PERPUSTAKAANUMP

COASTAL DEFENCE: A I I I I II III II CE OF LA BUAN

0000073577

SJIARIFAH NADIA BINTI SYED AHMAD

A report submitted in partial fulfilment of the

requirements for the award of the degree of

Bachelor of Civil Engineering

Faculty of Civil Engineering & Earth Resources

UNIVERSITY MALAYSIA PABANG

11

JUNE 2012

ABSTRACT

Coastal defense structure is a structure used as deterrent or breakwater to

mitigate erosion that occurred in coastal areas. However, failures often occur on the

structure due to problems such as poor installation which does not follow the

specifications. Another problem that normally caused the failure of coastal defence

structure is the weak bed protection. As such, a case study has been conducted at

Pantai Punggur, Johore that uses Labuan Block as coastal defense structure. The

Labuan blocks constitute of two concrete block type that are Type B in trapezium

shaped and Type A in square shaped. They are suitable to be used in the sandy beach

area as wave deterrent. It used geotextile as bed layer. This study aimed to evaluate

the effectiveness of Labuan Block at the stated area and factors that resulted in failure

for the structure. Two methodologies were applied in this study, first by analyzing

the hydrodynamic data such as wave, tide and soil profile to relate with the problem

occurred. The second method is by doing visual inspection to get the actual view of

the level of erosion and its effect on the study area. From the study, it was found that

block height arrangement was not enough to withstand the wave especially during

high tide. As a conclusion, suitable height arrangement and improvement on existing

bed protection is suggested so that the implementation of Labuan block is more

effective and able to last longer.

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ABSTRAK

Struktur perlindungan pantai adalah binaan yang digunakan sebagai penghalang

atau pemecah ombak di kawasan pantai bagi mengurangkan hakisan yang berlaku di

kawasan pantai. Tetapi seringkali berlaku kegagalan pada struktur tersebut yang

berpunca daripada beberapa masalah seperti cara pemasangan yang tidak mengikut

spesifikasi yang betul dan juga perlindungan pada dasar struktur yang agak lemah.

0kb itu satu kajian kes telah dijalankan di kawasan Pantai Punggur, Johor yang

menggunakan Labuan Blok sebagai struktur perlindungan pantai. Blok Labuan terdiri

daripada duajenis blok konkrit iaitu jenis B yang berbentuk trapezium danjenis A

yang berbentuk segiempat. Tanya sesuai digunakan di kawasan pantai berpasir

sebagai penghalang ombak dan menggunakan geotektil sebagai pelapik pada

dasamya. Kajian mi bertujuan untuk mengetahui sejauhmana keberkesanan

perlindungan dasar yang digunakan serta faktor-faktor yang menyebabkan kegagalan

pada struktur tersebut. Duajenis sumber makiumat digunakan dalam kajian mi iaitu

pertamanya dengan menggunakan data hidrodinamik pantai untuk mengaitkannya

dengan masalah yang berlaku. Sumber kedua adalah dengan melakukan lawatan

tapak bagi melihat kesan-kesan kegagalan yang berlaku bagi mengaitkannya dengan

kajian dari sumber pertama. Daripada hasil kajian didapati susunan ketinggian blok

tidak mencukupi untuk menghalang ombak terutamanya ketika air pasang. Selain itu,

geotekstil yang diganakan juga tidak berkesan sebagai perlindungan dasar yang

efektif. Sebagai penutup keseluruhan, susunan ketinggian yang sesuai serta

penambahbaikan kepada system perlindungan dasar yang digunakan telah

dicadangkan supaya Blok Labuan dapat bertindak sebagai penghalang ombak yang

lebih berkesan dan dapat tahan lama.

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vii

TABLE OF CONTENTS

Page

SUPERVISOR'S DECLARATION

STUDENT'S DECLARATION

DEDICATION

ACKNOWLEDGEMENTS iv

ABSTRACT

ABSTRAK

TABLE OF CONTENTS vii

LIST OF FIGURES x

LIST OF SYMBOLS xii

LIST OF ABBREVIATIONS xiii

CHAPTER I INTRODUCTION

1.1 General 1

1.2 Coastal Line in Malaysia 2

1.3 Coastal Defence Structures 3

1.4 Problem Statement 3

1.5 Objectives of The Study 4

1.6 Scope of Study 5

1.7 Significance of the Study 5

CHAPTER II LITERATURE REVIEW

2.1 Introduction 6

2.2 Types of Coastal Defence Structures

2.2.1 Seawall 7 2.2.2 Revetment . 7 2.2.3 Groin 9 2.2.4 Breakwater 9 2.2.5 Bed Protection using Geotextiles 11 2.2.6 Bed Protection in Wall Waves (Seawall) 12 2.2.7 Bed Protection Using Revetment 14

