level rise rate of 5.9 mm/yr (derived from IPCC (2007)) at highest high tide (HHT) is included for an extreme scenario. Scenarios of 0.33, and 0.6m SLR over this century were assumed. 28 Chapter 3 Potential Impacts of Sea Level Rise 29 The rise in sea level would affect the wetlands and lowlands, results in the acceleration of the coastal erosion, exacerbate coastal flooding, threaten coastal structure, raise the water table and increase the salinity of bays and aquifers. The main limitation, as explained earlier, for making accurate assessment of the vulnerability of the coastal zone to sea-level rise has been the lack of data on the topography of the coastal area to the desired accuracy (i.e. to enable the delineation of the maximum water level). As much as possible, data was derived from available toposheets of 40 m contour intervals, from which the maximum water level interpolateed. 3.1 Erosion An acceleration in sea-level rise will widely exacerbate beach erosion around the globe (Brown and McLachlan, 2002), although the local response will depend on the total sediment budget (Stive et al., 2002; Cowell et al., 2003a,b). The impacts of sea level rise, and increased coastal erosion and flooding hazards, will affect tourism and recreation activities in coastal communities, by effecting coastal transportation infrastructure and marina maintenance, dredging activities, boating safety, vacation housing and resort infrastructure (Craig-Smith et al., 2006; Walker et al., 2007). Most sites currently experiencing erosion can be expected to show continuing erosion in the future, and rates are likely to increase. Therefore, planning and development should not be based simply on historical rates of erosion, but should consider an appropriate additional setback to account for more rapid erosion over the life of a structure or other development. The loss of land attributable to sea level rise will occur from erosion of sandy shores and erosion prone cliffs. Shoreline recession results from the offshore transport of sand. On steep rock coasts, sea level rise may have an insignificant impact. The recession comes from the adjustment of the active profile to a new elevated water level. The cross-shore profile adjusts itself by redistribution of sediment, such that the active zone rises with the rise in sea level while maintaining the same cross-sectional profile. This results in a loss of beach area. The apparent loss of sediment is proportional to the width of the active zone. The best known and most widely applied model to estimate erosion has been developed by Bruun (1962), for application on straight sandy shores (see also Dean, 30 1990; Healy, 1991; 1996; Mimura and Nobuoka, 1995). In other erosion prone coastal environments alternative erosion models have to be used, which, however, are often based on the Bruun rule. An important limitation for the quality of data available for this assessment has been the data on coastal topography to the required scale and accuracy. Available topographic data for the pilot area is usually in the form of 1:10,000 scale maps. Unfortunately, these could not be obtained for the entire study area. Furthermore, maps obtained from the (General Authority for Lands and Surveying and Urban Planning) with 1:100,000 scale toposheets, of 1987, has been taken as base maps. In fact, such maps is not accurate enough for the intended purposes, showing contour intervals at 40 m levels only. The location of the HHT contour line has been found by interpolation between the 0 and the 40 m contour. To get the actual elevations from the shoreline, several ground truthing topographic profiles were surveyed along Khormaksar coast. Elevations relative to the current sea level were measured, and then the data were corrected to the MSL. The new elevations were incorporated to the base map. The analysis by Bruun assumes that with a rise in sea level, the equilibrium profile of the beach and shallow offshore moves upward and landward. Following a number of assumptions, Bruun derived the basic relationship for the extent of shoreline recession R, due to an increase in sea level, S: R = (L/B + h) S Where, L is the cross shore distance to the water depth h, taken by Bruun as the depth to which near shore sediments exist (depth of closure), and B is the height of the dune. The analysis is two-dimensional and assumes: a) the upper beach is eroded due to the landward translation of the profile; b) the material eroded from the upper beach is transported immediately into the offshore and deposited, such that the volume eroded is equal to the volume deposited; and c) the rise in the near shore bottom as a result of deposition is equal to the rise in sea level, thus maintaining a constant water depth in the offshore (SCOR, 1991). For the present study, the following values pertain: S = 0.33 m, 0.6 m; B was estimated at 1.0 m a long Khormaksar Beach and 1.5 along Foqm Bay; h is the depth 31 of closure in meters, which is calculated by the following equation derived by Dean (2002): H2 h 1.75H s 57.9 s2 gTs Where, Hs is the annual exceeded wave height in a 12-hour period, and Ts is the associated wave period. As there are no records of wave characteristics for the study area, the total wave height was estimated from sea and swell waves using the following: Total Wave Height = [(Wind Wave Height)2 + (Swell Wave Height)2] 1/2 Wind wave height estimated from the wind speed following Quayle (1980), as 0.5 m. Whereas, the swell wave height was used following Red Sea and Gulf of Aden pilot (1987) as 2 m. Hs = (0.52 + 22) 1/2 After estimating the depth of closure (h), the cross shore distance (L) was estimated following Dean (1990): L = (h/A)3/2 Where, A is the scale parameter determined from the median sediment size (D50). For that, sediment samples were collected from Khormaksar beach and the (D50) was estimated after the grain size analysis of the samples. Using the above parameters, the Bruun rule gives a depth of closure of 3.2 m. Consequently, the recession of the shoreline was estimated at about 23 m and 41 m along the eastern part of the study area (Khormaksar till Al Alam), for rise in sea level of 0.33 m and 0.6 m, respectively, and about 18 m and 33 m, respectively, along the western shoreline (Foqm Bay). This was translated to a potential land loss along the entire shoreline of the pilot area (length 23 km) about 48 and 86 ha, respectively. 32 3.2 Inundation Sea level rise will lead to inundation of coasts worldwide with some small Island States, possibly facing complete inundation. Low-lying coastal areas such as deltas, coastal wetlands, and coral atolls may face inundation as a result of sea level rise. Land loss resulting from inundation is simply a function of slope, the lower the slope, the greater the land loss. In addition, the survival of coastal wetlands is dependent upon sediment availability and local biomass production, as well as the potential for these ecosystems to migrate inland. Healthy, unobstructed wetlands in settings with continuing sedimentation are expected to be able to cope with projected global sea level rise, although ecosystem characteristics may change. However, with the continuing urbanization of the coastal areas, people build structures just above the marshes. The increase in sea level will put a squeeze on these wetlands between built structures and the coast, which will result in the reduction of production of organic materials, which is essential for nearby ecosystem. As described earlier, the topographic structure of the coastal plain of Aden comprises of three classes: the rocky sub-littoral coasts, medium energy sandy coastal plains with fine sands, and fine substrates of low energy of mud/fine sands. The second and third classes are more vulnerable to inundation due to sea level rise and climate change as the coastal slope is less the 5º. As explained in chapter 2, two plausible future sea level rise scenarios for the Governorate of Aden coastal region are provided in Table 3.1. Scenarios are based on observed rates for: Aden mean sea level rise rate of 3.3 mm/yr, and extreme sea-level rise rate of 5.9 mm/yr, at HHT is included for an extreme scenario. Scenario for water levels was estimated in meters above MSL, as follows. SWL = {(rate/1000) x (year - 2008)} + HHT – MSL Scenarios of 0.33, and 0.6 m SLR over this century were assumed. Sea level rise for Aden Governorate for 2020, 2050, 2080 and 2100 based on these scenarios are shown in Table 3.1. Values are shown as metres above MSL, which is 1.4 m above CD for Aden, from the year 2008. The total land area that would be inundated under the various climate change scenarios is substantial. With the proposed sea level rise of 33 cm, the percentage of the inundated area is 43 Km2, which represents 5.7% of the total 33 area of Aden Governorate (about 750 km2). The inundated area would increase to about 45 km2 (6%) for SLR of 60 cm. Inundation will unevenly affect Aden Governorate coastal area. Khormaksar, Al Tawahi Bay, the coastal beach between Khormaksar and Al Alam (Abyan Coastal Beach), Aden lagoons and wetlands are the most affected regions. About 3.90 km2 will be inundated in the dens populated area of Khormaksar, Al Mansoora, and Al Mua’alla Districts for SLR of 33 cm, while 4.35 km2 would be inundated for SLR of 60 cm. The total socio-economic loose is described in chapter 4. Table 3.1: Sea level rise scenarios for Aden Governorate for 2020, 2050, 2080 and 2100 based on observed rate of sea level rise (3.3 mm/yr), and the global extreme scenario 5.9 mm/yr. Water level scenarios are expressed as meters above a local MSL (1.4 m above CD) occurring at HHT to provide an upper limit for each scenario. Scenario observed rates of SLR (3.3 mm/yr) at HHT Global extreme (5.9 mm/yr) at HHT 2008 1.03 2020 1.07 1.10 2050 1.17 1.28 2080 1.27 1.45 2100 1.33 1.57 3.3 Saltwater Intrusion As sea level rises, fresh groundwater and surface water could be displaced by saline water, which could have substantial adverse impacts on drinking-water supply and agriculture. It is important to note that saltwater intrusion is already occurring in many coastal regions, owing to overexploitation of surface water and groundwater ( Han et al., 1995). With growing populations in coastal regions, saltwater intrusion due to this problem is expected to occur more widely, and may enhance the rate of saltwater infiltration. Therefore, it is likely that sea-level rise will exacerbate an already adverse situation. Assessing the extent of saltwater intrusion in groundwater is difficult because it depends on many factors that are locally variable