Project II : Assessment and Monitoring Water Supply Network in Al Morouj District – Al Riyadh
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ACKNOWLEDGEMENTS
This end of study project was supported by College of Engineering in Salman
Bin Abdelaziz University and in collaboration with National Water Company in Al
Riyadh in order to study and analyze the water supply network in Al Morouj district in
the north area of Al Riyadh.
At first, we express our sincere thanks to National Water Company, the Civil
Engineering Department of College of Engineering in Salman Bin Abdelaziz
University and the King Abdulaziz City for Science and Technology (Space Research
Institute) for their support and cooperation. We would like to think Dr. Ossama Said
Al Thafer Dean of College of Engineering and Supervisor of this project to accept
to taking part of this project and give their constructive criticism and insightful
comments from an earlier draft to this final version of this manuscript.
Special thanks to Dr. Khaled KHEDER Assistant Professor in Civil
Engineering Department of College of Engineering in Salman Bin Abdelaziz
University at Al Kharj, who helped us to insight and suggested improvement
concerning the modeling using FLAC software and GIS methodology, be grateful for
his comments.
We hope that this applied study project using new technology will help to
further the progress of monitoring and management a water supply network in the
North of the Capital of Saudi Arabia especially in Al Morouj district.
M. S. Al Harthi – M. A. Al Semari – M. A. Zoman – Y. M. Dossary
Academic Year : 2012 - 2013
‫‪Project II : Assessment and Monitoring Water Supply Network in Al Morouj District – Al Riyadh‬‬
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‫ملخص‬
‫إن املتتبع للتطور العمراين السريع الذي تشهده مدينة الرايض و خاصة املنطقة الشمالية منها (حي املروج) يالحظ تطور كبري يف‬
‫إستهالك املياه الصاحلة للشرب ن تيجة هلذا التطور الدميوغرافية الكبري ولذلك أجنزت الشبكات التحتية إبستعمال القنوات احلديدية‬
‫والبالستي كية لتوصيل املياه الصاحلة للشرب لكل أحياء مدينة الرايض ومنها حي املروج‪ .‬كما أنه تقوم الشركة السعودية للمياه ابلسهر على‬
‫سالمة هذه الشبكة ابلقيام ابلتصاميم الالزمة ملد القنوات والصيانة الدورية للشبكات اليت حتت التشغيل‪ .‬من اخلالل املعاينات امليدانية‬
‫واإلحصاءا ت لفواتري إستهالك املياه يف املنازل الحظت شركة املياه أبنه هناك كميات ليست هبينة من املياه تفقد أثناء توزيع املياه على‬
‫املنازل ولذلك يدخل هذا املشروع يف هذا اإلطار إبستخدام التقنيات احلديثة (النمذجة الرقمية ونظم املعلومات اجلغرافية واإلستشعار عن‬
‫بعد) ألجل مراقبة ومتابعة التغريات لكمية املياه عرب الشبكة التحتية حلي املروج ابلرايض‪ .‬من أهم النتائج اليت توصل إليها املشروع إنه خالل‬
‫الفرتة األخرية (العشرة سنوات األخرية) هناك زايدة كبرية يف إستهالك املياه الصاحلة للشرب مبدينة الرايض ونظرا لقلة املوارد املائية ابملنطقة‬
‫وجب ترشيد اإلستهالك ومتابعة وصاينة الشبكة التحتية من أجل تفادي الكميات من املياه اليت تفقد أثناء التوزيع‪ .‬من خالل النمذجة‬
‫الرقمية بواسطة برانمج (‪ ) EPANET2‬ونتائج الربامج املستعملة من طرف شركة املياه تبني أنه هناك نسبة هامة من املياه املفقودة خالل‬
‫التوزيع تصل إىل ‪ % 51‬من الكمية اليت تضخ من اخلزان املخصص حلي املروج‪ .‬كما تبني من خالل هذه النمذجة الرقمية أنه هناك هبوط‬
‫غري عادي للضغط يف بعض نقاط الشبكة بسبب اجلهد الزائد وظاهرة التآكل للمواد املستعملة والظروف املصاحبة لعملية دفن هذه‬
‫األانبيب‪ .‬كذلك لفهم سلوك املواد املستعملة بعد عملية الدفن بعدة سنوات مت اإلعتماد على برانج النمذجة الرقمية (‪)FLAC5.00‬‬
‫لتحديد املناطق ذات اجلهد العايل حول أنبوب واحد دفن على عمق واحد مرت حتت املنزل مرورا حتت الطريق‪ ،‬حيث تبني أنه هناك إزدايد‬
‫كبري للجهد حول األنبوب حسب نوعية األمحال الفوق األرضية الناجتة عن وزن املنازل أو وزن الشاحنات والسيارات اليت متر عرب الطرق‬
‫اجملاورة هلذا األنبوب‪ .‬من أجل املراقبة الدقيقة لكل الشبكة التحتية‪ ،‬من الضروري بناء قاعدة بياانت جغرافية (‪)Geo-database‬‬
‫بواسطة برانمج نظم املعلومات اجلغرافية (‪ )ArcGIS10‬و اليت يتم اإلعتماد فيها على عدة مصادر (املرئيات الفضائية‪ ,‬نظم حتديد املواقع‬
‫(‪ )GPS‬والزايرات امليدانية حلي املروج مبدينة الرايض) مما يساعد شركة املياه على مراقبة حالة األانبيب يف الشبكة وتتبع النقاط واألانبيب‬
‫الغري سليمة على مدار الساعة‪ .‬يوصي هذا املشروع ابستكمال النمذجة الرقمية املقرتحة ابألخذ بعني اإلعتبار التذبذب احلاصل يف‬
‫منسوب املياه اجلوفية احململة للمواد واألمالح اليت أتثر على خصائص املواد اليت تصنع منها األانبيب ومواد الدفن‪ ,‬كما يتعني الرتكيز يف‬
‫املستقبل القريب على كيفية تطوير منظومة (‪ )SCADA‬وإدماجها مع نظم املعلومات اجلغرافية ملراقبة هذه الشبكة عن بعد‪.‬‬
‫‪Academic Year : 2012 - 2013‬‬
‫‪M. S. Al Harthi – M. A. Al Semari – M. A. Zoman – Y. M. Dossary‬‬
Project II : Assessment and Monitoring Water Supply Network in Al Morouj District – Al Riyadh
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ABSTRACT
During the last decade, the Al Riyadh city has experienced significant
population growth specially in the northern area (Al Morouj district). However, we
observed a high consumption of quantities of drinking water according to this
important demographic growth. For this reason, the water company continues the
completion of the drinking water network of the city of Al Riaydh using ductile iron
and PVC pipelines to supply drinking water to all districts specially Al Morouj.
Otherwise, the Water Society gives a great importance for the maintenance and
the monitoring of the drinking water network. In the sense, efficient monitoring of
water distribution networks have long been a challenge for management, even in
countries with a well-developed infrastructure and good operating practices.
Improperly managed water networks might result in increased cost of supply,
insufficient supply of potable water, inconvenience, not satisfied customers and more.
Such problems might not only be caused by operating a poorly maintained
infrastructure but also by excessive use or misuse of water due policy of some
governments to provide low tariffs for water usage.
The numerical modeling carry out by the software EPANET 2 gives that a
considerable quantity of water lost during the distribution through the water supply
network. This amount can reach 15 % referring a many different simulations made by
software EPANET 2 and other software used by the water company.
Aimed to minimize these problems water utilities are required to introduce
improvements by operating their system based on real time data communicated from
remote sites using Supervisory Control and Data Acquisition (SCADA) solutions for
water systems combined with combined with Geographical Information Systems
(GIS).
M. S. Al Harthi – M. A. Al Semari – M. A. Zoman – Y. M. Dossary
Academic Year : 2012 - 2013
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Leak detection and use of Pressure Regulating Valve (PRV) stations may
significantly improve the situation. These measures have to be complemented with
adapted water conservation programs aimed at minimizing excessive water usage.
These initiatives shall combine to form a "water strategy" for conserving this valuable
resource and making it available at an affordable price.
INTRODUCTION
Al Morouj District takes part of Al Riyadh city which is located in the central
region of Saudi Arabia. It is around 1 km2 in the north of Al Riyadh (See Figure I - 1
& Figure I - 2). During the last decade, the Al Riyadh city has experienced significant
M. S. Al Harthi – M. A. Al Semari – M. A. Zoman – Y. M. Dossary
Academic Year : 2012 - 2013
Project II : Assessment and Monitoring Water Supply Network in Al Morouj District – Al Riyadh
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population growth specially in the northern area (Al Morouj district). However, we
observed a high consumption of quantities of drinking water according to this
important demographic growth. For this reason, the water company continues the
completion of the drinking water network of the city of Al Riaydh using ductile iron
and PVC pipelines to supply drinking water to all districts specially Al Morouj.
In fact, National Water Company attached a great importance to fight against
the unexpected head-loss within the water supply network in this district. There is
need to explain the true scenario by digital modeling and GIS based on the geospatial
data from satellite images. Since the loss of flow is the most frequent problem, the
National Water Company has been focusing its attention to flow and pressure
calculation as one of the priority tasks to be accomplished in order to avoid the loss of
flow close to the urban area.
M. S. Al Harthi – M. A. Al Semari – M. A. Zoman – Y. M. Dossary
Academic Year : 2012 - 2013
Project II : Assessment and Monitoring Water Supply Network in Al Morouj District – Al Riyadh
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CHAPTER I :
Methodology and Literature Review
I - 1 – Study area :
Al Morouj District takes part of Al Riyadh city which is located in the central
region of Saudi Arabia. It is around 1 km2 in the north of Al Riyadh (See Figure I - 1
& Figure I - 2). During the last decade, the Al Riyadh city has experienced significant
population growth specially in the northern area (Al Morouj district).
M. S. Al Harthi – M. A. Al Semari – M. A. Zoman – Y. M. Dossary
Academic Year : 2012 - 2013
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However, we observed a high consumption of quantities of drinking water
according to this important demographic growth. For this reason, the water company
continues the completion of the drinking water network of the city of Al Riaydh using
ductile iron and PVC pipelines to supply drinking water to all districts specially Al
Morouj.
M. S. Al Harthi – M. A. Al Semari – M. A. Zoman – Y. M. Dossary
Academic Year : 2012 - 2013
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Figure I - 1 – Al Riyadh city1.
Figure I - 2 – Al Morouj District.
I - 3 – Project problem :
National Water Company attached a great importance to fight against the
unexpected head-loss within the water supply network in this district. There is need to
explain the true scenario by digital modeling and GIS based on the geospatial data
from satellite images. Since the loss of flow is the most frequent problem, the National
Water Company has been focusing its attention to flow and pressure calculation as
one of the priority tasks to be accomplished in order to avoid the loss of flow close to
the urban area in.
For this reason, we intend to expect many head-loss within the water supply
network in Al Morouj district. We distinguish the following problems :
Satellite Image GeoEye-1 from Research Institute of Space in King Abdelaziz City for Science and Technology
M. S. Al Harthi – M. A. Al Semari – M. A. Zoman – Y. M. Dossary
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 Unexpected head-loss within the water supply network in this district taking into
account the internal and external factors linked to this network;
 The loss of flow is the most frequent problem regarding the high level of water
consumption during the last ten years;
 The age of the network and the degradation due to excessive loading nearby the
network2 allow to create a zone of failure around the pipelines.
I - 4 – Project objective :
The project objective is to resort to new technology (Modeling and GIS)
applications in order to help to take decision by calculating the head-loss within the
network, by estimating the excessive stresses due to the loading surface and by
designing a Digital Mapping and building Geo-database in order to identify with more
accuracy the risk zones according to the underground water supply network in Al
Morouj district.
At the first, we shall investigate the area of study by visiting many locations to
make a measurement in different points of the network (pressure and flow).
After that we shall introduce the network within the EPANET 2 software to
estimate head-loss and its distribution within the water supply network.
Depending the ground the maximum depth is 1 m 2
M. S. Al Harthi – M. A. Al Semari – M. A. Zoman – Y. M. Dossary
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At the third time, we shall compare the above results with those calculated by
the analytical hydraulic formulation given by teacher in the class.
Finally, we shall propose an addition geospatial data using GIS software in
order to integrate multi-layers overlapping with the water supply network. This
procedure allows to help for decision to find the multi-leakage in the system when
introducing updated data function time.
I - 5 – Project methodology :
This applied project methodology that will be adopted consist of :
 At the first a literature review synthesis concerning the water resources for water
supply, using methods to finding leakage within the network and new technology3
used to monitoring and controlling the head-loss and degradation in term of soil and
rock mechanical modeling.
 Second, we shall propose a methodology to estimate the head-loss in the network
using hydraulic software (EPANET 2) and compare the results with those observed in
the field in different points of the network.
 After that, we shall make a necessary updating concerning the geotechnical
proprieties of materials used at the time of execution of the network in order to
validate the FLAC modeling discussed in the last chapter of this project. the
Application of software for help to decision 3
M. S. Al Harthi – M. A. Al Semari – M. A. Zoman – Y. M. Dossary
Academic Year : 2012 - 2013
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experiments which will be realized in geotechnical laboratory in Department of Civil
Engineering, College of Engineering at King Saoud University.
 In the field and in order to know the true geometry of these underground network a
surveying measurements will be conducted and also to know the depth of each single
pipeline.
 After collecting data available and consulting the geo-database in GIS of the
National Water company, we propose the methodology to improve the GIS application
for water supply network monitoring and controlling and to help to take decision.
 Finally, a recommendations will be proposed to continue to improve this content of
this project by a new project involving new group of students for the next semester of
this academic year 2013.