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2.3 Labuan Block Structure 15

CHAPTER ifi METHODOLOGY

11 Hydrodynamic Profile in the Study Area 16

3. 1.1 Hydrography Survey 16 3.1.2 Determination of the Sea Depth through Hydrography

Survey 17

3.2 Identify Coastline Profile 17 3.2.1 Types of Shoreline 18 3.2.2 Types of Soil Profiles in the Coastal Area 20 3.2.3 Wave Theory 20 3.2.4 The Tide 21 3.2.5 Wind 22 3.2.6 Current 23

3.3 Monitoring and Observation of the Coastal Defence Structure 23

CHAPTER IV ANALYSIS AND DISCUSSION

4.1 Introduction 24

4.2 The Labuan Block 26

4.3 Pantai Punggur Condition 27 4.3.1 Soil Profile 27

4.4 Design 4.4.1 Design Wave 29 4.4.2 Design Wind 30 4.4.3 Design Tide 32

4.5 Implementation of Construction and Installation 33

4.6 Discussion 4.6.1 Monitoring of Labuan Block Performance 36 4.6.2 Shortcoming of Scour, Stability and Erosion 38

4.7 Improvement on Geotextile as Bed Protection Layer 43

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CHAPTER V CONCLUSION AND RECOMMENDATION

5.1 Introduction 45

5.2 Conclusion 45

5.3 Recommendation 48 5.3.1 Improvement in Bed Defence Structure 49 5.3.2 Arrangement of Blocks from Ground Level 49 5.3.3 Use of Gravel as Bed Layer 49 5.3.4 Use of Cascading as Bed Protection 50 5.3.5 Monitoring of Construction and Materials Used 52

REFERENCES

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APPENDICES

A Table of Tidal at Pantai Punggur, Johor (2007-2009) 55

B Soil Classification Chart (AASTM D 2487) 64

C Standard Criteria of Geotextile Installation 65

LIST OF FIGURES

Figure No.