and often poorly understood. These factors include subsoil characteristics such as porosity and conductivity of the aquifer, hydraulic resistance of the aquitard, and hydraulic variables such as groundwater flow and recharge. Also, the geohydrology is important because this determines whether a 34 freshwater aquifer is confined, semi-confined, or unconfined; sea level rise will not result in saltwater intrusion in confined aquifers. Saltwater intrusion in groundwater can be assessed using analytical methods or mathematical modelling. One commonality of the analytical methods is that they are all based on the Badon Ghijben-Herzberg principle, which describes the equilibrium of two stationary immiscible fluids of different density (Badon Ghijben, 1889; Herzberg, 1901). Thus, these methods assume that a sharp interface exists between fresh and saline groundwater. The Ghyben-Herzberg principle provides an initial estimate of the inland extent of saltwater intrusion in a simple unconfined aquifer of infinite depth. This theory assumes two fluids separated by a sharp interface and ignores many of the complexities found in real aquifers. The principle assumes that an equilibrium condition exists between the saltwater offshore and a freshwater flowing from upland area down toward the ocean. As shown in Figure 3.1, since the saltwater is 1.025 times denser than the freshwater, the saltwater/freshwater interface lies a distance below mean sea level (H) for a given height of the freshwater above mean sea level (h). The product of the density of saltwater times its height is balanced by the density of freshwater times its height. In equation form: 1.025 x H = 1.0 x (h + H) At any point in time, for every foot that the freshwater table lies above mean sea level, the depth to the saltwater is 12 m (40 ft) below mean sea level. Therefore each increment of sea level rise reduces the freshwater capacity of the aquifer by 40 times (Gornitz, 1991). Currently, Aden Governorate water supply depends largely on underground sources (Tuban & Bana Delta Basins, which are located in other governorates (Lahj & Abyan), and extracted from Bir Naser, Bir Ahmed, Rowa and Tuban well field (GAWSP-II STAGE, 2001). Bir Nasser Well field is situated 25 km north of Aden Governorate at the middle of Delta Tuban (Lahj Governorate). It is the main source of water supply for Aden as it covers 40% of the requirements (Haidera, 2007). 35 Figure 3.1. Saltwater intrusion in a coastal aquifer. Bir Ahmed aquifer is the only well field located in Aden Governorate. It is mainly alluvium sand gravel and clay, and is a continuity of Delta Tuban (Figure 3.2). It is the second main water source for Aden Governorate, especially for Little Aden and its suburbs. Specific conductance (SC) readings for Bir Ahmed increase from 1800 to 2400 µS/cm, in the northwest to a range between 3000 and 5000 in the area to the east. The interface between the fresh water and saltwater is at 500 m depth, since the water level depth is about 10 - 12 m above sea level. The increase of sea level will result in land propagation of this boundary. It was stated in the previous studies (Sogreah, 1981) that by maintaining the extraction levels at 5 Mm3/yr from Bir Ahmed, 12 Mm3/yr from Bir Nasser and 10 Mm3/yr from Tuban, it would be possible to protect these well field from deterioration, high salt content and fast water level drop due to over extraction. Number of wells in each well field, production and static water level up to the year 2001 are summarized in Table 3.3. 36 Figure 3.2. Base map of Delta Tuba and Delta Abyan (Source: Komex 2002). 37 Table3.2: Summary of well field production capacity and water level average drops up to the year 2001 (Source: Haidera, 2007). Number of wells Total Production (MCM/yr) Quantity for Aden (MCM/yr) Static level (m) Average Drawdown (m/year) Bir Nasser (Lahej) 32 12 11.687 55-65 1.5 Bir Ahmed (Aden) 16 7 5.625 40-50 1 Tuban (Lahej) 19 5 3.263 60-70 2 Rowa (Abyan) 19 12 8.243 12-22 0 Total 86 36 28.818 Well field The detailed study by Komex (2002) described the distribution of the saline water in the ground water of Abyan and Tuban deltas, based on existing and new geophysical data. Contours of the saltwater intrusion front were drawn on the geophysical interpretation maps for the Abyan and Tuban deltas as shown in Figure (3.3). In their analysis, they found that in the Lower Abyan delta, brackish to saline groundwater is interpreted to exist, encroaching from the south, east and west, up to a distance of 12 km from the coast. The deeper part of the saltwater intrusion front, at an elevation of –400 meter above sea level (masl), is subparallel to the coastline more than 10 km inland. The front is interpreted to be located at shallower depths as the coastline is approached up to an elevation of –100 masl. Between this elevation and surface, the saltwater intrusion front appears to rotate counterclockwise and penetrate further inland in the eastern portion of the Abyan area (Figure 3.3a). To get clear idea about the extent of saltwater intrusion into Delta Abyan, line B profile constructed by Komex (2002), using 1-D soundings from the WRAY report (1995), and 2- D Electric Resistivity Tomography (ERT) cross-sections A604 and A603, was adopted in this study. It is a southeast to northwest profile approximately 17.3 km long (Figure 3.4). In the southeastern portion of the profile, low resistivity values suggest that saltwater intrusion may be present in this layer to a distance of 4 km along the entire profile. Below the alluvium, a sandstone layer is interpreted. This layer is, probably, laterally continuous, and the lateral variations in resistivity are thought to be related to groundwater salinity changes from north to south. The 38 a b Figure 3.3. Contour lines of saltwater intrusion in (a) Abyan delta, and (b) Tuban delta (source: Konex, 2002). Figure 3.4. Resistivity cross-section: Line B Abyan delta (Source Komex 2002). 39 southern end has resistivity values that vary between 0 and 15 ohm-m, and is most likely an area of saltwater intrusion. The northern end has resistivities that vary between 40 and 80 ohm-m, reflecting a freshwater aquifer. It appears that the further inland position of the shallow portion of the saltwater intrusion front on the east side of the Abyan area is related to incursion of saltwater along unconsolidated, more permeable sediments, whereas the deeper inland dipping wedge is contained entirely within consolidated sediments. This is evident on the eastern side of cross-section line D (Figure3.5). Line D is located in the Upper Abyan delta area. It is a west to east profile, which is approximately 14.7 km long, and was constructed using 1-D soundings from the WRAY report (1995). Resistivity values in the upper part of the eastern side of section range from 0 to 15 ohm-m, and this is interpreted to be an area of shallow saltwater intrusion. The western end has resistivity values that range from 40 to 80 ohm-m (Figure 3.5). The extent of the saltwater intrusion will extend further inland by rising sea level, for the proposed scenarios of 0.33 and 0.6 m. The interface between the saltwater and freshwater will extend 160 m and 240 m inland and 16m and 24 m upward, respectively, effecting the well field in that region. In Tuban Delta, the boundary of saltwater intrusion is constrained by offset Wenner soundings and Electric Resistivity Tomography (ERT) data collected during Komex investigation. It is also supported by observations made in Bir Ahmad well field. Only the interpreted –50 masl and –100 masl contours are displayed in Figure (3.3b). The contours are approximately parallel to the coastline, about 10 km inland on the eastern side of Tuban area. Where the contour lines are close to each other, this indicates a steep saltwater intrusion front. In the southern portion of the Tuban area, the saltwater intrusion front is interpreted to be less steep and located within about 5 km from the coastline. In the west and central portions of the delta, along cross-section line E (Figure 3.6), brackish water is interpreted to exist at depth. Bir Nasser well field is located along the eastern side of this section, where possible brackish water deeper than 150 m is threatening the water quality of this water field. With the rising sea level of 0.6 m, the level of the intrusion could rise to the well depth and effect the mean source of ground water of Aden Governorate. 40 Figure 3.5. Resistivity cross-section: Line D (Source: Komex, 2002). Figure 3.6. Resistivity along the eastern side of section E in Tuban delta (Source: Komex, 2002). 41 Line G is a southeast to northwest profile in the southern part of the Tuban Delta, and is approximately 13.6 km long. Resistivity logs from wells 15, 16 and 17 in the Bir Ahmad well field are also used to construct this cross-section (Figure 3.7). The upper layer consists of unsaturated silts and sands, which is continuous to the whole length of the cross-section. It, generally, has a thickness of between 5 and 15 m, and is characterized by medium to high resistivity, with resistivity values between 60 and 80 ohm-m. The second layer consists of sand and gravel with silt, and is continuous from 3000 m to the end of the profile. It is characterized by resistivity values between 80 and 100 ohm-m, and represents the aquifer from which the Bir Ahmed well field produces groundwater at a maximum depth of 64 m. A third layer of silt and clay is found beneath the sand and gravel layer and is continuous from 3000 m to the end of the line. It is characterized by low resistivities (less than 30 ohm-m). In addition, this layer may contain brackish water toward the bottom of the section. In the Bir Ahmad field sands, cobbles are reported in this layer as well. The first 3000 m of the section are characterized by a saltwater intrusion. The saltwater intrusion front dips northward, and is interpreted to intersect the bottom of the section at a distance of 5500 m along the line. Figure 3.7. Resistivity cross-section: Line G Tuban delta (Source: Komex, 2002). 