HYDROLOGICAL RIVER MODELING FOR SUNGAI LEMBING AREA BUKIT

KENAU USING INFO WORKS RS

BASYIR BIN MANSOR

A thesis submitted in fulfillment of the

requirements for the award of the degree of

Bachelor of Civil Engineering

Faculty of Civil Engineering & Earth Resources

Universiti Malaysia PAHANG

DECEMBER 2010

ABSTRACT

Flood is an overflow or accumulation of an expanse of water that submerges land.

It may result from the volume of water within a body of water, which overflows,

resulting that some of the water escapes its usual boundaries. Floodplain and near river

area nowadays are at risk of flood. Buldt Kenau area is also included. Whenever there are

high precipitations, the water level will increase and could cause flood. Mitigation could

be technical and nontechnical, structural and nonstructural. Structural mitigation such as

constructing channels and sewers were the main method of flood mitigation. Infoworks

software is chose to estimate the critical water level where flood could happen. This

study can be used to help to prevent flood problem for the people especially at Pahang

River. The objective of this study is to develop and validate 1-Dimensional hydrological

modeling of Sungai Lembing on area Bukit Kenau using Infoworks RS. Hydrological

data are collected from JPS and Map area obtained from JUPEM. Infoworks RS are used

to simulate the flood event on Bukit Kenau. Steady and unsteady flow simulations were

run for 20 and 50 ART. Rational method is used based on Manual Saliran Mesra Alam

(MASMA) for the design rainfall calculation. The results shows that at some area, the

water level is higher that left or right bank of the river, so that area will have risk of

flood. The simulation water level on JPS station is 1.8m and actual level is 1.81 im, so the

error calculated is 0.61%, which is allowable. Some methods can be taken for flood

mitigation such as increasing the section area of the river or increasing height of bank so

that the flow will have more space. The ability of Infoworks RS to run flood simulation

on Sungai Lembing area Bukit Kenau is acceptable as the error calculated from

validation process are small.

V

ABSTRAK

Banjir adalah lebihan aliran atau permukaan air terkumpul yang melimpah ke

permukaan tanah. Banjir boleh disebabkan kuantiti air yang melebihi aliran,

menyebabkan sebahagian darinya terkeluar dari kawasan yang sepatutnya. Kawasan yang

berhampiran sungai berdepan dengan risiko banjir. Kawasan Bukit Kenau juga terbabit.

Bilamana terdapat kadar hujan yang tinggi, paras air akan meningkat dan boleh

menyebabkan banjir. Kawalan banjir boleh secara teknikal atau tidak, berstruktur ataupun

tidak. Kawalan berstruktur seperti membina terusan dan saluran adalah kaedah utama

kawalan banjir. Perisian Infoworks digunakan untuk menganggar paras air kritikal

dimana banjir boleh berlaku. Kajian mi boleh digunakan untuk membantu mengawal

masalah banjir terutamanya di kawasan Sungai Pahang. Objektif kajian mi adalah untuk

membina dan mengesahkan model hidrologi 1-dimensi di Sungai Lembing kawasan

Bukit Kenau menggunakan Infoworks RS. Data hidrologi diperolehi dari JPS dan peta

kawasan dari JUPEM. Infoworks RS digunakan untuk simulasi kejadian banjir di Bukit

Kenau. Simulasi aliran mantap dan tidak mantap dijalankan untuk 20 dan 50 ART.

Kaedah rasional diguna berpandukan Manual Salman Mesra Alam (MASMA) untuk

kiraan rekabentuk hujan. Keputusan menunjukkan sesetengah kawasan mempunyai risiko

banjir. Paras air simulasi di stesen adalah 1.8m dan paras sebenar adalah 1.811, dan ralat

Yang dikira adalah 0.61%, maka boleh diterima. Antara kaedah yang boleh digunakan

untuk mengawal banjir seperti memperluas keratan rentas sungai atau meninggikan

tebing sungai supaya mempunyai lebih ruang untuk aliran. Keupayaan Infoworks RS

untuk melakukan simulasi banjir di Sungai Lembing kawasan Bukit Kenau boleh

diterima pakai kerana kesalahan yang dikira dari proses pengesahan adalah sangat kecil.