I - 6 – Literature review :
Extension of epanet for pressure driven demand modeling in water distribution
system [1]. Electronic Management Systems from Motorola Improve Efficiency of
Water Projects [2]. Help References. Working with ArcGIS Spatial Analyst. ESRI.
Egypt Multipurpose Land Cover Database (Africover). Food and Agriculture
Organization of the United [3]. Estimating Legitimate Non-Household Night Use
Allowances [4]. Estimating Background Leakage [5]. Pressure-driven demand and
leakage simulation for water distribution networks. Atmospheric Chemistry and
Physics [6]. Analysis of Flow in Networks of Conduits or Conductors [7]. Household
Night Consumption [8]. User Guide and Theory of Finite Difference Method [9].
Integration of RF communications for Distribution Automation with Dual Redundancy
M. S. Al Harthi – M. A. Al Semari – M. A. Zoman – Y. M. Dossary
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[10]. Integrating geographical information systems and multiple criteria decisionmaking methods [11]. Leakage Estimation from Night Flow Analysis [12]. Losses in
Water Distribution Networks [13]. Managing Water Infrastructures with SCADA
Systems [14]. Managing Leakage [15]. Manual of DMA Practice [16]. Managing
water leakage - Economic and technical issues [17]. Natural Rate of Rise of Leakage
[18]. A semi-pressure-driven approach to reliability assessment of water distribution
networks [19]. Performance Indicators for Water Supply Services [20]. Report 26
Leakage Control Policy & Practice [21]. EPANET 2 users manual [22]. Introduction
to Rock Mechanics [23]. The influence of underground workings on slope instability :
A numerical modeling approach [24]. Technology and Equipment for Managing
Water Losses [25]. Introduction to Water Transport and Distribution [26].
Multicriteria Evaluation for Urban and Regional Planning [27]. Water Loss Control
Manual [28].
I - 7 – Time table of the projects :
● Project I : Methodology and literature review.
SECOND TERM (2012) : Project I
Months
N° TASKS REQUIRED
1
Literature review
2
Collect data from field by surveying
3
Acquisition data and spatial data
M. S. Al Harthi – M. A. Al Semari – M. A. Zoman – Y. M. Dossary
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2
3
4
5
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requirement
● Project II : Water supply network modeling works.
FIRST TERM (2013) : Project II
Months
N°
TASKS REQUIRED
1
Running Water EPANET 2 software
2
Building Geo-database based on satellite
Image GeoEye
3
Running FLAC modeling Software
4
Writing a final report
M. S. Al Harthi – M. A. Al Semari – M. A. Zoman – Y. M. Dossary
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2
3
4
5
6
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CHAPTER II :
WATER RESOURCES FOR AL RIYADH
II - 1 – Existing water resources :
● Introduction :
Riyadh city is supplied by desalinated seawater and by groundwater as shown in
Table II-1. Currently, five well fields are operational outside the city (Haer/Nisah,
Buwayb, Salboukh, Wasia and Hunaï) in addition to the water wells operated within
the city supplying the water treatment stations located in the centre (Malaz,
shemessey, Manfouha). The desalination plant Jubail 2 which supplies Riyadh is
operated by the Saline Water Conservation Corporation (SWCC). In 2005 (1425H) as
M. S. Al Harthi – M. A. Al Semari – M. A. Zoman – Y. M. Dossary
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a result of commissioning of the new Hunai well field located 200 km east of the city,
groundwater amounts in 2005 for 51% of the total water supply against 35% in 2004.
In July 2004, Jubail 2 supplied Riyadh with 897,000 m³/day while in July 2005 the
supply decreased to 705,000 m³/day.
● Groundwater :
Riyadh city is supplied by about 200 wells connected to eight Water Treatment
Plants :
● Wasia;
● Salboukh;
● Buwayb;
● Shemessey;
● Manfouha 1 and 2;
● Malaz;
● Hunai;
● Haer and Nisah.
Five main well fields are located in a perimeter of 250 km radius around
Riyadh, essentially to the East : Al-Hunaï, Wasia, Buwayb and Salboukh and Nisah
well field in the South.
The present capacity of the different well field is shown in Table II - 1 below.
Table II - 1 : Present well fields capacities4.
Sources : VEALIA Full Audit of Water and Wastewater Services – City of Riyadh Report 4
M. S. Al Harthi – M. A. Al Semari – M. A. Zoman – Y. M. Dossary
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Table II - 1 shows that the well field production capacities are adequate for
Haer, Manfouha, Salboukh, Buwayb, Wasia and Hunaï to allow full use of the
capacity of the WTPs. Concerning Malaz and Shemessey, new boreholes are being
drilled and the planned production capacity of the WTPs should be reached soon. The
delay is not important regarding the production volume. Concerning Salboukh and
Buwayb, new boreholes are also being drilled and some are already completed. These
new boreholes, if productive, would provide the required potential supply to the new
water plants being constructed in Salboukh and Buwayb. Depletion of water levels of
several meters has been assessed in the Minjur aquifer. Regarding the Salboukh and
Buwayb water treatment plants, the life span of the underground water resource is
estimated to be around 25 to 30 years ahead, if the existing extraction rate is kept.
Concerning the Wasia-Biyadh aquifer, depletion rates appears to be less than one
meter per year in Wasia well field. However, recent drilling in the well fields may
increase this depletion rates. Extraction in Hunaï (aquifer Umm Er Radhuma) is too
recent for estimating the depletion rate. GDWRR have suggested that in general
treatment capacity is limited by borehole production – not necessarily as a result of
reducing water table problems but of the performance of the well and the screen itself.
In some boreholes the casing in the confining strata had failed causing contamination
from the shallow aquifers while screening failures at lower levels plug the boreholes
with sand. Some of the problems were due to insufficient raw water mains capacity
and it is understood that schemes are in hand with the Network Department to address
M. S. Al Harthi – M. A. Al Semari – M. A. Zoman – Y. M. Dossary
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the problems of failing raw water lines. There are a number of plans to drill new
boreholes to get production back to nearer the original plant capacity.
The majority of the city boreholes have diesel driven turbine pumps - part of the
reason for this is the difficulties of availability and reliability of electricity in the more
remote well field areas.
● Wasia :
The well field of Wasia is located east of Riyadh, at about one hundred
kilometers and coordinates are roughly 25°10’N and 47°30’E. Wasia is a deep
groundwater source commissioned in 1400H (1980) abstracting water from 48 wells in
the Wasia aquifer. The treatment process at Wasia consists of cooling, pH correction
and iron precipitation. Treated water is chlorinated and pumped to High Point
Terminal.
The depth of the wells ranges from 390 to 500 m with a static water level at
about 250 m below ground surface. The pumps are set at 290 m below ground. (New
wells currently being drilled are around 500 m deep) The WTP of Wasia produced
from the 24th December 2003G to the 22nd January 2005G approximately 80.5 Mm³
water which amounts to 209,279 m³/d. During that period of time, only two days were
off. The designed capacity of the plant is 210,000 m³/d. The actual capacity of the
wells ranges from 100 m³/h to 230 m³/h considering that according to a daily report
(12/06/2005) of the W&P Department :
● 6 wells are out of use;
● 10 wells are having equipment maintenance;
●18 wells are spared;
● 30 wells are in use.
M. S. Al Harthi – M. A. Al Semari – M. A. Zoman – Y. M. Dossary
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The same report indicated a production of 148,765 m³ for that day. This is
equivalent to about 6,200 m³/h, thereby 206 m³/h per well. Considering that 48 wells
are currently available for production with a mean production capacity of 200m³/h per
well, the well field current production capacity may be estimated at 230,400 m³ per
day. According to the given figures, current well field capacity is thereby sufficient for
supplying the WTP. Wasia currently delivers around 230 tcmd to HPT where it is
blended 1:4 with water from Jubail. The water treatment plant was originally intended
to reduce hardness and iron by using a combination of lime and soda. In around
1416H (1996) it was decided to only add lime to reduce the turbidity because the final
product hardness after blending at HPT was satisfactory. Another project is now under
study to develop some additional 300 tcmd in Wasia well field. This additional
amount of water will be conveyed in the future to Riaydh City.
● Salboukh :
The well field of Salboukh is located about 50 km North-West-North of Riyadh.
Started in October 1978, it consists of 19 boreholes from which fifteen were dug from
1396 H to 1398 H, one in 1410 H and three in 1423 H. The depth of the wells ranges
from 1,180 to 1,320 meters according to the W and P Department. Nevertheless,
completion reports show that final depth of the boreholes was about 1,600 meters. The
groundwater static level is about 280 to 330 meters below ground surface. The well
field may be included into a square of 20 by 20 km. Distances between boreholes are
at least 2.5 km. Eleven new wells were drilled recently to have a new additional
capacity for Salboukh WTP of 60 tcmd. The total cumulative length of transmission
pipes from the wells to the WTP is of about 70.6 km (with diameters ranging from 300
to 800 mm). The WTP of Salboukh produced from 24th December 2003 till 22nd
January 2005 approximately 21.2 million m³ of water which amounts to
55,045m³/day. During that period of time, the WTP produced water every day. The
M. S. Al Harthi – M. A. Al Semari – M. A. Zoman – Y. M. Dossary
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designed capacity of the plant is 60,000 m³/day. The actual capacity of the wells
ranges from 180 m³/h to 270 m³/h considering that according to a daily report
(12/06/05) of the W&P Department :
● Four wells are not used anymore;
● Two wells are having equipment maintenance;
● One well is spared;
● Eleven wells are used.
The same daily report indicated a well production of 65,000 m³ and for the
WTP of 55,192 m³ for that day (12/06/2005). This is equivalent to about 2,708 m³/h,
or 246 m³/h per well. Considering that 12 wells are currently available for production
and a mean production capacity of 240 m³/h per well, it appears that the well field
current production capacity may be estimated to 69,120 m³ per day that is sufficient to
supply the WTP. The treatment process was designed by Degremont and includes the
following major components :
●18 Nr wells complete with pumps, pipes, valves, power supply, transformers, starters
etc. (Office wall chart showed 10 in operation, 4 under maintenance, 2 standby);
● 8 Nr Water coolers / decarbonators;
● 6 Nr precipitators;
● 6 Nr two stage filters;
● Low pressure feed pumps, high pressure feed pumps, micro filters;
● 5 Modules of 2 blocks of three stage reverse osmosis units;
● 3 Sets of Booster pumps;
● 7 Sets of Power generation diesel alternators.
This facility is reported to be typical with the other Riyadh treatment works
being of a similar design (these are the plants at Manfouha, Buwayb and Shemessey).
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Water arriving at the treatment works is cooled from 70 degrees C to a range
between 30 to 35 degrees C and decarbonated in eight towers. Heavy deposits of iron
oxides on the cooling tower packing are removed by dismantling each tower yearly for
cleaning.
Water from the cooler is distributed 75% to the 6 precipitators with the
remainder passing directly to the filters. Water entering the precipitators is chemically
dosed with lime, soda, ash and polyelectrolyte. Following the precipitation stage the
water is acid dosed for pH correction prior to two stages filtration, 6 sets of up flow
followed by down flow rapid gravity filters. Filters are washed daily using air
followed by air and water. The 25% flow bypassing the precipitators is filtered using 2
sets of identical up flow / down flow rapid gravity filters and this water is then used
for blending with the desalinated water from the reverse osmosis process.
Flow for desalination is pumped via microstrainers to the R.O. pumps and is
dosed with acid and anti- sealant. There are 5 R.O. modules of 2 blocks each 3 stage
using Dupont membranes with an 85% conversion rate. Membranes are chemically
cleaned at three monthly intervals. Membranes are replaced approximately every five
years on a rolling program.
The desalinated water is blended with the filtered water, chlorinated and then
gravitates to the city distribution system.
Initially the treatment works and the well pumps were supplied with electricity
from the treatment works power plant which consists of seven 2.5 MW diesel
alternator sets. Power is now supplied from the national power company and the diesel
alternators are undergoing an overhaul and are available for use as standby.
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It is currently planned to duplicate the treatment works with 11 new wells,
including power generators and using only the chemical handling facilities associated
with the existing works.
It was noted that some instruments associated with the RO plant had been
replaced, however in view of the age of the plant complete replacement of the
instrumentation at an early date may be prudent.
● Buwayb :
The well field of Buwayb is located at about 65 km north-east of Riyadh. In
operation since 1399H (November 1979), it consists of 18 boreholes that were all dug
in 1399H. The depth of the wells ranges from 1,200 to 1,450 meters or from 1,810 to
2,025 meters. However, according to completion reports, real depths should be around
1,500 to 1,600 meters.
The groundwater static level ranges from 260 to 320 meters below ground level.
The well field covers a L-shape area with its base facing west and fitting into a square
which sides are 20 km long. The minimum distance between boreholes is about four
km. 12 new wells have being drilled recently to produce additional capacity of 60
tcmd. The Water Treatment Plant is located in the NE corner of the well field. The
total cumulative length of transmission pipes from the wells to the WTP is of about
70.5 km (diameters ranging from 300 to 800 mm). The present designed capacity of
the plant is 60 tcmd. The actual capacity of the wells ranges from 220 m³/h to 270
m³/h considering that according to a daily report (12/06/2005) of the W&P
Department :
● Two wells are not used anymore;
● Five wells are shut down for equipment maintenance;
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● Eleven wells are operational.
The same W&P Department daily report indicated a well production of 68,589
m³ and for the WTP of 58,518 m³ for that day (12/06/2005). This is equivalent to
about 2,858 m³/h, thereby 260 m³/h per well. Considering the range of the production
capacities for the wells, this value seems high. A value of 238 m³/h per well would be
achieved with 12 operated wells. Nevertheless, considering that 11 wells are currently
available for production and a mean production capacity of 240m³/h per well, it
appears that the well field current production capacity may be estimated to 63,360
m³per day which is just sufficient to supply the WTP. Buwayb WTP is understood to
be identical to Salboukh and, overall, experiences similar problems in terms of
reliability and quality.
