i BEACH RESPONSE DUE TO THE PRESSURE...

i

BEACH RESPONSE DUE TO THE PRESSURE EQUALIZATION MODULES (PEM)

SYSTEM

MOHD SHAHRIZAL BIN AB RAZAK

A project report submitted in 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

JUNE 2009

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Especially dedicated to my beloved family, fellow friends and to everyone who involves

in my life, you will always be in my heart……………………..

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ACKNOWLEDGEMENT

I would like to convey my sincerest thanks to my supervisor Professor Hadibah

Binti Ismail for her dedicated guidance, valuable assistance and endless encouragement

throughout the accomplishment of this project.

I am grateful to the staff of Department of Irrigation and Drainage Malaysia who

had been very helpful in providing assistance throughout the work. Special thanks are

also extended to Director of Department of Irrigation and Drainage, Malaysia for his

permission to allow the accessibility of data for this project. My thanks are also extended

to other lecturers for their advice whether directly or indirectly in improving my Master

Project. Also not forgetting my friends especially Mr. Bahman Esfandiar Jahromi, Miss

Hasmida Hamza, and Mr. Abdul Haslim Shukor Lim for their guidance in helping me to

clarify any problems related to this study.

I am indebted to my employer Universiti Putra Malaysia and Ministry of Higher

Education for providing me the opportunity and the financial means to pursue this study.

Last but not least, my deepest and eternal gratitude to all those who had helped directly

or indirectly in my project.

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ABSTRACT

Coastal erosion is a significant problem with dramatic effects on the coastline.

There is an urgent need to introduce new and cost-effective measures that can mitigate

the impacts on the shoreline. This study has been initiated to investigate the response of

the beach at Teluk Cempedak due to the beach nourishment and Pressure Equalization

Modules (PEM) system. The objectives of this study are the determination of closure

depth and effectiveness of the system in treating the erosion process. The depth of

closure was examined using both data from a series of beach profile surveys and from

empirical formulae. The widely accepted Fixed Depth Change (FDC) method was

explored and the hc before and after the installation of PEM system was investigated.

The research found that multiple closure points can occur along the profile lines. The

closure depth after the installation of PEM system was found to be deeper and the

closure point is further seaward at the southern part of the beach. The Hellemeier‟s

equation over predict hc by 76 %, however it reveals that the equation is still robust in

determining an upper limit of hc. The simplified equation was developed at Teluk

Cempedak beach in predicting closure depth and can be equated to 0.98 times H0.137.

From the survey data, it is found that after three years, the total sand volume and beach

elevation are significantly higher in PEM areas. Generally, the result presented indicates

the decreasing value of rate of erosion. Thus it revealed that PEM system is able to

stimulate accretion of sand and yet slow down the erosion process. However, based on

the sand volume distribution pattern, after three years, it is obviously seen that the

accretion of sand occurring at the northern part while erosion process is taking place in

the southern part of the beach. Based on the distribution pattern of bed elevation over the

chainage, overall, the upper part of the beach is convex unlike earlier i.e before the

installation of PEM system, where the beach was low and concave. This phenomena

indicates that the system contribute to a significant accretion of sand and thus created a

higher beach level at about 10 m to 55 m towards the sea. However, this trend only can

be seen at a certain chainage. The PEM efficiency in terms of increment in bed elevation

can only be observed at CH 400 till CH 800 while at CH 900 towards the south, the

efficiency is decreasing. This shows that the accretion of sand is only occurring at the

northern part and the beach is eroding at the southern part. Therefore, based on the

available four years record of data, there is a certain part of the beach benefiting from the

PEM system. However, some parts are still experiencing the erosion process.

