FLOOD HAZARD AND RISK ASSESSMENT THROUGH INCORPORATING GIS WITH HYDRODYNAMIC MODELLING: CASE STUDY OF MUDA RIVER

by

RABIE A. A. HUSSEIN

Thesis submitted in fulfillment of the requirements for the degree of Doctor of Philosophy

December 2009

ACKNOWLEDGEMENTS

ALHAMDULLILAH. Praise to ALLAH SWT ALMIGHTY AND MOST MERCIFUL for

the successful completion of this research

Many people have assisted me during my doctoral graduate research, and I am

grateful to them. I would like to thank my supervisors, Prof. Dr. Aminuddin Ab.

Ghani, Prof. Dr. Nor Azazi Zakaria and, Assoc. Prof. Sr. Dr. Mohd Sanusi S.

Ahamad for their help, guidance and encouragement throughout my research and

writing.

I would like to express my appreciation to all the staff in River Engineering and

Urban Drainage Research Centre (REDAC) and Universiti Sains Malaysia

especially the Institute of Postgraduate Studies for the fellowship granted to me.

Thanks to Mr. Osama Abu Libda for giving all numerous valuable advices during

study.

I wish to thank my family, especially my father, for all their support throughout the

years and for the value they've placed on education. Finally, my sincerest thanks

go to my wife, Heba, for the unconditional support and cortinual encouragement

throughout and for understanding my needs. Thanks for all the loving sacrifice.

Rabie Ali December 2009

ii

ACKNOWLEDGEMENTS

TABLE OF CONTENTS

LIST OF TABLES

LIST OF FIGURES

LIST OF ABBREVIATION

LIST OF SYMBOLS

ABSTRAK

ABSTRACT

TABLE OF CONTENTS

CHAPTER ONE: INTRODUCTION

1.0 Background

1 .1 -- Flooding and Flood Management in -Muda River

1 .2 Problem Statement

1 .3 Research Objectives

1.4 Research Scopes

1.5 Organization of the Thesis

Page

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1

3

10

10

11

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CHAPTER TWO: HYDROINFORMATICS IN FLOOD RISK MANAGEMENT

2.0 Background 14

2.1 Hazard, Risk and Flood Risk Management 15

2.1.1 Risk Analysis 19

2.1.2 Risk Assessment _19

2.1.3 Risk Planning 20

2.2 Modern Approaches of Flood Risk Assessment 22

2.3 Hydroinformatics 24

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2.4 Numerical Flood Simulation 28

2.4.1 Model Categorization 30

2.4.2 Model Selection 33

2.5 One-Dimensional Flood Modelling Approach 34

2.6 Flood Mapping 35

2.7 Types of Flood Hazard Mapping 37

2.7.1 Flood Extent Maps 38

2.7.2 Flood Depth Maps 39

2.7.3 Maps of Other Flood Parameters 39

2.7.4 Flood Danger Maps 40

2.7.5 Exposure and Coping Capacity Maps (Damage Maps) 40

2.7.6 Qualitative Flood Risk Maps 42

2.7.7 Risky Places Maps (or Approximation Maps) 43

2.8 Summary 44

CHAPTER THREE: DESCRIPTION OF STUDY AREA

3.0 Introduction 46

3.1 Geography 46

3.2 Climate 48

3.3 Geology and soil 50

3.4' Ecology & Environment 51

3.5 River Geomorphology 53

3.6 Anthropological Activities 57

3.7 Summary 61

CHAPTER FOUR: RESEARCH METHODOLOGY

4.0 Background 62

4.1 Data Acquisition 64

4.2 Data Management 67 iv

4.2.1 Data Representation 67

4.2.2 Data Registration and Georeferencing 77

4.3 Data Analysis 78

4.3.1 Qualitative Flood Behavior Analysis 78

4.3.2 Quantitative Flood Behavior Analysis 82

4.3.3 Model Synthesizing 90

4.4 Model Calibration and Verification 93

4.5 Flood Hazard Assessment 93

4.5.1 Hazard Mapping 94

4.5.2 Flood Return Period and Exceedance Probability 96

4.6 Flood Risk Assessment 98

4.7 Risk Communication 102

CHAPTER FIVE: RESULTS & DISCUSSION

5.0 Background 104

5.1 Geomorphological Characterization 104

5.1.1 Sinuosity Analysis 104

5.1.2 Channel Profile Analysis 105

5.2 Flood Behavior Characterization 114

5.2.1 Flood Simulation & Analysis 114

5.2.2 Model Calibration 117

5.2.3 Running the Simulation 119

5.3 Flood Risk Analysis 124

5.3.1 Flood Depth Mapping 124

5.3.2 Flood Return Period 132

5.4 Flood Risk Assessment 138

5.5 Impacts of Flood Management 140

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CHAPTER SIX: CONCLUSIONS & RECOMMENDATIONS

6.1 Conclusions

6.2 Recommendations

BIBLIOGRAPHY

PUBLICATION LIST

APPENDICES

144

146

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158

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LIST OF TABLES Page

2.1 Types of River Channel Hazards (Downs and Gregory, 2004) 16

2.2 Comparison between Different Hydraulic Software Packages 32

Commercially Available in the Market

2.3 Recent scientific studies and national works on flood risk 44

mapping in Europe (Modified from Koivumaki, et al., 2010)