42 Bir Ahmed is an older well field that has been progressively enlarged in extent, and now contains 25 wells. As it is located closer to the coast than Bir Naser, there has been concern over increasing chloride content in abstracted water. The data from NWSA shows a rise in both nitrate and conductivity. Increased conductivity over time may reflect increasing intrusion of saline water from the ocean, or up-coning if a wedge of saline water has intruded under the well field. This increasing in conductivity will be accelerated due to sea level rise. 3.4 Increasing Flood Frequency Probability Although inundation by increases in mean sea level over the 21st century and beyond will be a problem for unprotected low-lying areas. The most devastating impacts are likely to be associated with changes in extreme sea levels resulting from the passage of storms (Gornitz et al., 2002), especially as more intense tropical and extra-tropical storms are expected (Meehl et al., 2007). Coastal area would become more vulnerable to flooding due to mainly four reasons: (i) A higher sea level would provide a higher base for storm surges to build upon; (ii) Beach erosion would leave particular properties more vulnerable to storm waves; (iii) Higher water would reduce the coastal drainage and hence increase the risks of flooding due to rainstorms; and (iv) a rise in sea level would raise water tables. Storm surges are temporary extreme sea levels cause by unusual meteorological conditions. The resulting coastal flooding is a major issue damaging livelihoods, causing great distress, and in the extreme, loss of life. As many as 2 million people may have been killed by storm surges in the last 200 years, mainly in south Asia (Nicholls et al., 1995). Sea level rise will raise the mean water level, and hence allow a given surge to flood to greater depths and penetrate further inland. Globally, about 200 million people live in the coastal flood plain (below the 1 in 1,000 year flood elevation) (Nicholls and Hoozemans, 2002). The increased sea surface temperature would also result in frequent and intensified cyclonic activity, and associated storm surges affecting the coastal zones (Wu et al., 2002; Unnikrishnan et al., 2006). The concept of risk is considered appropriate in the context of assessing the consequences of sea level rise on flooding for the population in the coastal zone. As rising sea levels intensify flood hazards, some human responses might be expected. 43 Based on the definition of risk, Population at Risk (PaR) is defined as the product of the population density in a certain risk zone, and the probability of a hazardous flooding event in this risk zone. The resulting number is interpreted as the average number of people expected to be subject to flooding events per time unit (year). Hence, PaR has also been termed as “average annual people flooded”. As a general approach, the following steps were undertaken in Global Vulenrability Assessment (GVA) to determine the PaR for the various scenarios (Hoozemans et al., 1993): Assessment of the height of maximum flood level theoretically threatening the low-lying coastal zone; Determination of the flood prone area and calculation of the area contained between the coastline and the maximum flood level; Assessment of the present state of protection against flooding; Determination of the coastal population densities for the present and future state; and Determination of the Population at Risk with and without measures, with and without sea-level rise, and for conditions in the years, 2004 and 2029. Sea-level rise and changes in coastal population are unconstrained. In all scenarios, there are large potential increases in coastal population, which is reinforced by the assumption of coastal attraction of population. The current population of Aden Governorate according to the 2004 Census is 598,419, and by 2030, it would increase to 1.5 million (considering a growth rate of 3.53% for Aden population). The effect of sea level rise on extreme water levels (i.e. surge height) is an explicit part of the analysis. Relative sea level rise simply displaces these extreme water levels upwards. Exposure is measured as a function of the population living below the 1 in 1000-year storm surge. Following the GVA steps described above, risk is measured using the average number of people flooded per year in the following section. In the calculation of storm surges, we follow the method outlined by Nicholls (2006), where storm surges are calculated as follows: 44 Current storm surge = S100 Future storm surge = S100 + SLR + (UPLIFT × 100 yr) / 1000 + SUB + S100 × X Where, S100 = 1-in-100-year surge height (m); SLR = sea level rise in meters; UPLIFT is continental uplift/subsidence in mm/yr (0.16 mm/yr (Peltier, 2004; Unnikrishnan and Shankar, 2007)); SUB = 0.5 m (applies to deltas only), we don't have deltas in the study area, for that we take SUB = 0.0; X = 0.1, or increase of 10%, applied only in coastal areas currently prone to cyclones/hurricanes, also not applicable for our study area. We calculated surges using data associated with the coastlines, and download coastline information from the DIVA GIS database. We use the following attributes in this analysis: 1. S100 = 2.5 m: 1-in-100-year surge height (from GVA data in DIVA). 2. SLR = projected sea level rise (0.33 m, and 0.6 according to the two scenarios) 3. UPLIFT = - 0.16mm, estimates of continental uplift/subsidence in mm/yr from Peltier (2004). Hence, the future storm surge equation in this case well be modified as following: Future storm surge = S100 + SLR + (UPLIFT × 100 yr) / 1000 For the first scenario the future storm surge will be 2.81 m above the MSL, which is 1.4 m above CD, resulting in the height of the maximum flood level of 4.24 m for the first scenario and 4.50 m for the second scenario above CD. Accordingly, the flood prone area, the area contained between the coastline and the maximum flood level would be vulnerable to storm surge flooding, which could cover most of the coastal plain of Aden Governorate, including Khormaksar, Al Mansoorah, Al Mua’alla, Al Buraiqah, the beach between Ras Umran and Foqm. This would effects about 50% of the populated area of Aden Governorate, where the present average population density considering that the population is equally distributed, is 800/km2. The 45 population density is expected to increase to 2100/km2 in 2030, considering growth rate of 3.53%. This is in consensus with the latest study by (Dasgupta et al., 2009), which considered Yemen as one of the top five most vulnerable low-income countries with more than 50% of their coastal areas at risk, for exposed populations, and more than 50% of coastal urban areas lie within the potential impact zones. 3.5 Ecological Impacts The short duration of this work and limited funding necessitated the use of existing data sources on wildlife resources and habitat requirements. It is hoped that this study will encourage future research on coastal wildlife populations and habitat to incorporate analyses of the impacts of sea level rise and climate change. Whereas there were limited data on vertical accretion rates for wetlands, Sabkah and sediment dynamics of beaches and dunes along Aden coastal area, a retrospective air photos based dated 1975 analysis was conducted for the coastal lagoon in little Aden (Figure 3.8). These analyses provided insight on how wet land, Sabkah habitats and beaches have responded to past storms and changes in sea level, as a basis for considering how they may respond in future. Aden Reefs, mud flats, wetlands, salt pans and tidelands provide nursery and feeding areas for many marine species and migratory birds. They considered as an important staging and wintering area for migratory waterfowl, especially shorebirds, gulls and terns. The most important feeding area for shorebirds is the mudflats at Khormaksar. In addition, they also provide important buffer areas for storm protection and to control erosion. Wetlands restricted extension further inland was primarily due to the construction of a road through it since the British colonization of Aden. Also, in the same period, the building of the causeway across Aden lagoons also changed the hydrology and also physically destroyed some natural area. These wetlands are particularly at risk where coastal flood barriers and human settlement prevent their migration inland. As sea 46 Figure 3.8. Khor Bir Ahmed shown in recent Google image, with compare with its situation in an aerial photography of 1975. Notice the effect of sea level rise on the salt pans in the first image, as it is almost submerged by sea water. 47 rise, these habitats are subjected to inundation, storm surges, saltwater intrusion, and erosion. If less sediment is available, wetlands and mud flats that are seaward of the roads will not be able to maintain appropriate elevations in the face of rising seas. They will be unable to accrete sufficient substrate as sea level rises, and gradually altered to inundated area, thereby eliminating critical habitat for many coastal species. Organisms need specific conditions to thrive or survive. These conditions will be altered as the climate changes. In wetland, there is a delicate balance between salinity, dissolved oxygen, turbidity, bottom composition, and temperature. A change in any of these factors may affect the health and survival of the flora and may also lead to the death, migration, or ill health of the organisms living among it. Much of Aden rocky shore habitats dominate in areas with heavy wave action facing the open water. Rocky shores are areas of bedrock that are exposed between high and low tide. They are areas of interface between marine and terrestrial ecosystems. Rocky habitats provide a hard substrate for many marine species. However, this ecosystem considered at high risk as the intertidal zone shifts with sea level rise. Organisms that are slow growing or are essentially sessile, such as the limpet during maturity, may not adapt quickly enough to the pace of a shifting intertidal zone and subsequently reduce in number. Species are distributed on the shore primarily according to tolerance of water immersion and emersion. Intensification in storm activity resulting from climate change could, therefore, create an unstable environment where sheltered habitats are lost. This would affect breeding grounds as hiding places for juvenile fish are moved before they have a chance to grow to maturity, and small invertebrates may be washed away. Increased wind and wave action could also strip the shore of photosynthesizing flora and therefore affect the entire food web dependent on them. The rise in the sea water level eliminates the sandy coastal habitat of Aden and species dependent on it, such as Ghost crabs, birds and Hawksbill turtle Eretomchelys imbricata. These animals use the beaches as foraging and reproduction areas and lays eggs. Such rise will have unfavorably effects since their reproduction areas will become narrower indicating that sea turtles will suffer the most from SLR. The IPCC predicts that a sea level rise of 0.5m will eliminate 32% of sea turtle nesting grounds. 