Study on Backwater Impact of Kuching Barrage

STUDY ON BACKWATER IMPACT OF KUCHING BARRAGE

Dayang Harom Awang Sam

Bachelor of Engineering with Honours TC (Civil Engineering) 175 D273 2009 2009 Universiti Malaysia Sarawak Kota Samarahan

tk BORANG PENYERAHAN TESIS

Judul: STUDY ON BACKWATER IMPACT OF KUCHING BARRAGE

SESI PENGAJIAN: 2005 - 2009

Saya DAYANG HARONI AW ANG SANI (HURUF BESAR)

mengaku membenarkan laporan projek ini disimpan di Pusat Khidmat Maklumat Akademik, Universiti Malaysia Sarawak dengan syarat-syarat kegunaan seperti berikut:

I. Hakmilik kertas projek adalah di bawah nama penulis melainkan penulisan sebagai projek bersama dan dibiayai oleh UNIMAS, hakmiliknya adalah kepunyaan UNIMAS. 2. Naskhah salinan di dalam bentuk kertas atau milcro hanya boleh dibuat dengan kebenaran bertulis daripada penulis. 3. Pusat Khidmat Maklumat Akademik, UNIMAS dibenarkan membuat salinan untuk pengajian mereka. 4. Kertas projek hanya boleh diterbitkan dengan kebenaran penulis.Bayaran royalti adalah mengikut kadar yang dipersetujui kelak. 5. * Saya membenarkanltidak membenarkan Perpustakaan membuat salinan kertas projek ini sebagai bahan pertukaran di antara institusi pengaj ian tinggi. 6. ** Sila tandakan (" )

c=J SULIT (Mengandungi maklumat yang berdwjah keselamatan atau kepentingan Malaysia seperti yang termaktub di dalam AKTA RAHSIA RASMI 1972).

c=J TERHAD (Mengandungi maklumat TERHAD yang telah ditentukan oleh organisasil badan di mana penyelidikan dijalankan).

1c=J TIDAK TERHAD ~. (TANDA T ANGAN PENULIS)

Alamat tetap: LOT 1679, LORONG B 26,

KAMPUNG MUHIBBAH, PROF. DR F. J. PUTUHENA ( Nama Penyelia ) 95000 SRI AMAN, SARAW AK

I Tarikh: Tarikh:

CATATAN * Potong yang tidak berkenaan. ** Jika Kertas Projek ini SULIT atau TERHAD, sila lamplrkan surat daripada pihak berkuasal organisasi berkenaan deogan menyertakao sekali tempoh kertas projek. Ini perlu dikelaskan sebagai SULIT atau TERHAD.

PKSl2000 The following Final Year Project Report:

Title STUDY ON BACKWATER IMPACT OF KUCHING

BARRAGE

Name : DAYANG HARONI A WANG SANI

Matric No. : 13937

has been read and approved by:

PROF. DR. F.J. PUTUHENA Date

Project Supervisor STUDY ON BACKWATER IMPACT OF KUCHING BARRAGE

DAYANG HARONI AWANG SANI

This project is submitted in partial fulfillment of the requirements for degree of Bachelor of Engineering with Honours

(Civil Engineering)

2009

Faculty ofEngineering

UNIVERSITI MALAYSIA SARAWAK

2009 Dedicated to my beloved family members, friends, and all parties involved.

11 ACKNOWLEDGMENT

Firstly, I would like to express appreciation to God for giving me the strength along the completion of this project. I also want to express my thanks to my supervisor,

Prof. Dr. Frederik Josep Putuhena for his guidance and assistance along with the completion of this project.

I want to acknowledge the staffs in the Hydrological Section of Department of

Irrigation and Drainage, Kuching, Sarawak for their cooperation in providing the data required in this project.

I wish to acknowledge to Darrien Mah Yau Seng for his considerable time and assistance in helping me for my study.

My special thanks also dedicated to my beloved family members and friends for their motivation and moral support.