● Shemessey :
The nine wells supplying Shemessey WTP do not belong to a real well field.
They are located in different places :
● Three in Hijaz (drilled in 1394 H, 1421 H and 1423 H);
● Three in Nmarqiva (drilled in 1394 H);
● Two along Riyadh - Salboukh road (wells Salboukh 1 – drilling date is unknown –
and Salboukh 6 – 1398 H);
● One in Irqah (not used anymore);
Well depths range from 1,110 to 1,700 meters, the deepest being in Hijaz.
Groundwater levels range from 270 to 300 meters below ground level in Salboukh
road and from 220 to 250 meters below ground level elsewhere (apart from Nmarqiva
3, 280 meters). These differences are mainly related to the topography of the area but
the elevation of the different wells was not provided.
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Lengths and diameters of the transmission lines are not known.
Four new wells have being drilled recently along the Riyadh-Salboukh road in
order to replace old wells which are not used anymore (Salboukh 2 to Salboukh 4) and
Salboukh 1. According to the drilling specifications they are drilled down to 1,700
meters. The WTP is located in the west of Riyadh city and is composed of the
following parts :
• The cooling towers;
• A pretreatment consisting in softening and filtration;
• A RO plant.
The average output is about 30,000 m³/d of softened water. The water is
blended with by passed water and water produced by other sites (shallow wells of
Nissah and Beaja). The total production of Shemessey is about 84,000 m³/day :
• 30,000 m³/day of softened water;
• 11,000 m³/day of filtered water (by pass);
• 43,000 m³/day from other sites.
In normal operation, output is pumped directly to Badia BPS, via a new main
laid 17 years ago. The alternative is for gravity or pumped supply to the network.
Shemessey PS can also take water from Main Zone, when the treatment plant is shut
down.
The water treatment line comprises the following stages :
• Cooling tower;
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• Softening by injection of lime slurry and soda ash, precipitation and settling;
• Primary acidification;
• Double sand filtration;
• Buffer tank;
• Chemical conditioning (secondary acidification, antiscalant injection);
• Reverse osmosis;
• Treated water tank;
• Treated water pumping.
● Manfouha :
The plant of Manfouha has been built in two phases: first phase (Manfouha 1) in
1967, second phase (Manfouha 2) in 1972.
Twenty-six wells are supplying the Manfouha WTP. As a matter of fact, they do
not belong to a real well field. They are located in a number of different localities,
mainly in the South of Riyadh city :
● Four in Dakana (dug in 1387H, 1392H, 1398H and 1420 H);
● Three in Baejah (drilled in 1388 H, 1391 H and 139 8H);
● Six in Haer (among which three drilled in 1374 H, one in 1398 H, one in 1425 H);
● Two in Al-Jezah (drilled in 1398 H);
● Six in Al Kharj (four drilled in 1379 H, one in 1398 H and one in 1424 H);
● The five last wells are located in the factories (1425 H), inside Manfouha WTP
(1422 H), one in Mansouriah (1398 H), one in Namal al Wardi (1425 H) and last in
Swardi (1398 H).
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Well depths range is from 290 to 2,297 meters or even less, the deepest being
the factories wells and Dakana 2. If wells drilled to a depth of 2,297 meters are
astonishing, at least two different aquifers are tapped :
● Shallow aquifer (to a depth of maximum 200 meters) tapped by four Haer wells
and which are planned to be abandoned;
● Deep aquifer (probably Minjur and Jilh) tapped by the other wells (including Haer
2 and deep Haer).
Groundwater levels range from 160 to 200 meters below ground level for deep
aquifers. Lower values are found, nearing 120 meters but this is mainly related to the
topography and possibly to the measurement date which is not provided (values lower
than 160 meters are only found in old wells (at least 26 years). The elevation of the
different wells was not provided.
The average daily productions of softened water of Manfouha 1 and 2 are
respectively 23,250m³/day and 35,269m³/day.
A set of valves allow the connection of each incoming raw water pipe to both
treatment lines.
When both plants are running, the raw water from the two origins is partially
mixed in the cooling tower.
Lengths and diameters of the transmission lines are not known. Nevertheless,
Baeja 1 is located at about 30 km from the WTP. Six new wells are required by the
WPD, in order to replace old wells (Mansouria, Baeja 1, Kharj 3, Swedi, Deep Haer
and Haer 12). According to the drilling specifications they should be drilled down to
1,700 meters.
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Manfouha pumping stations 1 and 2 deliver through separate lines, with
“pressure holding” valves on each line into the central zone.
● Malaz :
Malaz WTP is the smallest of the city treatment plants with a nominal capacity
of 24 tcmd built in 1967. The well field is composed of five wells among which two
are not used anymore. The wells are located inside Riyadh city but do not form a real
well field. The three wells are Malaz 1 and 2 and “Railway 1”. The airport well and
“Railway 2” are not used anymore. Malaz 1 and 2 are respectively 1,300 and 1,424
meters deep.
According to Wells & Plants Dept. four new wells have been drilled recently,
some are already supplied with electricity but they are not yet connected with
transmission lines. New wells are: Al-Lagoon, Ulisah, Nasria and Ma’Ather. Drilling
specifications for Riyadh wells provided by Wells & Plants Dept indicated that the
depth of the new wells should be 1,700 meters and would tap the Minjur aquifer. This
depth seems a bit high for brand new wells which are likely to tap both Minjur and Jilh
formations. Two other wells are required by WPD in replacement of wells located at
Railway station (wells 1 and 2). Locations are in Al-Manakh Garden and Prince
Salman Road in Al Fiasilisa.
The present production of the plant is about 10,000 m³ per day (9,820 m³/d on
yearly average in year 1424H – typically 11,500 m³/d according to the operators).
The RO stage has been recently replaced, but the new RO plant is not yet
commissioned.
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The water is featured by a high temperature and a high TDS. The raw water is
taken from three deep wells.
The treatment process is similar to Shemessey and Manfouha with 8 coolers, 3
precipitators, 4 RG filter units and 4 blocks of RO membranes.
Treated water storage is one rectangular 10 tcm reservoir from which five
pumps deliver water into the central zone at a head of around 40 m.
Treatment sludge from both Malaz and Shemessey plants is pumped some
distance to walled dumping areas. It is noted that this site could be better utilized for
development of housing in future years.
● Hunaï :
The well field of Al-Hunaï is located east of Riyadh at a distance of about 200
kilometers. It consists of 65 wells. The well field occupies an area of about 10 x 15
km. The depth of the wells ranges from 400 to 500 meters with a groundwater static
level at about 250 m below ground surface.
The elevation ranges from 340 to 360 meters above mean sea level.
This well field is being completed and is operated since Thul-Quada 1425 H.
The water supply needs of Riyadh are transmitted daily to SWCC which is providing
to Al- Hunaï WTP the required production volume. Water from the Hunaï WTP is
mixed with Al- Jubaïl desalinated water and a small part of Wasia water in HPT.
As the capacity production of the wells exceeds the capacity of the plant, a
choice has to be made among the wells. This is done automatically through an
algorithm based on the following points with a minimum volume to be provided :
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• The minimum pressure in the well;
• The lowest running hours per line.
Well operation is remotely controlled. A SCADA system is in use.
The pumps are located at a depth of 240 meters below ground level. All wells
are equipped with a magnetic flowmeter (respecting 2.5 to 3 meters straight flow on
each side of the device).
Raw water production cost is not yet known for this well field.
● Haer and Nisah :
The well field of Haer and Nisah is located south of Riyadh at a distance of
about 30 km. It consists of :
● 21 Nisah boreholes from which three have been drilled in 1384H, one in 1404H, one
in 1408H, two in 1410H, two in 1413H, nine in 1415H and one in 1418H. For the two
last ones, drilling date was not provided.
The depth of the wells ranges from 152 to 220 meters with a groundwater static
level at a depth of 60 to 110 meters.
The wells are located along a west-east axis due to the existence in this area of
the Nisah graben. The perimeter of the area is 1.5 km wide for 8 km in length. The
minimum distance between two boreholes is about 250 meters. It is worth mentioning
that nine new wells have being drilled recently in the past two years.
Nisah wellfield pumps to Haer WTW where it is chlorinated and pumped to
Shemessey. We understand that production could be increased but there are some
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constraints on the raw water transmission lines, however, this situation is being
addressed by some new GDWRR raw water pipeline projects.
The Water Treatment Plant of Al-Haer is located about 17 km north to the well
field. As a matter of fact, only chlorination is performed in the plant. Elevation ranges
from 530 to 550 meters above mean sea level.
The Haer well field consists of deep and shallow wells. The deep wells are:
Beeja 1, Beeja 2, Beeja 3 and Haer Deep Well pumping from a deep aquifer with
wells up to 2000 m deep (with the pumps set 270 m below ground). The abstracted
water temperature is 75 degrees Celsius and requires cooling prior to chlorination at
Haer and is pumped to Shemessey.
GDWRR have commented that the Al-Haer shallow wells are of poor quality
and may be abandoned.
● Desalinated Supplies :
The Jubail 2 desalination plant on the eastern coast north of Damman has a
capacity of 1,000 tcmd.
After deduction of local supplies to Jubail and the naval base the water available
for Riyadh is 700-800 tcmd.
Two 60 inch diameter steel pipelines each 457 km long have a design capacity
of 765 tcmd to transfer water to HPT. The lines operate at full capacity and have done
so since 1992. Collectively the Jubail – HPT system is called the Riyadh Water
Transmission System (RWTS). The system was originally planned to be developed at
5 year intervals as follows :
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● Line A together with pump stations A : 1, 3 & 5;
● Pump stations A : 2, 4 & 6;
● Line B together with pump stations B : 1, 3 & 5;
● Pump stations B : 2, 4 & 6.
The system was expected to reach full capacity by 2012. However, the whole
system was built in a single phase. As a consequence, Riyadh had a plentiful supply of
water for 10 years until 1992 when the demand for water began to outstrip supply.
Design of the line is based on oil pipe technology, with in-line boosters (6 nr),
operating at 50 bar plus with a design life of 30 years. Line valves are at 30 km
intervals, cross-connections at the booster stations (at 90 km intervals). The maximum
theoretical pumping capacity is 830 tcmd, but in practice this maximum is now limited
to 800 tcmd due to the ageing of the system.
Line C from Jubail to HPT has been built (60 inch diameter) and is now
operational since end of 1422 H. The C line is ‘primarily’ to feed Qassim province,
and has its own 90 tcmd desalination plant. Cross connections were constructed at
Jubail, en route and at HPT to enable combined operation with the A and B lines.
The Saline Water Conversion Corporation (SWCC) has an agreement with
GDWRR for an average flow of 765 tcmd. However and in order to cope with the
increasing demand a new desalination project is planned (the Ras El Zour project); this
project will deliver additional 800 tcmd to Riyadh city at different strategic storage
locations (HPT, TGNW, TGSW and TGW). The project was expected to be
operational by May 2008 (1429 H), however and due to some delays it is expected that
the project will be able to deliver the planned quantities at required locations by 2011
(1432 H).
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Table II - 2 shows the city and regional well fields and WTPs.
Table II - 2 : Capacities/dates of Commissioning of Riyadh water well fields5.
II - 2 – Future water resources :
● Introduction :
The resources development plan has been drawn according to different sources
of information : official, non official documents and discussion with various
stakeholders. This information has been discussed in the previous chapters and is
summarized in Table II - 3 below :
All flows are in m3/day 5
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● Planned water resources developments :
The resources development plan has been drawn according to different sources
of information : official, non official documents and discussion with various
stakeholders. This information has been discussed in the previous chapters and is
summarized in Table II - 3 below :
● New development of groundwater resources :
Three options regarding groundwater resources are currently being studied by
the WRDD (Water Resources Development Department) :
● A new well field near Wasia (it was indicated as a potential resource in TWI MP of
2002);
● A new well field in Al Bakhra (West of Riyadh, it was also indicated as a new
resource in TWI MP of 2002);
● A new well field about 250 km south of Riyadh, near Layla (new potential area)
The new well field near Wasia would be located south of the Riyadh-Dammam
road, at about 100 km from Riyadh. It is intended to tap the Biyadh formation, which
thickness in the area is bigger than Wasia’s. About one hundred wells are planned up
to a depth of about 500 meters. The expected production capacity is 240m³/h per well,
which means a total well field capacity of 576,000m³/day or 210.24 Mm³/year. A
modeling of the aquifer is intended to be performed during the preliminary studies.
For WRDD, it is the next well field to be implemented for Riyadh supply.
Concerning Al-Bakhra (50 km west of Riyadh), a feasibility study was
completed about three years ago. It was intended to tap the Minjur aquifer close to the
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outcropping area but the study showed that the upper part of the Minjur aquifer was
eroded and that due to important faults in this area the water was not of good quality
(mixing waters from different aquifers). At present, drilling of this well field is still
under consideration.
The third potential well field is located about 250 km south of Riyadh and
intends to tap the Umm Er Radhuma aquifer. Feasibility studies are on-going but
yields of up to 600m³/h are expected according to the WRDD.
Regarding the development of other aquifers tests were performed in the Saq
aquifer 25 years ago but results were not positive. Heavy temperature (higher than in
Minjur) as well as high TDS are to be expected in the Saq. Nevertheless, this aquifer is
known for its productivity in the North - West of the country and tests at shallower
depth North-West of Riyadh could be performed.