48 If sea level rise significantly higher than this over the 21th century, which is expected, many more vital nesting sites will be threatened. Turtles are reliant on temperature sex determination, where temperatures of 29.2°C produce a 50:50 sex ratio in sea turtle populations. Higher temperatures will lead to the feminization of populations, which will affect breeding success. Hawksbill turtles depend upon coral reef ecosystems at various stages of their life-cycle. The shelves and caves formed by coral reefs provide resting and sheltering areas for this species. Adult hawksbills feed almost exclusively upon reef fauna and rise of reef water temperature will kill the corals, and its associated fauna, which turtles depend on. Tropical coral reefs are increasingly threatened by shifts in the world’s climate, overfishing and declining water quality. However, the changes in the temperature and acidity rates kill and solidify the corals. The corals bleaching incident in 1997 - 1998, in the reefs of Red Sea, Gulf of Aden and Socotra Archipelago was due to the increase in the temperature of the sea water that caused mass death of corals (Abubakr and Al Saafani, 2006). In fact, death of corals will lead to the destruction of biodiversity of the seas and causes a decrease in the absorption of CO2, which is responsible for global warming. As corals provide the basis of reef ecosystems, their loss will be enormous on the economic value of Yemen (in terms of tourism and fisheries). As for crustaceans, the increase in the CO2 amount, this is among the causes of climate change results in the decline of sea water’s pH, and thus the acidification of the sea water. This incident will negatively affect the marine crustaceans’ fauna, due to the dissolving of its calcium carbonate external skeletons by the acidic sea water. Extinction of these small crustaceans found at the bottom of the nutrition chain can change the entire sea ecosystem. 3.6 DIVA Model European project DINAS-Coast (Dynamic and Interactive Assessment of national, regional and global vulnerability of Coastal Zones to Climate Change and Sea-level Rise) has developed tools to help policy makers interpret and evaluate coastal vulnerability. The tool, called DIVA, enables analysis of a range of mitigation and adaptation scenarios. The project has attempted to predict the global impact of climate 49 change on the coastal zone for the next 100 years, involving a range of mitigation and adaptation scenarios. The DIVA method uses the project DINAS-Coast database, the first comprehensive integration of state-of-the-art scientific data, knowledge and models from climatology, coastal morphology and ecology, economics, geography and computer sciences. DIVA is specifically designed to explore the vulnerability of coastal areas to sea level rise. It comprises a global database of natural system and socioeconomic factors, relevant scenarios, a set of impact-adaptation algorithms and a customized graphicaluser interface. Factors that are considered include erosion, flooding, salinisation and wetland loss. DIVA enables user-selected climatic and socioeconomic scenarios and adaptation policies, on national, regional and global scales, covering all more than 180 coastal nations (McFadden et al., 2004). DIVA can be applied both globally and at a national scale. The segmentation of the world's coastline was performed on the basis of a series of physical, administrative and socio-economic criteria, producing 12,148 coastline segments in total. For sitespecific applications, the model would have to be modified to incorporate local variables. At this stage, at the national scale, DIVA provides initial perspectives on vulnerability of the coast to climate change. That requires further development, including adopting a more customized local-scale coastal segmentation, for use at a sub-national scale. The coastal area of Aden Governorate was divided by DIVA model into four segments 1489-1492, which extends from Ras Umran to Al Alam. The region from Ras Umran to Qa'awa was considered as a part of Lahj Governorate and covered by segment number 1488. DIVA model was used to investigate the effect of sea level rise in the costal area of the Gulf of Aden as an integral way. The output from DIVA was compared with the vulnerability assessment approach used in this project. Two different cases was created using two different regional scenarios, which gave two sea level rise projections similar to that proposed in section 2.6. The input parameters for the two cases were the same, for each segment, which selected to mach the real situation. The output from the model shows underestimated result compare with the output of the vulnerability analysis described in sections 3.1 - 3.5. The expected eroded coastal 50 area was estimated to be 56 ha for SLR of 0.6, and 26 ha for SLR of 0.33 m from the DIVA run. Whereas, from the vulnerability analysis, the total land loss, due to erosion, was estimated to be 86 and 48 ha for SLR of 0.6 and 0.33 m, respectively. Coastal floodplain population were 28,000 in 2010 from DIVA output, while from the socioeconomic analysis the total population were 67,000 in 2008. The under estimation of the impacts by DIVA model was due to the coarse resolution of the input data and also due to the fact that the division of the coastal region into these segment was not representing the actual situation. For example, segment 1490 represents Al Tawahi Bay, which about 13 km; the length of this segment was 2 km only. In despite of the underestimation of the impact by DIVA model, it also show the risk of the sea level rise on the coastal area of Aden Governorate, as shown in Figure 3.9. This figure shows the beach nourishment cost for different coastal segments in Governorate of Aden, where the cost increases from 1.4 million US$/yr in 2010 to 2.6 million US$/yr 2100. The segment location is seen in Figure 3.9b. The cost of see floods for each coastal segment per year, show that the cost increases exponentially after 2030 for Khormaksar region till it reach 36 million US$/yr (Figure 3.9c). The figure underestimates the loss in other segments especially along Al Tawahi Bay (segment 1490). 51 a) b) c) Figure 3.9. Output from DIVA model. a) The nourishment coast for each segment along the coastal area of Aden. b) The coastal segments of Aden Governorate. c) the coast of sea flood in US$ per year. 52 Chapter 4 Socioeconomic Impacts 53 Aden is one of the Yemeni main cities, which have well developed public services. The water service and electricity networks reach 92% of the houses in the city, and sewer network is reaching 78.2% houses (Census of 2004). During the past two decades, Aden has been attracting investments and projects, which encouraged people to migrate towards it. Aden population increased between 2005 and 2007 by an average of 3.53%, which is higher than the national average (3.02%). This has activated the construction processes, as about 492 construction permits have been issued during the last three years (2005 – 2007). The roads stretched by an average of 4.8%, the communication cables by an annual average of 6.1%, and the educational schools by an annual average of 15%. The declaration of the Government to make Aden a free trade zone has led to energize the economical growth of the city, accompanied with good development of infrastructure and public services projects. Figure 4.1 illustrates the important sectors among the governorate, and the residential and industrial areas. The massive development of the expected socioeconomic activities should be steered towards avoiding the adverse effects on environment produced from those activities. The evaluation of the expected economic losses in Aden Governorate as a result from sea level rise (33 – 60cm), was depending on 2008 available data. The topographic toposheets and aerial photographs of Aden Governorate have been utilized to build a DEM maps using GIS techniques. Those maps subjected to different analysis to find out the areas which are likely to be inundated during the expected sea level rise of 33 and 60cm. This has been followed by ground truth investigations including visits to the vulnerable sites and confirmation of the elevation and slope of coastal zone by performing several cross transects along the coasts of Aden. The present investigations showed that the area, which are likely to be inundated when sea level rises are the beaches of Khormaksar, wetlands, and the beaches close to Aden refineries at Buraiqah (Figure 4.2). The total area of Aden, which is expected to be submerged with the rise of sea level by 33 cm and 60 cm, would reach about 43 and 45 km2, respectively. 54 Figure 4.1. Map of important sectors in the Governorate of Aden. 55 Figure 4.2. Map of Aden Governorate showing the expected inundated area due to the SLR of 33 and 60 cm. 4.1 Houses and Residential Area The expected submerged area in Aden, when it is subjected to sea level rise, includes a part of the residential area in Khormaksar, Al Mansoora, and Al Mua’alla Districts, with a total area of 3.90 km2 at the rise of 33 cm, and 4.35 km2 at 60 cm. From (Figure 4.3), it’s clearly shown that Khormaksar is the most affected area. According to the Population, Housing and Establishment Census (2004), the number of houses likely to be inundated are about 11,482 houses, which are 11.88% of the total number of buildings in the governorate (Table 4.1). These houses are occupied by 10,440 families, who are representing about 11.5% of the total number of families live in Aden. It has been evaluated that about 68,843 persons (about 11.68% of Aden population), in those places would suffer from Sea level rise. The total expected losses of the national economy, according to 2008 socioeconomic situation, because of sea level rise (33 – 60 cm) in Aden Governorate are expected to be 143,400 million YR. This total loss includes the costs against demolition and cleaning of constructions in order to covert these areas into new recreational beaches. 56 Figure 4.3. Map of the most sensitive areas of the Governorate, which area vulnerable to inundation due to SLR of both, 33 and 60cm. 57 Figure 4.4. 3D view of Aden Governorate shows the areas to be inundated by SLR of 33cm. 58 4.2. Land Value Terrestrial land inundation is considered a loss of part of the national economy productive fixed assets, in addition to loss of front extension of the State Exclusive Economic Zone (EEZ). Therefore, submersion of terrestrial land is a real loss for the national economy in short and long terms. The total loss of land value is estimated to be around 96,525 million YR. 4.3. Saltpans Area It was estimated that the total losses of saltpans area by about 2,000 million YR (Table 4.1). 