integrated modelling for coastal alluvium aquifer at...

i

INTEGRATED MODELLING FOR COASTAL ALLUVIUM AQUIFER AT

KG. TEKEK, TIOMAN ISLAND

LIEW KUET FAH

A project report submitted in partial fulfillment

of the requirements for the award of the degree of

Master of Engineering (Civil - Hydraulics and Hydrology)

Faculty of Civil Engineering

Universiti Teknologi Malaysia

NOVEMBER, 2006

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To my beloved parents and family

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ACKNOWLEDGEMENTS

For the accomplishment of this master project, I would like to take this

opportunity to express my deepest appreciation to my supervisor, Assoc. Prof. Dr.

Norhan Abd. Rahman, for his enthusiastic effort, suggestions, advices and guidance

during the preparation of this report. Appreciations are also dedicated to my co-

supervisor, Professor Toshiharu Kojiri of Water Resources Research Centre, D.P.R.I

Kyoto University for his willingness to comment and provide suggestions for

improvements on the results of this project.

I also gratefully acknowledge the panels of my project presentation,

consisting of Dr. Noor Baharin, Dr. Supiah Shamsudin, Ir. Ahmad Kamal and Prof.

Narayanan for their comments, opinions and suggestions to produce a better report.

I would like to extent my appreciation to my friends especially Siti, Shah,

Kamarul, Zulkifli and Hakim for their supports, cooperation and assistances during

my studies in Master program.

Last but not least, deepest thanks are expressed to my beloved parents and

family members for their moral support on my decision to further study. Without

them, I would not have been able to complete my course.

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ABSTRACT

Sufficient water supply plays an important role in busting the continuous growth of

tourism industry for an island. Tioman Island as one of the well-known marine

tourism attraction in Malaysia still highly relies on the limited surface water source

to supply water for the local residents and tourists. Thus, exploration for the

groundwater source is essential as an supplement for the existing water supply

system to cater for the increasing water demand in the future. Utilization of surface

water and groundwater will prevent the total reliance on a single resource which

avoids the water scarcity problem during drought seasons and also occurrence of

groundwater overdraft. Groundwater modellings in this study are developed with

MODFLOW2000 based on the available data to determine the hydraulic heads and

drawdowns of groundwater due to different pumping rates and saline intrusion

effects are simulated with the SEAWAT2000 model. The linear optimization

problem is solved with GAMS to maximize the rate of pumping for groundwater to

fulfill the quantity and quality requirements. The aquifer system would be capable to

support withdrawal of groundwater up to 5.8 MLD and cater for water demand till

year 2015. The hydraulic drawdown has greater influence for the optimization of

pumping rate compared to saline intrusion effects. With additional supply from

surface water source of 4 MLD, the combination system could cater for the water

demand up to year 2025.

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ABSTRAK

Bekalan air yang mencukupi memainkan peranan penting bagi perkembangan

industri perlancongan yang berterusan di sebuah pulau. Pulau Tioman sebagai salah

satu tumpuan perlancongan marin yang terkenal di Malaysia masih bergantung

kepada sumber air permukaan yang terhad untuk membekalkan air kepada penduduk

tempatan dan pelancong. Dengan itu, penerokaan sumber air bumi adalah penting

sebagai sumber tambahan bagi sistem bekalan air yang sedia ada untuk menampung

keperluan air yang semakin meningkat pada masa depan. Penggunaan air permukaan

and air bumi akan mengelakkan masalah kekurangan air pada musim kemarau dan

berlakunya pengepaman air bumi yang berlebihan. Model MODFLOW2000 telah

digunakan dalam kajian ini untuk membentuk model simulasi berdasarkan kepada

data yang sedia ada untuk menentukan turus hidraulik air bumi disebabkan oleh

pengepaman pada kadar alir yang berbeza. Model SEAWAT2000 pula menganalisa

kesan pencerobohan air masin pada setiap kadar pengepaman. Masalah penyelesaian

linear diselesaikan dengan GAMS untuk memperolehi kadar pengepaman yang

maksimum dan memuaskan syarat kuantiti dan kuality. Hasil kajian menunjukan

sistem akuifer mampu mengeluarkan air bumi sebanyak 5.8 MLD dan menampung

keperluan air sehingga tahun 2015. Penurunan turus hidraulik menunjukkan

pengaruh yang lebih besar berbanding dengan pencerobohan air masin dalam proses

mengoptimumkan kadar pengepaman. Dengan bekalan tambahan sebanyak 4 MLD

daripada sumber air permukaan, sistem kombinasi dapat menampung bekalan air

sehingga tahun 2025.

