PREDICTION OF WAVE PROPAGATION, WIND WAVE EFFECTS AND ENERGY DISSIPATION NEARSHORE OF SUNGAI SARAWAK ESTUARY

(1)

PREDICTION OF WAVE PROPAGATION, WIND WAVE EFFECTS AND ENERGY DISSIPATION NEARSHORE OF SUNGAI SARAWAK ESTUARY

SITI ZALEHA BINTI KAMALUDDIN

This project is submitted to Faculty of Engineering, University Malaysia Sarawak

in partial fulfilment of the requirement for the

degree of Bachelor of Engineering with Honours (Civil Engineering) 2009

(2)

UNIVERSITI MALAYSIA SARAWAK

R13a BORANG PENGESAHAN STATUS TESIS

Judul: PREDICTION OF WAVE PROPAGATION, WIND WAVE EFFECTS AND ENERGY DISSIPATION NEARSHORE OF SUNGAI SARAWAK ESTUARY

SESI PENGAJIAN: 2008/2009

Saya SITI ZALEHA BINTI KAMALUDDIN

(HURUF BESAR)

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

1. Tesis adalah hakmilik Universiti Malaysia Sarawak.

2. Pusat Khidmat Maklumat Akademik, Universiti Malaysia Sarawak dibenarkan membuat salinan untuk tujuan pengajian sahaja.

3. Membuat pendigitan untuk membangunkan Pangkalan Data Kandungan Tempatan.

4. Pusat Khidmat Maklumat Akademik, Universiti Malaysia Sarawak dibenarkan membuat salinan tesis ini sebagai bahan pertukaran antara institusi pengajian tinggi.

5. ** Sila tandakan (  ) di kotak yang berkenaan

SULIT (Mengandungi maklumat yang berdarjah keselamatan atau kepentingan Malaysia seperti yang termaktub di dalam AKTA RAHSIA RASMI 1972).

TERHAD (Mengandungi maklumat TERHAD yang telah ditentukan oleh organisasi/

badan di mana penyelidikan dijalankan).

TIDAK TERHAD

Disahkan oleh

(TANDATANGAN PENULIS) (TANDATANGAN PENYELIA)

Alamat tetap: LOT 1097 PIASAU JAYA, JALAN 2B, FASA 2,98000,

MIRI SARAWAK

NORAZLINA BINTI BATENI Nama Penyelia

Tarikh: 17 APRIL 2009 Tarikh: 17 APRIL 2009

CATATAN * Tesis dimaksudkan sebagai tesis bagi Ijazah Doktor Falsafah, Sarjana dan Sarjana Muda.

** Jika tesis ini SULIT atau TERHAD, sila lampirkan surat daripada pihak berkuasa/organisasi berkenaan dengan menyatakan sekali sebab dan tempoh tesis ini perlu dikelaskan sebagai SULIT dan TERHAD.

(3)

The Following Final Year Project:

Title : Prediction of Wave Propagation, Wind Wave Effects and Energy Dissipation Nearshore of Sungai Sarawak Estuary

Author : Siti Zaleha Binti Kamaluddin Matrix Number : 15310

Was read and certified by:

_______________________ ___________________

Norazlina Binti Bateni Date Project Supervisor

(4)

i

ACKNOWLEDGEMENT

The final year project had been very tough and challenging task. Firstly, Alhamdulillah, I have successfully finished the project. Thanks to ALLAH the most gracious and merciful. Very big thanks to my supervisor, Madam Norazlina Binti Hj.Bateni for her help, support, advice and motivation. My thanks also go to my supportive friends and course mate who contribute upon completion of my project.

My appreciation also awarded to the following department; Department of Irrigation and Drainage (DID) and Malaysian Meteorological Services (MMS) for their wind and wave data of Sarawak river estuary and also the department of Civil engineering UNIMAS. Lastly, my gratefulness and affection goes to my parents who give priceless support and motivation to me during completion of my project. Thank you so much for the contributions.