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ABSTRAK

Hakisan pantai merupakan masalah ketara yang memberi kesan kepada

perairan pantai. Oleh itu, terdapat tindakan segera untuk memperkenalkan kaedah

baru dan lebih menjimatkan yang mana dapat mengatasi masalah hakisan pantai

ini. Kajian ini telah dijalankan untuk menyiasat tindak balas pantai terhadap

penambakan pantai (beach nourishment) dan sistem Pressure Equalization

Modules (PEM). Objektif utama kajian ini adalah penentuan kedalaman tertutup

(closure depth) dan keberkesanan sistem dalam merawat hakisan pantai.

Kedalaman tertutup telah dikenalpasti menggunakan kedua-dua data iaitu data

ukur bersiri dan formula empirikal. Kaedah Perubahan Kedalaman Tetap telah

digunakan dan kedalaman tertutup sebelum dan selepas pemasangan sistem PEM

telah disiasat. Kajian menunjukkan bahawa beberapa kedalaman tertutup boleh

berlaku di sepanjang garis ukur. Kedalaman tertutup selepas pemasangan sistem

PEM didapati lebih dalam dan lokasi titik kedalaman tertutup jauh menghala ke

tengah laut khususnya di bahagian selatan pantai. Persamaan Hellemeier didapati

lebih tinggi dengan lebihan purata 76 % bagaimanapun mendedahkan bahawa

persamaan ini masih kukuh bagi menentukan nilai had teratas untuk hc.

Persamaan ringkas telah dicipta bagi pantai Teluk Cempedak dalam menentukan

kedalaman tertutup dan boleh disamakan dengan 0.98 kali ketinggian ombak

H0.137. Daripada data ukur juga, jumlah isipadu pasir and ketinggian pantai

didapati lebih tinggi di kawasan pemasangan sistem PEM selepas tiga tahun

pemantauan dijalankan. Umumnya, hasil keputusan menunjukkan bahawa kadar

hakisan telah menurun. Ini menunjukkan bahawa sistem PEM berupaya

mengumpul pasir sekaligus melambatkan proses hakisan. Walaubagaimanapun,

berdasarkan kepada jumlah pengagihan isipadu pasir, jelas menunjukkan

bahawa pengumpulan pasir hanya terjadi di bahagian utara pantai manakala

proses hakisan masih berlaku di bahagian selatan pantai. Berdasarkan kepada

bentuk pengagihan bagi ketinggian pantai pula, secara keseluruhannya, bahagian

atas pantai lebih cembung berbanding sebelumnya yang mana ianya lebih

cekung. Fenomena ini menunjukkan bahawa sistem PEM menyumbang kepada

pengumpulan pasir seterusnya meningkatkan ketinggian pantai pada jarak 10 m

hingga 55 m menghala ke arah laut. Bagaimanapun, keadaan ini hanya berlaku di

kawasan-kawasan tertentu sahaja. Keberkesanan PEM dari segi peningkatan

ketinggian pantai hanya berlaku di CH 400 hingga CH 800 sementara di CH 900

menghala ke selatan pantai pula menunjukkan penurunan peratus keberkesanan.

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Ini menunjukkan bahawa pengumpulan pasir terjadi di bahagian utara pantai

manakala proses hakisan masih berlaku di bahagian selatan pantai. Oleh yang

demikian, berdasarkan kepada data ukur bagi 4 tahun kerja pemantauan, terdapat

sebahagian kawasan pantai yang mendatangkan manfaat daripada sistem PEM

manakala sebahagiannya lagi masih mengalami proses hakisan.