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TABLE OF CONTENTS

CONTENTS PAGE

DECLARATION OF ORIGINALITY AND EXCLUSIVENESS ii

DEDICATION iii

ACKNOWLEDGEMENT iv

ABSTRACT v

ABSTRAK vi

CONTENTS vii

LIST OF TABLES xi

LIST OF FIGURES xii

LIST OF APPENDICES xv

CHAPTER 1 INTRODUCTION 1

1.1 Background of the study 1

1.2 Objectives of study 2

1.3 Scope of study 3

1.4 Importance of study 3

CHAPTER 2 LITERATURE REVIEW 5

2.1 Groundwater Hydrology 5

2.1.1 Groundwater and Hydrologic Cycle 5

2.1.2 Groundwater Movement 7

2.1.3 Groundwater Recharge and Discharge 8

2.1.4 Aquifer and Confining Beds 8

2.2 Groundwater Quality 10

2.2.1 Saline Intrusion in Coastal Zones 11

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2.3 Type of Groundwater Models 13

2.4 Historical Review of Groundwater Modelling

in Malaysia 15

2.4.1 Historical Review of Groundwater

Modelling in Kelantan 15

2.4.2 Historical Review of Previous Studies of

Alluvial Aquifer in Tioman Island 17

2.5 Historical Review of MODFLOW and SEAWAT

Application for Tymbaki Aquifer, South Central

Crete, Greece (2005) 20

2.5.1 Site Description and Basin Hydrogeology 21

2.5.2 Simulation Models 23

2.5.3 Discretization, Boundary Condition and

Aquifer Parameters 23

2.5.4 Simulation Results and Conclusion 25

2.6 Optimization Modelling 27

2.6.1 Linear Programming 28

2.7 Historical Review of GAMS Application for

Groundwater Management in the Goksu Delta

At Silifke, Turkey (2001) 30

2.7.1 Objective Function and Constraints 31

2.7.2 Results and Discussion 34

2.8 Summary 36

CHAPTER 3 METHODOLOGY AND STUDY AREA 37

3.1 Modelling of Groundwater and Optimization 37

3.2 Description of the study area 37

3.2.1 Geology and Hydrogeology 42

3.2.2 Climate 44

3.2.3 Topography 44

3.2.4 Water Resources of Study Area 46

3.2.5 Hydrology 46

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3.3 Groundwater Modelling 46