4.4. Educational Structures There about 42 educational structures including governmental and private schools and institutions. According to the information of Ministry of Education, the average cost of each school with 10 classrooms and their supplementary buildings, is US $ 250,000 (50 million YR). If the costs of construction walls, gates, labs, furniture, etc, are added, the cost of each school will reach up to 80 million YR. In addition to schools, there is a vocational training institute, maritime technical institute and trading institute, which have a total value of 800 million YR. Hence, the grand total losses because of sea level rise with respect to educational field, might reach approximate 4,160 million YR. 4.5. Health Structures According to the health facilities survey, sea level rise is expected to attack several health constructions, including: one hospital, 7 health and childhood and motherhood centers, and 10 health buildings. The total estimated values are anticipated to reach up to 11,700 million YR. 4.6. Roads According to the available information and maps, the total length of roads to be submerged by sea level rise is approximately 41.33 km. The average cost of 59 Table 4.1. Areas which will be subjected to inundated in Aden Governorate. District / Area Khormaksar District Gazerat Al Omal area Al Shabat area Ali Hussain Abdul Nabi area Al A’awlaqi area Al Dawh area Abi Zar Al Ghaffari area Gamal Area area Al Ahmady area Al Gandoh Al Shamali area Al Gandoh Al Ganubi area A’abood area Al Selfador area Al Dobilain area Mohammed Nagi area Molhem area 8 March area Gazi Alwan Unit Al Mansoora District Al Ahmady area Fadhl Abdullah area Nagwa Makawi area (50 %) Raimi Al Gharbiyya area Al Sena’ah area Khadeegah area (75 %) Al Dawh Al Sharqiyyah (50 %) Al Dawh Al Gharbiyyah (33 %) Maged Abu Shadr (30 %) Al Mua’alla District Aden Port Dock A’abr and Nagran area Ben Dahhan area Ghadega area 30 November area Mahdy Saleh area Al Olofi area Al Salam area Al Wadea’ah area Al Ansi area Omar Ali area Al Buraiqah District No residential area is affected Total No. of Houses No. of Families Total Population 95 86 460 669 353 577 218 395 668 566 140 523 88 328 150 1210 59 73 80 434 592 349 473 137 347 603 552 130 488 90 313 144 1049 14 490 439 3023 4590 2110 2941 819 2127 4260 3926 775 2918 860 2401 1162 7100 126 104 471 229 456 326 485 450 340 69 79 465 212 426 309 464 465 268 65 564 3365 1407 2812 1937 3213 3170 1674 390 5 16 247 399 189 415 104 232 126 130 104 5 16 219 368 165 392 97 221 113 125 98 28 309 1360 2199 387 2391 624 1236 613 672 525 11482 10440 68843 constructing one kilometer of asphalted road is 32 million YR. Hence, the total amount of losses with respect to roads is expected to be about 1,322 million YR. 60 4.7. Electricity The losses in electrical energy facilities are expected by losing their infrastructure in addition to the electrical network to the houses which are going to be inundated. There are 3 electrical power stations in the area: Khormaksar station, Shenaz station and Al Mansoora station. The total cost of each is US$ 50 million, US$ 5 million and US$ 25 million, respectively. The total losses of the electrical infrastructure are expected to be about 1,600 million YR. One should take into consideration, the electrical network losses, which amount to about 1,195 million YR, and the losses in streets lamps are expected to be about 30 million YR. The grand total loss in power facilities is likely to reach an amount of 17,225 million YR. 4.8. Water and Sanitation Networks Rise in sea level will definitely damage the water and sewage networking system. All the systems would be flooded by sea water, as well as the intrusion of salty water into the water sources. The estimated losses, according to available data, would be US$ 1800 for each house affected by the rise of sea level. The total expected losses would reach up to 4,302 million YR, taking into account that each house is connected with the networks of water supply and sewage. 4.9. Communications Network Approximately, the number of telephone lines in Aden is equal to the number of houses. That means, almost each house has a landline connection. Therefore, with respect to available data, the total expected losses in communication network are estimated to be 299 million YR. 4.10. Tourism Structures Aden, as a coastal city, has become a tourism destination from across the country, or even from the neighboring countries (Gulf States). The government has been developing several tourism facilities in order to attract tourists. As the beauty of Aden is in its natural and clean beaches, almost all the recreational structures and hotels are concentrated in the coastal area close to these beaches. 61 With reference to the available data; the total expected losses in tourism industry are approximately 3,800 million YR. This includes the damage expected in the big, medium and small hotels, as well as the recreational beaches. 4.11. Aden International Airport Aden International Airport is locating in the most vulnerable area to sea level rise, Khormaksar. It is surrounded by water from both, southern and northern, sides. Even it has been necessary to fill up the adjacent wetlands in order to complete the airport runway structure. In case of sea level rise, the total anticipated losses from subjection to flooded water are about US$ 500 million, which is equal to 100 billion YR. 4.12. Other Constructions Excluding all the above mentioned structures, here we are going estimate the total losses in other constructions. These constructions include: Buildings that are used for political, cultural, social or economical activities, factories and workshops, clinics and private hospitals, mosques, shops, poultry farms, etc. These constructions do not include any of the above mentioned structures, in order to avoid any repetition in estimated losses. According to available data, it is estimated that there are total of 23,778 constructions in Aden Governorate. Approximately 12 % of those buildings are likely to be flooded by sea level rise, which are accounted to total of 2853 buildings to be flooded. If the above mentioned structures of health, educational, water and electricity fields are excluded, the remaining buildings are about 2785. The total expected losses in those constructions, whether they are small, medium or big buildings, are to reach 25.5 billion YR. It has been found that the grand total economic losses due to sea level rise by 33cm are equal to 410,233 million YR (Table 4.2). Whereas, at 60cm rise the losses would approximately reach 459,461 million YR. As the average annual growth of different establishments in Aden Governorate is increasing by 1.5%, the expecting economic losses in 2050 are expected to reach approximately 767,136 million YR. 62 Size of production facilities operating in the governorate of Aden and the anticipated exposure to flooding due to sea-level rise is 2.8% of the total facilities operating in the Republic of Yemen. In light of expectations of GDP, which is estimated by 5,723 billion YR, expectations of total GDP until 2050, with an average annual rate of 5%, and growth reach about 44,410 billion YR. It is, therefore, expected to reach the loss in gross domestic product for a period of two years to about 2487 billion YR. Table 4.2. Expected economic losses due to sea level rise (33cm) in Aden Governorate. Category Lands value Saltpans Residential Buildings Educational Institutes Health Centers value Asphalted Roads Electricity Services Water and Sanitary Sewers Communication Network Aden International Airport Tourism establishments Other Commercial and Industrial establishments Grand Total 63 Losses Amount (in million YR) 96,525 2,000 143,400 4,160 11,700 1,322 17,225 4,302 299 100,000 3,800 25,500 410,233 Chapter 5 Adaptation Strategies 64 5.1 The Need for Adaptation Adaptation is processes through which societies make themselves better able to cope with an uncertain future. Adapting to climate change requires taking the right measures to reduce the negative effects of climate change (or exploit the positive ones) by making the appropriate adjustments and changes. Stakeholders play a major role in defining the appropriate strategy for adaptation to climate change. Finding the crucial balance between stakeholders’ unique environmental, social, political and economic interests is dependent upon participation of a wide range of stakeholders, including residents, community leaders and government representatives, among others. Each brings unique expertise, insights, priorities and power to the community adaptation process. In this regards a questionnaire was distributed among wide range of stakeholders in Governorate of Aden including government representatives, community leaders, NGOs, scientists and local communities. Their inputs were of great help in preparing this chapter. Future vulnerability depends not only on climate change but also on the type of development path that is pursued. Thus, adaptation should be implemented in the context of national and global sustainable development efforts. 5.2 Adaptation to Climate Change The aim of coastal vulnerability approaches is to help coastal communities adapt to risks of longer-term climate change and accelerated sea-level rise. However, shorterterm impacts of climate variability including extreme storm surges, flooding and enhanced erosion are also possible risks of future climate change (Clark et al., 1998; Wu et al., 2002). This is an important distinction in that adaptations of countries and communities will likely occur in response to changes in frequency and magnitude of short term, climate variability events rather than gradual, longer-term change in average conditions such as sea-level rise (Smit et al., 1999). As mentioned earlier, Yemen has a long coastline of more than 2300 km. This long coastline makes Yemen one of the most vulnerable countries to climate change and sea level rise. The high vulnerability of Yemen is attributed largely to its weak institutional capacity and lack of proper infrastructure, low adaptive capacity, and the prevailing climate. A number of factors can explain this very low adaptive capacity: a 65 weakening ecological base, poverty, corruption and high dependence on the natural resource. Improving adaptive capacity is important in order to reduce vulnerability to climate change. In this regards Yemeni government has to implement effective strategies to cope with climate change. Effective adaptation strategies come from the ground up (i.e., from the community affected), rather than from the top down. Adaptation strategies need to include a wide spectrum of approaches, from policy and law to engineering and technology. Environmentally sensitive approaches can also be effective in minimizing change and cost. Raising public awareness and adjusting cultural values and perspectives can also be cost- and results-effective. 