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TABLE OF CONTENTS

TITLE i

CONFESSION ii

DEDICATION iii

ACKNOWLEDGEMENT iv

ABSTRACT v

ABSTRAK vi

TABLE OF CONTENTS viii

LIST OF TABLES xv

LIST OF FIGURES xvi

LIST OF ABBREVIATIONS xx

LIST OF SYMBOLS xxii

LIST OF APPENDIX xxiv

CHAPTER TITLE PAGE

I INTRODUCTION 1

1.1 Introduction 1

1.2 Statement of Problem 4

1.3 Objectives of Study 6

ix

1.4 Scope of Study 7

1.4.1 Study Area 7

1.4.2 Data Collection and Analysis 8

1.4.3 Determination of Closure Depth 9

1.5 Terminology Used in This Study 9

1.5.1 Beach Nourishment 9

1.5.2 Closure Depth 10

1.5.3 Equilibrium Profile 10

1.5.4 Pressure Equalization Modules System 11

1.6 Importance of Study 11

II LITERATURE REVIEW 13

2.1 Introduction 13

PART A: BEACH NOURISHMENT/ DEPTH OF CLOSURE/

BEACH EQUILIBRIUM PROFILE

2.2 Beach Nourishment 14

2.2.1 Definition(s) of Beach Nourishment from

Different Perspectives 15

2.2.2 Advantages and Disadvantages of Beach

Nourishment Activities 16

2.3 Identification of the Depth of Closure 18

2.3.1 Estimation of the Depth of Closure 23

2.3.2 Depth of Closure and Vertical Datum 24

2.4 Previous Case Study- Determination of Depth of Closure 24

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2.4.1 Ocean City, Maryland 25

2.4.2 Pria de Fero, Algarve, South Portugal 25

2.4.3 Kelantan Coast, Malaysia 26

2.5 Equilibrium Beach Profile 27

PART B: PRESSURE EQUALIZATION MODULE (PEM)

SYSTEM

2.6 Pressure Equalization Module (PEM) System

Application Concept 30

2.6.1 The Advantage of PEM System 32

2.7 Design Criteria of Pressure Equalization Module (PEM)

System at Teluk Cempedak Beach, Kuantan 33

2.7.1 System Installation 35

III RESEARCH METHODOLOGY 39

3.1 Introduction 39

3.2 Study Area 40

3.3 Data Set 43

3.3.1 Beach Profile Survey 43

3.3.2 Winds and Waves Data 44

3.3.3 Tidal Data 44

3.3.4 Bed Sediment Data 45

3.4 Measurement Techniques 47

3.4.1 Beach Profile Measurement 47

3.4.2 Historical Shoreline Changes 48

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3.4.3 Tidal Data Measurement 49

3.4.4 Aerial Photograph 49

3.5 Data Analysis 50

3.5.1 Determination of Depth of Closure from

Beach Data Profile 50

3.5.2 Determination of Depth of Closure from

Empirical Formula 53

3.6 PEM Effectiveness Evaluation 53

IV DATA ANALYSIS AND RESULTS 56

4.1 Introduction 56

4.2 Description of Study Area 57

4.3 Data Set 58

4.3.1 Beach Profile Survey 59

4.3.2 Wave Data Analysis 62

4.3.3 Tidal Height Information 64

4.3.4 Sediment Properties 65

4.4 Determination of Depth of Closure from Beach Profile

Survey 69

4.5 Depth of Closure for Pre-Project Condition (2003) 69

4.5.1 Closure Depth at CH 700 and CH 1400 69

4.5.2 Closure Depth at CH 100 70





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4.6 Summary of Depth of Closure for Pre-Project Condition 82

4.7 Depth of Closure for Post-Project Condition 83

4.8 2005 Beach Profile 83















4.9 Summary of Depth of Closure for

2005 Post-Project Condition 98


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4.10.5 Closure Depth at CH 500 until CH 800 103



4.10.8 Closure Depth at CH 1100 and CH 1200 107


4.10.10Closure Depth at CH 1400 110


















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4.14 Comparison of hc between Pre-Project Condition and