1.1 Coastal line in Malaysia 2

2.1 Seawall 7

2.2 Revetment 8

2.3 Effects of sediment movement around the groin 9

2.4 Connected breakwater 10

2.5 Separate breakwater 10

2.6 Non-woven geotextile 11

2.7 Position geotextile of coastal erosion defence structure as a bed layer 12

2.8 Curved wall of bed protection 13

2.9 Shape dimension curve wall of bed protection 13

2.10 Grouted riprap 14

2.11 Rock revetment, Kedah 15

2.12 Rock revetment, Malacca 15

2.13 Labuan block structure in Seberang Perai Utara, Pulau Pinang 16

3.1 Straight coastline 18

3.2 Bay coastline 19

3.3 Cape coastline 19

3.4 The effect of wind speed and wave size 21

4.1 Location of Pantai Punggur from Johor 25

4.2 Location of Pantai Punggur from Pekan Rengit and Senggarang 25

4.3 Labuan block consisting of two orders of arrangement Type A (squares)

and one Type B (Trapezium) and dimensional measurements in

milimeters (mm) . 26

4.4 Distribution of the sandy size profile in Pantai Punggur 28

4.5 Wave Rose refer on 68 years of waves data in Pantai Punggur 30

4.6 Wind Rose on 20 years (1975-1995) from October to March from

the collection of wind data by the Malaysian Meteorological

Department in the Senai Airport, Johor 31

4.7 Wind Rose on 20 years (1975-1995) from April to September from

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Page

the collection of wind data by the Malaysian Meteorological

Department in the Senai Airport, Johor 32

4.8 Dredging of sand for blocks Type A installation 34

4.9 Geotextile use as bed layer 35

4.10 Location of Labuan Block installed in Pantai Punggur 35

4.11 Reference tide level where Land Survey Datum (LSD) is 0.58 meters

above the level Admirality Chart Datum (ACD) 36

4.12 Labuan Block installation 37

4.13 High tide and large waves that occur in December 2005 at Pantai

Punggur 38

4.14 The effect from bed erosion that occurred cause of Labuan Block

structure fallen and leans 39

4.15 Overflow occurs resulting in back scouring 40

4.16 Scour process occurs at bed protection 41

4.17 Scour process that occur closer to main structure 42

4.18 The critical scour process where it has reached main bed structure that

cause failure 43

5.1 Failures of Labuan Block structure in Pantai Punggur 48

5.2 The use of gravel rock as bed layer on Labuan Blocks 50

5.3 Cover rocks are arrange in front of the Block Type A 51

5.4 Toe scouring surface is happening in front of Block Type A will be

protected by a rock cover in natural (gravitational) 51

5.5 Failure on Labuan Block build in Malaysia in Pantai Batu Manikar,

Labuan, Sabah 52

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LIST OF SYMBOLS

Speed

W Wavelength

P Period

xli

LIST OF ABBREVIATONS

ASTM Amerian Society for Testing and Materials

ACD Admirality Chart Datum

CD Chart Datum

HAT Highest Astronomical Tide

LAT Lowest Astronomical Tide

LSD Land Survey Datum

SWL Still Water Level

xlii

CHAPTER I

INTRODUCTION

1.1 General

The coastal area is a transitional area between land and sea. These areas are

often attracted by people with the daily activities, from recreational one through to

activities economic related such as port construction. It has a potential to become a

developing area, especially where there are related to commercial, agriculture, industry

and tourism carried by resident or authorities nearby.

The coastal area is characterized by its own ecosystem with wildlife and habitat

functions of each nature are closely aligned with each other. Complex phenomena that

occur on the beach are waves and tides. This situation interferes the daily activities of

people in coastal areas, especially those related to tourism and trade. Other than that, it

can indirectly lead to coastal erosion that can damage the natural habitat and structure

that have been built in that area.

Therefore, the use of coastal engineering structures is important to prevent the

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phenomenon that may affect human daily activities. The uses of wave barriers, piling,

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groin, and others are examples of coastal defence structures that commonly used to

protect or at least reduce the damaging effect on the beach.

1.2 Coastal Line in Malaysia

As an ocean surrounded country, Malaysia has a long coastline, where the size

and the distribution are as in Figure 1.1 below:

COAST LINE OF MALAYSIA

Length = 4809 km

(Including Langkawi, Pulau Pinang and Labuan)

7UCOAST LINE OF MALAYSIA

WEST MALAYSIA = 1972 kmSabah= 1743 km

West Coast = 1386 kmSarawak= 1035 km

East Coast = 586 kmLabuan =59 km

Figure 1.1 Coastal line in Malaysia (Faridah Jaafar Sidek, 2009)

From the total length of coastline in Malaysia, 4809 km, 29 percent or about

1400 km from the total length exposed to the phenomenon of erosion. Along 232 km if

the coastline is at a critical point, 221 miles at a moderate level and the remaining about

over 946 km are in the normal level.

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1.3 Coastal Defence Structures

Coastal defence structure is a construction erected on the beach to prevent and

break the waves. The main functions of coastal protection structure are to reduce the

impact of wave and dissipate energy to create more tranquil waters.

Nowadayas, various types of coastal defence structures are often used such as types

of floating breakwaters, stack stones, breakwater wall, composite breakwaters and also

porous breakwaters. Selection of appropriate coastal defence structure provides a great

influence in preventing high wave energy approaching the beach thus and lead to a

more tranquil wave.

In addition, the coastal areas are also a complex area and thus the solution used to

protect the shoreline are varies depending on the sites condition. In other words, the

coastal areas have unique and different hydrodynamic characteristics.

Technical knowledge on the types of coastal defence structure is not the only thing

required when selecting and designing, but it is also important in the process of

construction and maintaining the structure. Therefore, the first action needs to be

considered by engineers, is to identify the weaknesses and advantages of each type of

coastal defence structures and to study the geography and hydrography effect on coastal

areas.

1.4 Problem Statement

Coastal defence structures help in preventing coast erosion or at least minimise

the impact. However, this structure has a certain life span of effectiveness where it

depends on the type of structure and the factors of wave resulting in an area. Often the

structure of a coastal defence failed prematurely in its effectiveness and this certainly

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endangers the protected areas. One of the important elements of the structures that

should be emphasized is to avoid a premature failure of the bed protection layer.