5.3 Adaptation Strategies and Plans Adapting to climate change will require adjustments and changes at every level from community to national and international. Communities must build their resilience, including adopting appropriate technologies while making the most of traditional knowledge, and diversifying their livelihoods to cope with current and future climate stress. However, developing countries capacity limitations makes adaptation difficult. Limitations include both human capacity and financial resources. Outputs from the UNFCCC workshops and meetings highlighted that the most effective adaptation approaches for developing countries are those addressing a range of environmental stresses and factors. Strategies and programs that are more likely to succeed need to link with coordinated efforts aimed at poverty alleviation, enhancing food security and water availability, combating land degradation and reducing loss of biological diversity and ecosystem services, as well as improving adaptive capacity. Sustainable development and the Millennium Development Goals is a necessary backdrop to integrating adaptation into development policy. 5.3.1 Current experiences and lessons on adaptation In spite of the low adaptive capacity of Yemen, the government has developed adaptation strategy for Aden city to face the great climate internal variability and extreme events. Aden's coastal zone management strategies and its adaptation plans was formulated for sustainable management, it suggested 300 m setback for coastal area, which will help to reduce the vulnerability to climate change. This leads to the formulation of goals for future coastal zone management concerning sea level rise. 66 The Master Plan Strategy has been undertaken as part of the Port Cities Development Program to establish a spatial strategy for the long term development of the city and provide an overall framework for the preparation of infrastructure and sector plans. An unusually increasing sea level may increase people’s vulnerability in the short term, but it may encourage adaptation in the medium to long term. This reinforces the observation that local people have perceived, interacted with, and made use of their environment with its insufficient natural resources and changing climatic conditions in what could be seen as practical coping mechanisms. This is particularly true for the sea level rise prone Aden area, which is susceptible to frequent climatic hazards. Other strategies are included in table 5.1. According to the IPCC Fourth Assessment Report, climate change is already happening, and will strengthen even if global greenhouse gas emissions are curtailed significantly in the short to medium term. This fact combined with Yemen’s vulnerability to climate change means that planned adaptation is becoming necessary. 5.3.2 Adaptation requirements Since climate is changing and climate variability is expected to increase in frequency and intensity. As mentioned in chapter 3, Aden Governorate is vulnerable to sea level rise and climate change. Most of the coastal area considered as a lowland region, which will need immediate protection, especially highly populated regions like Khormaksar. Other areas, which are less populated, require other type of adaptation options. Education and awareness formation on climate change among governments, institutions and individuals should be viewed as a necessary step in promoting adaptation to climate change in Yemen and especially in Aden. Linking research to existing local knowledge of climate related hazards and involving local communities in adaptation decision making. Needing for effective communication between the supply-side and demand-side communities of climate information in Aden, and the need to work on means by which climate information can be incorporated into the livelihood strategies of potential users. Build credibility of rainfall forecasts and improving their dissemination and use. 67 Table 5.1. Adaptation measures in coastal areas to be highlighted in national communications of Yemen (modified UNFCCC, 2007) Reactive adaptation Anticipatory adaptation Enhance the household level and local Integrated coastal zone communities to participate in the management plan for Aden is decisions of environmental changes. already created and approved in Establish early warning systems and Ministerial Decree. promoting transfer knowledge and Better coastal planning and zoning sharing of experience on adaptation Development of legislation for action directly undertaken by those coastal protection who are vulnerable, with increase the Research and monitoring of coasts cooperation with international and coastal ecosystems organization. Protection of economic infrastructure Public awareness to enhance protection of coastal and marine ecosystems and promotion of sustainable tourism Building dikes and beach reinforcement Protection and conservation of supra littoral vegetation 5.3.3 Adaptation strategy For the purposes of identifying and reducing vulnerability to climate change, those areas and activities exposed to rapid environmental changes (e.g., beach erosion, flooding) and longer term climate changes, should serve as the focus for future work on developing adaptation strategies. Anticipated impacts and areas of concern for erosion and flooding hazards, as assessed by the research team, are identified in chapter 3. Adaptive strategy development, however, was community-driven and defined, based on the questionnaire in addition to the involvement of the stakeholders in discussion with research experts. It is also suggested that climate change and sea level rise impacts to these areas and activities be exclusively considered in future land use and resource planning and policy development (Walker et al., 2007). Yemen have ratified the international environmental conventions, namely biodiversity, climate change and desertification, yet support is still needed from their development partners to ensure effective implementation of their emerging strategies 68 and plans, as well as to fully exploit the opportunities that could be achieved. One of the problems facing Yemen in the implementation of these conventions is their integration into national development programs and establishing synergies and linkages among them according to UNFCCC requirements. There is also a need for employing an integrated and synergetic approach among national level development partners for addressing the requirement of sustainable development (ICZM). Currently, various national institutions have enacted environmental action plans to address environmental degradation. Several strategies and plans have been formulated in Yemen including national environmental action plans, biodiversity plans, coastal management plans and wetland conservation strategies. 5.3.3.1 Adaptation options for sea level rise Identification of adaptation options was carried out by designing and administering a questionnaire based on direct communication with stakeholders in vulnerable areas. The objective was to collect information and to upgrade the awareness of stakeholders. Scientific, engineering, and economic evaluations of the obtained adaptation options were carried out based on pre-specified criteria. An adaptation decision matrix approach based on cost effectiveness of adaptation measures was also evaluated. Identifying evaluation attributes is an important topic. The following attributes were found to be the most important: expenses, net benefits, environmental impacts, robustness and flexibility, chance of success, feasibility, and fairness. Each adaptation option will be evaluated based on the above-mentioned attributes Yemen is considered under the low human development category, characterized by being highly vulnerable and lacking basic elements for development. In addition to this, Yemen suffers a lot of poverty-related problems that could directly impact the human capital (the major pillar in development), including malnutrition and the increased incidence of epidemic and other diseases. Climate models suggest that Yemen will be particularly adversely affected by climate change especially seal level rise between 33 to 60 cm and is expected to lose substantial land, infrastructure, and tourist revenue along its entire coastal zone area (> 2300 km). This would be an added burden to Yemen, which is already struggling with lots of vital issues of development that require urgent attention. 69 The socioeconomic study illustrates the impacts of climate change at Aden Governorate, caused by sea level rise, concluding that Aden is highly vulnerable to sea level rise in the absence of protection. However, the total losses caused by 33 cm above normal sea level, would reach YR 410.2 billion. Part of Al Mansoorah and Khormaksar will be highly affected during flood and could be lost. It suggests that the optimum cost–benefit response to land loss due to sea-level rise would be widespread protection rather than abandoning populated and exposed coastal land. Adaptive strategies can be classified as “managed retreat”, “accommodation” and “protection”, which are comprised of a variety of options, as shown in Table 5.2. The protection option consists of hard and soft technologies: dikes, seawalls, revetment as a hard one and beach nourishment, wetland restoration as a soft one. The concept requires an understanding of the entire processes influencing shoreline dynamics to enable appropriate intervention when necessary. It includes: I- Set Back It means allowing space between the shoreline and associated coastal hazard and property to act as buffer. This measure is most suited for coastal areas that are not yet developed. Natural buffer should be established between 300-500 m inland, starting from the high tide. The advantage for such measure is that it enables nature to take its own course and avoids the need to put up expensive protection with resources, which are often not available. Even in the event that resources are available, they could be used for other developmental purposes. II- Full Protection The structures include revetments, dikes, sea walls, groins and jetties structures. Groins that designed to trap sand as it is moved down the beach by the long-shore drift. Groins are made of rock, wood, or steel. They are useful to retain the sediments already on the beach or new sand deposited from the nourishment. Dikes and seawalls are already been practiced in Al Mukalla and Al Hodeidah, however their effect and designs have to be tested and evaluated. 