Post-Project Condition 126

4.15 Estimation of Predictive Closure Depth by

Hallemeier‟s Equation 128

4.16 PEM Effectiveness Evaluation 130

4.16.1 Total Sand Volume Changes 130

4.16.2 Beach Level Changes 136

4.16.3 Distribution Pattern of Beach Level Changes 137

4.16.4 PEM Efficiency 139

V CONCLUSIONS AND RECOMMENDATIONS 143

5.1 Introduction 143

5.2 Recommendation 147

5.2.1 Criteria of Limit Line 147

5.2.2 Standard Deviation Depth Change (SDDC)

Method 148

5.2.3 Profile Survey 148

5.2.4 Predictive Formula for Each Chainage 149

REFERENCES 150

APPENDICES 154

xv

LIST OF TABLES

NO. TITLE PAGE

1.1 List of Coastal Erosion Areas in Malaysia 5

4.1 Data Available for This Study 58

4.2(a) Centerline Coordinates of Selected Survey Data Set and

Its Correspondence Depth (Before Installation of

PEM System) 61

4.2(b) Centerline Coordinates of Selected Survey Data Set and

Its Correspondence Depth (After Installation of

PEM System) 61

4.3 Tidal Level Along Study Shoreline (meter, LSD) 65

4.4 Summary of Design Size Ranges for Borrow Sand 67

4.5(a) Sand Size Analysis (upper beach face for pre-project condition) 68

4.5(b) Sand Size Analysis (lower beach face for pre-project condition) 68

4.6 Closure Depth for 2003 Pre-Project Profile 82

4.7 Closure Depth for 2005 Post-Project Profile 98



4.10 hc Simplified Equation Compared with Effective hc 2007 128

4.11 Total Sand Volume and Sand Gain or Loss at the Study Area 132

4.12 PEM Efficiency 140

xvi

LIST OF FIGURES

NO. TITLE PAGE

1.1 The Location of Study Area at Teluk Cempedak Beach, Kuantan 7

2.1 Schematic Diagram of the Depth of Beach Profile Closure 19

2.2 Definition Sketch of the Closure Depth 20

2.3 Pressure Equalization Module – schematization 30

2.4 PEM Function Dewatering the Beach 32

2.5 Design of Pressure Equalization Module Pipes 34

2.6 Preparation for PEM Installation on 9th

July 2004 37

2.7 Preparation of borehole for PEM Installation on 9th

July 2004 37

2.8 Placement of PEM Pipe 38

2.9 Exposed PEM Pipe at Chainage 800 38

3.1 Site Study Area 40

3.2 The Beach Slope is Steeper Due to Erosion Problem 41

3.3 The Beach is Narrower and Recreational Activities are Limited

for Beach Visitor 41

3.4(a) Beach Condition Before the Installation of PEM System 42

3.4(b) Beach Condition After the Installation of PEM System 42

3.5 Location of Sediment Samples and Sand Source 46

3.6 The Algorithm of Closure Depth Determination 52

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3.7 Research Methodology Chart 55