VI

TABLE OF CONTENT

CHAPTER TITLE PAGE

DECLARATION

DEDICATION

ACKNOWLEDGEMENT iv

ABSTRACT v

ABSTRAK vi

TABLE OF CONTENT vii

LIST OF TABLES xi

LIST OF FIGURES S xii

LIST OF SYMBOLS xiv

LIST OF APPENDICES xv

INTRODUCTION 1

I.I. Problem statement 2

1.2. Objective 3

1.3. Scope of study 3

1.4. Location of Study 4

1.5. Significance of Study 6

2 LITERATURE REVIEW 7

2.1. Introduction 7

VII

2.2. Flood 8

2.3. Types offlood 11

2.3.1. Flash Floods 11

2.3.2. Urban Flooding 12

2.3.3. Coastal Flooding 13

2.3.4. River Flooding 14

2.3.5. Ponding (or Pluvial Floods) 16

2.3.6. Estuarine 16

2.3.7. Muddy 17

2.3.8. Other 17

2.4. Causes of Flood 17

2.4.1. The Role of Precipitation 18

2.4.2. Tropical Storms 19

2.4.3. Seasonal Flooding 20

2.4.4. Coastal Flooding 21

2.4.5. Tsunamis 22

2.4.6. Dam & Levee Failures 22

2.5. Flood Mitigation 23

2.5.1. Increasing Storage Capacity 23

2.5.2. Improvement on Forecast and Warning 24

2.5.3. Floodproof 24

2.5.4. Levees 25

2.5.5. Dams 26

2.5.6. Sandbagging 26

2.5.7. Specialized Glass Storefront Barriers 27

2.5.8. Gates 27

2.5.9. Hinged Flood Gates 27

2.5.10. Removable Flood Barriers 28

2.6. Infoworks RS, 28

VIII

Ix

2.6. 1. Overview 28

2.6.2. Workgroup Model Management 29

2.6.3. Model Building Tools 30

2.6.4. Results Interpretation 31

3 METHODOLOGY 34

3.1. Introduction 34

3.2. Flowchart of Methodology Study 35

3.3. Flowchart for Infoworks 36

3.4. Data Collection 37

3.4.1. River Maximum Capacity 37

3.4.2. Design Rainfall Calculation 38

3.4.3. Cross Section Data 38

3.4.4. River Flow/Discharge 39

3.4.5. Determining the Number of Flow Cross 41 Sections

3.4.6. Determining the Mid-Point of the Cross Section 41

3.4.7. Adjusting the Sensor Depth at a Cross Section 42

14.8. Measuring Velocity 43

3.4.9. Calculating Flow 43

3.4.10. Rainfall Data 44

3.5. Simulation 47

4 RESULTS ANALYSIS AND DISCUSSION 48

4.1. Introduction 48

4.2. Simulation 49

4.2.1. River Design 49

4.2.2. Cross Section Data 50

4.2.3. Design Rainfall Calculation 51

4.2.4. Rainfall Profile 52

4.2.5. Subcatchment Area 53

4.3. Simulation Results 54

4.3.1. Steady Flow Simulation 54

4.3.1.1. Steady Flow for 20 AR1 54

4.3.1.2. Steady Flow for 50ARl 57

4.3.2. Unsteady Flow Simulation 57

4.3.2.1. Unsteady Flow for 50 ARI 58

4.4. Flood Mitigation Solution 59

4.5. Calibration and Validation 67

4.6. Discussion 68

S CONCLUSIONS AND RECOMMENDATIONS 70

5.1. Introduction 70

5.2. Conclusion 71

5.3. Recommendation 71

REFERENCES 73

Appendices A-E 75-90

x

LIST OF TABLES

TABLE NO. TITLE

PAGE

4.1 River design on every chainage

49

4.2 Water level on Chamage ch4 68

xi

LIST OF FIGURES

FIGURE NO. TITLE PAGE

1.1 Map of the location of Bukit Kenau 4

1.2 Close-up map of Bukit Kenau 5

2.1 Effect of flood on 2007 on the way to Paloh Hinai 9

2.2 Wave overtopping a coastal embankment. 14

2.3 Data flagging to mdicatae data source. 30

2.4 Geographical model building 31

2.5 Input and result data 32

2.6 Longitudinal section of channel 32

2.7 Cross section of channel 33

2.8 Calibration and analysis 33

3.1 Flowchart of methodology study 35

