FLOOD ESTIMATION AND RIVER ANALYSIS

OF SUNGAI ISAP, KUANFAN

MUHAMMAD HAZ WAN BIN HUSSIN

A project report submitted in partial fulfilments of

the requirements for the award of the degree of

Bachelor in Civil Engineering

Faculty of Civil Engineering and Earth Resources

Universiti Malaysia Pahang

NOVEMBER 2014

ABSTRACT

The purpose of this paper was to expose the people about the flood

occurrences in Kuantan in the past few years and to analyse the rainfall and river

cross section data to estimate the next flood event as well as studying the river

behaviours and properties. This study was carried out due to the flood event that

occurred in the Kuantan city during the monsoon period. Heavy rainfall occurres

every year and often causes flooding problem in Kuantan city due to the. overflow

from Sungai Lembing and Kampung Panching. Although flood is difficult to avoid,

we still can forecast the flood and take some precautions. Infoworks TM by

Wallingford Software was used in order to estimate the flood events by analysing the

design rainfall produced from actual rainfall data for the past few years (2009) during

September to March which acquired from Department of Irrigation Drainage (DID)

and the current river cross-section data, which acquired from private company, site

survey and Google Earth. This study gave the results of flood occurrence on 100

years AR! and the suitable solution was proposed.

ABSTRAK

Kajian kertas kerja mi adalah bertujuan untuk mendedahkan pada orang

rarnai mengenai kejadian-kejadian banjir yang melanda negeri Pahang terutamanya

di Kuantan pada beberapa tahun yang lepas dan juga untuk menganalisa hujan dan

keratan rentas sungai bagi tujuan menganggar kejadian banjir di masa akan datang

disamping mempelajari sifat-sifat dan ciri-ciri sungai itu sendiri. Kajian mi telah

dijalankan kerana rnasalah banjir yang berlaku di Kuantan pada musim tengkujuh

beberapa tahun yang lepas. Hujan lebat yang turun mencurah-curah pada setiap tahun

dan limpahan air sungai dari Sungai Lembing dan Kampung Panching biasanya

dikaitkan dengan kejadian banjir di Kuantan. Walaupun banjir amatlah sukar untuk

di elakkan, ianya rnasih botch di ramal dan kita seharusnya akan menjadi lebih

bersedia dalam mengambil langkah-langkah peringatan sebelum menghadapi banjir.

Penisian Infoworks TM oleh Wallingford Software telah digunakan bagi tujuan

simulasi sungai untuk meramal kejadian banjir dengan cara menganalisi data hujan

rekaan berdasarkan data hujan sebenar bagi tempoh kritikal dalam tahun 2009 yang

diperoieh daripada Jabatan Pengairan dan Saliran (IPS) danjuga menganalisa bentuk

keratan rentas sungai terkini yang diperoleh daripada syarikat persendinian, kerja

lapangan dan juga penisian Googie Earth. Kajian mi menunjukkan kejadian banjir

berlaku pada ulangan 100 tahun dan penyelesaian yang sesuai telah dicadangkan

untuk kemudahan masa hadapan.