3.3.1 MODFLOW2000 47

3.3.1.1 Spatial and Time Discretization 49

3.3.1.2 Governing Equation 50

3.3.2 SEAWAT2000 51

3.3.2.1 Temporal Discretization 53

3.3.2.2 Head and Equivalent Freshwater 54

Head in SEAWAT2000

3.3.2.3 Variable-Density Groundwater 55

Flow Equation

3.4 Simulation Setup 56

3.4.1 Simulation Time Steps 58

3.4.2 Boundary Condition 58

3.4.3 Data Input Parameters 58

3.4.4 Model Assumptions 59

3.5 Optimization Model 59

3.5.1 General Algebraic Modeling Systems

(GAMS) 60

3.5.2 Objective Function 60

3.5.3 Constraints 60

3.5.4 Water Consumption Projection 63

3.6 Integrated Modelling Approach 63

CHAPTER 4 RESULTS, ANALYSIS AND DISCUSSIONS 66

4.1 Introduction 66

4.2 Simulation Results for MODFLOW2000 67

4.2.1 Calibration Process 67

4.2.2 Simulation Analysis 70

4.3 Simulation Results for SEAWAT2000 79

4.3.1 Calibration and Validation Process 79

4.3.2 Simulation Analysis 81

4.4 Optimization Results 94

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CHAPTER 5 CONCLUSIONS AND RECOMMENDATIONS 97

5.1 Conclusions 97

5.2 Recommendations 98

REFERENCES 99

APPENDICES 102

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LIST OF TABLES

TABLE NO. TITLE PAGE

2.1 Application of groundwater modelling at

Tioman Island 20

2.2 The calibrated model parameters 24

2.3 Application of groundwater management and

Optimization modelling in coastal aquifer of Malaysia 28

3.1 Processes and Packages of MODFLOW-2000 48

3.2 Projected water consumption for Kg. Tekek 63

4.1 Values for constant parameters 67

4.2 Cases considered for the calibration process 68

4.3 Calibration analysis results for Case (1) 69

4.4 Calibration analysis results for Case (2) 70

4.5 The aquifer influence coefficients of drawdown

for TEK1 76

4.6 Calibration results for SEAWAT2000 80

4.7 Validation results for SEAWAT2000 80

4.8 Calibrated parameters for SEAWAT2000 model 81

4.9 Optimization results for pumping well TEK1 95

4.10 Water supply for combine system 96

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LIST OF FIGURES

FIGURE NO. TITLE PAGE

1.1 Location of Tioman Island 4

2.1 Hydrological Cycle 6

2.2 Flow paths associated with local, intermediate

and regional flow systems 7

2.3 The aquifer and the confining beds 9

2.4 Saltwater intrusion occurrence due to pumping well 12

2.5 Location map of the Tymbaki and Mesara basin 21

2.6 Geological map of Tymbaki basin 22

2.7 Geological cross section of Tymbaki basin 22

2.8 Rainfall and streamflow infiltration recharge zone 25

2.9 Simulated extent of seawater intrusion into the

Tymbaki aquifer at various depth 26

2.10 Seawater intrusion along section C1 at the end of

120th stress period 26

2.11 Seawater intrusion along section C1 at the end of

240th stress period 26

2.12 The Goksu Delta 31

2.13 Correlation between simulation model results and

optimization model results for hydraulic heads 34

2.14 Correlation between simulation model results and

optimization model results for chloride concentrations 35

2.15 Trade-off curves between maximum pumping rate

and chloride concentration limit 35

3.1 Groundwater simulation and optimization model

for the study 38

3.2 Methodology Flow Chart 39

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3.3 Groundwater modelling process flow chart 40

3.4 Location of Kg. Tekek in Tioman Island 41

3.5 Geologic map for Tioman Island 42

3.6 Geological cross section for Kg. Tekek aquifer system 43

3.7 Topography map for Tioman Island 45

3.8 Finite difference grid 50

3.9 Simulation modes available with the

SEAWAT2000 programme 53

3.10 Horizontal plane and vertical section of the

Groundwater models 57

3.11 Input and output for integrated modelling 65

4.1 Hydraulic conductivity zoning plan for

Kg. Tekek (isotropic heterogeneous) 68

4.2 Location of pumping wells at Kg. Tekek 69

4.3 Hydraulic head contour due to pumping of 1 MLD 71





4.8 Hydraulic head at TEK1 77

4.9 Hydraulic head at TEK3 and TEK4 78

4.10 Relationship between hydraulic drawdown

and pumping rate at TEK1 79

4.11 Concentration contour (saline intrusion) on

horizontal plane due to pumping of 0.5 MLD 82


vertical section due to pumping of 0.5 MLD 83


horizontal plane due to pumping of 1 MLD 84


vertical section due to pumping of 1 MLD 85




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4.23 Relationship between saline intrusion length

and pumping rate 94

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LIST OF APPENDICES

APPENDIX PAGE

A1 Analysis results of groundwater in Kg Tekek 103

(source : ALS Technichem (M) Sdn. Bhd. 28 March 2003)

A2 Analysis results of groundwater in Kg. Tekek 104

(source : ALS Technichem (M) Sdn. Bhd. 28 March 2003)

(continue)


(source : FELDA AGRICULTURAL SERVICES SDN. BHD.

8 July 2004)

A4 Analysis results of groundwater in Kg. Tekek

106

(source : FELDA AGRICULTURAL SERVICES SDN. BHD.