4.1 Data Type and Specification 66

4.2 Characteristics of Landsat 6 Imagery Data 67

4.3 Characteristics of SPOT 5 Imagery Data 67

4.4 -

Spatial data representation and their relevant geographic attributes 68

in the study area

4.5 Roughness values for Land use Features in the Study Area, 88

Muda River

4.6 Water Depth Classes Suggested by the Japanese Flood Fighting Act 2001 94

4.7 Flood Damage Factors for Agricultural and Houses 100

4.8 Unit values of properties and crops 101

4.9 Total Estimated Flood Damage for a Flood Event 102

5.1 Simulated Inundation Areas according to Land Use Categories 121

5.2 Simulated Inundation Areas for Urban Areas during 6th October 124

2003 Flood

5.3. The reference damage factors for each land use classification category 128

used for risk mapping in Muda river based on JICA 1999, 2000

vii

5.4 Summary estimates of flood damage on agriculture and urban land 139

use categories

5.5 Economical Damage estimates of urban land use sub-categories 139

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LIST OF FIGURES Page

1.1 Three Controls of River Morphology and Behavior: Upstream, 4 Downstream and Local (Schumm, 2005)

2.1 Elements of an Integral Risk Management as Proposed by 18 Ammann (2006)

2.2 Framework for the Integral Risk Management as Proposed by 18 Ammann (2006)

2.3 Risk Cycle and Possible Measures for Risk Reduction and Mitigation 21 (Ammann, 2006)

2.4 Classification of flow as Steady and Unsteady 31

2.5 Model-based selection criteria (Ewbank eta., 2001) 33

2.6 Types of flood damage (Sturgess, 2000) 41

3.1 Topographic map of Muda River. basin 47

3.2 Mean annual rainfall isohyets of Muda River basin 49

3.3 Soil Type in Muda River Basin 51

3.4 Nipah trees are widespread along Muda River 52

3.5 Topography of Muda River as shown from Google earth 54

3.6 Flood inundation area in P.Pinang and Kedah(9-10 October 2003) 55

3.7 Riverbed gravel materials 56

3.8 Riverbed sand materials at the Muda River mouth 57

3.9 Land use Classification of the Study Area, Mud a River 58

4.1 Overview of the road map of research methodology in this study 62

4.2 Collected field GPS samples in X, Y coordinates 68

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4.3 Space imagery used to extract and classify the land cover/land use 69

activities in the study area

4.4 Image supervised classification map of land use/land cover units of 70

the study area performed by ENVI image processing software

4.5 Map features and attributes of the geographic features of urban 70

land use in the study area

4.6 Map Features and attributes of the geographic features of 71

agricultural land use and natural vegetation land cover in the study

area

4.7 3D digital surface representation of the study area in TIN format 72

4.8 3D digital surface representation of the study area for flood 73

mapping purpose (2009)

4.9 Extrapolation of water levels from the 1 D model and the irregular 74

terrain topography ( 1 D modeling approach)

4.10 Representation of ground surface roughness of the study 76

area attributes synthesized from lnfoWorks RS

4.11 Channel planform characterization measures based on number 80

of channels, sinuosity and lateral stability (source: Brierley and

Fryirs, 2005)

4.12 Classification of channel types (after Rosgen 1994) 81

'· 4.13 Location of the 261 Cross Sections along Muda River Sub- basin Model 84

4.14 typical cross sectional profile of chainage downstream 200m 84

4.15 Model input hydrograph (Upstream) 85

4.16 Tidal information for Muda River (downstream) (Julien et al., 2006) 85

X

4.17 Schematic representation of river cross-section against the 87 distribution of ground roughness zones at chainage (a) CH39.50 and chainage (b) CH15.00

4.18 Scheme of data processing in synthesizing the GIS flood model

4.19 Flowchart of database development, management and geoprocessing adopted in the study

4.20 Work flow of 100 year flood probability modeling used in the study

5.1 Comparisons of the Present Cross-Section (New Bridge) and the Cross-Section from the Year 1993 (Old Bridge) (Julien et al., 2006)

5.2 Change to the Longitudinal Profile of the Muda River

5.3 Changes in the land use and land cover of the Muda area during the period1984-2001

5.4 Channel Adjustment in Response to Urbanization as Hypothesized by Roberts (1989) (Source: Brierley and Fryirs, 2005)

5.5 Geomorphic adjustments (responses) to the land use change by deforestation activities modified after Brierley and Fryirs, 2005)

5.6 Distribution of Sand Mining in Muda Channel, Kedah State

5.7 Flood peaks of the Mud a River from 1960 to 2005

5.8 Flood Frequency Analyses for the Muda River@ Ladang Victoria based on Gumbel Extremal Type I for discharge data of 1960 to 2005

5.9 A schematic representation of the river's cross-section against the distribution of ground roughness zones at (a) CH 39.50 and (b) CH 15.00

5.1 0 A comparison between the predicted and observed water l~vel values at (a) CH 14.0 and (b) CH 41.2.

5.11 Real time geographical visualization of the 2003 flooding event as processed in lnfoWorks RS (CH 28.00-CH 31.00)

5.12 Maximum flood depth for the existing channel indicating the bund requirement (CH 34.4)

5.13 Hydrograph of the 1984 Flood

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121

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5.14 December 2005 peak flow flood (CH 15.00- CH 20.00) 122

5.15 October 2003 peak flow flood (CH 15.00- CH 20.00) 123

5.16 Simulated Depth Map during 6th October 2003 Flood 125

5.17 Flow Chart for Flood Damage Computation 127

5.18 Flood hazard map of urban areas of Muda River 129

5.19 Flood hazard map of Wet Paddy of Muda River 130

5.20 Flood hazard map of Rubber &Oil Palm of Muda River 131

5.21 Comparison of Design and Observed Hydrograph (Julien et al., 2006) 132

5.22 Existing cross section CH33.8 for the flood event 2003 134

5.23 Design cross section CH33.8 for the flood event 2003 134

- ...