4.1 Profile Line at Study Area 60

4.2 Histogram of Design Wave Height 62

4.3 H0.137 Wave from SSMO Wave Data (1949-1983) 63

4.4 Relationship between Wave Height and Wave Period 64

4.5 Plan View for Distribution of Design Sand Size 67

4.6 Closure Depth (hc) at CH 100 for 2003 Pre- Project Profile 70












4.18 Closure Depth (hc) at CH 100 for 2005 Post- Project Profile 82

4.19 Closure Depth (hc) at CH 200 for 2005 Post - Project Profile 83








xviii




























xix






4.59 Closure Depth at Teluk Cempedak beach, Kuantan 127

4.60 Closure Point at Teluk Cempedak beach, Kuantan 127

4.61 Total Sand Volume (m3) 131

4.62 Sand Gain and Loss for Year 2005 134



4.65 Sand Volume Distribution Pattern 135

4.66 Average Beach Level 70 m wide 136

4.67 Beach Level at CH 400 and CH 500 137





4.72 PEM Efficiency at CH 400 and CH 500 141





xx

LIST OF ABBREVIATIONS

CED Coastal Engineering Division

CEM Coastal Engineering Manual

CH Chainage

cm centimeter

DID Department of Irrigation and Drainage Malaysia

EDM Electronic Distance Measuring

FDC Fixed Depth Change

hc Depth of Closure

HAT Highest Astronomical Tide

LAT Lowest Astronomical Tide

LSD Land Survey Datum

m meter

mm millimeter

MSL Mean Sea Level

MHW Mean High Water

MHHW Mean Higher High Water

MLHW Mean Lower High Water

MLW Mean Low Water

MHLW Mean Higher Low Water

xxi

MLLW Mean Lower Low Water

MMD Malaysian Meteorological Department

MRCB Malaysia Resource Corporation Berhad

NOS National Ocean Survey

PEM Pressure Equalization Modules

SDDC Standard Deviation Depth Change

SSMO Synoptic Shipboard Meteorological Observation

USGS U.S Geological Survey Quadrangles

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LIST OF SYMBOLS

A profile scale parameter with dimensions of length to the 1/3 power

D16 size of material of which 16% is finer



Dc/ h*/ hc closure depth

g gravity

h water depth at distance y from the shoreline

hCi depth of closure, innershore; from profile survey

hcm depth of closure, middleshore; from profile survey

hco depth of closure, outershore; from profile survey

He non breaking significant wave height that is exceeded 12 hour per t years

or ( 100/730t)% of the time

H0.137 significant wave height exceeded 12 hours in a year

H/Hs annual mean significant wave height

m fore shore slope of the beach profile

t time

Te wave period associated with He

xxiii

y equilibrium beach profile

vb amplitude of the wave induced bottom velocity

ρ mass densities of water

ρ s mass densities of sediment

σH standard deviation

xxiv

LIST OF APPENDIX

APPENDIX TITLE PAGE

A Profile Surveys from the Coastline of Pantai Teluk Cempedak

Kuantan 2003, 2005, 2006, and 2007 154

1

CHAPTER I

INTRODUCTION

1.1 Introduction

Land based activities and natural physical processes have resulted in significant

modifications of the shorelines in many countries, with drastic effects on the coastal

geomorphology as well as on the coastal infrastructures. There is an urgent need to

introduce new and cost-effective measures that can mitigate the impacts on the

shorelines. In many locations, coastal erosion is a significant problem with dramatic

effects on the coastline. The impact on coast-near infrastructures and property can be

massive. Until now the urgent need for coastal erosion protection, has forced society to

2

use costly solutions with bulky constructions and beach nourishment, where the

dredging part of the process is very hostile to the marine environment.

Coastal protection can generally be divided into hard engineering and soft

engineering (Ghazali, 2005). Hard engineering structures such as revetments, seawalls,

bulkheads and groynes are considered traditional erosion protection structures with

distinct functions. These are typically constructed of quarry stones or concrete units.

Seawalls and revetments are constructed parallel to the shoreline and form a barrier

between waves and the coast. Whilst preventing any further loss of material landwards,

waves reflected by the seawall causes scouring at the toe in front of the seawall and

eventual lowering of the beach. Thus where recreational space is concerned, the use of

seawalls and revetments are not beneficial in the long run as the end result is a

deepening or steepening of the sea bed in front of the structure resulting in loss of beach

space.

The term „soft engineering‟ is normally used to describe methods that depart

from hard protection structures that use quarry stones or concrete blocks as the main

structural component. The use of sand either as a fill material placed directly on the

eroding beach or encased within geotextiles are amongst the methods that qualify as soft

engineering. In beach nourishment, loose sediments are imported and placed on the

target beach to form a wider beach berm as a buffer for waves. The „new‟ beach will

then continue to be shaped by the natural forces i.e. wind, wave and tidal currents, to an

equilibrium shape. Beach nourishment is now common and is the preferred method of

protecting or rehabilitating eroding recreational beaches (Ghazali, 2004). The

construction process however involves dredging, transport and placement of sand in a

marine environment which causes water quality problems, habitat displacement and

stress to marine life. Beach nourishment is also considered semi-permanent and requires

replenishment as time progresses.