8 July 2004)(continue)

A5 Water Quality Monitoring (6 June- 7 June 2004)

107

by Universiti Teknologi Malaysia

A6 Water Quality Result During Pumping Test In Kg. Tekek 108

by Universiti Teknologi Malaysia

A7 Water Quality Result During Pumping Test In Kg. Tekek 109

by Universiti Teknologi Malaysia. (continue)

A8 Analysis results of groundwater in Kg Tekek 110

(source : ALS Technichem (M) Sdn. Bhd. 31 December 2003)




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A12 Analysis results of groundwater at various depths in Kg. Tekek 114

(source : Department of Environment 2001 - 2005)

A13 Analysis results of groundwater at various depths in Kg. Tekek 115

(source : Department of Environment 2001 - 2005)

B1 Constant Discharge Pump Test Record (Tek 1) 116



B4 Recovery Test (Tek 1) 119



B7 Recovery Test (Piez 7) 122

B8 Constant Discharge Pump Test Record (Piez 1) 123







C Optimization Model 130 - 132

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CHAPTER 1

INTRODUCTION

1.1 Background of the Study

Tioman Island, as one of the marine tourism destination in Malaysia, is

located in the South China Sea, 56 km off Mersing. The island having a total area of

about 131 km2, spanning about 11 km from west to east and 20 km from north to

south, is the largest among a group of 64 volcanic islands in the South China Sea.

Noted for its crystal clear water and marine life, the island in the vicinity of 2°43’00”

to 2°54’00” N latitude and 104°06’00” to 104°12’30” E longitude, have attracted

many tourists both local and abroad annually. In addition to fishing activities,

tourism has become a very important income generating activity on the island.

Due to the importance of water as the basic criteria for the development of

tourism, many studies have been carried out to determine the water availability on

the island. Based on this purpose of study, Nazan Awang (1988) had suggested Kg.

Tekek and Kg. Juara to be the potential areas for surface water and groundwater

extraction on the island. The study also explored into annual water yield from surface

as well as groundwater sources in Kg. Tekek by using simulation model based on the

site collected data.

Presently, the limited availability of surface water sourced from the river

system serves as the main source of water supply in the vicinity for domestic and

tourism demands. Groundwater utilization is only available in certain parts of the

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area on the island in the form of individual wells. Groundwater system for public

water supply is still virtually non-existent. The government’s intention to promote

Tioman Island as a tax-free tourist based island will further burden the water stress.

Thus exploration for new reliable water sources is essential to cater for the increasing

water demand due to population and tourist growth.

The extraction of available groundwater will be the best solution for the water

crisis problem on Tioman Island other than water transfer from the mainland. The

main concern for groundwater aquifer to be developed as public water supply will be

the maximum yield available. Pumping of groundwater may cause deleterious side

effects if proper management and water conservation aspects are neglected. For

coastal aquifer system, water quality degradation due to saline intrusion effects may

limit the application of groundwater, therefore careful study should be carried out on

groundwater aquifer to ensure a sustainable water supply of the area.

1.2 Objectives of Study

The objectives of this study include:

a. To predict the available yield of the groundwater flow system due to different

pumping rate on Tioman Island.

b. To study the saline intrusion effects under different pumping rate.

c. To study the maximum pumping rate of groundwater for optimization.

3

1.3 Scope of Study

The study on groundwater aquifer system at Tioman Island involves scopes

as listed below:

a. The study will focus on the groundwater system in Kg. Tekek, Tioman Island

(Figure 1.1).

b. The simulation process involves groundwater numerical models, which

include MODFLOW for groundwater flow and SEAWAT for saline intrusion

effects.

c. The optimization of pumping rate that involves application of simulated

results into linear programming for GAMS.

1.4 Importance of Study

As the basic human need, water is an essential criterion that enables the

continuous growth in tourism industry of Tioman Island. The analytical data in 1999

provided by Hassan indicated that the surface runoff is limited and inconsistent, with

fluctuating water amount following the annual climatic changes. In order to ensure

continuous availability of water supply to local residents and tourists, alternative

water sources will be required to supplement or replace diminished surface water

supplies. Groundwater resources available in several areas on the island will be a

potential option to the solution of the crisis, but extensive studies are still required to

determine the advantages and disadvantages of implementation.

4

Figure 1.1: Location of Tioman Island.

99

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