5.24 Long sectional profile for 2003 flood of the existing cross sections 135

5.25 Long sectional profile for 2003 flood of the design cross sections 136

5.26 Design cross section CH33.8 for the for 100 design hydrograph 136

5.27 Design hydrograph in consideration of climate change effect 137

5.28 Design long sectional profile 138

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LIST OF ABBREVIATION

ARI = Average recurrence interval

CH = Chainage

FCRP = Flood Control Remediation Plan

DID = Department of Irrigation and Drainage

EO = Earth Observation

FFA = Flood frequency analysis

FEQ = Full Equations Model

GIS = Geographic information system

GPS = Global positioning system

HEC = Hydrologie Engineering Centre

ICT = Information communication technology

JICA = Japan international cooperation agency

KEDA = Kedah Regional Development Authority

LIDAR = Light Detection and Ranging

RDBSM = Relational database system management

RS = Remote sensing

SCAD A = supervisory control and data acquisition systems

SID = Satellite image database

QdF = Flow duration frequency

UNET = A one-dimensional unsteady state hydraulic model

WSPRO = A computer model for Water-Surface PROfile computations

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LIST OF SYMBOLS

Symbol Definition

A cross sectional area of flow (m2)

B stream top width ( m)

g Gravitational acceleration

v cross-sectional average velocity (m/s)

kn 1.486 for English units and kn = 1.0 for Sl units

n Manning coefficient of roughness

R hydraulic radius (m)

s slope (m/m)

s Sinuosity

L channel length (m)

straight-line valley length (m)

y stage (m)

Q Discharge (m3/sec)

q Lateral flow into the channel per unit length of channel

X Distance along the channel(m)

t time

s, Friction slope

K conveyance

R hydraulic radius

T The return period

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BAHAYA DAN PENILAIAN RISIKO BANJIR BERDASARKAN GABUNGAN GIS DENGAN PEMODELAN HIDRODINAMIK: KAJIAN KES DARIPADA SUNGAI MUDA

ABSTRAK

Sungai Muda telah menghadapi banjir bermusim dan mengakibatkan kerosakan

yang serius dan menjejas tahap ekonomi dengan memusnah penempatan penduduk

dan harta benda di kawasan tadahan Sungai Muda. Banjir pada tahun 2003

merupakan peristiwa yang paling membinasa berlaku dalam sejarah kawasan tadahan

Sungai Muda. Perubahan dari segi geomorfolgi, kelakuan banjir dan impak kepada

Sungai Muda telah dikaji dalam kajian ini dengan pengintegrasian antara pakej

perisisian khusus dan teknik permodelan komputer untuk menjangka perubahan

langsung terhadap kelakuan sungai dan membantu dalam meramal dan

menghubungkan dengan risiko banjir. Kekasaran permukaan tanah telah dibangunkan

melalui beberapa lawatan tapak di kawasan kajian. Kekasaran permukaan ini

merupakan satu input yang amat panting bagi permodelan hidraulik. Keputusan

daripada penyelakuan model hidrodinamik satu dimensi menunjukkan kawasan yang

luas telah ditenggelami banjir di sekitar dataran banjir dan juga kerosakan teruk pada

kawasan yang berciri-ciri penempatan penduduk dan kegunaan tanah pertanian.

Penilaian bencana dan analisis risiko pada dua jenis gunaan tanah menunjukkan

bahawa kerugian ekonomi pada banjir tahun 2003 (RM 27.6 juta) adalah setinggi lima

kali ganda berbanding dengan banjir yang sebelum ini (1982) bagi tempoh 20 tahun

(RM 3.87 juta). Kerugian yang besar ini boleh dihubungkan dengan perubahan-

perubahan dramatik pada sistem sungai yang mempunyai sejarah dan kontemporari

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eksploitasi manusia yang tidak mapan di kawasan tadahan Sungai Muda ini, iaitu

dengan peningkatan kerentanan terhadap bencana hakisan dan penurunan kekasaran

permukaan tanah. Model bagi peristiwa banjir kala ulangan 100 tahun juga telah dibina

untuk menilai keberkesanan pembinaan ban bagi menampung kenaikan paras banjir

semasa berlakunya banjir besar. Penyelakuan model telah menunjukkan bahawa reka

bentuk ban yang dicadangkan mempunyai kapasiti yang cukup untuk menampung air

banjir dengan kapasiti tambahan setinggi 1.5 m. Hasil keputusan permodelan

menunjukkan pembinaan ban dapat mengurangkan risiko banjir ke status sitar, dan

seterusnya akan melindungi kegiatan manusia yang berada di dataran banjir. Pada

jangka panjang, sungai ini mungkin mengalami penyesuaian geomorfik tanpa

dipengaruh oleh bencana banjir; akan tetapi di masa hadapan latidakstabilan luar biasa

·sa luran dan penyesuaian · geomorfik mungkin bertarilbah besar dan dengan demikian

berlakunya peristiwa banjir di kawasan kajian. Pemodelan komputer yang dilakukan

dalam kajian ini dapat meningkatkan lagi pemahaman tentang perilaku jangka panjang

dan perilaku banjir di Sungai Muda.