Lastly, my thanks also dedicated to those who are involved either directly and indirectly in this project.

III ABSTRAK

Kuching Barrage telah dibina di Sungai Sarawak dan mempunyai lima pintu jejari dan

untuk mengawal tahap air sungai di Sungai Sarawak dan satu pintu kapal. Semasa hujan

lebat, pintu-pintu sekatan akan buka sepenuhnya untuk mengalirkan air hujan yang

berlebihan bergantung kepada tahap air laut. Penyelidikan ini telah menghasilkan

model-model simulasi untuk beberapa scenario banjir supaya dapat menganalisis

backwater impact di Sungai Sarawak yang berpunca dari operasi Kuching Barrage.

Langkah-Iangkah ketja dan pendekatan model hidrodinamik dengan menggunakan

perisian Geographical Information System (GIS) and Info Works River Simulation (RS) telah diguna untuk simulasi-simulasi banjir. Scenario banjir yang dibincangkan adalah

seperti keadaan banjir semasa pintu sekatan ditutup atau dibuka, aliran air sungai yang

sekata, semasa ombak tinggi dan rendah, peristiwa banjir yang kecil dan besar. Peta

banjir dibina untuk menilai backwater impact di Sungai Sarawak semasa peristiwa

banjir berlaku. Kawasan tadahan Sungai Maong dipilih untuk menyelidik perbezaan

backwater impact di Sungai Sarawak dengan mengukur panjang jalan yang dibanjiri air.

Profil-profil banjir dihasilkan dengan menggunakan Info Work RS. Kesan positif dan

negatif backwater impact juga telah dibincangkan. Keputusan-keputusan daripada

penyelidikan ini menunjukkan bahawa operasi Kuching Barrage, tahap tinggi ombak,

dan aliran air sungai mempengaruhi backwater impact di Sungai Sarawak.

iv ABSTRACT

Kuching Barrage has been constructed and comprises of five radial gates controlling

Sarawak River water level and a ship lock. At times of heavy stonn, barrage gates will be fully opened to discharge the excess stonn water depends on sea water level. This study had generated simulations model for several flood scenarios to analyse and identify the backwater impact of Sarawak River due to Kuching Barrage operations.

The methodology and hydrodynamic modeling approach using Geographical

Infonnation System (GIS) and InfoWorks River Simulation (RS) softwares had been developed for flood simulations. The flood scenarios that been discussed comprising when barrage gates is closed and open, with average river flows during high tides and low tides, small flood event and extreme flood event. The flood mappings were developed to evaluate the backwater impacts in Sarawak River during flood event.

Maong River catchments areas were chosen to study the differences of backwater impact of Sarawak River by measures the length of roads inundated. The flood profiles had been generated by Info Work RS. The positive and negative of backwater impacts were discussed. The results of this study had shown that the barrage operations, tide levels and river flows had influenced the backwater in Sarawak River.