70 III- Beach Nourishment Beach nourishment, artificially placing sand on the beaches, is a viable engineering alternative for shore protection and the principal technique for beach restoration. Beach nourishment creates a “soft” (i.e., non-rigid) structure by adding sand to make a larger sand reservoir and a wider beach to effectively dissipate wave energy, thus not only controlling beach erosion but also providing protection from storm and flooding damages. IV- Managed Retreat and Accommodation There are several options for managed retreat and accommodation strategies. For example, land-use planning in coastal zones, such as using building setbacks or allocating low lying vulnerable lands to lower value uses (i.e., parks rather than housing), will help reduce the overall vulnerability to sea-level rise as well as current coastal hazards. Table 5.2 lists the main biophysical effect of relative sea level rise and the possible adaptation responses. The selection between those responses was done based on the attribute mentioned above. Table 5.2. The main biophysical effects of relative sea level rise, including examples of possible adaptation responses (modified Nicholls and Tol, 2006) Biophysical effect 1. Inundation, flood and storm damage e.g. surge (sea) Possible adaptation responses Dikes/surge barriers, building codes/flood wise buildings, land use planning/hazard delineation 2. Wetland loss (and change) Land use planning, managed realignment hard defenses, nourishment/sediment management. Coast defenses, nourishment, building setbacks 3. Erosion (direct and indirect morphological change) 71 5.3.3.2 Recommended measures Based on the vulnerability analysis (Chapter 3) and socioeconomic analysis (chapter 4) several regions were identified as vulnerable to sea level rise biophysical impact. The possible adaptation options for each region are discussed below. I- Khormaksar - Al-Alam This coastal area is characterised by lowland sandy beaches extends from Khormaksar to the boundary between Aden Governorate and Abyan Governorate at Al-Alam. Its western part is highly populated area and considered highly vulnerable to sea level rise. The possible adaptation option is building hard protection, Dike, since it is the only option to protect the highly populated area of Khormaksar. The proposed structure to build the dike has a typical dimension of 4 m height, 10 m base width, and 2.5 m crown width. The estimated cost of the dike per m cubic is 42 US$ and for one km is 1.7 million US $. Building a dike along the shoreline of 10 km long will cost 17 million US$. The other constructing option is to rise the existing coastal road of 33 m width with 4 m high for the dike along the seaside of the road, this will rise the cost to about 40 million US$. II-Salt Pans This region extends from the Marine drive between Khormaksar and Caltex roundabout till the west, to the region east of the Airport. It is considered as a backyard of Khormaksar and the coastal region to its east along Abyan beach. The protection of the region from sea level rise will destroy its value as a respiration system for the coastal area as local communities name it. It is protected region from the wave action since the water supply for this region comes from the inner harbour side. The real risk from the sea level rise and storm surge is for flooding Khormaksar populated area from this side. The adaptation option for this region can be done by raising the inner boundaries of these basins by about 2 m, this option will allow them to continue functioning and protect the populated areas behind it. This protection will cost about 250000 US$ assuming the length of this region is about 12 km. 72 III- Al Tawahi Bay Al Tawahi Bay extends between the headlands of Little Aden and Aden, from Caltex Roundabout to the Farcy Bay. It is characterized by wetland of fine substrates (mud/fine sands) of low energy. This region is flat coastal area with slope of ~ 2º. It is vulnerable to sea level rise inundation and flooding from the highland, since it is the extension for the Tuban valley (Al Wadi Al kabir). The best adaptation option is setback of ~500 m to allow the rising sea to extend inland. The hard protection will not be the right option for this region since it will make the region more vulnerable to the highland flood of Al Wadi Al kabir and will block its connection with the sea. The difficulty with this option is the inundation of wetland due to sea level rise, especially for the areas where the constructions and road are close to the coast. These constructions will not allow the wetlands to migrate inland, which will result to the loss of the wetland in that region. IV- The Sheltered Sandy Bay to the West of Ras Foqm This region is similar to Al Tawahi Bay with fine sand/silt. The adaptation option is set back between 300-500 m from the high tide. The advantage in this region is that it still unpopulated area and new constructions should follow these recommendations. V- The Region from Ras Umran to Qa'awa This coastal stretch is still unpopulated area, there are no constructions along the coastline, and it is characterized by sandy beaches with high dunes compare with the flat coastal plane of the other regions in the Governorate. The appropriate adaptation option is a set back of 300 m. VI- The Headlands of Aden and Little Aden These are rocky beaches and will not be affected by the sea level rise as the sandy beaches. However, there are several important sandy beaches they enclose, which would be vulnerable to erosion due to sea level rise. These beaches are valuables as recreational and tourism sites and the loss of these beaches would affect the tourism 73 sector. The appropriate adaptation option is a retreat for the eroded sand to reduce the loss for tourism sector. VII- Managed the extraction of groundwater As mentioned in chapter 3, the saltwater intrusion into the groundwater of the well fields of Bir Ahmed and Bir Nasser, would be a threat to the major water supply of the governorate. It was stated previously (Sogreah, 1981) that by maintaining the extraction levels at 5 Mm3/yr from Bir Ahmed, 12 Mm3/yr from Bir Nasser and 10 Mm3/yr from Tuban, it would be possible to protect these well fields from deterioration, high salt content and fast water level drop due to extraction. By reducing the extraction rate, the balance between the saltwater and freshwater would reduce the risk of the saltwater intrusion due to sea level rise. This is can be done by exploring other sources of water supply for the governorate, either from desalination plants or getting more water supply from other governorates. Nonetheless, adaptation by protection still leaves large populations at risk from flooding, when caused by tropical storms and similar events (Nicholls and Leatherman, 1995b). 5.4 Integration of the Adaptation into National Policy and Planning After evaluating the vulnerability of the human coastal resources in Aden, there is a need to define targets for coastal zone management practices. These practices are concerning sea level rise effects and to provide policy advisers and decision-makers with some information to support coastal management using the best available adaptation options. The evaluation of the coastal zone management strategies, in combination with intensive literature review, and the results of the sensitivity and vulnerability assessments described above, form the base for formulation the policy options and targets for the entire coastal zone of Aden. Incorporating or integrating climate change adaptation into planning processes is a necessary strategy for sustainable development over the long term. Climate change impacts do not happen in isolation. Impacts in one sector can adversely or negatively 74 affect another. Sectors can be affected directly and/or indirectly by climate change and indeed sometimes a change in one sector can offset the effects of climate change in another sector. In Yemen, there are difficulties in integrating adaptation concerns into national policy due to low staff capacity for planning, monitoring and evaluation; poor data on adaptation options and lack of mechanisms for information sharing and management across sectors; and limited awareness of adaptation among stakeholders and the population. Lack of cooperation among ministries seems to be a major barrier to progress on adaptation. In order that real progress can be made, key governmental departments (such as Ministry of Planning and International Cooperation) need to be involved in the development of adaptation strategies. In the same way, national and local development planning authorities have to be informed by the relevant outputs of impact and vulnerability assessments. One positive advance in this regard is the establishment of the Climate Change High Committee, which involve several ministries in addition to Environment Protection Authority (EPA). The committee will help to implement the adaptation options into the development plan. Environmental and sectoral institutions need to be strengthened in order to be able to address the complexities of addressing and coordinating the implementation of adaptation actions. There are a number of actions that can help facilitate adaptation and integration of adaptation into policy, including actions at the local level (e.g. strengthening coping strategies and feedback to national policies). At the national level (e.g. inter-agency coordination in the environmental sector and legal provisions for mainstreaming) and the regional level (e.g. incorporating climate change risks in projects of regional development agencies and the creation of intersectoral committees to be engaged in the formulation of adaptation plans). At the international level, it was noted that the UNFCCC, other Conventions and other international organizations could play a catalytic role in exchange of experiences, and in facilitating the development of region-wide and sector-wide approaches. Policy and development planners require effective tools and frameworks for developing, disseminating and building capacity for adaptation and integrating it into policy at all levels (UNDP, 2004). The legislative changes and recognition by all government ministries would help facilitate incorporation of climate change 75 adaptation into future policy. The new high committee can help in integrating adaptation into policy. 