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FLOOD HAZARD AND RISK ASSESSMENT THROUGH INCORPORATING GIS WITH HYDRODYNAMIC MODELLING: CASE STUDY OF MUDA RIVER

ABSTRACT

Muda River has been for many years experiencing seasonal floods and causing

serious damage and economical loss to human settlements and property in the Muda

basin. The 2003 flood was the most devastating event throughout the history of the

river. The geomorphological changes, flood behavior and impacts of the ~uda River

have been investigated in this study using integration of specialized software packages

and computer modeling techniques to envisage the consequent changes projected on

the river, and assisting in predicting and communicating the flooding risk. Ground

surface roughness was delineated through several field visits to the study area. This

ground roughness acts as a significant input data for hydraulic modeling purpose. The

results of one-dimensional hydrodynamic modeling showed a wide spatial extension of

flooding inundation in the vicinity of the floodplain, and indicated damage severity on

households and agricultural land use features located in these highly inundated areas.

Hazard assessment and risk analysis on these two land use types revealed that the

economical damage of the 2003 flood (RM 27.6 million) was five times than that of the

last flood (1982) in a 20-year-period (RM 3.87 million). This enormous loss can be

attributed to the dramatic changes imposed on the riverine system by much historical

and contemporary unsustainable human exploitation of the Muda basin land assets,

increasing its vulnerability to erosion hazards and decreased ground surface

roughness. The 1 00-year flood event model was also reconstructed in order to

xvii

investigate the effectiveness of the proposed bund in controlling the increase in water

depth during extreme flooding conditions. The modeling indicated that the proposed

bund has enough capacity to contain safely the flood water, with an additional capacity

of containing extra 1.5 m of flooding water without exceeding the breaching point. The

modeling result also suggests the effectiveness of the proposed bund structure in

reducing the flooding risk, protecting thereby the human activities in the floodplain. On

the long run, the engineered river may experience localized geomorphic adjustments

without initiating flood hazard; but under futuristic extensive and extraordinary channel

instabilities, geomorphic adjustments may become magnified, initiating thereby flooding

event in the study area. The computer modeling performed in this study improved the

understanding of the long-term behavior of Muda River and its flooding behavior.

xviii

1.0 Background

CHAPTER ONE INTRODUCTION

Natural hazards, as one of the elements of global ecodynamics, are

caused by natural processes independent from the existence of the humans.

Natural disasters can arise from weather patterns (e.g. tornadoes, storms, floods,

and hurricanes.), changes in Earth's crust (e.g., earthquakes, volcanoes, and

landslides) and climatic conditions (e.g. droughts, bush fires, cold snaps, etc.).

Natural risks result from natural hazards when humans are exposed to them

(Proske, 2008; Kondratyev et al., 2006). Since the earliest emergence of

civilization on Earth, the humans have described natural disasters, such as the

Noah's flooding in The Holy Quran. Flood disasters, either driven by natural or

man-made forces, account for about a third of all natural disasters by number

and economic losses and are responsible for over half the deaths on a global

scale. In the poor and heavily populated Asia, flood disasters continue to cause

the largest number of deaths. The global factors that might govern the future

prospects for flooding are related to population growth, press'ure on land use,

climate change and insurance market response. Unfortunately, flood disasters'

share in insured losses is relatively small, with an average of fewer than 1 0%

(Knight, 2006). As the fast developing Asian countries face pressures of urban

expansion and demand for more floodplain to be developed, they are expected to

continue setting up flood management for the sake of community safety,

sustainable development and resource management.

1

Flood hazard is the only significant natural hazard that affects Peninsular

Malaysia (Chan, 1993). Flooding is a byproduct of the interaction between a

natural events system and a human use system. Continuous changes in land use

and climate affect the geomorphology of river systems (Toy et al., 2002; Houben

et al., 2006). Aside from natural causes, the rapid development of modern

Malaysia is causing changes in the natural hydrological regime which could have

very serious consequences if not foreseen and allowed for in the design of

development (Toebes and Seng, 1975). Flooding is a serious problem in

Malaysia where drainage systems are poor and there exists a relatively high

water table and flat topography. Many anthropogenic land use patterns (e.g.

agriculture, industrialization, commercial, residential) are concentrated along

rivers· and in the vicinity of floodplains and submergible areas throughout

Malaysia; thus are seriously subjected to the flooding catastrophes over the time.

In the light of Malaysia's 2020 vision to be an industrial nation, more and more

floodplain areas are expected to be developed, thereby exposing even more

people and property to flood risk. This necessitates the need to set up efficient

and effective flood management schemes and initiate engineering projects on

national scale to alleviate the imposed risk to an acceptable level.

Dealing with flood management necessitates dealing with a huge amount

of datasets; be they environmental, technical, economic, or social. Experience

shows that increasing complicated problems in flood management entails the

need for an integrated view, multidisciplinary methodology and smart solutions

2

that are no longer simple to generate or implement. The complexity in flood

management needs, therefore, to be uncovered, comprehended and its behavior

to be simulated, analyzed and predicted to make flood decision­

making/management feasible, efficient and effective. Fortunately, the modern,

revolutionized digital technologies and the advent of computer-based hydro­

modeling come to fulfill this requirement - hydroinformatics as emerging

technology. The application of this technology becomes important in hydraulics

studies and provides value as it relies on physical sciences, natural sciences,

ICT and social awareness (i.e., sociotechnology) (Price, 2006; Abbott et al.,

2005).