● On-going and planned desalinated development projects :
The discussions held and the limited data provided by SWCC indicate a twofold
approach for water desalinated supply :
● Rehabilitation and modernization of the existing facilities;
● Construction of new plants.
The same is applying for Riyadh city. However, no detailed information was
given about the intended investment in both rehabilitation and construction.
In February 2004, SWCC has appointed UK consultant Mott Mac Donald
(Global Water Intelligence, “Planning the future of SWCC”, April 2005) to look at the
possibility of extending the life of two plants among them Jubail Phases 1, 2A and 2B.
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The implementation of a rehabilitation program will aim at extending the life of the
plants of at least ten years. The results of this study and thus the rehabilitation program
were not made available to us.
With a nominal working life of 25 years, it was expected that the plant would be
close in 2008. Thames Master Plan suggests the limit of 2011 due to expected poor
efficiency and reliability of boilers. However, assuming the above implementation of a
rehabilitation program, it can be reasonably said here that the life of Jubail 2 could be
extended up to 2020 as per of the willingness of SWCC to extend the life of this plant
of at least ten years. However, the refurbishment works and upgrading will certainly
have an impact on the production of the plant. It is reasonable to think that among the
four sections of the plant, one out of four will be stopped for refurbishment. A period
of six months is assumed as the duration of the rehabilitation works. Once works at a
section are completed, another section is being refurbished. Therefore, during two
years, the production capacity is being reduced by 216,000m³/day (90% availability).
In its Master Plan, TWI indicated that two further development stages for Jubail
plant were confirmed by SWCC. The information was given that the first, Jubail 3
(production capacity : 450,000m³/day) would be operational in 2008G and the second
Jubail 4 (production capacity : 350,000m³/day) in 2010.
However, the actual information indicates that Jubail 3 will only serve the eastern
province cities. In its official website, SWCC indicates that two plants projects under
study are under study for the supply of Riyadh :
● Jubail 4 with a production capacity of 450,000m³/day, which is assumed to start
production in 2010 as per Thames Master Plan;
● Ras Al-Zoor with a production capacity of 800,000m³/day, which is assumed to start
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production in late 2011.
However, written information and discussions with SWCC officials have
confirmed that at the present time Ras Al Zoor Project is the only project to be
considered as relevant for Riyadh city. Therefore for the construction of the supply
demand balance, Ras Al Zoor is considered as the sole planned desalinated source.
Given that the original design life of the Line A and Line B pipelines was
around 30 years, the construction of a Line D pipeline is possible. SWCC consider that
there is significant residual life remaining but feel that a Line D line would improve
flexibility.
In the new tender launched by SWCC the 2 lines are called Line D and Line E.
These lines are to be constructed by 1432 H.
Table II - 3 : Planned water resource projects6.
Water Master Supply Master Plan 1428 – 1450 H : Ministry of Electricity and Water - Riyadh
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Figure II - 1 - Summary Supply / Demand Balance7.
Figure II - 1 - Summary Supply - Demand Balance8.
Water Master Supply Master Plan 1428 – 1450 H : Ministry of Electricity and Water - Riyadh 7
Water Master Supply Master Plan 1428 – 1450 H : Ministry of Electricity and Water - Riyadh 8
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II - 3 – Conclusions :
Referring to the table (Table II - 3) and the figure (Figure II - 1) given that the
planned water resource projects until 1450 H compared to supply and demand balance
indicates that the consumption increases from year to year and can reaches 2400 tcmd.
This situation allows to give a great importance to the water supply network in order
to minimize the loss of flow during the distribution and monitoring this network using
the new technology (modeling, GIS, Remote Sensing).
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CHAPTER III :
Theory of Leakage and Control
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III - 1 – Introduction :
As water networks deteriorate, they become prone to leakage. In addition, new
networks frequently include leaks as a result of poor installation practice and incorrect
materials. Where the distribution network comprises hundreds or thousands of
kilometers of pipe work, it is not an easy task to locate the bursts and breakages,
particularly as many are invisible. This situation progressively worsens until, in
extreme cases, it becomes necessary to ration the water for part of the day by closing
off the supply. The solution is to create a permanent leakage control system by
dividing the network into a number of sectors called DMA so that the leakage in each
sector can be quantified and the detection activity can always be directed to the part of
the network with the most leakage. Once an acceptable level of leakage is achieved,
the flow into the area is usually monitored to enable new leaks to be identified
immediately.
III - 2 – Control of leakage using DMA :
The traditional approach to leakage control has been a passive one, whereby the
leak is repaired only when it becomes visible. The development of acoustic
instruments has significantly improved the situation, allowing invisible leaks to be
located as well. But the application of such instruments over the whole of a large
water network is an expensive and time-consuming activity. The solution is a
permanent leakage control system whereby the network is divided into District
Metered Areas (DMAs) supplied by a limited number of key mains, on which flow
meters are installed. In this way it is possible to regularly quantify the leakage level in
each DMA so that the leakage location activity is always directed to the worst parts of
the network. An important factor in lowering and subsequently maintaining a low
level of leakage in a water network is pressure control. The division of the network
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into DMAs facilitates the creation of a permanent pressure control system, thus
enabling pressure reduction in DMAs which reduces the level of background leakage,
the rate of flow of individual bursts and the rate of the annual burst frequency. Many
water distribution networks are managed without using DMAs. However those that
have successfully achieved low leakage levels without DMAs tend to have a
combination of high quality infrastructure in good condition, an efficient repair
operation and low, stable pressures.
III - 3 – Theory of DMA management :
The key principle behind DMA management is the use of flow to determine the
level of leakage within a defined area of the water network. The establishment of
DMAs will enable the current levels of leakage to be determined and to consequently
prioritize the leakage location activities. By monitoring flows in the DMAs it will be
possible to identify the presence of new bursts so that leakage can be maintained at the
optimum level. Leakage is dynamic and whilst initially, significant reductions can be
made, levels over a period of time will tend to rise unless on-going leakage control
is carried out. DMA management should therefore be considered as a method to
reduce and subsequently maintain a low leakage level in a water distribution network.
The key to DMA management is the correct analysis of the flow to determine whether
there is excess leakage and identify the presence of new leaks. Real Losses are the
difference between the system input and the total customer consumption (corrected for
measurement inaccuracies) in a defined area. This is made up of Leakage (from mains,
services up to the point of consumption and storage tanks) and Overflows (mainly
from storage tanks). Traditionally real losses were quantified as a volume and were
calculated on an annual basis. However, this approach does not allow the necessary
fine control of leakage to be achieved as it can take several months for a major change
to be identified and the precision of leakage measurement is poor. The extent of
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leakage can be gauged by assessing the 24-hour flow pattern of a network. A limited
variation between the minimum and peak flow, particularly in a network with little
industrial night use, is indicative of a leaky network. However this approach does not
allow the leakage level to be directly quantified. Leakage is most accurately
determined when the customer consumption is a minimum, which normally occurs at
night. This is the principle of minimum night flow originally recommended in the UK
document Report 26 (1980). The size of the DMA will influence the level of burst
leakage that can be identified. A large DMA will tend to have more leakage and
customer night use, which will mean that a burst represents a smaller percentage of the
minimum night flow, thus reducing its definition. Figure 1 shows the typical variation
of minimum night flow in a DMA in which there is little seasonal variation in night
consumption. The presence of reported and unreported bursts can be identified.
III - 4 – Control of leakage using DMA Design Network :
● Introduction :
The technique of leakage monitoring requires the installation of flow meters at
strategic points throughout the distribution system, each meter recording flows into a
discrete area, which has a defined and permanent boundary. Such an area is called a
District Meter Area (DMA).
The design of a leakage monitoring system has two aims :
● To divide the distribution network into a number of DMAs, so that the flows into
each district can be regularly monitored, enabling the presence of unreported bursts to
be identified and leakage to be calculated with confidence.
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● To manage pressure in each or a group of DMAs so that the network is operated at
the optimum level of pressure.
Depending on the characteristics of the network, a DMA will be :
● Supplied via single main (preferable) or multiple feeds;
● A discrete area (i.e. no flow into adjacent DMAs);
● An area that cascades into an adjacent DMA (to be avoided if at all possible).
An effective permanent leakage control system will :
● Maximise the accuracy of measurement of leakage within DMAs;
● Facilitate the location of the leaks;
● Limit of if possible eliminate the number of closed valves;
● Minimise the changes to the hydraulic and qualitative operation of the existing
network.
● DMA Design criteria :
The factors that should be taken into account when designing a DMA are :
● The required economic level of leakage;
● Size (geographical area and number customer connections);
● Housing type i.e. blocks of flats or single family occupancy housing;
● Variation in ground level;
● Water quality considerations;
● Pressure requirements;
● Fire fighting capacity;
● Target final leakage level;
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● Number of valves to be closed;
● Number of meters used to monitor flow ideally minimized;
● Large metered customers should have their meters measured as export meters from
the DMA.
● Infrastructure condition.
The over-riding factor is to successfully create the DMAs without significantly
affecting the quality of service to the customers. This is particularly important in
networks where the existing operating pressures are already low. It should also be
remembered that the reduction in leakage that the creation of DMAs allows will also
tend to increase the operational pressures within the network. A DMA boundary
should not necessarily be considered definitive. With the change in operating
conditions, it might be necessary to modify the boundary. For this reason it is usually
better to create a boundary by closing valves rather than cutting the pipes. However
care must be taken to ensure that these valves are leak tight and that their accidental
opening is avoided.
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CHAPTER IV :
Water Supply Planning Criteria
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IV – 1 – Introduction :
The water transmission and distribution system will be sized to meet the peak
daily demand under continuous supply conditions in the base forecast approved by
GDWRR, Demand Scenario A. It is recommended that the following standards are
adopted for design and operation.
It is expected that it will remain a statutory requirement and that consumers will
continue to want their own ground level storage to supply their own elevated roof
tanks. This practice is considered appropriate given the perceived need to control or
limit the maximum volume of water used by individual consumers. Without ground
level tanks, it will become necessary to design the transmission system for higher peak
flows and higher distribution pressures.
IV – 2 – Peak Factors :
Flow rates within a balanced network where the demand is always satisfied by
the supply are subject to significant variations that can be defined as follows :
The annual trend : It is the yearly variation of the total annual water demand due
to the demographic development. In general, in developing areas, the annual trend
follows a geometric progression in the form of exponential variation where the
increment is the annual demographic development rate. Consequently the average
water flow for a certain year n is :
ADD(n) = ADD(n-1) . (1 + d)
ADD(n) = ADD(0) . (1+d)n
Where :
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ADD(n) is the average day demand in year n
ADD(n-1) is the average day demand in year (n-1)
ADD(0) is the average day demand in reference year 0
d is the demographic development rate
The seasonal variation : within a year, the monthly water demand varies from
month to month due to seasonal variations. In general, for areas lying outside the
tropical zones, the seasonal variation follows a sine curve where the maximum
corresponds to the hot season and the minimum to the cold season.
The water flow for a certain month in a year n is given by :
AMD = K . ADD(n)
Where :
K : is the seasonal variation coefficient
The Maximum Monthly flow is given by :
PMD = KM.Max . ADD(n)
Where :
WM. : is the maximum average monthly flow
KM.Max : is the average peak month factor
Applying the same approach at the scale of the week, one gets :
PWD = KW.Max . ADD(n)
Where :
PWD : is the peak week demand;
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KW.Max : is the average peak week factor.
The Weekly variation: due to the variation of activity within a week, or
eventually to certain social uses, during certain days of the year, the water demand and
consequently the water flow rates within the network might show variations. A peak
day demand is encountered and the corresponding flow rate PDD can be expressed as :
PDD = KD.Max . ADD(n)
Where :
PDD : is the peak day demand;
KD.Max : is the peak day factor.
The Daily Variation: due to the variation of the human activity within a day, the
water demand fluctuates. Normally the water demands are higher during the day and
show a drop in the night after dinner time. The maximum hourly water demand is then
expressed as :
PHD = Kh.Max . PDD = Kh.Max .KD.Max . ADD(n)
Where :
WH. : is the maximum hourly flow;
Kh.Max : is the peak hour factor.
By definition the Peak Day Factor is higher than the Peak Week Factor, which in turn
is higher than the Peak Month Factor. Here below a justification for the various peak
factors to be recommended for Riyadh and based on historical data.
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Riyadh has been through rapid demographic development during the last few
decades where the historical annual demographic development rate is close to 8%. In
parallel, due to this rapid demographic development, water demand has been
increasing with a trend higher than the water supply development, hence leading to a
shortage in distribution. For the above stated reason, the distributed flow in the
network does not reflect the effective variation in the demand. Indeed, based on
historical water supply data of years 1420 H and 1425 H, one can notice that the
effective Peak Day Factor drops from 1.20 to 1.1929 since the distribution is limited
by the available resources.
In order to provide a more realistic approximation of the seasonal and daily
variation, it is suggested to use the historical data of years 1409H, 1410H where the
available water resources were enough to fully cover the water demand.
The monthly data made available are given in Figure 5-1. From Figure 5-1, one
can deduce the following data : d = 6% and KM.Max=1.1.
IV – 2 – Diurnal Variation :
In the Riyadh Water Master Plan study conducted by Thames Water, data
analysis was conducted and diurnal patterns were established for each class of user as
reviewed here below.
The residential daily pattern shows a normal double peak pattern corresponding
to the morning and peak around 11 : 00 and an evening peak at 6 : 00 pm almost in
line as diurnal patterns in other countries.
Commercial daily pattern follows roughly the commercial opening hours.
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Industrial demand shows a flat pattern during working hours, with another flat
outside working hours.
Similarly to the Industrial demand, Governmental demand shows a flat pattern
during working hours and off-peak demand outside working hours.