Waves and currents that hit the coastal defence structures can eventually lead to

erosion and scour at the base of the structure. For a long time, this erosion and scour

will cause the structure to be less effective as a coastal defence system. Therefore, bed

protection is important as one of the criteria that should be well planned before the

construction start. Failure of bed protection to works in accordance with planning policy

contributes to the failure of the structure and result in loss of construction cost.

For many years, coastal engineers have realized that the effect of scour and

erosion, if not monitored will be the main cause of structural failure, especially to the

structures located near the shallow water (Eckert JW, 1983).

1.5 Objectives of the Study

This study aims to identify the impact and the function of the actual bed

protection of coastal defence structures on selected area, which is Pantai Punggur, Batu

Pahat, Johor. Factors that influence the effectiveness of bed protection such as wind,

wave and soil characteristics will be described in order to define and study the level of

suitability of the structures installed. This study will also identify whether there is any

other reasons besides the failure of bed protection.

Hence, with the data and information obtained, a conclusion is made. In addition,

suggestions will be also provided to overcome the problems on of bed protection of a

coastal defence structure.

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In order to achieve the targeted aim, the objectives in this study are as listed below:

1. To understand and identify the impact and the actual function of bed protection

installed together with coastal protection structures.

2. To study the coastal hydrodynamic conditions such as profile waves, tidal water

level and type of shoreline for the selected area.

3. To study the factors that caused the failure of bed protection.

1.6 Scope of Study

The scopes of this study are as follows:

1. Select the study area.

2. Identify the existing coastal defence structures built in the study area.

3. To define problems related to bed protection that causes failure of structures.

4. Analysis on the data obtained for selected area.

1.7 Significance of the Study

The coastal areas in Malaysia have become one of the fastest growing areas in

course of trade, tourism and leisure. The beaches in Malaysia are unexceptional in this

case where the coastal areas in Malaysia also well. Due to rapid development along the

coastal area, the problem such as coastal erosion eventually occurs. In order to

overcome the shortcoming, coastal engineers build the coastal defence structure to

reduce wave impact and thus prevent the coastal erosion.

As mentioned in Section 1.3 that the bed protection is an important element to

ensure the stability of a coastal defence structure. Thus this study is very important to

identify the problems and the factors that caused failure of the bed protection.

CHAPTER II

LITERATURE REVIEW

2.1 Introduction

Previously, several studies have been conducted on the bed protection for

coastal defence structures. These studies either in general or only focuses on one area.

They discussed various types of bed protections that suitable as coastal defence

structures and also to identify the failure factors of the bed protection.

However, differences in profile for coastal areas, such as sandy or muddy

beaches like those in Malaysia makes it difficult for researchers to thoroughly study of

the effects of varying coastal erosion. Due to this, a separate study should be conducted

for each coastal area where the system is planned to be implemented. It is required as

the information needed varies for every coastal area.

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I

2.2 Types of Coastal Defence Structures

2.2.1 Seawall

Sea wall as in Figure 2.1 is a strong structure and a vertical structure that works

to protect coastal areas from the effects of strong waves. While in areas with low wave

energy levels, it is used to separate land areas of the coastline. It is used and constructed

together with other materials such as piles of steel, concrete blocks, gabion and timber

piles.

Land

Seawall

Ocean

Figure 2.1 Seawall

2.2.2 Revetment

Revetment is a form of a layer that is installed directly on the beach slopes,

fortress or embankment to protect coastal areas from wave energy and strong streams.

S

These structures are built to sustain the use of existing coastal areas, serve to maintain

the use of existing coastal areas and also serve to protect the slopes on the beach. It may

be built covering the slope surface as a whole or in porous to allow water to run through

after the wave energy is dissipated. Figure 2.2 shows the revetment structure built on

the beach.

-0

Edge surface

Coastal

Figure 2.2 Revetment

Revetments are usually built of armorstone for areas exposed to high wave energy

or riprap for the environment of low energy waves. They are built with a combination of

small stones and geotextile layer which acts as a filter and the bottom. Both of these

layers provide on bed protection structure and allow water to flow past the structure. It

also supports the entire structure on it to be more stable.

2.2.3 Groin

Groin is a coastal stabilizing structure which is an oldest and commonly used. It

is construction which extends perpendicular to the beach. Usually they are built in series

and serve as a trap or retaining sand and protect coastal areas that lie between the series.