1.1 Flot>ding and Flood.Management in Muda River·

Floods are extreme natural phenomena that develop slowly and affect

gradually on the environment. With increased in global warming, large-scale

floods are possible in wider territories (Kondratyev et al., 2006). Flood hazard

has been and will continue to be a threat for Malaysians, especially when

humans choose to occupy floodplains, ignore the dangers of such hazard zones,

over-develop land and deplete natural resources at rates that natural system can

neither cope with nor adapt to. The damages for an annual flood, a 1 0-year flood

and a 40-year flood are estimated to beRM 3 million, RM 18 million and RM 44

million respectively (Chan, 1993).

Stream channels are complex systems in space, time and causality (Lane

and Richards, 1997). A change often triggers another, causing multiple

3

responses to a single influence (Schumm, 1977). In fluvial systems, variability in

the river's behavior and response to natural and anthropogenic activities is

subject to three types of controls (Schumm, 2005): upstream, downstream and

local, as illustrated in Figure 1 .1 .

Local Controls

Bedrock-Alluvium Tributaries

Active Tectonics Valley Morphology

UPSTREAM CONTROLS

Climate (Hydrology)

DOWNSTREAM CONTROLS

Figure 1.1 Three Controls of River Morphology and Behavior: Upstream, Downstream and Local (Schumm, 2005)

According to Figure 1.1 , river response to human impacts will vary

depending upon sediment characteristics, climate and the type of river, which

results in uncertainty and unpredictability concerning the effect of controls

(Phillips, 2002). Generally, for important land use changes, deforestation,

afforestation and urbanization, experimental data interpreted for use under

4

Malaysian conditions indicated to the following observations (Toebes and Seng,

1975):

I. Land use changes have at least as great an effect on the hydrology as in

temperate zones

II. water yield increases upon deforestation and decreases upon

afforestation

Ill. peak flows and flood volumes increase (for smaller catchments) upon

deforestation and urbanization

IV. Low flows and high water table due to high infiltration rate increase upon

deforestation but tend to do the reverse upon urbanization

Muda River 1s a major source for water supply and sand mining for the

northern states of Malaysia. It has been affected dramatically by unsustainable

human activities that sacrificed environmental values for the sake of national

development. The land draining into this river has been rapidly changing and

cleared for agriculture, industrial and urban development. Forested areas are

reduced. This has been caused by the growth of population size. These activities

contribute to the increase in the amount of runoff entering the river and thereby

exposing the population to the risk of flooding. Considering these disturbances

and the complexity and variability can a river reach over the time and space, as

perceived earlier in Figure 1.1, one can stereotype the dramatic scenario of the

consequences in changing Muda River's flooding behavior as a result of its

natural response to the changing controls.

5

Significant damages and losses of property, life and money had been

associated with flood disasters in Malaysia. Muda River experiences floods

almost every year (recurrent event), each differing only in their magnitude. The

October 2003 flood saw 45,000 people affected with catastrophic damages.

Many problems were associated with catastrophic flood of Muda River including

riverbank erosion, river pollution and reduction of water resources. (JICA, 1995).

The appearance of conditions of danger to Muda River community is

mainly connected with the probability of the flooding catastrophe as a result of

poor landscape management. The catastrophe threatens human life and

therefore their prevention through formalized prediction is a necessary element of

safe arid sustainable development of Muda basin iri future.

The importance of sustainable development of the valuable riverine

systems of the nation must be recognized. The Malaysian government initiated

and generously allocated resources for a new "Flood Control Remediation Plan

(FCRP)" devoted to study, design and implement flood mitigation projects in the

Muda River district. The plan aims at better understanding of the dynamics of

Muda River's flooding, defining options for flood loss prevention, design criteria

for proposed mitigation measures and plot a strategy for flood management for

Kedah State's vulnerable resources. The proposed mitigation works ·were

structural and nonstructural, and ranged from changing river geometry, design

6

discharge and bund height, channel realignment, flood diversion to constructing

piers and bridges. (JICA, 1995)

Given that the current proposed FCRP flood mitigation (control) projects in

Muda River are expected to change the. flooding behavior of the river in future (in

reference to the conceptual view shown in Figure 1.1 ), it is important to

investigate and predict these behavioral changes and their spatia-temporal

consequences in terms of project investment, feasibility and impact assessment.

Knowing the character and predicting the behavior of meandering rivers is

also important for sound management and planning, especially as rates of down­

valley migration and lateral channel shifts occur, both on spatial and temporal

dimensions (Richards et a/., 2005). As development of infrastructure in

developing Asian countries is the most damaged by natural disasters such as

flooding, the problem of risk reduction due to infrastructure transformation turns

very important. The solution to this problem is connected with optimizing

processes of the use of land resources and working out ecological strategies.

Furthermore, quantitative and qualitative dynamism in urban development leads

to an overproportional increase in the vulnerability of such territories to flooding

risk. This situation is provoked by either the economic interests or socio-political

factors, when a large number of people are concentrated in a small area, which

drastically increases the risk to human life (Krapivin and Varotsos, 2007).

7

Therefore, the problem of regional infrastructure optimization is becoming with

the passage of time more urgent (Gurjar and Leliveld, 2005).