Leakage pattern is directly related to the pressure variations in the network.
Indeed, when pressure drops, leakage drops. But as a first approximation, and since
active leakage measures are assumed to be taken in the future, we assume that leakage
is constant throughout the day.
Recombining the patterns all together using a weight associated to the per capita
demand allocated at various design horizons gives an overall pattern showing a peak
during daytime of 1.35 as shown in Figure IV - 2 below.
In the Figure IV - 2, Residential pattern were measured on site by Thames
Water in 2000 on a residential area feed on continuous basis. Other patterns
(commercial, industrial, governmental, etc.) have been taken from Thames Water
mathematical model.
As long as intermediate supplies continue, demand patterns will be distorted
from what will occur in future when continuous supplies are established, and it will
not be possible to establish more accurate information to Riyadh more than this
previous survey.
As one can notice, the actual diurnal peak factor is limited to 1.35 occurring
10:00 a.m.
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Compared to other similar cities in the region, Abu Dhabi, according to Abu
Dhabi Water and Electricity Authority - ADWEA, the daily diurnal factor is 1.6. It is
worth mentioning that Abu Dhabi city has a continuous water supply system with
similar climatic conditions as Riyadh and also similar water distribution mode, i.e.
water is supplied to a private ground reservoir from which the customer takes his
water.
Based on ADWEA's data, we strongly recommend adopting a diurnal factor of
1.6 instead of the 1.35 derived from measured residential water demand fluctuation.
Consequently the Peak Flow Factor can be calculated by multiplying the Peak
Day Demand by the diurnal factor thus leading to 1.25 x 1.6 = 2.
Figure IV - 1 – Seasonal Demand Variation within Riyadh city for the period 1409 – 1410 H.
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Figure IV - 2 – Demand Patterns and Associated Overall Pattern.
This additional peak factor offers an additional allowance to cope with any
reasonably unforeseen development in the Project Area.
As a result of this analysis, the Peak Hour Flow can be derived from the
Average Flow through the following formula :
PHD = KD . KH . ADD
Using the data recommended into our study, it leads to :
PHD = 1.25 x 1.6 x WAv = 2 ADD.
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This recommendation is line with various textbooks30,31 where the peak factor
is correlated to the population. Normally, for cities hosting a population above 2
million, the ratio of peak hourly flow to annual average is 2.
In summary the following peak factors shall be used :
Peak Week Demand (PWD) = 1.15 x Average Daily Demand (ADD);
Peak Day Demand (PDD) = 1.25 x Average Daily Demand (ADD);
Peak Flow Demand (PFD) =1.6*Peak Day Demand (PDD) = 2*Average Day Demand
(ADD).
In the design of the water supply network, different peak factors have to be
considered depending upon the involved component. Transmission and production
system should be designed taking into consideration the Peak Week Demand factor
since the demand is leveled up by the storage reservoirs. Distribution network is
designed to supply the peak demand of the peak day.
IV – 3 – Pipe Materials used in the network :
Water supply pipelines can be constructed of various materials: pre-stressed
concrete, reinforced concrete, asbestos cement, ductile iron, steel, GRP, or PVC or
High Performance Polyethylene.
The selection of pipe material should be based on technical and economical
considerations. Technical considerations encompass the adequacy of the material to
local conditions including the experience of operation teams and local contractors.
Taking into consideration the above cited criteria, a brief discussion is provided below
to evaluate the adequacy of various pipe materials.
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● Pre-stressed - Reinforced concrete :
Based on the experience of GDWRR, existing pipes are in poor condition and it
is recommended not to use concrete pipes in future works.
● Asbestos cement :
Jointing systems are unreliable and pipes require protection from traffic loading,
Due to the health hazards caused by asbestos during manufacturing, construction and
repair, this material is deemed obsolete and should be avoided.
● Ductile iron :
Ductile iron pipes have shown very good longevity of service life worldwide
and in particular in Riyadh where almost all large diameter pipes are ductile iron. In
general Ductile Iron shows to be less competitive as compared to steel pipes especially
for large diameter pipes. However the material choice will be subject to market
condition, ease of supplying the required material and labors’ skill which may dictate
the selection of a given material even for large diameters.
In order to protect ductile iron pipes against corrosion, pipes shall have standard
zinc coating on the exterior (ISO 8179) and bitumen coating applied according to BS
3416 or equivalent. Pipe shall also have epoxy lining from the interior in accordance
with AWWA C116.
● Steel pipes :
Steel pipes appear to have more economic advantages for large diameters and
high pressure, since it is stronger and lighter for a given strength. Special care should
be taken to protect the pipes against negative pressure under transient conditions since
its relative thin walls buckle readily. In addition, under the Saudi conditions, steel
might be subject to corrosion, due to the high temperatures and oxidizing condition,
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active protection measures should be taken consisting of cathodic protection. The
basic internal protection for steel pipes consists of an epoxy lining with a triple layer
polyethylene wrapping on the exterior.
All pipes less than or equal to 1200mm in diameter shall be ductile iron (DI),
while pipes of larger sizes shall be steel pipes. This is a MP level recommendation and
may be reviewed later on according to market condition and material availability.
● Plastic pipes :
1 - Polyethylene pipes : Polyethylene is a thermoplastic and has been widely
used for the production of pipes by an extrusion process for over 40 years.
The polyethylene pipes can be used at temperatures going up to 55 °C and are
recommended for the diameters lower than 300 mm.
Connections between the pipes by electro-weldable sleeve or butt fusion are
recommended but mechanical connection is strongly disadvised.
Advantages of PE pipes are that they are light and easy to handle, flexible but
strong and resistant to cracking, do not corrode, are chemically resistant, have a low
frictional resistance to water and can easily be cut to length.
Small diameter pipe can be supplied in coils and straight lengths can be joined
above ground and snaked into narrow non-man-entry trenches. Disadvantages are that
the strength of pipes, defined as their ability to withstand hoop stress, decreases with
time and reduces with increasing temperature. They are also liable to UV degradation
if exposed overlong to sunlight.
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For distribution mains PE pipes are supplied in 6 or 12 m straight lengths; their
flexibility makes the use of small angle bends largely unnecessary.
PE pipes can be jointed mechanically or with push fit joints (with longitudinal
strength) but are more usually jointed by butt fusion or electro-fusion which form a
continuous string and do not need thrust blocks.
2 - Polyvinyl chloride (PVC) pipes : PVC pipes are supplied in 6 m lengths
with spigot and socket rubber ring push fit joints.
The pipes are suitable for use in hot climates but attention should be paid to derating for temperature above 20ºC.
The main advantage offered by PVC is its resistance to corrosion; hence its use
for chemical transfer lines in water treatment works. It is not suitable for use in ground
contaminated or likely to be contaminated by detergents or solvents or from oil storage
areas. It is light in weight, flexible, and has easily made joints.
Fittings can be made in uPVC or metal, usually ductile iron. uPVC pipes are
degraded by ultraviolet light, the effect increasing with temperature so that the pipes
must not be exposed to sunlight in hot climates for more than a day or two.
The PVC pipes are not recommended because of the low sealing of the
mechanical joints which support the water leakages.
3 - GRP (Glass reinforced unsaturated polyester resin) : GRP is a composite
material consisting of three components and can be classified as a thermosetting
plastic. Base materials for manufacture are polyester resins as bonding agent, chopped
glass fibers as reinforcement and quartz sand as aggregate.
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There are two processes to manufacture the glass fibre pipes, the first by
filament winding and the second by centrifugation. It is recommended to adopt the
process by centrifugation.
The pipes in GRP are characterized by lightness, the abrasion resistance, the
frost and high temperatures resistance, resistance to the ultraviolet rays, resistance to
the chemical aggressions and great perenniality and longevity.
There are three classes of nominal stiffness of GRP pipes: SN 2500, SN 5000
and SN 10000. It is recommended to use the pipes in GRP with nominal stiffness class
SN 5000. Pipes of this stiffness class are applied for installations which are subject to
average load, for example for installations in soil mixtures at 3m burial depth with
wheel load of 60 tons.
The class of nominal pressure rating is given according to conditions of the
operating pressure in the network.
The pipes in GRP are recommended for all the range of diameter and
particularly for the large diameter (DN > 500 mm) especially in aggressive soils or
aggressive water transported.
Standards used: ASTM – D 3571, ASTM – D3754, ASTM – D 3262 and
AWWA – C 950.
IV – 4 – Design standard for pipe materials :
1 - Ductile Iron : Ductile iron pipe shall be manufactured in accordance with
the latest revision of ANSI/AWWA C151/A21.51. Fittings shall be ductile iron.
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Fittings shall conform to the latest revision of either ANSI/AWWA C110/A21.10 or
ANSI/AWWA C153/A21.53. Fittings and accessories shall be furnished with either
Push-on or Mechanical Type Joints in accordance with ANSI/AWWA C111/A21.11,
of latest revision.
2 - Steel Pipes : Steel pipe shall conform to AWWA C200. Pipe shall have ends
fabricated flanged joints, or welded joints :
● Pipe shall be supplied with an epoxy coating, shop-applied, and conforming to
AWWA C215.
● Pipe shall be supplied with an exterior protective coating in accordance with
AWWA C203 (hot applied, cold tar enamel coating) or AWWA C214 (cold applied,
tape coating). The hot applied, coal tar enamel coating (AWWA C203) shall consist of
Type B primer, coal tar enamel, and glassfiber outerwrap.
3 - (uPVC) Pipes & Fittings : uPVC pipes and connections should be
manufactured from solid uPVC conforming to Saudi Standards SAS 14, SAS 15 (type
15), if not otherwise specified.
Attention should be given to the manufacture of pipes from unplasticised
polyvinyl chloride material without any additions or filler because of their negative
influence on pipes strength.
Contractor should be aware that uPVC pipes with filler added at manufacturing
procedure will not be accepted.
uPVC fittings should be resistant to corrosion and safe for transmission of
potable water. Fittings should be in accordance with uPVC pipes and conform to saudi
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standards SAS14 & SAS15. Also fittings should conform to ISO 4435 or ISO 3633 if
not otherwise mentioned.
Pipes dimensions should conform to standards SAS14 and DIN 8062 19532 –
latest edition. Pipes should be tested according to the method described in section 7 of
the American Association for Testing and Materials (ASTM 1785)- latest edition.
If any degradation occurs in pipe materials, the test should be redone following
the agreement between the supplier and the client.
uPVC connections should be conformed to ISO/DIS 4422 standards and DIN
8063 standards.
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CHAPTER V :
Pipe Networks Theory and Simulation
using EPANET Software
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V – 1 – Pipe Networks Theory :
In municipal distribution systems, pipes are frequently interconnected so that
the flow to a given outlet may come by several different paths, as in Fig. 8.31. As a
result, we often cannot tell by inspection which way the flow travels, as in pipe BE.
Nevertheless, the flow in any network, however complicated, must satisfy the basic
relations of continuity and energy as follows :
● The flow into any junction must equal the flow out of it;
● The flow in each pipe must satisfy the pipe-friction laws for flow in a single pipe;
● The algebraic sum of the head losses around any closed loop must zero.
Most pipe networks are too complicated to solve analytically by hand using
rigorous (variable ) equations, as was possible in the simpler cases of parallel pipes
(Sec. 8.31). Nowadays they are readily solved by specially developed computer
programs (Appendix C.5). However, in many cases we cannot predict the capacity
requirements of water distribution systems with high precision, and flows in them vary
considerably throughout the day, so high accuracy in calculating their flows is not
important. As a result, the use of non-rigorous equations are very acceptable for this
purpose. The method of successive approximations, due to Cross9 is such a method
that was popular before the advent of computers. It consists of the following elements,
in order :
Step 1: By careful inspection assume the most reasonable distribution of flows
that satisfies condition 1 mentioned below.
H. Cross,(1936 [3]) Analysis of Flow in Networks of Conduits or Conductors, Univ. III. Eng. Expert. Sta. Bull. 286
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Step 2 : Write condition 2 for each pipe in the form :
hl  K * Q n ...............................................................................(5.1)
Where :
K and n : are constants for each pipe as described in Sec.8.19. If minor losses
are important include them as in Eq. (5.1), which yields
and
for
constant .We may include minor losses within any pipe or loop, but must neglect
them at the junction points.
Step 3 : To investigate condition 3, compute the algebraic sum of the head
losses around each elementary loop,
.Consider losses from clockwise
flows as positive, counterclockwise negative. Only by good luck will these add up to
zero on the first trial.
Step 4 : Adjust the flow in each loop by a correction
that loop and give
determination of
to balance the head in
. The heart of this method lies in the following
. For any pipe, we may write as following :
Q  Q0  Q.....................................................................(5.2)
Where :
Q : is the correct discharge and Q0 is the assumed discharge.
Then, for each pipe we can write the following equation :
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hl  K * Q n  K (Q0  Q) n  K (Q0n  n * Q n 1 * Q  ...).........(5.3)
If ∆Q is small compared with Q0 we may neglect the terms of the binomial
series after the second one, so that :
n 1
hl  Q0n  Q * K * n * Q0 ...............................................(5.4)
For a loop,
so because
is the same for all pipes we have
the following relationship :
Q
n
0
 Q K * n *Q0 ...............................................(5.5)
n 1
As we must sum the corrections of head loss in all pipes arithmetically (treating
all terms as positive), we may solve this equation for
Q 
  K * Q0 Q0n 1
n K * Q
n 1
0

since, from Eq. (5.5)
  hl
n
hl
Q0
as following :
..........................................(5.6)
We emphasize again that we must sum the
numerator of Eq. (5.6) algebraically, with due account of each sign, while we must
sum the denominator arithmetically. Note that the
in the numerator gives this
quantity the same sign as the head loss. The negative sign in Eq. (5.6) indicates that
when there is an excess of head loss around a loop in the clockwise direction, we must
subtract the
from clockwise
values and add it to counterclockwise ones. The
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reverse is true if there is a deficiency of head loss around a loop in the clockwise
direction.