(5)

ii

ABSTRAK

SWAN (Simulation WAves Near shore) ialah model simulasi ombak generasi ketiga yang digunakan untuk menganalisis parameter fizikal untuk muara Sungai Sarawak. Penyelidikan ini meliputi penyebaran ombak, kesan angin ombak dan pelesapan tenaga di kawasan pantai iaitu muara sungai Sarawak. Muara sungai Sarawak menghadapi masalah iaitu peningkatan dalam kadar pemendakan di kawasan kajian. Terdapat hasil ujian pemendakan pasir yang menunjukkan hasil di mana selepas pembinaan kunci air di hulu Sungai Sarawak, ini menyebabkan paras air yang masuk menurun dan menyebabkan kesan pemendakan di kedua bahagian hulu dan hilir sungai dengan anggaran kadar pemendakan pasir sebanyak 0.3 meter dalam setahun. Projek ini dijalankan dalam tiga (3) senario untuk model ombak iaitu Tahunan, Monsun Timur Laut dan Monsun Barat Daya. Selain itu, model ombak ini juga merangkumi analisis jangka masa panjang dan juga jangka masa pendek.

Analisis jangka masa panjang menggunakan taburan ekstrim 30 tahun Gumbel dan Weibull. Hasil kajian yang penting dari kajian ini ialah Hs, Tm01, Dir dan pelesapan tenaga dari sebelas (11) lokasi yang dipilih sepanjang kawasan muara sungai Sarawak.

(6)

iii

ABSTRACT

SWAN (Simulation WAves Near shore) is a third generation wave model that is use to investigate the physical parameters of Sungai Sarawak estuary. The investigation includes the prediction of wave propagation, wind wave effects and energy dissipation near shore of Sungai Sarawak estuary. Estuary of Sungai Sarawak faced with the problems of the increments in the sedimentation rate. There have been siltation test result shows that after a sluice construction at the upstream of Sungai Sarawak, it causes the tidal influx decreases and leading to some siltation at both upstream and downstream sides with an average siltation thickness of about 0.3m in a year. For this project, the wave modeling was developed for three (3) scenarios of Annual, Northeast and Southwest monsoon. Other than that, for each of the wave modeling scenarios, both short and long term analysis of waves also have been consider and carried out. The long term wave analysis are using Gumbel and Weibull statistical distribution functions for 30-year of return period. The main results for this project are Hs, Tm01, Dir. and energy dissipation. The results are from the eleven (11) selected area stretches along the Sungai Sarawak estuary.

(7)

iv

Appendix A

LIST OF APPENDICES

Wave statistic summaries- wave and swell Appendix B1

Appendix B2 Appendix C Appendix D

Wind percentage frequency Maximum surface wind data Admiralty tide table

1-D Nonstationary spherical coordinates (*.SPE)

(8)

v

LIST OF FIGURES

FIGURES PAGE

1.1 Satellite map of the study area 6

2.1 2.2

Regular Vs Irregular waves A schematic diagram of Rayleigh distribution showing the relative location of the parameters Hrms and Hs

12 14

2.3 Spatial wave profile 15

2.4 Wave motion 16

2.5 Typical crest pattern 20

3.1 Summary of methodology 36

3.2 3.3

3.4 4.1

Action balance equation Distributed regions in the computational grid due to erroneous boundary conditions are indicated with shaded areas SWAN GUI main menu Marsden square

49 52

54 58 4.2 Shoreline orientation and wave approach

direction

60 4.3

4.4 4.5

Annual wave rose Southwest wave rose Northeast wave rose

61 62 63

4.6 24 hours April wind rose 65

(9)

vi 4.7

4.8 4.9 4.10 4.11 4.12 4.13 4.14 4.15 4.16 4.17 4.18 4.19 4.20 4.21 4.22 4.23 4.24 5.1 5.2 5.3

24 hours May to September wind rose 24 hours October wind rose

24 hours March wind rose 24 hours Annual wind rose Bottom or Bathymetry data from bathymetry map

SWAN GUI main menu SWAN GUI main menu Bottom menu for 2-D mode Open bottom data of txt. format Bottom data

Estuary of Sungai Sarawak bottom condition

SWAN GUI main menu Obstacles sub-menu Compute option sub-menu

Output location (Evenly along transect) Output locations for individual coordinates