Risk as a measure of danger can serve as a guideline to resolve the

problem of controlling a set of circumstances that can disturb human habitats and

change conditions for the functioning of society. This includes getting estimates

of the levels of adversity for many different aspects. At the same time, risk also

has a subjective constituent which can be measured with the help of formal

methods of decision-making that take into account intuitive assessment of the

situation and psychological norms of perception of the environment. Furthermore,

optimizing the risk to insurance industry from natural disasters becomes every

·year an ev.er more urgent problem, since economrc losses ·are on the increase .

and are almost unpredictable. Evaluation of the risk and subsequent damage

requires interdisciplinary analysis of a vast amount of information (Krapivin and

Varotsos, 2007). This requires the flood expert to deal with a huge, complex

computer databases relating to the many physical, natural, technical,

economical, social and environmental aspects of flood risk.

Many types of flood controlling approach are being practiced in different

flood-prone river basins. One of these is using hydroinformatics as an integrated

flood management system to assist decision makers in encountering the issues

of complexity in watershed hydrology, river hydraulics and environmental

aspects. Computer modeling used in hydroinformatics can greatly improve the

8

understanding of the long-term behavior of Muda River and its flooding behavior

in the pre- and post Flood Control Remediation Plan (FCRP) phases. This will

assist the concerned parties on perceiving the level of insurance might be

prescribed for a successful flood management project and, therefore, resolving

urgent or potential problems that might arise on the long run, and/or earlier in the

project cycle.

The current thesis, therefore, comes to explore and address these

challenges and investigate the use of hydroinformatics in studying the natural­

anthropogenic interactions and their influence on the flooding behavior of Muda

River and the subsequent impacts upon implementing flood management

strategies. This research's interest comes in line with the global trend of

investigating the importance of the interconnection of human living standards and

natural process of flooding in the eye of digital technology. The state-of-the-art

developments of hydroinformatics have significantly enhanced the ease with

which computer model predictions can be computed and communicated. Its tools

aim at solving the problems of water engineering issues as a single entity with

available geospatial dataset collected, stored and processed by means of

Geographic Information System (GIS), Global Positioning System (GPS), remote

sensing and ground surveys. With the aid of hydroinformatics techniques in

simulating and predicting the consequences and assessing the impacts, the

outputs of this thesis will hopefully assist in optimizing the process of flood

characterization, in improving the flood management practices, in playing as a

9

feedback for these practices, in stereotyping negative-change consequences,

and in defining suitable alternatives to mitigate the negative effects in a sustained

manner.

1.2 Problem Statement

The flood event of 2003 of Muda River in Kedah State is considered as

the most damaging flood event within the last 50 year. Since that time natural

and land use changes have been affecting on flood behavior of the river. The

new implementation of the FCRP plan will have an impact on the flooding

behavior; therefore there is a need to assess the flooding behavior before and

after implementing the FCRP plan. The flooding behavior before applying

mitigation/prevention works will also differ -than in the post ·(FCRP) phase. The

assessment need to be qualitatively and quantitatively described to predict future

impact, recommend control measures or correct the existing, and to

communicate the risk to different concerned parties on the track towards

reducing the risk to an acceptable level.

1.3 Research Objectives

The present study is directed to employ the state-of-the-art techniques of

hydroinformatics in accomplishing the following objectives:

I. To determine the ground surface roughness of the study area based ori field

visits.

10

II. To assess of flood behavior pattern and its risk against a variety of site input

variables.

Ill. To assess of flood risk on proposed structural control works and recommend

new alternatives to manage possible hazard.

1.4 Research scopes

The scope and limitation of the present study are as follows

I. The modeling reach is limited from Ladang Victoria to the river

mouth of Muda River.

II. The ground surface roughness is based on field visit during the

years of 2007, 2008, and 2009. It's expected that the ground

surface roughness needs to be reevaluated after 5 years from

"2010. -

Ill. The flood risk map developed in this study should be reevaluated

every 5 years.

1.5 Organization of the Thesis

Chapter 2 in this thesis addresses the concept of hazard assessment and

risk management and the old and new developments of hydroinformatics in

water-based civil engineering works. The discussion is elaborated on those

issues concerning the concepts and approaches of risk mapping and modeling

with view of ICT role, scope, tools, methodologies and applications in· flood

investigations. Specific focus is given to discuss how hydrological modeling

avails of the potential of geospatial technologies of remote sensing, GIS,

11

computer graphics and artificial intelligence, and in which they strengthen

hydrology as a science and as a profession. The chapter also outlines a literature

review of the previous works and recent developments pertaining to river flood

modeling and forecasting that lie within the interests of this thesis. The

discussion highlights the importance and value of coupling and linking a GIS with

other computing and modeling software packages to act in union towards

disseminating new intensive data of multiple nature, dimension and use. A

comparison in terms of capabilities, advantages and applications is drawn on

between the most common commercial software products used in flood

investigations by the experts.

Chapter 3 provides a description of the study area, Muda River, Kedah

State. The description deals with the natural, physical, environmental and

historical site use of Muda basin, supported with desk study maps, space

imagery and ground photographs.

Chapter 4 deals with the general research methodology adopted to

achieve the ultimate objectives of this study. Details on methods, techniques and

procedure of data collection, data management, data treatment, data processing

and visualization employed in the study are elaborated.

Chapter 5 represents the findings of flood simulation modeling and

analysis computationally and graphically. Synthesized results and assessment of

12

the simulated flood behavior change and its impacts on spatial and temporal

bases are discussed and verified with statistical and thematic information. The

outcome is directed to support the decision making process regarding current

and future flood management practices.