Step 5 : After we have given each loop a first correction, the losses will still not
balance, because of the interaction of one loop upon another (pipes which are common
to two loops receive two independent corrections, one for each loop). So we repeat the
procedure, arriving at a second correction, and so on, until the corrections become
negligible.
We may use either form of Eq. (5.6) to find
As values of
appear in both
the numerator and denominator of the first form, we can use values proportional to the
actual
to find the distribution. The second form is more convenient for use with pipe
friction diagrams for water pipes.
An attractive feature of this approximation method is that errors in computation
have the same effect as errors in judgment and the process eventually corrects them.
As noted earlier, varying demand rates usually make high solution accuracy
unnecessary with pipe networks. However, if high manual accuracy is required for
some reason, we can first solve the problem in a similar manner to the preceding
example using the Darcy-Weisbach
in Eq. (5.1) and constant
use the resulting flows to adjust the and
values. Then we can
values, and repeat the process (more than
once if necessary) to refine the answers. The value of such refinement is questionable,
not only because of uncertainties in the demand flows, but also because of
uncertainties in the e values (pipe roughness). Usually when we adjust
values they
change by only a few percent.
We can solve simple networks without approximation and manual iteration by
solving simultaneous equations using equation solving software like that in Mathcad
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and Excel. For networks containing
pipes,
Darcy -Weisbach equation with variable , and
equations are required if using the
equations are required if using the
simplified Eq. (8.95) with constant friction factors. These required equations include
(a) the usual (condition 2) flow equations for each pipe (four or one per pipe,
depending on the equations used);
one of the
nodes (as these imply continuity at the last node);
sum of the head losses around
find for each pipe are
and
flow continuity equations (condition 1) at all but
equations for the
loops (condition 3). The unknowns we want to
and
using the Darcy-Weisbach equation, or only
using Eq. (5.1).
The pipe-network problem lends itself well to solution by use of a digital
computer. Programming takes time and care, but once set up, there is great flexibility
and it can save many hours of repetitive labor. Many software packages are now
available to simulate water distribution networks.
V – 2 – Analytical Calculation for Pressure :
As mentioned below, we shall compare the results from different sources. In
fact, according to field measurements and digital simulations. At the first, by using the
Hazen-Williams formula to estimate pipe Headloss for full Flow as following :
hl  4.727 * C 1.852 * d 4.871 * L..........................................(5.7)
Where :
C: Hazen-Williams roughness coefficient;
d : Pipe diameter (ft);
L : Pipe length (ft).
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Figure V - 1 – Head loss in the case of Flow in Qin.
● Minor losses :
Minor head losses (also called local losses) are caused by the added turbulence
that occurs at bends and fittings. The importance of including such losses depends on
the layout of the network and the degree of accuracy required. They can be accounted
for by assigning the pipe a minor loss coefficient. The minor head loss becomes the
product of this coefficient and the velocity head of the pipe, i.e..
Notes :
K = minor loss coefficient;
v = flow velocity (Length/Time);
g = acceleration of gravity (Length/
).
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Where :
= 0
So :
We know that :
V=
V=
So
To find the total head of reservoir for Al Morouj Area we know that :
D = 1.2 m
A=
So :
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m
The table V – 1 below shows the pressure measured in the three points of the
network where we observe a difference between a pressure measured and simulated
by the software EPANET. This difference has been expected by other methods and
software10.
Table V - 1 : Planned water resource projects.
Point No
P (measured)
P (Simulation)
Location in the
network
(See Figure V - 2)
Morouj 1
24.4 psi
1.68 bar
30.46 psi
2.10 bar
Fire hydrant 1
23.2 psi
1.60 bar
30.48 psi
2.10 bar
Fire hydrant 2
29.0 psi
2.00 bar
30.46 psi
2.10 bar
Figure V - 2 – Point location in the network.
National Water Company – Al Riyadh 10
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● Conclusions :
Taking into account the zero elevation for the reason of missing data during the
period of the present project, and according to short distance between these points in
the network, the pressure measured must be the same or close. Regarding this finding
conclusion we think there is leakage in the fire hydrant 1 zone.
V – 3 – Simulation using EPANET 2 :
Hydraulic simulation modeling using EPANET 2 computes junction heads and
link flows for a fixed set of reservoir levels, tank levels, and water demands over a
succession of points in time. From one time step to the next reservoir levels and
junction demands are updated according to their prescribed time patterns while tank
levels are updated using the current flow solution. The solution for heads and flows at
a particular point in time involves solving simultaneously the conservation of flow
equation for each junction and the head loss relationship across each link in the
network. This process, known as “hydraulically balancing” the network, requires using
an iterative technique to solve the nonlinear equations involved. EPANET 2 employs
the “Gradient Algorithm” for this purpose.
V – 4 – Results and interpretations :
Hydraulic simulation modeling using EPANET 2 computes junction heads and
link flows for a fixed set of reservoir levels, tank levels, and water demands over a
succession of points in time. From one time step to the next reservoir levels and
junction demands are updated according to their prescribed time patterns while tank
levels are updated using the current flow solution. The solution for heads and flows at
a particular point in time involves solving simultaneously the conservation of flow
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equation for each junction and the head loss relationship across each link in the
network. This process, known as “hydraulically balancing” the network, requires using
an iterative technique to solve the nonlinear equations involved. EPANET 2 employs
the “Gradient Algorithm” for this purpose.
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Figure V - 1 – Analysis of pressure using EPANET 2 software.
Figure V - 2 – Analysis of head using EPANET software.
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Figure V - 3 – Distribution of Pressure and Head using EPANET 2 software.
Figure V - 4 – Profile of Head variation in the inlet junctions of network calculated by
EPANET 2 software.
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Figure V - 5 – Profile of Head variation in the middle of network calculated
by EPANET 2 software.
Figure V - 6 – Profile of Head variation in the outlet of network calculated
by EPANET 2 software.
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CHAPTER VI :
Modeling single pipeline using FLAC software
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VI – 1 – Introduction :
Riyadh city is supplied by desalinated seawater and by groundwater as shown in
Table II-1. Currently, five well fields are operational outside the city (Haer/Nisah,
Buwayb, Salboukh, Wasia and Hunaï) in addition to the water wells operated within
the city supplying the water treatment stations located in the centre (Malaz,
shemessey, Manfouha). The desalination plant Jubail 2 which supplies Riyadh is
operated by the Saline Water Conservation Corporation (SWCC). In 2005 (1425H) as
a result of commissioning of the new Hunai well field located 200 km east of the city,
groundwater amounts in 2005 for 51% of the total water supply against 35% in 2004.
In July 2004, Jubail 2 supplied Riyadh with 897,000 m³/day while in July 2005 the
supply decreased to 705,000 m³/day.
VI – 2 – Finite Differences :
The finite difference method is perhaps the oldest numerical technique used for
the solution of sets of differential equations, given initial values and/or boundary
values (see, for example, Desai and Christian 1977). In the finite difference method,
every derivative in the set of governing equations is replaced directly by an algebraic
expression written in terms of the field variables (e.g., stress or displacement) at
discrete points in space; these variables are undefined within elements.
In contrast, the finite element method has a central requirement that the field
quantities (stress, displacement) vary throughout each element in a prescribed fashion,
using specific functions controlled by parameters. The formulation involves the
adjustment of these parameters to minimize error terms or energy terms.
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Both methods produce a set of algebraic equations to solve. Even though these
equations are derived in quite different ways, it is easy to show (in specific cases) that
the resulting equations are identical for the two methods. It is pointless, then, to argue
about the relative merits of finite elements or finite differences: the resulting equations
are the same.
However, over the years, certain “traditional” ways of doing things have taken
root: for example, finite element programs often combine the element matrices into a
large global stiffness matrix, whereas this is not normally done with finite differences
because it is relatively efficient to regenerate the finite difference equations at each
step. As explained below, FLAC uses an “explicit,” time marching method to solve the
algebraic equations, but implicit, matrix-oriented solution schemes are more common
in finite elements. Other differences are also common, but it should be stressed that
features may be associated with one method rather than another because of habit more
than anything else.
Finally, we must dispose of one persistent myth. Many people (including some
who write textbooks) believe that finite differences are restricted to rectangular grids.
This is not true! Wilkins (1964) presented a method of deriving difference equations
for elements of any shape: this method, also described as the “finite volume method,”
is used in FLAC. The erroneous belief that finite differences and rectangular grids are
inseparable is responsible for many statements concerning boundary shapes and
distribution of material properties. Using Wilkins’ method, boundaries can be any
shape, and any element can have any property value — just like finite elements.
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VI – 3 – Explicit, Time-Marching Scheme :
Even though we want FLAC to find a static solution to a problem, the dynamic
equations of motion are included in the formulation. One reason for doing this is to
ensure that the numerical scheme is stable when the physical system being modeled is
unstable. With nonlinear materials, there is always the possibility of physical
instability —e.g., the sudden collapse of a pillar. In real life, some of the strain energy
in the system is converted into kinetic energy, which then radiates away from the
source and dissipates. FLAC models this process directly, because inertial terms are
included — kinetic energy is generated and dissipated. In contrast, schemes that do not
include inertial terms must use some numerical procedure to treat physical
instabilities. Even if the procedure is successful at preventing numerical instability, the
path taken may not be a realistic one. One penalty for including the full law of motion
is that the user must have some physical feel for what is going on; FLAC is not a black
box that will give “the solution.” The behavior of the numerical system must be
interpreted.
The general calculation sequence embodied in FLAC software is illustrated in
Figure VI -1. This procedure first invokes the equations of motion to derive new
velocities and displacements from stresses and forces. Then, strain rates are derived
from velocities, and new stresses from strain rates. We take one time step for every
cycle around the loop. The important thing to realize is that each box in Figure VI -1
updates all of its grid variables from known values that remain fixed while control is
within the box. For example, the lower box takes the set of velocities already
calculated and, for each element, computes new stresses. The velocities are assumed to
be frozen for the operation of the box —i.e., the newly calculated stresses do not affect
the velocities. This may seem unreasonable because we know that if a stress changes
somewhere, it will influence its neighbors and change their velocities. However, we
choose a time step so small that information cannot physically pass from one element
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to another in that interval. (All materials have some maximum speed at which
information can propagate.) Since one loop of the cycle occupies one time step, our
assumption of “frozen” velocities is justified—neighboring elements really cannot
affect one another during the period of calculation. Of course, after several cycles of
the loop, disturbances can propagate across several elements, just as they would
propagate physically.
Figure VI - 1 – Basic explicit calculation cycle.
The previous paragraph contains a descriptive statement of the explicit method;
later on, a mathematical version will be provided. The central concept is that the
calculation “wave speed” always keeps ahead of the physical wave speed, so that the
equations always operate on known values that are fixed for the duration of the
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calculation. There are several distinct advantages to this (and at least one big
disadvantage!): most importantly, no iteration process is necessary when computing
stresses from strains in an element, even if the constitutive law is wildly nonlinear. In
an implicit method (which is commonly used in finite element programs), every
element communicates with every other element during one solution step: several
cycles of iteration are necessary before compatibility and equilibrium are obtained.
Table VI -1 below compares the explicit and implicit methods. The disadvantage of
the explicit method is seen to be the small time step, which means that large numbers
of steps must be taken. Overall, explicit methods are best for ill-behaved systems—
e.g., nonlinear, large-strain, physical instability; they are not efficient for modeling
linear, small-strain problems.
Table VI - 1 : Comparison of explicit and implicit solution methods.
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VI – 4 – Lagrangian Analysis :
Since we do not need to form a global stiffness matrix, it is a trivial matter to
update coordinates at each time step in large-strain mode. The incremental
displacements are added to the coordinates so that the grid moves and deforms with
the material it represents. This is termed a “Lagrangian” formulation, in contrast to an
“Eulerian” formulation, in which the material moves and deforms relative to a fixed
grid. The constitutive formulation at each step is a small-strain one, but is equivalent
to a large-strain formulation over many steps.
VI – 5 – Plasticity Analysis :
A common question is whether FLAC is better-suited than a finite element
method (FEM) program for plasticity analysis. There are many thousands of FEM
programs and hundreds of different solution schemes. Therefore, it is impossible to
make general statements that apply to “The Finite Element Method.” In fact, there
may be so-called finite element codes that embody the same solution scheme as FLAC
as mentioned before. Such codes should give identical results to FLAC.
FEM codes usually represent steady plastic flow by a series of static equilibrium
solutions. The quality of the solution for increasing applied displacements depends on
the nature of the algorithm used to return stresses to the yield surface, following an
initial estimate using linear stiffness matrices. The best FEM codes will give a limit
load (for a perfectly plastic material) that remains constant with increasing applied
displacement. The solution provided by these codes will be similar to that provided by
FLAC. However, FLAC’s formulation is simpler because no algorithm is necessary to
bring the stress of each element to the yield surface: the plasticity equations are solved
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exactly in one step. Therefore, FLAC may be more robust and more efficient than
some FEM codes for modeling steady plastic flow.
FLAC is also robust in the sense that it can handle any constitutive model with
no adjustment to the solution algorithm; many FEM codes need different solution
techniques for different constitutive models.
For further information, we recommend the publication by Frydman and Burd
(1997), which compares FLAC to one FEM code and concludes that FLAC is superior
in some respects for footing problems (e.g., efficiency and smoothness of the pressure
distribution).