TABLE OF CONTENTS

CHAPTER

DESCRIPTION PAGE

TITLE I

DECLARATION ii

DEDICATION iii

ACKNOWLEDGEMENT iv

ABSTRACT v

ABSTRAK vi

TABLE OF CONTENTS vii

LIST OF FIGURES xii

LIST OF TABLES xiv

LIST OF ABBREVIATION xv

LIST OF APPENDICES xvi

I INTRODUCTION 1

1.1 introduction 1

1.2 Problems Statement 3

1.3 Objectives 4

1.4 Scope of Study 4

1.5 Significant of Study 5

AL

II LITERATURE REVIEWS 6

2.1 Introduction 6

2.2 Water Cycle 7

2.3 Factors Affecting Flood 8

2.11 Rainfall (precipitation) 8

212 Geomorphic Effects 9

2.3.3 Channel Section! River Cross-Section 10

2.3.4 Urbanization 10

2.3.5 Land Used 11

2.4 River Catchment 12

2.5 Catchment Factors 12

2.5.1 Topographical Shape 13

2.5.2 Shape 13

2.5.3 Size 13

2.5.4 Soil Type 14

2.5.5 Land Used 14

16 Practical Flood Estimation 14

2.6.1 Last Flood Event 15

2.6.2 GIS Data 15

2.6.3 Rainfall 16

2.6.4 Index Flood 16

2.7 Tides; the Important Factors in Changing

Flood Frequencies 18

2.7.1 Tidal Datum and Range 20

2.7.2 Influenced of Tides to

Flood Occurrences 21

IA

2.8 Flood Risk Management 22

2.9 The importance of River and Flood Plain

Management 24

2.10 River Modelling 25

2.11 Physical Laboratory Studies 26

112 Flood Benefits 26

ifi

METHODOLOGY 27

3.1 Introduction 27

3.2 Research Methodology 29

3.3 Overall Process for the Research 29

3.4 Preparation of Early Data 32

3.4.1 Available Data 33

3.4.2 Predicted Data and Assumption Data 33

3.4.3 Accuracy Test for Data 33

3.5 Computer Modelling 34

3.6 Standardization of the Parameters 34

3.7 River Simulation 36

3.8 1nfoworks Tm 36

3.8.1 Introduction 36

3.8.2 Creating the New Master Database 37

3.8.3 Creating the Network 39

3.8.4 Creating, Drawing and Linking

the Cross Section 40

3.8.5 Creating Boundary and

Hydrological Event 41

3.8.6 Validating the Network 45

3.8.7 Simulation Process 46

3.9 Manual Saliran Mesra Alam (MSMA) 48

3.9.1 Time Concentration for

Natural Catchment, tc 48

3.9.2 Rainfall Intensity (D and Rainfall

Depth (P) Calculation Method 50

3.9.3 50 Years and 100 Years ART Rainfall

Intensity (I) and Rainfall Depth (P)