As in Figure 2.3 where the offshore drift will bring particles together and next it will

get stuck in the groin that leads to the direction waves and form reclamation.

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Particle - Direction movement Wave along coastline

Offshore Drift

1 Actual Coastline , Reclamation

V New Coastline _.—

L AEN

Figure 2.3 Effects of Sediment Movement around the Groin

2.2.4 Breakwater

Breakwaters are structures that constructed generally parallel to the coastline. It

works to mitigate wave energy approaching the protected coastal area. There are two

types of breakwaters which are the breakwater that connected to the beach (shore Connected) as shown in Figure 2.4 and also a separate breakwater to the beach (offshore) as shown in Figure 2.5.

Land

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Ocean

Breakwater

Figure 2.4 Connected Breakwaters

Breakwater

Ocean

Figure 2.5 Separate Breakwater

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2.2.5 Bed Protection using Geotextiles

In the construction of coastal structures, geotextile used as a filter, as a

separation tool and also as reinforcement of the soil structure. The often used filter is

the type of filter that allows water to flow through it. However, this filter normally

trapped the sand or soil particles as shown in Figure 2.6. A separation part is installed

at the base of the structure to prevent the materials from mix up example a mix up of a

weak soil layer (subgrade) with a layer of strong aggregates. It is also used as

reinforcement for road paving and the retained movement of the lateral embankment

constructed on soft ground.

Figure 2.6 Non-Woven Geotextile (www.geofabrics.com , 16/4/2010)

Geotextiles used in coastal structures must be permeable so that it can reduce the

hydrostatic pressure resulting from wave energy and also the movement of ground

water. To increase the effectiveness, the geotextile must be designed according to grain

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size rocks, ground water level and wave conditions for particular areas. Figure 2.7

shows the cross section of geotextile installation as a bed layer for coastal structure. It

also must be durable and has a good filtering ability for long lasting. (Whiteneck

L.W.;Hockney L.A, 1989).

Figure 2.7 Position Geotextile of Coastal Erosion Defence Structure as a Bed

Layer

2.2.6 Bed Protection in Wall Waves (Seawall)

Engineer has to consider that the wave wall built will minimised the

reoccurrence of erosion. A simple rule to be followed is to dissipate wave energy in the

horizontal rather than vertical. Particular attention should be given to the weak part of

the whole structure especially at the base of the wall.

One of the types of wall is composed of a sloping apron with two curved wave

wall, one on the water (seaward) and one in the land (landward) as shown in Figure 2.8

and Figure 2.9. The bed of this structure is covered by sand beaches. This apron has a

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ratio of 3:1 angle and constructed using 200mm thick concrete locked block overlay

100mm drained aggregate (pea shingle drainage). The loss of the materials at this

structure is avoided by using plastic fabric filter.

Figure 2.8 Curved Wall of Bed Protection (Thorn,R.B., and Roberts, A.G, 1981)

U

-t

Figure 2.9 Shape Dimension Curve Wall of Bed Protection (Thom, RB., and Roberts,

A.G, 1981)

2.2.7 Bed Protection Using Revetment

The engineers realized that the use of wave wall is costly, so other alternative

such as revetment was selected. Different from wave wall, wave energy that affected the

coastal defence structure will be absorbed by the revetment. Protection by revetment is

also known as water permeable protector (permeable sea defences).

Top of ernbankryent

Upstream Iap-.-.

a Lowest cpated PCVjj . . Rc,ck riprp

• GrveIbedthrg . •

Fèrry tenaI (end or fitter fbric} . *

Figure 2.10 Grouted riprap (Thorn, R.B., and Roberts, A.G, 1981)

Rock riprap consists of a heterogeneous mixture of irregular shaped rocks

placed over gravel bedding and a sand filter or geotextile fabric. The smaller rocks help

to fill the spaces between the larger pieces forming an interlocking mass. The filter

prevents soil particles on the embankment surface from being washed out through the

spaces (or voids) between the rocks. If the riprap is sparse or if the filter or bedding

material is too small, the filter material will wash out easily. But this problem can be

overcome by the use of gabion cages of steel wire to wrap the rock that is not easily

moved by streams and waves. Figure 2.11 and Figure 2.12 show the revetment

installation at Kedah and Malacca.

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