VI – 6 – Field Equations :
The solution of solid-body, heat-transfer or fluid-flow problems in FLAC
invokes the equations of motion and constitutive relations, Fourier’s Law for
conductive heat transfer, and Darcy’s Law for fluid flow in a porous solid, as well as
boundary conditions. This section reviews the basic governing equations for the solid
body; corresponding equations for groundwater and thermal problems are provided in
Section 1 in Fluid-Mechanical Interaction and Section 1 in Optional Features,
respectively. The same method of generating finite difference equations applies to all
sets of differential equations.
VI – 6 – 1 – Motion and Equilibrium :
In its simplest form, the equation of motion relates the acceleration, d ˙u/dt , of a
mass, m, to the applied force, F, which may vary with time. Figure VI - 2 illustrates a
force acting on a mass, causing motion described in terms of acceleration, velocity and
displacement.
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Figure VI - 2 – Application of a time-varying force to a mass,
resulting in acceleration, velocity and displacement.
When several forces act on the mass, Eq. (1.1) also expresses the static
equilibrium condition when the acceleration tends to zero—i.e., F = 0, where the
summation is over all acting forces. This property of the law of motion is exploited in
FLAC when solving “static” problems. Note that the conservation laws (of momentum
and energy) are implied by Eq. (1.1), since they may be derived from it (and Newton’s
other two laws).
.
du
m
 F ..........................................(7.1)
dt
Where :
m : mass;
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.
u
: velocity;
t : time; and
F : body force.
In a continuous solid body (Equation (7.1) is generalized as follows :
.
 ui  ij


 gi ..........................................(7.2)
t
x j
Where :
 : Mass density;
t
: Time;
xi : Components of coordinate vector;
g i : Components of gravitational acceleration (body forces); and
 ij : Components of stress tensor.
In this equation, and those that follow, indices i denote components in a
Cartesian coordinate frame, and summation is implied for repeated indices in an
expression.
VI – 6 – 2 – Constitutive relation :
The other set of equations that apply to a solid, deformable body is known as
the constitutive relation, or stress/strain law. First, strain rate is derived from velocity
gradient as follows :
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.
 .

1   ui  u j 
eij 

..........................................(7.3)
2  x j xi 


.
Where :
.
e ij : Strain-rate components; and;
.
u i : Velocity components.
.
 ij : M ( ij , eij , K )..........................................(7.4)
Where :
K : is a history parameter (s) which may or may not be present, depending on the
particular; and
: : Means “replaced by”.
In general, nonlinear constitutive laws are written in incremental form because
there is no unique relation between stress and strain. Eq. (7.4) provides a new estimate
for the stress tensor, given the old stress tensor and the strain rate (or strain increment).
The simplest example of a constitutive law is that of isotropic elasticity :
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.
 ij : M ( ij , eij , K )..........................................(7.4)
Where :
K : is a history parameter (s) which may or may not be present, depending on the
particular; and
: : means “replaced by”.
VI – 7 – FLAC software and modeling :
VI – 7 – 1 – Methodology of modeling :
The study using models in the case of underground single pipeline, requires to
admit a easy hypotheses taking into account the ground complexity and to simplify it.
In fact, we often work with two dimensions (plan deformation hypothesis 11). To
explain how the mechanical stresses due to the loading on the surface spreading down
to the surface, a continuous model using finite difference element has been proposed
applying the finite difference method (Fast Lagrangian Analysis Continua (Itesca,
2005 [3]). This method is based on the digital calculations adapted for rock and soil
mass (see above).
Within this model based on finite difference method, the initial stresses
estimation before making underground single pipeline depend strongly on limit
boundary conditions of the model. However, to minimize the boundary effect, the
dimension of the model must be 5 to 10 times the interest zone in this case the pipeline
Strain εzz a long the underground pipeline is considered as zero 11
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in cross section (diameter 30 cm). To take into account the symmetry of the pipeline,
the dimension of a final cross section is indicated in the Figure VI – 3 & 4 . In the
bottom of this model, the vertical displacements are nulls. On the lateral limits and for
the reason of symmetry of model, the horizontal displacements are too nulls.
To better explain the stresses state within the pipeline, soil and rock mass, a
simulation phase by phase has been undertaken. In a first model, we estimate the
initial stresses without the underground pipeline (phase of materials consolidation).
After that, we simulate the effect of pipeline and at the same time we cancel the
displacement received at the time of consolidation and reinitialize the stresses. This
method of calculation phase allows to predict areas of the model with exaggerated
stresses.
The table (Table VI – 1) below shows a reference geotechnical characteristics
of materials and shallow layers introduced within the model.
Table VI - 1 : Reference geotechnical characteristics of materials and shallow
layers12.
Layers
 (KN/m3) C (MPa)
 (°)
Rc (MPa)
Rt (MPa)
Compaction soil
22
0.30
30
5.0
0.50
Foundation layers
25
0.50
35
5.0
0.50
Upper limestone
layers
25
0.30
35
10.0
1.00
Lower limestone
layers
25
0.50
35
4.0
0.40
Richard E. Goodman, (1989, [15]), Introduction to Rock Mechanics, University of California at Berkeley
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VI – 7 – 2 – Results and interpretations :
The first model concerning the materials consolidation (Figure VI – 5 & 6)
indicates that the initial stresses during the consolidation phase are in accordance with
the stresses in the natural state. The major principal stress a long vertical profile
increases to reach 0.01 MPa from the surface to 1 m depth. The same variable a long
horizontal profile at the underground pipeline (Figure VI – 7 & 8) oscillates around
0.0024 MPa.
The second model in which we take into account the underground pipeline
(Figure VI – 9 & 10) indicates that the minor principal stresses just above the pipeline
reaches 7.0 MPa at about 1 m depth.
The shear stress contour zone according to the plan deformation hypothesis
(Figure VI – 11 & 12) indicates the areas of the cross section where additional
compression and tension will be developed. The shear stress may reach 3.0 MPa in
each upper side of the pipeline. The shear strain also may reach 8 cm according this
model.
The principal stresses tensor according to the plan deformation hypothesis
(Figure VI – 13 & 14) indicates the magnitude of the tensor stresses around the
pipeline cross section and approximity of it, where we observe a redistribution of
tensile stresses in each upper side of the pipeline and in the bottom. We observe too an
increasing compression stresses magnitude due the surface loading increasing.
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Figure VI - 3 – Grid model and limit conditions used in FLAC5.00.355 software.
Figure VI - 4 – Zoom in the interest zone in the model.
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Figure VI - 5 – Creating vertical profile passing by the interest zone.
Figure VI - 6 – Major principal stress (Sig1) according to the vertical profile
(Consolidation phase).
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Figure VI - 7 – Creating horizontal profile passing by the interest zone.
Figure VI - 8 – Major principal stress (Sig1) according to the horizontal profile
(Consolidation phase).
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Figure VI - 9 – Creating horizontal profile passing above the pipeline cross section.
Figure VI - 10 – Major principal stress (Sig1) according to the horizontal profile
(After execution phase).
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Figure VI - 11 – Shear stress (Sxy) contour zone according to the plan deformation hypothesis
(After execution phase).
Figure VI - 12 – Shear strain (Ssi) contour zone according to the plan deformation hypothesis
(After execution phase).
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Figure VI - 13 – Principal stresses tensor according to the plan deformation hypothesis
(After execution phase).
Figure VI - 14 – Principal stresses difference contours according to the plan deformation hypothesis
(After execution phase).
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CHAPTER VII :
GIS Technology for Water Supply
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VII – 1 – What is GIS :
GIS technology combines mapping software with database management tools to
collect, organize, and share many types of information. Data is stored as thematic
layers in geo-database (data identified by its location coordinates) that can be accessed
and shared from the field, within a department, and across an entire enterprise. You
decide which layers are relevant. Utilities typically combine utility layers with land
base, parcel, street, land-use, and administrative area layers.
Figure VII - 1 – Geo-referenced layers in GIS.
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Figure VII - 2 – Multi-departmental system to apply GIS.
VII – 2 – GIS used for Water supply :
Utility keeps track of vast amounts of information about assets; distribution,
collection, and drainage networks; customers; and financial records. All this
information has a connection with location, whether it be the site of a water main or a
customer’s meter. Geographic information system (GIS) technology uses these
geographic connections to integrate key database systems, streamline asset data
management tasks, and help to visualize important geospatial relationships. Using GIS
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helps customer more effectively manage water distribution, sewer collection, and
storm water drainage networks as well as related planning and customer care. We can
think of a GIS as a “location-based operating picture” that unifies the databases
essential to diverse activities.
Significantly more powerful and flexible than a computer-aided design (CAD)
system, a GIS stores both attributes and images of pipes, valves, meters, manholes,
and so forth, as objects with location coordinates. The maps created link upstream and
downstream objects through strong object-to-object network connectivity and indicate
normal flow direction through the pipe network. GIS is a true model of the network
and can be used to :
● Track and report on assets in the network inventory;
● Generate inputs into hydraulic modeling software;
● Create a common operational picture for access to network operations information.
In creating a single database of assets, we can eliminate redundant data
collection and maintenance activities. The shared database enables engineering to
produce maps, finance to calculate asset valuations, maintenance to track work
activities, and operations to create network models.
GIS technology also uses geographic relationships to link and merge disparate
databases. For example, we can place a demographic layer projecting future
population values on top of an existing sewer manhole layer and use it to estimate
future loadings at specific nodes on the network. We can also overlay water well data
on hazardous material information to determine proximity and assess contamination
risks.
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VII – 3 – Sharpen Planning and Engineering Analyses :
GIS software (ArcGIS10 for example) allows you to represent a project in
three-dimensional form and visualize the impact of facilities on the landscape during
the design process. Data can be combined with other computer-aided engineering
functions to assist in the planning and scenario testing of multiple designs.
Water agencies use GIS software to map the full extent of their water
distribution systems and link them to a database, defining each element including
reservoirs, pipe segments, services, and system appurtenances. As a result, job
planning, equipment inventory, and flow analysis become automated procedures
integrated into one intelligent database.
Planning and engineering tasks that you can accomplish easily using GIS
software include :
● Watershed and groundwater management modeling;
● Water distribution system master planning;
● Population and demand projections;
● Water quality monitoring;
● Hazardous materials tracking and underground tank management;
● Well log and data management;
● Site analysis;
● Geo-bibliography (past studies);
●Development review and approval;
● Right-of-way engineering;
● Automated mapping;
● Capital improvement project tracking;
● Underground service alert.
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VII – 4 – Conclusions :
In this chapter we have focused to learn GIS software and built the Geodatabase concerning the water supply network of Al Morouj. Our work involves the
following parts :
● Acquisition spatial data : To build this geo-database, satellite image GeoEye has
been taken from Space Research Institute in King Abdelaziz City for Science and
Technology, this image is characterized by high level of accuracy which is 0.5 m by
PIXEL13.
● Geo-referencing : To taking into account the geographical coordinates in the map
using Project system14 the water supply network has been displayed as layer on the
satellite image (Figure VII - 3).
● Attribute data : To introduce all attribute data characterizing the different layers in
the Geo-database, a database has been introduced within the ArcGIS10 software in
which all parameters linking to the network saved in the system (Figure VII – 4 & 5).
● Design of layers : To taking into account the internal and external factors
overlapping with water supply network, it is necessary to design all layers in the Geodatabase in order to analyze the given problem according the multiple aspects. For this
reason some internal and external layers have been introduced in this Geo-database
such as junction, linked points, parcels. (Figure VII – 6 & 7 & 8).
The small element of image called PIXEL (Picture Element)
13
UTM (Universal Transverse Mercator) zone 38 14
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Figure VII - 3 – Water supply network geo-referenced using GeoEye Satellite Image.
Figure VII - 4 – Water supply network designed as spatial database in english.
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Figure VII - 5 – Water supply network designed as spatial database in English and Arabic.
Figure VII - 6 – Parcels designed as spatial database.
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Figure VII – 7 – Linked points and valves designed as spatial database.
Figure VII - 8 – Junctions designed as spatial database.
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VIII - CONCLUSIONS :
The National Water Company gives a great importance for the maintenance and
the monitoring of the drinking water network. In the sense, efficient monitoring of
water distribution networks have long been a challenge for management, even in
countries with a well-developed infrastructure and good operating practices.
Improperly managed water networks might result in increased cost of supply,
insufficient supply of potable water, inconvenience, not satisfied customers and more.
Such problems might not only be caused by operating a poorly maintained
infrastructure but also by excessive use or misuse of water due policy of some
governments to provide low tariffs for water usage.
Referring to the second chapter, the future planned water resource
projects until 2040 compared to supply and demand balance indicates that the
consumption increases from year to year and can reaches 2400 tcmd. This situation
allows to give a great importance to the water supply network in order to minimize the
loss of flow during the distribution and monitoring this network using the new
technology (modeling, GIS, Remote Sensing).
Referring to the third, fourth, fifth and sixth chapters, Hydraulic simulation
modeling using EPANET 2 computes junction heads and link flows for a fixed set of
reservoir levels, tank levels, and water demands over a succession of points in time.
From one time step to the next reservoir levels and junction demands are updated
according to their prescribed time patterns while tank levels are updated using the
current flow solution. The solution for heads and flows at a particular point in time
involves solving simultaneously the conservation of flow equation for each junction
and the head loss relationship across each link in the network. This process, known as
“hydraulically balancing” the network, requires using an iterative technique to solve
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the nonlinear equations involved. EPANET 2 employs the “Gradient Algorithm” for
this purpose.
Referring to seventh chapter, modeling using FLAC 5.00 software has been
undertaken. An excessive compression and tensile stresses have been found above the
single underground pipeline and around it. However, a failure by shear stresses can be
involved and develop fractures in each upper side of the pipeline.