Calculation Methods 52

IV RESULTS, ANALYSIS AND DISCUSSION 53

4.1 Introduction 53

41 Simulation Results 54

4.3 Results on Steady Flow Simulation 54

4.3.1 Steady Flow 54

4.3.2 Steady Flow Analysis 56

4.4 Results on 50 Years ART Simulation 57

4.4.1 Rainfall Events 57

4.4.2 Longitudinal Section Detail on

50 Years ART 59

4.5 Results on 100 Years AR! Simulation 60

4.5.1 Rainfall Events 60

4.5.2 Longitudinal Section Detail on

100 Years ART 62

4.6 Relationship between Depth and Flow Rate 63

4.6.1 Analysis based on the Value of

River Depth and Flow Rate 63

4.6.2 Graph of Depth versus Flow Rate 64

4.7 Solution for the Flood Problems 68.

4.7.1 Introduction 68

4.7.2 Options for the Flood Solution 68

4.7.3 Analysis on the Proposed Options 69

4.7.4 100 Years ART Simulation with

Embankment 70

4 . 8 Discussion 72

V CONCLUSIONS 73

5.1 Conclusions 73

5.2 Recommendations 74

REFERENCES 75

APPENDIXES 78

LIST OF FIGURES

FIGURE NO TITLE PAGE

1.1 Location of Kuantan Towns 2

2.1 Natural Water Cycles 7

2.2 Geomorphic Effects on Flood Potential 9

2.3 Land Used of Pahang State 11

2.4 Sketches of Common Type of Tides 19

2.5 Tidal Datum And Tidal Levels 21

2.6 Limit of Tide as Function of Upstream Flow 22

27 Construction of the Tunnel to Intercept the Flow

of Water Through City in Kuala Lumpur 24

2.8 Cross Section based on the Concept of the Development

Banks of the River Facing River 25

3.1 Sungai Isap Catchment Areas (not to scale) 28

3.2 Overall Processes Involved In the Research 31

3.3 Main Processes (Flow) of River Modelling Using

Infoworks Im 35

3.4 Getting Started 37

3.5 Creating Master Databases 38

3.6 Network Images Load 39

3.7 Cross Section Properties Window 40

3.8 Completed Linked Cross Section 41

3.9 Selecting the Boundary Condition 42

3.10 Event Type Selections 42

3.11 Network + EventsWindow 43

3.12 Boundary Properties 43

3.13 Data of Hydrological Flow is Keyed in 44

WE

3.14 Boundary Nodes, along with the Cross Section 44

3.15 Output Validation and Error Message 45

3.16 Schedule Controllers before Running the Simulation 47

3.17 The Simulation Results Icons 47

3.18 Illustration of Sungai Isap Catchment Areas 48

4.1 Longitudinal Sections for Sungai Isap (Steady Flow) 55

4.2 The Differences between Two Sections with

Different Bed Elevation 56

4.3 Calculated Hydrograph for 50 Years AR! 57

4.4 Longitudinal Simulations for 50 Years AR! 59

4.5 Calculated Hydrograph for 100 Years AR! 60

4.6 Longitudinal Simulations for 100 Years ART 62

4.7 Cross Section for CH 300 (Critical Section With

Less Depth) 63

4.8 Cross Section for CH 900 (Non-Critical Section With

Higher Depth) 64

4.9 Rating Curve for CH 300 66

4.10 Rating Curve for CH900 67

4.11 The Longitudinal Sections for the Simulation

with 4m Embankment 70

4.12 The Different between the Areas Containing Water for CH 300 (Critical Section) 71

LIST OF TABLES

TABLE NO TITLE PAGE

2.1 Attributes of Spatial Objects in GIS .17

3.1 Information and Data Required 32

3.2 Coefficient for the IDF Equation 51

3.3 Calculation Methods for 50 Years and 100 Years

I and P Value 52

4.1 Volumetric Analysis from 50 Years AR! Hydrograph

Results 58

462 Differences of Volumetric Analysis between

50 Years AR! and 100 Years AR! Hydrograph Results 61

4.3 The Value of Flow Rate and Depth for CH 300 65

4.4 The Value of Flow Rate and Depth for CH 900 65

LIST OF ABBREVIATION

NO ABBREVIATION

1 DID Department of Irrigation and Drainage

2 WK Kuantan Municipal Council

3 DSM Department of Survey and Mapping

4 MACRES Department of Remote Sensing Malaysia

5 DOA Department of Agriculture

6 GIS Geographic Information System

7 CN Curve Number

8 1-1) One Dimensional

9 2-1) Two Dimensional

10 3-1) Three Dimensional

11 MSMA Manual Saliran Mesra Alam

12 ARI Average Reoccurrences Intensity

13 CH Chainage

14 Q Flow Rate of Water (rn3/s)

15 Itc Time of Concentration

16 Fe Conversion Factor

17 L Length of Flow Path from Catchment devided

to outlet (km)

18 A Area of the Catchment

19 S Slope of Stream Flow

20 I Rainfall Intensity (mm/hr)

21 P Rainfall Depth (mm)

22 RIt Average Rainfall Intensity for ARI

23 t Duration, time (hr, thin, sec)

24 a, b, c, d Fitting Constant from IDF curve

LIST OF APPENDIXES

APPENDIX NO TITLE PAGE

A Recorded Rainfall Data for Station Bukit Kenau

from 23 March 2009 to 30 March 2009 (DID) 79

B List of Critical Cross-Section Obtained from

Google Earth

81

C Google Maps Input for Network Modelling 85

D Tabulation (Manning) for Several Critical Section 87

CH4PTER I

INTRODUCTION

1.1 Introduction

Flood is an overflow or an accumulation of an expense of water that

submerges land. It is also can be refer to the inflow of the tide or the backflow of the

river; which occurs at the location where the rivers meet. From a geological

perspective, floods are natural consequences of stream flow in a continually

changing environment. The streams receive most of their water input from

precipitation and the amount that falling in drainage basin varies from day to day.

Based on the role of precipitation, the amount and time which precipitation takes

places is not constant for any given area. Overall, the water cycle is a balanced

system and the reason for the flood to occur is a large amount of precipitation,

causing the river/ basin to overflow due to not efficient cross section of the river

itself. As the amount of water is increase, the stream must adjust its velocity and

cross section in order to form .a balance. The discharge increase as more water is

added through rainfall, tributary streams, or from the groundwater seeping into the

stream resulting in floods due to increase of width, depth and velocity of streams

(Ismail, DID).

Most town in Pahang state received heavy rainfall in monsoon period which

results in flood in low area especially near the flood plain area. Heavy rainfall in

such high area (Sungai Lembing and Kampung Panching) results in increasing water

level in the river below their level such as Sg. Isap and Sg. Kuantan. According to

the report released by Department of irrigation and Drainage (DID) Pahang, the

factors that affecting this phenomenon are heavy rainfall in Sungai Kuantan valley

along with heavy tides and the shallow section of Kuantan's river estuary and poor

drainage systems.

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Figure 1.1 Location of Kuantan Towns (Google Maps)

The location of Kuantan town (Figure 1.1) which is surrounded by several

rivers and their tributaries make the town widely open to the flood event in addition

with the factors mentioned above. in addition with shallowness of the Kuantan River

valley due to the sedimentation from various human activities resulting in the

capability of river to hold the huge amount of water is low, hence, causing the flood

occurrence.