Chapter 6 highlights the conclusion and recommendations this study

comes up with. Future work and proposed developments regarding Muda River

basin and flood management are also projected for further investigation and

study by prospective researchers and interested personnel.

13

CHAPTER TWO HYDROINFORMATICS IN FLOOD RISK MANAGEMENT

2.0 Background

The advancement in Information Communication Technology (ICT) in

general and Geographic Information Systems (GIS) in particular has created

countless opportunities for developing decision support for flood studies.

Consequently, the decision-making process to manage the hazard of flood events

has become more feasible, time- and cost-effective using computer aids and

mapping tools found in GIS. In general, the procedures of data collection, data

management, data processing, data representation and data communication of

flooding risk have benefited widely from computer development and GIS. These

tasks are now becoming operationally optimized in a new branch of computer­

based hydrological studies, called "hydrofnformatics" which will be defined ·later in

this chapter.

This chapter addresses the aspects of flood risk management in the era of

digital technology. It highlights the framework of flood risk management and the

power, practicality and the revenue gained from applying hydroinformatics tools in

this framework through reviewing the recent developments and previous works

published in the scientific literature. The chapter paves a space for the mapping­

based flood hazard assessment and elaborates on the various types, configuration

and usefulness of flood risk mapping and modeling systems to ultimately

disseminate a proper decision for flood risk management endeavor.

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2.1 Hazard, Risk and Flood Risk Management

Hazard is a naturally occurring or human-induced process, or event, witt

the potential to create loss. Risk is the actual exposure to a hazard (Smith, 2001)

De Bruijn and Klijn, (2009) indicated that flood risks can be defined as 'thE

combination of the probability of a flood event and of the potential adversE

consequences for human health, the environment, cultural heritage and economic

activity associated with a flood evenf. Therefore, flood risk has two components

(Samuels, 2006b; Helm, 1996):

I. The probability of a flooding event occurred, and

II. The consequence of the flood event's impact which may be desirable or

undesirable

So that the objective measurement of risk can be formulated by the following

equation:

Risk = Probability x Consequence

And to establish flood risks, both flood probabilities and consequences must be

considered or - alternatively - flood hazard and the vulnerability of the flood-prone

area (Gouldby & Samuels, 2005).

River channel hazards can arise naturally from geomorphologic processes,

from activities of land use, or from a response to channel management actions '·

(Downs and Gregory, 2004 ). These hazards are subject to a host of changing

variables, such as time, discharge, sediment load and base level. Types of river

channel hazard (Table 2.1) can be categorized into the following (Schumm, 1988):

I. abrupt, producing a catastrophic event, such as dramatic channel widening in

response to a large storm event;

15

II. progressive change that leads to rapid change, such as meander's growtl

leading to a meander cut-off;

Ill. progressive change that has slow but progressive results such as bank erosion

Table 2.1 Types of River Channel Hazards (Downs and Gregory, 2004)

Erosion • Incision • Knickpoint

formation and migration

• Bank erosion

Deposition • Aggradation • Back and downfilling • Formation of berms

Pattern Change • Meander growth and

shift • Island and bar

formation and shift • Meander cut-offs • Avulsion

Metamorphosi!l • Straight to

meandering • Straight to braide • Braided to

meandering • Braided to straigt • Meandering to

straight • Meandering to

braided

Flood hazards are characterised in terms of flood probability, flood depth

flow velocity, water level rise rate, and other factors. Hazard dimensions can bE

characterized in terms of where, when, how long-lived and how much adjustmen

occurs. Flood managers dealing with such dimensions should understand thE

location, likelihood, persistence and magnitude of prospective hazards

Management options then can be evaluated besides predictions on the

dimensions adjustments resulted from applying these options (Downs anc

Gregory, 2004). Flood impacts comprise both direct and indirect impacts, or

tangibles (usually property and economy) and intangibles, such as people

(fatalities, injuries, psychological damage, etc.) and ecosystems. Generally, in

flood impact assessments, flood damage and fatalities are considered first (De

Bruijn and Klijn, 2009).

Recent research in flood studies has recognized that adopting risk-based

approach in flood management has proven to be better over the traditional flood

protection strategies (De Moel et al., 2009). This is because risk has many

16

dimensions in management practice in terms of safety, economy, environmental

and social issues; thus the process of decision-making will cover multiple issues

and go in accordance to the risk manager's needs. Risk also has been the main

focus of mitigation procedures of integrated flood management projects (Green et

al., 2000). Since risk is typically concerned with the likelihood of undesirable

consequences that would harm society, property or the environment, hence; the

practice is directed towards preventing or managing possible impacts of a flooding

event. Therefore, risk should form the framework for managing and

communicating the effects of flooding (Samuels, 2006a). Both spatial and temporal

scales of flooding consequences must be taken to avoid inadequate, biased

decision-making process (Samuels, 2006b). Aven and Kristensen (2005)

discussed that risk can be considered both as a way of expressing uncertainty,

· and as a collection of perceptions. This means that risk should be considered to be

a judgement rather than a fact. The 'probability' approach is an expression for the

state of knowledge, that depends on the information and the knowledge of the

individual who assigns it. Hence, no universal and true probability exists

(Raaijmakers et al., 2008).