v LIST OF TABLES

Tables Page Number

1.1 Historical Flood Events Recorded in Sarawak from 2

year 1962-1999, before the operation of barrage

1.2 Historical Flood Events Recorded in Sarawak from 3

year 2000-2007, after the operation ofbarrage

4.15 Summary ofComparison ofScenarios 59

VI LIST OF FIGURES

Figures Page Number

2.1 Location of Kuching Barrage 10

2.2 Kuching Barrage 11

2.3 Radial Gate ofKuching Barrage Cross Section 11

2.4 Marina Barrage Cross Section 13

2.5 Marina Barrage Operation 14

2.6 Thames Barrier 15

2.7 Scheme for Equation of Continuity 21

2.8 Scheme for Equation of Energy in a cross section 25

2.9 Scheme of the Equation of Energy between two sections 27

2.10 Hydraulic Scheme ofa Weir 31

2.11 Floodplain 33

2.12 Relationship of Fundamental of Flood Reduction Studies 33

3.1 Model Development by GIS 39

3.2 Calibration of2003 Flood Level at Upstream and 41

Downstream of Barrage

3.3 Calibration of February Flood at Upstream ofShiplock 42

vii 3.4 Calibration of February Flood at Satok Bridge 42

3.4 Calibration of February Flood at Batu Kawa Bridge 43

4.1 Flood Mapping during Barrage Gates is closed up to 47

1.9m

4.2 Flood Profile during Barrage Gates is closed 47

4.3 Flood Mapping during High Tides and Low Tides 49

for Scenario 2

4.4 Comparison of Flood Mapping of Maong River 49

Catchments Area during High Tides and Low Tides

for Scenario 2

4.5 Flood Profile during High Tides for Scenario 2 50

4.6 Flood Profile during Low Tides for Scenario 2 51

4.7 Flood Mapping during High Tides and Low Tides 52

for Scenario 3

4.8 Comparison of Flood Mapping of Maong River 53

Catchments Area during High Tides and Low Tides

for Scenario 3

4.9 Flood Profile during High Tides for Scenario 3 54

4.10 Flood Profile during Low Tides for Scenario 3 54

4.11 Flood Mapping during High Tides and Low Tides 56

for Scenario 4

V1l1 ,..

4.12 Comparison of Flood Mapping of Maong River 57

Catchments Area during High Tides and Low Tides

for Scenario 4

4.13 Flood Profile during High Tides for Scenario 4 58

4.14 Flood Profile during Low Tides for Scenario 4 58

ix ,.... Pusat Kludmal wnal iJt. UNIVER.S ITf MALAYSIA SARAWAK

TABLE OF CONTENTS

Page Number

Acknowledgment III

Abstrak IV

Abstract V

List ofTables VI

List of Figures VII

Chapter 1 INTRODUCTION

1.1 Background of Study 1

1.2 Statements of Problem 4

1.2.1 Flood after Kuching Barrage Operation 4

1.2.2 Backwater impact due to the Barrage Operation 5

1.3 Objectives 6

1.4 Scope of Work 6

1.5 Organization of Report 7

Chapter 2 LITERATURE REVIEW

2.1 Barrage 9

2.1.1 Kuching Barrage 9

x ,..

II 2.1.2 Marina Barrage 12

2.1.3 Thames Barrier 15

2.2 Backwater Impact 19

2.2.1 Equation of Continuity 21 I' 2.2.2 Equation ofEnergy 24

2.2.3 Flow Over Weir 29

2.3 Flood Mitigation 32

2.4 Application of Geographical Information System (GIS) 35

2.5 Application of Info Work River Simulation (RS) 37

Chapter 3 METHODOLOGY

3.1 Backwater Development 38

3.2 Initial and Boundary Conditions 39

3.3 Calibrations of Model 40

I' 3.4 Flood Simulation and Mapping 43

Chapter 4 RESULTS AND DISCUSSION

4.1 General 45

4.2 Flood Simulation Results 46

4.2.1 Scenario 1 : High Tides and the Barrage Gates 46 I is Closed

4.2.2 Scenario 2: Average Flows, High Tides, 48

and Low Tides

xi 4.2.3 Scenario 3 : Small Flood Events, High Tides, 52

and Low Tides

4.2.4 Scenario 4 : Extreme Flood Events, High Tides, 56

and Low Tides

4.3 Discussions 59

Chapter 5 CONCLUSIONS AND RECOMMENDATIONS

5.1 Conclusions 61

5.2 Recommendations for Future Study 62

REFERENCES 63

Xll CHAPTERl

INTRODUCTION

1.1 Background of Study

Kuching city is located on the Sarawak River. Some division of the Kuching city js located in very flat and low lying area, thus the probability to subject of significant tidal action and susceptible to river flooding are high. The floods were the worst to hit

Sarawak after 1963, where thousands in Kuching, Bau, Kota Samarahan and Sibu were evacuated. Kuching suffered estimated losses of RM3.2 million in the 2003 floods and

RM7.4 million during floods in the subsequent year (Bemama.com. 1996).