1.2 Problems Statement

Kuantan, the capital city of Pahang state is located in the east of Malaysia,

known as 'gateway to east coast', is a fast growing commercial city in the east coast

of peninsular Malaysia with the population of more than 400 000 peoples. However,

since its location is in the centre among Sungai Lembing, Sungai Isap, and the

estuary of Kuantan river, the Kuantan city is clearly exposed to the worst world

disaster; flood. For the past few years, Kuantan has faced with a worst flood which

results in evil destruction and loses. The Municipal Council of Kuantan (WK) have

carried out many solutions to cop& with this problem especially to the famous area

such as Sungai Isap including the construction of embankment and a man made lake

as a catchment during heavy rainfall or monsoon period but the scenario became

even worst from year to year (Mat Ropi, MPK).

Every year during the monsoon periods (September February), Kuantan

town encountered a flood that can be predicted. The heavy rainfall causes the low

area to be flooded. Normally, the flood reached two metres and the worst was

recorded in 2,001 (approaching four metres). When the flood stroke, residential area

in Kuantan town suffers from lack of food and human resources and after the flood

disappears, this town is covered with mud and waste. This phenomenon has become

a norm every year (Mat Ropi, WK).

The main factors that cause the authorities failed to give a warning to the

residents are lack of flood estimation equipment and data regarding previous flood

and river channel. The residents cannot make a connection of the water level from

the river's valley with the flood level that will occur. Thus the early warning that

have been released is useless without knowledge (Arkib Berita Harian).

The DID, has come out with several methods to cope with this problem

including installation of device that can give an early warning such as sign board and

siren. In addition, online flood warning system also has been set up. Flood mitigation

project is also under construction at Sungai Isap (Ismail, DID).

1.3 Objectives

In order to make this study successful, three objectives have been

determined. It works as a guide line so that the outcomes of this study can be easily

achieved. The objectives are;

. To determine the river cross section.

• To analyse hydrological data for critical river sections.

• To propose the possible solution.

1.4 Scope of Study

The scope of study includes simulating the river using Jnfoworks TM software

using gathered data from local authorities. This study involved in the catchment area

of Sungai isap. In this study, a river network was established using the Google

satellite images data and the analysis were carried out using river modelling and

simulation.

The river simulation was carried after all the data were inserted and the

networks were created. The river flow from upstream to downstream was marked in

the model. Two experiments were carried out; the first, using the 50 years of design

rainfall (50 years ARE) and the second one is 100 years of design rainfall (100 years

ARE). The simulating process was conducted by mean of steady flow and different

rainfall events to get various results.

1.5 Significant of Study

River simulating is the best option to study the behaviours of flood and what

are the influenced factors. By creating the river model based on the actual data and

GIS image, the true phenomenon of what is really happened can be understood.

The limitation of human activities along the flood plain area could be

established after a river simulating was conducted and the hazard risk map was

produced. Through this study, the effect of rainfall to the flood occurrences and

behaviours could be determined. Thus, for the future, the appropriate early solution

could be implemented for a certain types of rainfall. This increase the public

awareness of the next flood event by predicting based on the rainfall behaviours.

This study is also expected to be able to help the responsible agencies and authorities

to river and river basin management to apply more efficient approach for the purpose

of analysing and producing the best design practise in overcoming the flood

problems.

ChAPTER II

LITERATURE REVIEWS

2.1 Introduction

Malaysia is an equatorial climate country with having wet and dry seasons

every year. There are two types of wet seasons occurs in the peninsular Malaysia;

Southwest Monsoon that affect west coast of peninsular Malaysia and Northeast

monsoon that affected east coast of peninsular Malaysia (also known as "musirn

tengkujuh"). Kuantan town, located in Pahang state was one of the developed towns

in east coast of peninsular Malaysia and has been experiencing this phenomenon for

a few decades. Each year, Malaysia have received 3500mm of annual rainfall

(average) which indirectly placed Malaysia as one of the riches country with water

source. In Malaysia, river play an important role since its usage approaching 98%

compare to ground water, 2% in daily activities (Ismail, DID).