3

Beach nourishment, also called artificial nourishment, replenishment, beach fill,

and restoration, comprises the placement of large quantities of good quality sand within

the near-shore system usually to address a continuing deficit of sand, manifested by

shoreline recession (Dean, 2002). The term nourishment applies to both the initial

placement of material and to later nourishments for the projects where multiple

placements occur. The terms beach nourishment may be used to differentiate between

material that is placed on the sub-aerial beach and its underwater extensions from profile

nourishment or berm placement which involves the placement of material offshore with

the anticipation that either the material will provide protection to the shore from erosion

by reducing the effects of waves.

SIC, Skagon Innovation Centre (Jakobsen, 2007) has invented an

environmentally friendly coastal protection system. The SIC system is based on Pressure

Equalization Modules (PEM). A long term and comprehensive test of the efficiency has

been carried out on the west coast of Denmark. Furthermore, a three year scientific

research programme was performed in year 2005. The obtained result shows that the

system is far more efficient than conventional methods such as groins, breakwaters, and

sand nourishment. Due to the well-known lee side erosion effect, groins and breakwaters

create even greater erosion in adjacent coastal areas. Furthermore, Jakobsen reported that

sand nourishment by dredging is in general terms a very expensive approach (about

130,000 USD/km/year in Denmark), but unfortunately, it is an inefficient solution since

usually the sand will disappear during the first spring period.

4

1.2 Statement of Problem

The evolution of the coast is produced by natural processes that occur on a broad

time scale ranging from hours to millennia. Beach erosion is one such process that

occurs when the losses of beach sediment exceed the gains. As this volume of sediment

decreases, the beaches become narrower. When backed by fixed developments, beaches

are unable to respond naturally to changes, resulting in a cessation of beach/dune

interactions, instability of the fronting beach, and a reduction of sediment inputs into the

sediment budget. In the absence of development, coastal erosion is not a hazard. The

presence of large and expensive communities in the coastal zone creates the potential for

major disasters resulting from erosion. Erosion is typically episodic, either with the

shore recovering afterward or with the episodes being cumulative and leading to a

progressive retreat of the shoreline and property losses. The erosional impact on

properties depends on the width of the buffering beach and on the nature of the beach as

defined by the morphodynamics model of Wright and Short (1983).

Malaysia has about 4809 km of coastline. Of the 4809 km of coastline, about

1415 km is at present subject to erosion of various degree of severity (Annual Report

DID, 2007). Along the coast, sediment is continuously being moved. When the rate of

sediment entering and leaving the coast equals, the coast is said to be in dynamic

equilibrium. Erosion occurs when, over a period of time, the volume of sediment

transported out is greater than that transported into the coast. It follows that the reverse

will result in accretion. The erosion process occurs continuously and as a result, the

beach slowly retreats. This is normally indicated by the formation of beach scarp along

the coast.

Erosion may be amplified during monsoon period when high water levels,

associated with the season, result in waves breaking directly against the scarp, causing

loss of material. Though, some of this material might be returned to the shore by the

5

swells after the monsoon, the quantity returned is normally much less; hence the nett

result is erosion. Control of coastal erosion has now become an important economic and

social need. Table 1.0 shows the list of coastal erosion areas in Malaysia. From this

table, it can be concluded that 73.40 % or 52.1 km of the total length of coastline in

Pahang area has been eroded. To this end, the government is implementing a strategy to

control the erosion problem. The government has spent about RM 15,400,000.00 to

invest in a new system for control of coastal erosion called the Pressure Equalization

Module (PEM). The system has been successfully installed at the Teluk Cempedak

beach in Pahang and is the first coastal erosion project applying this method in Malaysia

and Asia (Annual Report DID, 2004).