5.4.1 Capacity-building Capacity building at local, national and regional levels is vital to enable Yemen to adapt to climate change. It is important for stakeholders and sponsors to recognize the role of universities and research centers. Enhanced support is needed for institutional capacity building, including establishing and strengthening research centers and building up hydro-meteorological stations. Training for stakeholders in all sectors would help the development of specialized tools for planning and implementing adaptation activities, and thus, promote action by local and national governments according to UNFCCC (2007). 5.4.2 Education and Training Education and training of stakeholders, including policy and decision makers, are important catalysts for the success of assessing vulnerabilities and planning adaptation activities, as well as implementing adaptation plans. It is important to communicate both successful and unsuccessful efforts at planning and implementation to avoid future mistakes. Short policy cycles are a major challenge in keeping decision makers up to date according to UNFCCC (2007). Effective training and capacity building needs supports and funding from external agencies and donors. Training is also needed for models to be effectively applied and used for assessments at the national or regional level. Promoting better access to funding and synergy with sources of funding, universities researches have to be directed and supported to deal with all national concerns in general, and environmental conservation concern such as climate change in particular. Collaboration between educational, training and Yemeni research institutions would help to enable the formal exchange of experience and lessons learned among different institutions of the respective regions. Universities and research centers have a special role to play in educating and building the capacity of stakeholders in key sectors. According to UNFCCC (2007), climate change and adaptation issues should be integrated into education curricula. 76 Effective international collaboration also helps to enable training on, and structured dissemination of, international and national activities on adaptation with a view to retaining experts working in their region, and promoting the exchange of information between experts from key sensitive sectors. It is also important to assess, systematize and disseminate knowledge about adaptation measures taken, including indigenous ones (UNFCCC, 2007). Knowledge and information in Yemen is widely considered as a personal and agencies properties that cannot be provided to any one outside their initial owner. 5.4.3 Public awareness It is essential to involve the Yemeni media in raising awareness of climate change risks and the need for adaptation should be raised among key sectors and mass media, using current events, such as economic, weather and health crises, as a basis to promote adaptation measures with co-benefits. Improving public awareness and developing overall communications strategies makes targets climate change science accessible to the average citizen, which can reduce their vulnerability. Besides raising awareness at local levels, it is also important to involve high-level policymakers to ensure integration of climate change risks into national development policies (UNFCCC, 2007). A communication strategy is an effective way of elaborating and communicating between knowledge providers and stakeholders on climate change risks and adaptation needs, targeting actors ranging from those at the grassroots level to the national and regional policymakers, using appropriate language (UNFCCC, 2007). 77 Chapter 6 Conclusion and Recommendations 78 6.1 Conclusion Coastal area of the Governorate of Aden was selected as a pilot area for the vulnerability and adaptation assessment as a part of the Second national Communication. Range of assessment methods were adopted including stakeholders involvement, GIS, Bruun Rule and DIVA model. Two plausible future sea level rise scenarios for Governorate of Aden coastal region gave SLR of 3.3 mm/yr and 5.9 mm/yr. The biophysical effect of SLR includes erosion of sandy shores, inundation of the low land, destruction of coastal critical habitats, saltwater intrusion into the surface and ground water, and increases of the flood frequency probability. About 48 ha and 86 ha of sandy shores would be eroded due to the SLR of 33 and 60 cm respectively. This loss of sandy beaches will affect the tourism and recreation activities in the coastal communities, especially along Khormaksar, Gold Moor, Foqm Bay beach and the rest of sandy beaches. The total land area that would be inundated with the proposed sea level rise of 33 cm is 43 km2, which represents 5.7 % of the total area of Aden Governorate (about 750 km2). This would increases to about 45 km2 (6%) for SLR of 60 cm. Khormaksar, Al Tawahy Bay, the coastal beach between Khormaksar and Al Alam (Abyan Coastal Beach), Aden lagoons and wetlands are the most affected regions. About 3.90 km2 will be inundated in the dens populated area of Khormaksar, Al Mansoora, and Al Mua’alla Districts for SLR of 33 cm, while 4.35 km2 would be inundated for SLR of 60 cm. The saltwater intrusion into Delta Abyan, extends to a distance of 4 km of the southeastern portion of the delta. The extent of the saltwater intrusion will extend further inland by rising sea level, for the proposed scenarios of 0.33 and 0.6 m. The interface between the saltwater and freshwater will extend 160 m and 240 m inland and 16m and 24 m upward, respectively, effecting the well field in that region. In Tuban Delta, the contours of saltwater intrusion are approximately parallel to the coastline, about 10 km inland on the eastern side of Tuban area. Bir Nasser and Bir Ahmed well fields would be affected by salinity intrusion due to sea level rise. The future storm surge will be 2.81 m above the MSL for the first scenario, resulting in the height of the maximum flood level of 4.24 m for the first scenario and 4.50 m for the second scenario above CD. This would effects about 50% of the populated 79 area of Aden Governorate, where the present average population density considering that the population is equally distributed, is 800/km2. The population density is expected to increase to 2100/km2 in 2030, considering growth rate of 3.53%. The output from DIVA was compared with the vulnerability assessment approach used in this project. It shows underestimated result compare with the output of the vulnerability analysis. In despite of the underestimation of the impact by DIVA model, it also shows the risk of the sea level rise on the coastal area of Aden Governorate. The total socio-economic loose include loss in the infrastructures, livelihoods. Total of the houses at risk of inundation under the first scenario are about 11462 houses (11.88%) in Aden governorate. The grand total economic losses due to sea level rise by 33cm and 60cm is equal to 410,233 and 459,461 million YR respectively. Identification of adaptation options was carried out by designing and administering a questionnaire based on direct communication with stakeholders in vulnerable areas. The protection option consists of hard and soft technologies: dikes, revetment as a hard option and beach nourishment, wetland restoration as a soft one. This includes: set back, full protection, beach nourishment, managed retreat and accommodation. Accordingly, the coastline of the governorate was divided into six regions depending on the adaptation options and the topographic nature of that region. 6.2 Recommendations Adapting to climate change will involve adjustments and changes at every level from community to national and international. Communities must build their resilience, including adopting appropriate technologies while making the most of traditional knowledge, and diversifying their livelihoods to cope with current and future climate stress. Most of the coastal area in Aden considered as a lowland region, which will need immediate protection e.g. dike especially highly populated regions like Khormaksar. Natural buffer should be established between 300-500 m inland starting from the highest high tide (HHT) of the country low lands (sandy and muddy coastal areas). 80 Details survey of the important habitats in the coastal area of Aden governorate and the rest of the country coastal area should be implemented in order to gain better knowledge about the sensitive areas to the climate change and sea level rise. To improve the topographic maps of coastal area, Arial survey for entire Yemen coastal line should be conducted. Planning and development should not be based simply on historical rates of erosion, but should add an appropriate additional setback to account for more rapid erosion over the life of a structure or other development. To enable workable and effective adaptation measures, ministries and governments, as well as institutions and non-government organizations, must consider integrating climate change in their planning and budgeting in all levels of decision making. It is advisable to define targets for coastal zone management practices concerning sea level rise effects and to provide policy advisers and decision-makers with some information to support coastal management using the best available adaptation options. Environmental and sectoral institutions need to be strengthened in order to be able to address the complexities of identifying and implementing the adaptation actions. Enhanced support is needed for institutional capacity building, including establishing and strengthening research centers and building up hydro-meteorological stations. Yemen still need support from their development partners to ensure effective implementation of their emerging strategies and plans. Effective training and capacity building, including applicable modeling, needs support and funding, often from external authorities and donors. Collaboration between educational, training and Yemeni research institutions would help to enable the formal exchange of experience and lessons learned among different institutions of the respective regions. Climate change and adaptation issues should be integrated into education curricula. 81 It is essential to involve the Yemeni media in raising awareness of climate change risks and the need for adaptation should be raised among key sectors and mass media, using current events. 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