Table 1.1 shows the historical flood events recorded in Sarawak from year1962 to 1999 before operation of Kuching Barrage while the Table 1.2 shows the historical flood events recorded in Sarawak from year 2000 to year 2007 after the operation of

Kuching Barrage (DID, 2007).

1 Table 1.1 : Historical Flood Events Recorded in Sarawak From year 1962-1999,

before operation ofbarrage (DID, 2007)

Events Affected Flood Area Flood Height Jan. 1962 Sg. Sarawak 20 feet

Jan-Feb. I ~ole State affected 20 feet 1963 Feb. 1964 Sg. Sarawak 6 feet Sg. Sarawak, Matu, Dalat, Tatau District, Jan. 1967 Btg. Kemena, Bekenu, Miri and Btg. Baram Jan. 1978 Kuching Town Jan. 1980 Kuching Town Lundu, Sg. Sarawak, Samarahan and Jan. 1983 3-7 feet Sadong Jan. 1985 Sg. Sarawak, Kuching Town Mar. 1986 Kuching Town Dec. 1987 Btg. Kayan, Sg. Sarawak 4 feet Sg. Sarawak, Lundu areas, Sadong & Jan. 1992 6 feet Samarahan Mar. 1994 Kuching Town 1-2 feet 5 feet of water above Batu Feb. 1995 Sg. Sarawak and Kuching Town Kitang shophouses Feb. 1997 Kuching Town 0.15-0.3m

2 Table 1.2 : Historical Flood Events Recorded in Sarawak From year 2000-2007,

after the operation of barrage (DID, 2007)

Events Affected Flood Area Flood Height Jan. 1998 Kuching Town 0.25-2.00 m Lower Sg. Sarawak and some parts of Samarahan

Dec 1999 Sg Sarawak ( Kuching City) 0.1 - 0.55 m I Jan 2000 Sg. Sarawak ( Kuching City) 0.1 - 0.7 m Feb 2001 Sg. Sarawak 0.1 - 0.3 m Jan 2002 Sg Sarawak (3 times) 0.1 - 2.5 m Feb 2003 Sg. Sarawak 0.3- 3.0 m Kuching City 0.3- 1 m 24 - 27 Jan Sg Sarawak 2004 Kuching City 0.3 - 1.5 m 3 July 2005 Kuching 0.1 - 0.3 m 5 Oct 2005 Kuching 0.1 - 0.3 m

The Barrage is design based on the flood event in 1963. Therefore, Kuching

Barrage was constructed and completed in October 1997. Kuching Barrage located at the mouth of Sarawak River regulates the water level in Sarawak River and is operated by the Kuching Barrage Management Sendirian Berhad. Kuching Barrage is part of the

Sungai Sarawak Regulation Scheme (SSRS).

The operation of barrage started on January 1998 where to control the upstream level in Sarawak River, to regulate the river water from draining out and to prevent the

3 sea water from flooding in. Thus, the Kuching Barrage acts to prevent saline intrusion and to regulate water levels upstream of Sarawak: River. The barrage also acts as a small dam which holding additional amount of sea water behind it during low tide, thus maintaining sufficient water volume of Sarawak River (JKR 1994).

Kuching Barrage comprises the first-ever barrage and shiplock in South East

Asia The barrage has a flyover and two causeways one which across Santubong River at Bako and the other across Sarawak: River at Pending. The Kuching Barrage comprising a barrage of 5 radial main gates controlling the Sarawak River, ship lock and road bridge over both barrage and lock. The radial gates are normally closed to prevent upstream passage of sea water. A ship lock are provided and located to one side ofthe barrage to enable ships and river vessels to access upstream of the barrage.