SWAN GUI show file SWAN GUI run in progress

1-D and 2-D spectra results of SWAN GUI from Northeast scenario

1-D computation graph for mean wave direction (Dir) of Annual scenario

1-D computation graph for mean wave period (Tm01) of Annual scenario

65 65 66 66 67 69 71 72 73 74 74 77 77 78 78

79 80 81

83 84

(10)

vii 5.4

5.5

5.6

5.7

5.8

5.9

5.10

5.11

5.12

5.13

5.14

5.15

1-D computation graph for significant wave height (Hs) of Annual scenario

2-D computation graph for mean wave direction (Dir) of Annual scenario

2-D computation graph for mean wave period (Tm01) of Annual scenario

2-D computation graph for significant wave height (Hs) of Annual scenario

2-D computation graph for depth of Annual scenario

Significant wave height (Hs) graph for each of monsoon scenario

HGumbel graph for each of monsoon scenario

HWeibull graph for each of monsoon scenario

Mean wave period (Tm01) graph of Hsignificant for each of monsoon scenario Mean wave period (Tm01) graph of H_Gumbel for each of monsoon scenario

Mean wave period (Tm01) graph of HWeibull

for each of monsoon scenario Mean wave direction (Dir) graph of Hsignificant for each of monsoon scenario

85

86

87

88

91

92

95

96

(11)

viii 5.16

5.17

5.18

5.19

5.20

Mean wave direction (Dir) graph of H_Gumbel for each of monsoon scenario

Mean wave direction (Dir) graph of H_Weibull for each of monsoon scenario

Varience densities/energy densities for Annual wave model scenario

Varience densities/energy densities for Northeast wave model scenario

Varience densities/energy densities for Southwest wave model scenario

99

100

105

(12)

ix

LIST OF TABLES

TABLE ^PAGE

2.1 Probability distribution functions for long- term statistics

27

4.1 Wave conditions for each monsoon 61

5.1 Significant wave heights (Hs) results 90

5.2 Mean wave period results (Tm01) 94

5.3 Mean wave direction results (Dir) 98

5.4 Varience Densities (Vandens) / Energy Densities (E) for Annual wave model scenarios

102

103

104

(13)

x

LIST OF ABBREVIATION

ANN - DID -

Annual

Drainage Irrigation Department GUI - Graphical User Interface HAT - Highest Astronomical Tide Hs - Significant wave height

MMS - Malaysian Meteorological Services SSMO - Summary of synoptic Meteorological

observations

SWAN - Simulating Waves Nearshore NEM - Northeast monsoon

SWM - Southwest monsoon

(14)

xi

LIST OF SYMBOLS

T r - Return period σ - Standard deviation

P(x) - Extreme value distribution x - Wave height parameter K s - Shoaling coefficient H^s - Significant wave height

H1/ 3 - Average one third of maximum wave height T s - Significant wave period

d - Depth L - Wave length

K r - Wave refraction coefficient C - Celerity

T - Wave period

(15)

CHAPTER 1 INTRODUCTION

1.1 Introduction

Ocean engineering is the branch of engineering concerned with the design,

analysis and operation planning of systems that operate in an oceanic environment.

Examples of systems range from oil platforms to submarines, from breakwaters to sailboats. Nowadays, there is growing awareness of coastal problems since the past decade over the world for future research and development needs. Coastal engineering discussed and presented in this research has been limited to only the near shore zone, ranging from water depths that are just within the wave shoaling zone to the shoreline. Nearshore is indefinite zone extending seaward from the shoreline well beyond the breaker zone. The design waves for estuary Sungai Sarawak are generally based on the waves generated by wind. Estuaries are zones where fresh water debouches from river mouths into the sea causing stratification due to the density difference.

(21)

2

The principal coastal elements of the coastal zone of Sarawak are tides, winds and monsoon influences, wave action, sediment transport, littoral drift and mangroves. In ocean engineering, this inner coastal zone such as estuaries must given priority to make sure people are to live there in harmony with the environment. Wind generated waves are by far the largest contribution of energy from sea to the beach and near shore physical system. Air currents that caused by differences in air temperature above the oceans blow across the water and returning some energy to the water by generating wind waves. Winds that blow over the surface of oceans will generate waves.