3.2 Flowchart for Infoworks software 36

3.3 GPS leveling equipment 39

3.4 The data inserted into Infoworks 39

3.5 Flow measurement tool 40

3.6 Stream cross section illustrating mid-section method to 44 determine discharge

3.7 Rain gauge with data logger 45

3.8 Rainfall profile input into Infoworks RS 46

3.9 Example of Calculated Hydrograph 46

3.10 Longitudinal sections of water surface and channel data 47

4.1 Cross section data 50

XII

XIII

4.2 River cross section 51

4.3 Rainfall profile on area Bukit Kenau 52

4.4 Subcatchment area on Bukit Kenau 53

4.5 Long section for 20 ARI simulation 55

4.6 Crossection on Downstream (chainage, ch 1) 55

4.7 Crossection on Upstream (chl 1) 56

4.8 Crossection on Lower middle (ch4) 56

4.9 Crossection on Upper middle (ch8) 56

4.10 Long section for 50 ARI unsteady for time = Ohr 58

4.11 Long section for 50ARI unsteady for time = 4hr 58

4.12 Cross section of chamage ch4 for unsteady 50 ARI at time = 59 Ohr

4.13 Cross section of chainage ch4 for unsteady 50 ARIL at time = 59 4hr

4.14 Cross section chi before modified 60

4.15 New cross section for chi 60

4.16 Cross section chainage ch2 before modified 61

4.17 Cross section chainage ch2 after modified 61

4.18 Cross section chamage ch3 62

4.19 Cross section chainage ch4 before modified 62

4.20 Cross section for ch4 after modified 63

4.21 Cross section for chainage ch5 63

4.22 Cross section for chainage ch6 64

4.23 Cross section for chainage 67 64

4.24 Cross section for chainage ch8 before modified 65

4.25 Cross section for chainage ch8 after modified 65

4.26 Cross section for chainage ch9 before modified 66

4.27 Cross section for chainage ch9 after modified 66

4.28 Cross section for chainage chlO 67

4.29 Cross section for chainage chi 1 67

LIST OF SYMBOLS

A - Area of the crossection (m)

a, b, c, d - Coefficients for the IDF polynomial equations

D - Depth

I - intensity

n - Manning's coefficient

Q - maximum flow (m3/s)

R - hydraulic radius (m)

S0 - watercourse slope

t - time

tc - Storm duration

tp - Peak Hydrograph

V - Velocity

W - Width

xiv

xv

LIST OF APPENDICES

APPENDIX TITLE PAGE

A Design Rainfall Calculation

75

B Coefficient of 1DF Equation in Malaysia 77

C Rainfall data from 4/12/2009 time 00:00 to 08:00 78

D Calibration and Validation Calculation

E Cross Section Chainage Chi to Chi 1 80

CHAPTER 1

INTRODUCTION

A flood is an overflow or accumulation of an expanse of water that submerges

land. In the sense of "flowing water", the word may also be applied to the inflow of the

tide. Flooding may result from the volume of water within a body of water, such as a

river or lake, which overflows or breaks levees, with the result that some of the water

escapes its usual boundaries. While the size of a lake or other body of water will vary

with seasonal changes in precipitation and snow melt, it is not a significant flood unless

such escapes of water endanger land areas used by man like a village, city or other

inhabited area. Flood also could cause by soils, geology, floras, and non-natural

impoundments in the upper basin.