1.2 Statements of Problem

1.2.1 Flood after Kuching Barrage Operation

Based on the Table 1.2, the operation of the barrage has helped in decreasing the flood events. When heavy rain, the radial gates would be fully open to discharge storm water flow. During normal flows river water will be regulated through smaller flap gates at barrage to maintain a constant river level. The operation ofopening and closing radial gates in less time had help in to prevent excessive saline intrusion to reach the

4 bidmat Makluml1t Akadem' 'AK

water treatment. Before the barrage is operating, the saline contamination in water has become a big problem during treatment of water. Therefore, the saline contamination in water can be less after the barrage operation.

1.2.2 Backwater Impact due to the Barrage Operation

Backwater impact is the rise in surface elevation of flowing water upstream from and as a result of an obstruction to flow such as a narrow bridge opening, buildings or fill material that limits the area through which the water must flow. In stream gauging, a rise in stage produced by a temporary obstruction such as ice or weeds, or by the flooding of the stream below. The difference between the observed stage and that indicated by the stage-discharge relation is reported as backwater.

Due to these studies, the operation of opening and closing radial gate of the barrage are giving effect to the water level of Sarawak River. When the high tides and flooding, the gates are closed, thus produces backwater impact. When low tides and flooding, the gates are opened to flow the water to the sea. Then, when the water level ofSarawak River equated with sea water, the gates will be closed.

5 1.3 Objectives

The main objectives of this study are to study the backwater impacts of Kuching

Barrage to the environment and people in the affected area. Due to the operation of

Kuching Barrage, the sea water and river water are collide with each other, thus the backwater impact had been produced. These studies would determine the positive and negative impacts of operation of Kuching Barrage, thus, finding the solutions to overcome the negative impacts.

1.4 Scope of Work

The studies on backwater impacts of Kuching Barrage is done by constructing the backwater simulation on Sarawak River using software such as the Arc View GIS version 3.1 and Info Works River Simulation (RS) version 9.0. The Arc View GIS version 3.1 is use for mapping the Sarawak River while the Info Works River

Simulation (RS) version 9.0 is use to do the simulation of backwater. These studies using the software because the limitation of facilities to studies more details of affected

area besides the impact of backwater to the location site are too large to studies.

6 1.5 Organization of Report

This report is organized in the following outline :

Chapter 1

• Discussing the introduction of the background study, problem arising such as

flood after the Kuching Barrage operation, backwater impact due to the barrage

operation, objectives and scope of works of the study.

Chapter 2

• Literature Reviews on barrages such as Kuching Barrage, Marina Barrage, and

Thames Barrier. Besides that, there are also literature reviews on the backwater

impact, flood mitigation, and application of GIS and InfoWorks RS.

Chapter 3

• This chapter discussing the methodology of the study usmg the GIS and

InfoWorks RS software. The simulation models were developed to analyze and

evaluate the backwater impacts I Sarawak River during flood events. There are

four scenarios of flood events had been simulated which are the flood events

during barrage gates closed, average river flows, small flood events, and

extreme flood events during high tides and low tides.

7 Chapter 4

• This chapter discussing the results based on the flood events simulations from

the InfoWorks RS software. Beside that, the positive and negatives impact of

backwater were identified.

Chapter 5

• Chapter 5 summarizing all the results and discussion from Chapter 4 and several

recommendations are suggested to overcome the negatives impact.

8 CHAPTER 2

LITERATURE REVIEW

2.1 Barrage

A barrage can be defines as a barrier of artillery or depth charge fire, a weir or artificial obstruction at the mouth of a tidal watercourse. A barrage is built to increase the depth of water, maintain a separation between fresh and salt water, reduce the risk of tidal flooding up the river, and for tidal power generation. Barrage also is an artificial obstruction in a watercourse to facilitate irrigation.

2.1.1 Kuchlng Barrage

Kuching Barrage has been constructed on the Sarawak River to maintain the water level in Kuching city. Based on the Sungai Sarawak Regulation Scheme (SSRS), the objectives of the construction of Kuching Barrage are:

• To mitigate fluvial and tidal flooding in Kuching city.