Condensation

Sublimation ation - Evapotranspiration

- - Surface runoff

Evaporation

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storageWater storage

In oceans

Water storage in Ice and snow

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2.2 Water Cycle

Theoretically, flood is caused by an excess amount of rainfall in a long

direction. The ideal percentage of a water cycle balance in order to balance the eco-

system to avoid flood is clearly highlighted and as long as Malaysia is on the line, the

flood can be avoided. However, there are several factors that causing the water

balance system is disturbed. Since Malaysia received a few numbers of rainfalls

annually, the water source condition is usually affected by weather conditions and

natural water cycle (Strathler, 1997). The water in the earth surface is evaporated to

the atmosphere as a vapour and the group of water vapour in the atmosphere

produced clouds which finally condensed and precipitate to the earth as rainfall. This

process is known as precipitation (Syukri, 2009). Figure 2.1 and 2.2 indicate the

illustration and percentages of water cycle on the earth surface.

Figure 2.1 Natural Water Cycles (Strathler, 1997)

2.3 Factors Affecting Flood

Floods are natural consequences of stream flow in a continually changing

environment. The streams receive most of their water input from precipitation and

the amount that falling in drainage basin varies from day to day. Based on the role of

precipitation, the amount and time which precipitation takes places is not constant for

any given area In Malaysia river is known as a number one water resource and there

are several town and residential area widely developed in the flood plain area which

is known as a hazardous area because of its potential to be flood by water.

2.3.1 Rainfall (Precipitation)

Several factors have been listed down for affecting flood. The main factor

that caused flood is precipitation. For a short duration of rainfall in a small

watershed, flood also can be occurred and the danger accompanying is a high-water

velocity which can results in extremely large flood. From the rainfall (precipitation)

results, the runoff can be identified using available evaporation data as a catalyzer

(Walter and Francis, 2005) The spatial patterns of different between two rainfalls

with same average rainfall in one catchment can results in different runoff patterns.

When the stream flow for a catchment is combined with the precipitation, flood

event will occur. The evapotranspiration and evaporation has little influence of water

balance at daily time scale compare to rainfall (L.Siriwardena, 2005).

2.3.2 Geomorphic Effects

Geographical change also influence flood to occur. The geographical change

and mobilization of a flood plain area for human activities such as agricultural and

building dikes is known as a factor that results in residential are or city flooded with

water from the river during heavy rainfall (Erich J. Plate, 2002). Geomorphic effects

controls several factor such as magnitude, frequency, rate of sediment movement,

flood power, duration of effective flows, sequence of events and the channel

geometry. Changes in the channel bed configuration and bank erosion have been

considered as a measure of the geomorphic effectiveness of flows. For an example,

in the river bank of Tapi River, India, the condition along several location with

alluvial bank are steep but stable compared to the other section with gravely sandy

units which occurs to response for high flood. The velocity of the river's flow is

influenced by sediment load. The 'higher the ratio, the more increase in discharge

(Vishwas, 2002).

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Figure 2.2 Geomorphic Effects on Flood Potential (Erich J. Plate, 2002)

2.3.3 Channel Section/ River Cross-Section

Others factor that affect the flood is river cross-section or channel section.

The value of discharge is varying with channel width, depth and gradient. Flows get

deeper and faster as a discharge increase. in the other words, the flood power is

depended on the river section. During heavy rainfall, the stage and discharge increase

and the depth of flow are assumed to be negligible since the width-depth ratio is too

small. The rates of change in mean depth and velocity are greater than change in

width Thus, the increase in discharge is directly proportional to the depth which

influences the river to flow in high velocity and causing overflow or in the other

words, flood. The fact is, the river is more effective with depth compare to the width

(Vishwas, 2002).

2.3.4 Urbanization

Urbanization also listed as one of the factors that affecting flood.

Theoretically, the percentage rate of runoff increase due to urbanization because of

the rate of infiltration is limited when certain section is covered with concrete CN

also called as a curve number, is a percentage of constant runoff coefficients (value

from 0- 100%). The more CN value means the more urbanization in that area and the

less number of infiltration which results in increasing surface runoff. The CN value

also provides an indication of the watershed's water retention capacity (Gaume,

2003).

2.3.5 Land Used

The effect of land used in flood event is extremely remarkable. The early

study reported that the hydrologic responses related to slow, consistent change in

land used and increase in forest cover. Just like the urbanization, the change in land

used for human activities decrease the rate of infiltration and results in excess runoff.

For an example, the study for small catchment with vegetation and plant, similar to

Comet river catchment (L.Siriwardena, 2005), they found that annual runoff is

increased after the establishment of pasture and conversion to cropping. The results

suggest clearing the forest and crop in order to increase the runoff, so that the water

can easily flow to the river without floating the area within (L.Siriwardena, 2005).

• ___

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Oil palm Urban

Weiland Paddy Forest

Forest Virgin Forest

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Figure 2.3 Land Used of Pahang State (JUPEM