Floods can also occur in rivers, when the strength of the river is so high it flows

out of the river channel, particularly at bends or meanders and causes damage to homes

and businesses along such rivers. While flood damage can be virtually eliminated by

moving away from rivers and other bodies of water, since time out of mind, people have

lived and worked by the water to seek sustenance and capitalize on the gains of cheap

and easy travel and commerce by being near water. That humans continue to inhabit

2

areas threatened by flood damage is evidence that the perceived value of living near the

water exceeds the cost of repeated periodic flooding.

Flood estimation on flood plain and near river area is important for many

hydrological applications as they are difficult and could be use on many purposes.

Estimation of flood is required from various return periods for planning measures and

purpose of flood mitigation and reduces or prevents flood damage. One of the main

points in flood estimation is precipitation. Flood increases rapidly because high

precipitation exceeds the infiltration capacity of the soil, and thus causing high runoff

rate. Uncontrollable uses of land have made flood forecasting difficult because

impermeable surfaces reduce infiltration and accelerate runoff. Mitigation could be

technical and nontechnical, structural and nonstructural. Structural mitigation such as

constructing channels and sewers were the main method of flood mitigation.

Nowadays, ponding and nonstructural technique, mainly real-time process, has become

practical alternatives. Other flood mitigation methods are warning system, stormwater

channel management, storage pool, deepen and widen river, and so on.

1.1. Problem Statement

Floodplain and near river area in this day and age are at risk of flood. It seems to

happen often. Bukit Kenau area is also included. Whenever there are high precipitations,

the water level will increase and could cause flood. A flood is an overflow of an expanse

of water that submerges land. If flood occur at this area now, more people will be

affected by it. The flooding effects in that region will be a lot more severe. For that

reason, this study is created to minimize these effects.

3

Flood risk also occurs at area Bukit Kenau where it is close to Pahang River.

This is one of the factors that causes flood in that area. It becomes poorer if there is a

storm. While there are many ways in flood mitigation, such as increasing river depth

and cross section, Infoworks software is choosed to estimate the critical water level

where flood could happens. This study can be used to help to prevent flood problem for

the people especially at Pahang River. It is expected to be able to help the people in the

future and also help Department of Irrigation and Drainage, Malaysia (JPS) to solve the

flood problem.

1.2. Objective:

The objectives of this study are:

i) To develop and validate 1-Dimensional hydrological modeling of Sungai

Lembing on area Bukit Kenau using Inloworks RS.

ii) To obtain water depth, flow and velocity data of Sungai Lembing on area Bukit

Kenau for flood problem solving purpose.

1.3. Scope of Study

The scopes of study are as listed below:

i) Obtain the data needed such as rainfall data, crossection of the river, the

geometry of structure, perimeter watershed, water level and other data required.

ii) Understand and analyze more on Infoworks software in theory and practical.

iii) Site survey at Bukit Kenau to obtain data and information needed.

4

1.4. Location of Study

The study of study is Sungai Lembing on area Bukit Kenau. This area is low

level land and risk of flood when heavy rain. Human history shows that residential areas

are built near the river as the river will supply water for human life. The economy will

grow up on that area and many people will come. However, in this day and age, low

land level near the river is not suitable for inhabitant area as the flood will cause

damage. The study need to be made on Bukit Kenau area to reduce the damage.

Kampung $

KO

WVRi k.niptn

KUSMISO

Buft Sao"

KO" P Lemig N8d8

Kmpuig

Ah T

IPM —s rtr

, Kniung Siga

SLqai8a1u Pancig KUantan

KompLM

ci 1-1

Kuan,n

I Pandw9 $

Un

) KempLog Dew

Figure 1.1: Map shows the location of Bukit Kenau. (Source:

http://maps.google.com.my/)

\ I /

I

I

Sunga, Lembing - Krnpung -

JeraniTaar

I

I Ka4ig K461 ^U

yF

I

ping H --

I!i

Kampung Bayas

Figure 1.2: Close-up map of Bukit Kenau. (Source: http://maps.google.com.my/)

Figure 1.1 and Figure 1.2 clearly shows the location of residential areas

alongside the Sungai Lembing. Bkit Kenau is one of them. It is located on low level

land area,, plus near the river. Along the Sungai Lembing, there are many villages and

residential area built on the left and right. This is very dangerous because if heavy rain

happens, many people along the river will experience the effect of flood.