Table 1.0: List of Coastal Erosion Areas in Malaysia

State

Length of

Coastline

(km)

Length of Coastline Having Erosion Total Length of

Coastline

Category 1 Category 2 Category 3 Having Erosion

CRITICAL

EROSION

(km)

SIGNIFICANT

EROSION

(km)

ACCEPTABLE

EROSION

(km)

(km)

(%)

State

Length

Critically

Eroded

Perlis 20 4.4 3.7 6.4 14.5 72.50

Kedah 148 31.4 2.2 6.9 43.5 29.40

Pulau Pinang 152 42.4 19.7 1.1 53.2 41.60

Perak 230 28.3 18.8 93.1 140.2 61.00

Selangor 213 63.5 22.3 66.1 151.9 71.30

N.Sembilan 58 3.9 7.7 12.9 24.5 42.20

Melaka 73 15.6 15.1 6 36.7 50.30

Johor 492 28.9 50.3 155.6 234.8 47.70

Pahang 271 12.4 5.2 37.6 52.1 73.4

Terengganu 244 20 10 122.4 152.4 62.50

Kelantan 71 5 9.5 37.6 52.1 73.40

W.P Labuan 59 2.5 3 25.1 30.6 51.90

Sarawak 1035 17.3 22.3 9.6 49.2 4.80

Sabah 1743 12.8 3.5 279.2 295.5 17.00

Total 4809 288.4 193.3 932.8 1,415 29.41 %

6.0 % 4.0 % 19.4 %

Source: Annual Report, Department of Irrigation and Drainage, (DID) Malaysia (2007)

6

Based on the Detailed Design Report 2006, Teluk Cempedak beach has a history

of erosion. The beach area has undergone slow and steady erosion that has resulted in

the narrowing of the beach area, which has affected adversely on the recreational and

tourist activity in this area. Although the beach is classified as stable under the National

Coastal Engineering Study (NCES) of 1985, at present the average retreat rate is

estimated to be 0.8 m/year. If protective measures are not taken, the beach eventually

will be eroded, and the ocean waves approach the land will endanger the properties

located along the beachfront and in the hinterland. At present, coastal structures of

various designs had been built to protect the public recreational areas occupying the

northern part of the beach and the hotels on the southern part. However more efforts are

needed to protect and develop the beach to be among the best tourists‟ attractions in

Malaysia.

1.3 Objectives of Study

The main objective of this study is to investigate the response of the Teluk

Cempedak beach due to installation of the Pressure Equalization Module (PEM) system.

The specific objective of this study is to determine the depth of closure due to the

installation of the Pressure Equalization Modules (PEM) system as well as to evaluate

the PEM effectiveness based on total sand volume and beach level retained on the beach

after a specific time period. A comparison of results before and after the installation of

PEM system has been successfully investigated.

7

1.4 Scope of Study

1.4.1 Study Area

The location of the study area is at Teluk Cempedak on the East Coast of

Peninsular Malaysia near the town of Kuantan (see Figure 1.1). Teluk Cempedak is

situated in a pocket bay adjacent to Hyatt- and Sheraton Hotel and has a total length of

1100 metres. The beach called Teluk Cempedak is one of the main tourist attractions in

Pahang, where there are hotels and eateries occupying the northern portion of the beach,

while Hyatt and Sheraton hotels are situated in the southern part. The beach is located

between the headlands of Tanjung Pelindung Tengah and Tanjung Tembeling, with

Sungai Cempedak draining into the northern end of the bay. This river drains Bukit

Pelindung and discharges some sediment and moderately polluted water from developed

areas within its catchment. The bay has been developed for public recreation as well as

for local and international tourism activities.

Figure 1.1: The Location of Study Area at Teluk Cempedak Beach, Kuantan

Location of Study Area:-

Teluk Cempedak Beach,

Kuantan, Pahang

8

1.4.2 Data Collection and Analysis

Data collection is the most important part of this study. Data made available in

this study comprise the following:-

(i) Profile survey data.

(ii) Bathymetric data.

(iii) Wave data.

(iv) Wind data.

(v) Tidal data.

(vi) Bed sediment data.