This project stressed on physical and mathematical modeling of coastal processes for the study area, Sungai Sarawak. Simulation Waves Nearshore, SWAN will be used to modeling the design waves near shore of Sungai Sarawak from various return period. In the analysis of the coastal environment, spectral models are useful for determine the spectra in the region of interest, i.e. the region where wave data are needed for a design of a coastal structure or for other purposes.

SWAN is a phase averaging wave model designed to obtain realistic estimates of wave parameters in coastal areas, lakes or estuaries from given wind, bottom, and current conditions (Holthuijsen et al., 2004). SWAN represents a water wave

(22)

3

models that significantly improved accuracy in design. SWAN (Booij et al.1999, Ris et al.1999) is one of the most widely applied spectral wave models at present in coastal engineering studies. SWAN is currently being used in about 50 countries, 700 institutes are registered. It is a public domain to the user’s worldwide. In Russia, SWAN had been applied for hind casting waves for Barents, Caspian, Baltic, North, Okhotsk, Black, Azov, Mediterranean, Japan seas and Ladoga Lake.

1.2 Problem statement

According to Department of Irrigation and Drainage, Sarawak, 2000, Sungai Sarawak is important for Southwestern Sarawak as source of water, transportation and the inhabitants. The majority of the population lives in coastal areas in Malaysia. There is more than 80% population live along the 800 km coastline in Sarawak. The principal Uses of the Coastal Zone of Sarawak are human settlement, urbanisation, recreation, agriculture, industrial estates, amenity, timber processing and fishery. Sungai Sarawak near shore environments is facing problems with coastal landforms that exist because hydrodynamic of waves, currents, tides and wind processes erode, transport and deposit particles of sediment. Sedimentation is a major problem to Sungai Sarawak near shore. Sedimentary processes are among the most important but least understood aspects of the coastal environment.

Sedimentary processes are the result of fluid/sediment interactions, or more

(23)

4

specifically, the response of sediment particles to the forces produced by shoaling waves, tides, coastal currents and winds.

According to Xiaodong Zhao et al., 2003, the Sarawak River regulation project has just been built in the year 1997/1998. The project includes a water retaining dam to the constructed upstream of oil terminal and a sluice to be built 1.8km downstream of Ironwoods. The main function of the project is to adjust the upstream water level of Sarawak River, especially to keep a high water level near Kuching City to beautify environment. As the runoff of Sarawak River is rather small, the sluice gates are normally closed. The automatic opening and closing gates are only used to adjust the upstream water level. But when the floodwater comes, the sluice gates must be opened. This river regulation project gives impact to Sungai Sarawak estuary as there are increments in the sedimentation rate. The siltation test result show that after the sluice construction, tidal influx decreases, leading to some siltation at both upstream and downstream sides with an average siltation thickness of about 0.3m in a year.

(24)

5 1.3 Description of study area

Sarawak is Malaysia’s largest state located on the island of Borneo. It is located between longitude 109ô36’E and 115ô40’ E and latitude 0ô50’N and 5ôN. The study area is within Sungai Sarawak near shore. Sungai Sarawak is a major river in the Sarawak state in Malaysia with its upper reaches and middle reaches running through a hilly area. Sungai Sarawak has two main tributaries; Sungai Sarawak Kiri and Sungai Sarawak Kanan. Sungai Sarawak (Muara Tebas) length is 38Km or 21miles. The river bed of Sungai Sarawak is almost in the natural state of an alluvial plane river without any man-made embankment.

The cross section of river is mainly in U-shape. The width, depth and area of the estuary are relatively stable during 1978 to 1996 (Xiaodong Zhao et al., 2003).

The approach channel of Kuching port is the natural waterway of Sungai Sarawak containing two shoals, namely the Inner Bar and the Outer Bar, with the shallowest depth of 5.1m. The study areas boundaries are within the near shore of Sungai