6

1.5. Significance of Study

The result from this study can be used to upgrade and update the river

management system at Sungai Lembing. Scheduled maintenance can be made to the

river so as to reduce the risk of flood to minimum. This could provide optimum effect

against flood in the future.

From this Infoworks software, the hydrodynamic river modeling can be

developed to obtain the water depth, flow and velocity. These data can be used to

predict flood and water contamination treatment device design purpose. From the study,

the suggestion of solution can be made such as to increase the width or depth or the river

to mitigate flood.

The study also can prove the validation of Infoworks software in providing data

for flood estimation.

CHAPTER 2

LITERATURE REVIEW

2.1. Introduction

Water is essential in the life of any living things. Scientifically water are made of

two molecule of Hydrogen and one molecule of Oxygen. Roughly water covers around

70% of the Earth's surface. It is found mostly in oceans and other large water bodies.

Water in oceans forms 97% of surface water, 2.4% on glaciers and polar ice caps, 1.6%

of water below ground in aquifers and 0.001% in the air as vapor, clouds, and

Precipitation, and other land surface water such as rivers, lakes and ponds 0.6%. A very

small amount of the Earth's water is contained within biological bodies and

manufactured products (UNEP, 1995).

8

Fresh and clean water is essential to human and other living things. However, as

large water body such as river forms most of the surface water, too much of excess

water are not required because it can cause many problem in the future.

2.2. Flood

Flooding in general is caused by the inability of water to flow away rapidly from

an area due to certain factors, causing a build-up of volume and thus creating floods. As

an earth disaster, flood has caused many problems. Some of the effects of flood are

destroyed crops, severe losses and damage in property, disease and illness, and death.

Continuous flood also could affect a country's economy growth. Rebuilding a city after

flood will need a big amount of expenses. This, however, does not promise that

everything will be back like the time before flood. People will suffer of mental pressure

and trauma, faith and confidence in government will decrease, and the spirit to wake up

again will be hard to find.

In the case of Sungai Lembing, these flood contributing factors includes the area

that near to the river and probably the condition of the current drainage system which is

no longer suitable in handling the advent of torrential rains. The effect of flood can be

seen on Figure 2l

9

Figure 2.1. Image shows the effect of flood on 2007 on the way to Paloh Hinai.

Source http://pekanroyaltown.blogspot.coml2007/l 2/jalan-ke-paloh-hinai.html

Flood planning, forecasting, and emergency management can be greatly

enhanced through the use of models which have the ability to estimate the timing and

location of flooding. Until recently, flood modeling has been dominated by one-

dimensional models since these models are relatively simple and computationally quick.

However, these models do not represent any of the complex physical processes present

in floodplains and urban environments, and are therefore being discouraged by the

National Research Council for use in floodplain inundation studies. Two-dimensional

models based on the complete shallow water equations have a superior ability to resolve

flow velocity and. direction when compared to one-dimensional models. However, the

limitation of using two-dimensional models for flood planning, forecasting, and

emergency management is the increased computation cost. This dissertation presents the

development and validation of a two-dimensional model based on the complete shallow

water equations. For computational stability, the advective terms are resolved using an

upwind differencing scheme, with the scale and velocity vectors located on a staggered

grid. The model has been validated with laboratory experiments and has shown the

ability to accurately estimate both velocities and depths. In addition, simulation results

compared well to high water mark data collected from the Taum Sauk dam failure.