A detailed description of this data is discussed in the following chapter. This data

had been used to determine the depth of closure by using analytical procedure. Data

analysis involves the following scope of work:-

(a) Compiling, plotting and comparing series of survey data.

(b) Analysis of wave data to obtain the significant wave height and wave

period.

(c) Analysis of sediment data for determination of mean particle size (D50).

(d) Determination of closure depth using Hellemeier equation (1981).

9

1.4.3 Determination of Closure Depth

Depth of closure is an important concept in coastal engineering that defines the

seaward limit of significant net sediment transport along a wave-dominated sandy beach

profile over a period of time and is used to establish shoreline and volume change

relationships. The depth of closure can be observed along a specific segment of coast in

a series of profiles taken over a period of years as the depth at which the profiles

consistently come together within the accuracy of the survey procedures. (Robertson et

al, 2008).

Ferreira (2003) reported that the depth of closure is the depth that separates the

active cross-shore profile from a deeper zone where the sediment transport is much

weaker and where morphological changes are less perceptible. He suggested that this

depth should be determined by morphological comparison, existing some formulations

(e.g. Hallermeier, 1981, Birkemeier, 1985) that can be used for estimating a standard

annual value for each coastal region when a morphological approach cannot be used.

1.5 Terminology Used in This Study

1.5.1 Beach Nourishment

Beach nourishment involves the placement of large quantities of sand or gravel

in the littoral zone to advance the shoreline seaward. Such nourishment can be used to

create or to maintain a recreational beach or to build out the shore in order to improve

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the capacity of the beach to protect coastal properties from wave attack (Komar,1998).

Beach nourishment represents a soft solution and is the only form of shore protection

that attempts to maintain a naturally appearing beach.

1.5.2 Closure Depth

According to Nicholls et al (1998) in their Coastal Engineering Technical Note,

they claimed the depth of closure for a given or characteristic time interval is the most

landward depth seaward of which there is no significant change in bottom elevation and

no significant net sediment transport between the near-shore and the offshore.

1.5.3 Equilibrium Profile

Equilibrium beach profile is conceptually the result of the balance of destructive

versus constructive forces (Dean, 2002). The beach profile is the variation of water depth

with distance offshore from the shoreline. In nature, the equilibrium profile is considered

to be a dynamic concept, for the incident wave field and water level change continuously

in nature; therefore, the profile responds continuously. By averaging these profiles over

a long period, a mean equilibrium can be defined.

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1.5.4 Pressure Equalization Module System

Pressure Equalization Module (PEM) system is a new innovative system

originated from Denmark for beach erosion control. The system was successfully

installed in many countries all over around the world including Australia, Ghana,

Denmark as well as Malaysia. It is designed to stimulate accretion of sand on certain

beaches and to slow down the erosion process in some other beaches. PEM system is

radically different from other protection measures where hard structures like concrete

walls, rock embankment and groynes are used. This system has low impact on the

aesthetics of the beach area and thus represents a more environmental friendly coastal

protection method. It is assumed that under PEM influence the groundwater table in the

beach will be lower and the swash infiltration-exfiltration rate will decrease, that will

cause decreasing of intensity of the beach erosion in the swash zone.

1.6 Importance of Study

By the end of this study, the results presented will provide some base line

information for local engineers in order to suggest a better plan for beach protection in

other location by using a combination of PEM system and beach nourishment. Based on

the findings of this study, the following expected results can be drawn:-

(a) The depth of closure will be higher as well as the point of closure will be

further seaward and the width of the beach will be wider due to the effect of

the PEM system.

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(b) From this study, engineers will be able to utilize an analytical model,

specific to the local conditions, to predict depths of closure for areas where

the beach has been installed with a PEM system.

(c) The Pressure Equalization Modules system is expected to effectively create

a new beach by enhancing infiltration and sediment deposition.

(d) An effective PEM in combination with beach nourishment will be able to

extend the lifetime of a nourished beach considerably. This technique of

using a soft engineering approach could be applied to other beaches as well.

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