In order to design the hydraulic solutions works a Civil Engineering study will
be required in order to guaranty the stability of these underground pipelines within the
water supply network.
Referring to the last chapter, we have focused to learn GIS software and built
the Geo-database concerning the water supply network of Al Morouj. Our work
involves the following parts :
● Acquisition spatial data : To build this geo-database, satellite image GeoEye has
been taken from Space Research Institute in King Abdelaziz City for Science and
Technology, this image is characterized by high level of accuracy which is 0.5 m by
PIXEL15.
● Geo-referencing : To taking into account the geographical coordinates in the map
using Project system16 the water supply network has been displayed as layer on the
satellite image (Figure VII - 3).
The small element of image called PIXEL (Picture Element)
15
UTM (Universal Transverse Mercator) zone 38 16
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● Attribute data : To introduce all attribute data characterizing the different layers in
the Geo-database, a database has been introduced within the ArcGIS10 software in
which all parameters linking to the network saved in the system.
● Design of layers : To taking into account the internal and external factors
overlapping with water supply network, it is necessary to design all layers in the Geodatabase in order to analyze the given problem according the multiple aspects. For this
reason some internal and external layers have been introduced in this Geo-database
such as junction, linked points, parcels.
IX - RECOMMANDATIONS :
This applied project has been focused on Hydrologic modeling techniques, soil
and rock modeling and GIS Geo-database. Some results have been undertaken to
manage the head-loss within the water supply network in Al Morouj district. We
recommend continuing this study project by introducing spatial analyst in GIS aspects
in order to simulate the 3D distribution of water in the network.
In order to design the hydraulic solutions works according the present network
a Civil Engineering study will be required in order to choose the optimum depth and
materials used for good stability of these pipelines in the network.
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X - REFERENCES :
]1[
Cheung, P., Zyl, J. V., Reis, L., 2005. Extension of epanet for pressure driven
demand modeling in water distribution system. In: Proceedings of CCWI2005 Water Management for the 21st Century. Exeter, UK, pp. 215{226.
[2]
Electronic Management Systems from Motorola Improve Efficiency of Water
Projects, Dan Ehrenreich, Market Study Report, published in UK, 1999.
]3[
ESRI, ArcGIS9 Desktop Software , 2001. Help References. Working with
ArcGIS Spatial Analyst. ESRI. Egypt Multipurpose Land Cover Database
(Africover). Food and Agriculture Organization of the United.
]4[
Estimating Legitimate Non-Household Night Use Allowances, UK Water
Industry Research Ltd (1999)
]5[
Estimating Background Leakage, UK Water Industry Research Ltd (2003)
]6[
Giustolisi, O., Savic, D., Kapelan, Z., 2008. Pressure-driven demand and
leakage simulation for water distribution networks. Atmospheric Chemistry and
Physics 134 (5), 626{635, American Society of Civil Engineers.
[7]
H. Cross (1936), Analysis of Flow in Networks of Conduits or Conductors,
Univ. III. Eng. Expert. Sta. Bull. 286.
]8[
Household Night Consumption, UK Water Industry Research Ltd (2002)
[9]
ITASCA CONSULTING GROUP, (2005), FLAC Version 5.0, User Guide and
Theory of Finite Difference Method. Minneapolis, USA.
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[10] Integration of RF communications for Distribution Automation with Dual
Redundancy, Dan Ehrenreich, Samuel Katar, DA/DSM 97 Asia, Singapore
1997.
]11[ Jankowski, P., 1995. Integrating geographical information systems and multiple
criteria decision-making methods, International Journal of Geographical
Information Systems. Vol. 9, pp. 251-273.
]12[
Leakage Estimation from Night Flow Analysis, UK Water Industry Research
Ltd (1999).
]13[
Losses in Water Distribution Networks, M Farley and S Trow, (IWA
Publishing), (2003)
[14] Managing Water Infrastructures with SCADA Systems, Dan Ehrenreich,
Motorola Application Notes, July 2003.
]15[
Managing Leakage, UK Water Industry Engineering and Operations
Committee, (published by WRc)(1994)
]16[
Manual of DMA Practice, UK Water Industry Research Ltd (1999)
]17[
Managing water leakage - Economic and technical issues. London, Lambert A,
Myers S, Trow S. (Financial Times (FT Energy) Business Ltd), (1998).
]18[
Natural Rate of Rise of Leakage, UK Water Industry Research Ltd (1999).
]19[
Ozger, S., 2003. A semi-pressure-driven approach to reliability assessment of
water distribution networks. Ph.d., Arizona State University, Tempe, Arizona.
]20[
Performance Indicators for Water Supply Services (Second Edition), H Alegre,
JM Baptista, E Cabrera Jr, F Cubillo, P Duarte, W Hirner, W Merkel, R Parena,
(IWA Publishing), 2006.
]21[
Report 26 Leakage Control Policy & Practice, UK Water Authorities
Association (1980).
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]22[
Rossman, L. A., (2000). EPANET 2 users manual. EPA/600/R-00/57
http://www.epa.gov/nrmrl/wswrd/EN2manual.PDF.
]23[
Richard E. Goodman (1989), Introduction to Rock Mechanics, Second Edition,
University of California at Berkeley, John Wiley & Sons – New York.
[24] STEAD D., BENKO B., (1993) The influence of underground workings on
slope instability : A numerical modeling approach. Proceedings of the First
Canadian Symposium on Numerical Modelling Applications in Mining and
Geomechanics/ Montreal/ Quebec/ 27-30 March 1993. pp. 423-433.
]25[
Technology and Equipment for Managing Water Losses, Malcolm Farley,
(IWA Publishing),(2006)
]26[
Trifunovic, N., 2006. Introduction to Water Transport and Distribution
UNESCO-IHE
Lecture
2010.Waternet-English.
Notes
Series.
Tailor
and
Francis.
Waternet,
http://www.waternet.nl/algemene_onderdelen/english
re-trieved on: May 2010.
]27[
Voogd, H.,1983. Multicriteria Evaluation for Urban and Regional Planning.
Pion, London.
]28[
Water Loss Control Manual, J Thornton, (McGraw-Hill)(2002).
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APPENDIX I :
Photos from the study area “Al Mourouj”.
XI – APPENDIX I :
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Photo A - I - 1 – Valve of taking off/on water distribution.
Photo A - I - 2 – Faire hydrant type in Al Mourouj District.
Photo A - I - 3 – Measuring water pressure.
Photo A - I - 5 – Electronic devise water pressure.
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Photo A - I - 4 – Flow meter devise.
Photo A - I - 6 – Transfer data to the software.
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Photo A - I - 7 – Control Room of Water National Company At Al Riyadh.
Photo A - I - 8 – Team of work of Study project with High Senior-Level of Society.
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APPENDIX II :
Satellite Image GeoEye of Al Mourouj area.
XII – APPENDIX II :
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Photo A - II - 1 – Zoom in the satellite Image GeoEye -1 (2012).
Main pipeline Al Mourouj 1
Main pipeline Al Mourouj 2
Photo A - II - 2 – Main pipeline connecting Al Mourouj 1 and 2
in the satellite Image GeoEye -1 (2012).
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APPENDIX III :
File driver program for FLAC software
XIII – APPENDIX III :
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A - III – 1 – Introduction :
To carry out a FLAC model regarding the behavior of a single underground
pipeline within the water supply network in Al Morouj district at Al Riyadh city,
FLAC software allows to introduce the geometry of model, the material properties of
shallow layers and the boundary conditions by the intermediate a file called “driver
file” when using version FLAC without graphic interface.
Command lines below summarize the main steps to follow in order to lead to
the definitive model.
A - III – 2 – Grid :
The command lines below allow to display the grid of the model. It is necessary
to define the behavior law in this case Model Mohr :
g 50 50
m mohr
title
Behavior of underground water supply pipeline
A - III – 3 – Generation of the model :
The command lines below allow to generate the own model. It is necessary to
take into account the coordinates of the model and the interest zone :
gen 0 -50 0 -4 1 -4 1 -50 i 1 10 j 1 30 rat 1 0.9
gen 0 -4 0 -1.5 1 -1.5 1 -4 i 1 10 j 30 40
gen 0 -1.5 0 0 1 0 1 -1.5 i 1 10 j 40 51 rat 1 1.2
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gen same same 50 -4 50 -50 i 10 51 j 1 30 rat 1.1 0.9
gen same same 50 -1.5 same i 10 51 j 30 40 rat 1.1 1
gen same same 50 0 same 1 10 51 j 40 51 rat 1.1 1.1
gen adjust
gen circle 0 -1.3 0.3
gen adjust
A - III – 4 – Material proprieties and boundary conditions :
The command lines below allow to define the material proprieties and the
boundary conditions for this model. It is necessary to take into account the coordinates
of the model and the interest zone :
prop bulk=1e8 shear=0.3e8 fric=35
prop dens=2000 coh=1e10 ten=1e10
fix x i 1
fix x i 51
fix x y j 1
A - III – 5 – Gravity loading for consolidation phase :
The command lines below allow to load the model by the gravity in order to
account for the initial consolidation of the superficial layers :
set gravity=9.81
set=large
his ydis i=2 j=16
solve
save almorouj11.sav
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A - III – 6 – Changing loading on the surface above the underground pipeline :
The command lines below allow to apply a loading on the surface above the
underground single pipeline . The boundary conditions of the model and the material
properties remain the same during this second phase :
init xdis=0 ydis=0
m n reg 3,41
prop bulk=1e8 shear=0.3e8 fric=35
prop dens=2000 coh=1e10 ten=1e10
apply syy=-1e7 i=1 10 j=51
solve
save almorouj12.sav
A - III – 7 – Increasing material proprieties regarding the time :
The command lines below allow to increase the material proprieties in order to
take into account of aging of materials over time in the third phase of this model :
prop bulk=1e8 shear=0.3e8 fric=35
prop dens=2000 coh=1e10 ten=1e10
apply syy=-1e7 i=1 10 j=51
save almorouj13.sav
A - III – 8 – Using GIIC Interface of FLAC software :
For an advanced user and to perform the output and results after simulation, the
command lines remain very hard to use, however, the GIIC (Graphic Interface)
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becomes a best manner to work with FLAC software specially in the version 5.00 and
more. The figure below resumes the main tools in FLAC which allow to display an
interaction between the program and the graphic solution.
Figure A - III - 1 – GIIC Interface of FLAC software.
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TABLE OF CONTENTS
ACKNOWLEDGEMENTS ............................................................................................ 1
‫ ملخص‬................................................................................................................................ 2
ABSTRACT .................................................................................................................... 3
INTRODUCTION ........................................................................................................... 4
CHAPITER I : METHODOLOGY AND LITERATURE RVIEW
I - 1 – Study area : ........................................................................................................... 6
I - 3 – Project problem : .................................................................................................. 8
I - 4 – Project objective : ................................................................................................. 9
I - 5 – Project methodology :......................................................................................... 10
I - 6 – Literature review : .............................................................................................. 11
I - 7 – Time table of the projects : ................................................................................. 12
CHAPITER II : WATER RESOURCES FOR AL RIYADH
II - 1 – Existing water resources : ................................................................................. 14
II - 2 – Future water resources : .................................................................................... 31
II - 3 – Conclusions : ..................................................................................................... 37
CHAPITER III : THEORY OF LEAKAGE AND CONTROL
III - 1 – Introduction :.................................................................................................... 39
III - 2 – Control of leakage using DMA : ..................................................................... 39
III - 3 – Theory of DMA management :........................................................................ 40
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III - 4 – Control of leakage using DMA Design Network : .......................................... 41
CHAPITER IV : WATER PLANNING SUPPLY AND CRITERIA
IV – 1 – Introduction : ................................................................................................... 45
IV – 2 – Peak Factors : .................................................................................................. 45
IV – 2 – Diurnal Variation : .......................................................................................... 48
IV – 3 – Pipe Materials used in the network :............................................................... 52
IV – 4 – Design standard for pipe materials : ............................................................... 56
CHAPITER V : PIPE NETWORK THEORY AND SIMULATION
V – 1 – Pipe Networks Theory : ................................................................................... 60
V – 2 – Analytical Calculation for Pressure : ............................................................... 64
V – 3 – Simulation using EPANET 2 : ......................................................................... 68
V – 4 – Results and interpretations : ............................................................................. 68
CHAPITER VI : MODELING USING FLAC SOFTWARE
VI – 1 – Introduction : ................................................................................................... 74
VI – 2 – Finite Differences : ......................................................................................... 74
VI – 3 – Explicit, Time-Marching Scheme :................................................................. 76
VI – 4 – Lagrangian Analysis : ..................................................................................... 79
VI – 5 – Plasticity Analysis :......................................................................................... 79
VI – 6 – Field Equations : ............................................................................................. 80
VI – 7 – FLAC software and modeling : ...................................................................... 84
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CHAPITER VII : GIS METHODOLOGY APPLICATION
VII – 1 – What is GIS : ................................................................................................. 94
VII – 2 – GIS used for Water supply : .......................................................................... 95
VII – 3 – Sharpen Planning and Engineering Analyses :.............................................. 97
VII – 4 – Conclusions : ................................................................................................. 98
VIII - CONCLUSIONS : ............................................................................................ 102
IX - RECOMMANDATIONS : .................................................................................. 104
X - REFERENCES : ................................................................................................... 105
APPENDEX
XI – APPENDIX I : .................................................................................................... 108
XII – APPENDIX II : .................................................................................................. 111
XIII – APPENDIX III : ............................................................................................... 113
M. S. Al Harthi – M. A. Al Semari – M. A. Zoman – Y. M. Dossary
Academic Year : 2012 - 2013