For years, researchers around the world have been trying to apply computer

models to stimulate flood impact. Since the first applications, numerous computer

models have been developed to assist in flood mitigation planning and flood control

design. These models range in complexity and also in predictive capacity. Most flood

estimation models are one-dimensional and perform dynamic wave simulations or solve

the full Saint Venant equations consisting of a continuity and momentum equation (Judi,

2009).

Flood Modelling by using Computer Software become an integral part of flood

risk assessment in both urban and rural areas, providing a means of converting

catchment discharge into inundation extent, depth and in some cases flow velocity.

These models vary in complexity from solutions of the two-dimensional shallow water

to storage cell models based on Manning's equation. Common to all these models,

however, is the computational expense (or burden) for many real world applications.

Recently, developments in computer hardware have moved away from increasing clock

speed towards providing many computational cores that operate in parallel. For

example, desktop computers are now routinely sold with dual-core _86 general purpose

central processing units (CPU's) and this trend towards larger multi-core machines is

expected to continue in the future (Jeffrey et al.).

In this case, Infoworks RS Is used to create the Hydrodynamic River Modeling.

To decrease the computational cost, the two-dimensional model has been developed to

take advantage of now prevalent multicore computers through Java multithreading to

provide parallel computing on desktop computers. This desktop parallel computing

capability coupled with an efficient domain tracking algorithm is shown to decrease

computation time by as much as 200 times. Aside from an ability to provide more real-

time flood forecasting, this reduction in computation time makes the incorporation of

risk and uncertainty/ensemble forecasting more feasible for flood inundation modeling.

However, as the scale of the simulation is increased (urban to region), and with the

increasing availability and use of high resolution data, computation times will increase

(Judi, 2009).

2.3. Types of Flood

2.3.1. Flash Floods

In areas with steep slopes, heavy rain can cause a riverbed that held very little or

no water at first, to suddenly brim with fast flowing water. The rain water is collected on

the slopes, then flows downhill gathering speed and all the water comes together in the

river bed. The water level rises fast. The water flows over the river banks and floods the

area. Speed is the keyword. It all happens fast, it rains heavily. The water flows at high

speed. Because of this speed it has the strength to carry away heavy objects as you can

see in the videos of Boscastle in 2004, Vaison la Romaine in 1992, and the area of

Alicante in Spain in 2007. The flood stops as suddenly as it starts.

A flash flood is a very direct response to rainfall with a very high intensity or

sudden massive melting of snow. The area covered by water in a flash flood is relatively

small compared to other types of floods. The amount of water that covers the land is

usually not very large, but is so concentrated on a small area that it can rise very high.

Because of the sudden onset and the high travelling speed of the water, flash

floods can be very dangerous. The water can transport large objects like rocks, trees and

cars. Never drive through a flash flood, even if it doesn't seem to be very deep: the car

may be swept away by the sheer speed of the water.

12

When a dyke breaks along the sea or along a river, the water may flow in so

suddenly and with such speed that could be compared with a flash flood. (Floodsite

Project, 2008)

23.2. Urban Flooding

Flooding in urban areas can be caused by flash floods, or coastal floods, or river

floods, but there is also a specific flood type that is called urban flooding.

Urban flooding is specific in the fact that the cause is a lack of drainage in an

urban area. As there is little open soil that can be used for water storage nearly all the

precipitation needs to be transport to surface water or the sewage system. High intensity

rainfall can cause flooding when the city sewage system and draining canals do not have

the necessary capacity to drain away the amounts of rain that are falling. Water may

even enter the sewage system in one place and then get deposited somewhere else in the

city on the streets. Sometimes you see dancing drain covers.

Throughout Europe urban flooding happens fairly frequently. The virtual tour

shows two examples, Hull in England in 2007 and Mestre in Italy in 2007. The same

sort of thing can happen in rural areas and is then called ponding.

Urban floods are a great disturbance of daily life in the city. Roads can be

blocked, people can't go to work or to schools. The economic damages are high but the

number of casualties is usually very limited, because of the nature of the flood. The