In order to take effective and efficient decisions in flooding events, a

consistent, systematic and integral risk management ap~roach has to be designed

(Plate, 2002). Ammann (2006) proposed the concept of the integral risk

management of a natural hazard (Figure 2.1) where the process is composed of a

complete set of risk identification, risk analysis, risk assessment and planning of

mitigation measures. The general framework of this concept (Figure 2.2) involves

a strategic and systematic process of controlling the risk and a comprehensive risk

17

dialogue between all stakeholders. The cornerstone of this framework is tl

information of people at risk and of the authorities and agencies responsible f

flood management. Only if the people and decision makers are aware of the flo<

risk, and only if they are able to evaluate the risk, they can be expected

adequately respond to this thread.

Case situation

Actions

Measur:es decisions

Risk analysis assessment

Measures options

Figure 2.1 Elements of an Integral Risk Management as Proposed by Ammann (2006)

Risk Analysis Risk Assessment

Strategic Controlling

Risk Dialogue

Figure 2.2 Framework for the Integral Risk Management as Proposed by Ammann (2006:

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2.1.1 Risk Analysis

Risk analysis is the first phase and considered central in risk management

framework (Plate, 2002). In this phase, aspects of hazard analysis (i.e. source,

pathway, receptor and consequence), exposure analysis, impact analysis, risk

estimation and visualization are assessed. In terms of flooding, this phase is trying

to answer the following questions (Samuels, 2006b ):

I. Can the flood happen in the land?

II. What area is affected?

Ill. What causes the flood?

IV. How often does flood occur?

v. How deep is the flood?

VI. How rapidly does the flood rise?

VII. How long does the flood last?

VIII. Can any warning be given?

2.1.2 Risk Assessment

Flood risk assessment has gained increasing attention due to its importance

in flood management. In this phase, consideration is given to the protection goals

of lives and assets, the risk categories and risk aversion, trying to answer the

question of "what extent of flood is acceptable to happen?". This require

understanding the behavior of a flooding system, i.e. its physical, man-made

defense, economic, social, environmental aspects, statutory responsibility,

insurers, and stakeholders. Once the behaviour of the system is understood, many

dependent and independent issues could be identified, and a system failure

probability can be estimated and combined with knowledge of the consequences

19

(Samuels, 2006b). All in all, the assessment context has to do with complexity,

uncertainty and ambiguity of the risk.

Risk perception is vital to the assessment phase. Raaijmakers et al. (2008)

discussed a standard approach that integrates the conventional risk methodology

(technical expertise) with societal risk perception. This combination helps to

explain the influence of flood risk perception on risk-benefit trade-offs. Four types

of risk characteristics need to be considered in flood risk perception: (1) Ignorance;

(2) Safety; (3) Risk reduction; and (4) Control. Raaijmakers et al. (2008) believed

that "worry" is the characteristic that links risk perception to the risk-benefit trade-

off. If levels of worry are high, there will either be a demand for risk reduction in

terms of lower probabilities of damage or a demand for reduced

· effects/consequences. If levels of worry are low, the· individual believes that society

is in control, feels safe or is completely ignorant of the situation. In the latter case,

risk communication becomes important.

2.1.3 Risk Planning

In risk planning phase, relationships of risk-costs and marginal costs, and

integration of possible measures that are required to reach the protection goals are

assessed. These measures must be planned and checked for effectiveness and

undertaken to play valid management solutions that fulfill prevention, intervention

and reconstruction through risk cycle (Figure 2.3), and also meet sustainability,

acceptability, feasibility, and reliability criteria (Ammann, 2006).

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Reconstruction Recovery

Insurance

Prevention

Land-use planning measures (Hazard map) Technical (engineering) measures Biological measures

Organizational measures Emergency/crisis management

Figure 2.3 Risk Cycle and Possible Measures for Risk Reduction and Mitigation (Ammann, 2006)

Flood risk reduction and management have generic options aiming at

controlling the source, the pathway, the exposure and the vulnerability (Samuels,

2006b). In this case, risk can be controlled by addressing both the probability

through structural defenses and the consequences of flooding through non-

structural measures. As the actual provision of flood defenses requires economic

justification through cost-benefit analysis on a project .. by-project basis, risk

assessment comes here to determine whether the current provision is sufficient to

mitigate the flood risk and/or identify new protection measures towards controlling

the risk to acceptable levels (Samuels, 2006a). Therefore, to obtain insight into the

appropriateness of proposed measures, risk assessment is essential.

Mitigation approaches to deal with flood risk have changed over the past

and present time, between primitive approaches such as building houses on a

higher level or using boats to escape danger areas (White and Haas, 1975), to

21

engineering approaches such as the construction of dams and levees (Monroe e

al., 2007; Downs and Gregory, 2004 ). Advanced approaches included also flooc

risk mitigation for the public by providing forecasting and warning systems, whicl

allow appropriate emergency response to flooding in marginal areas and thE

potential failure of flood defenses (Samuels, 2006a). However, such mitigatior

tasks function at different spatial and temporal scales, and is often still lacking ir

flood assessment studies.

Land use planning combined with risk mapping contributes effectively ir

limiting the consequences of flooding. This has made floodplain mapping ~

common practice in most countries (Samuels, 2006a). New developments ir

computer visualization have also brought the attention to modeling and mappin~

· issues of flooding hazard and river complexity, and allowed for quantifying· the

prediction of uncertainty of the end-product at higher level (Savic and Khu, 2005).

2.2 Modern Approaches of Flood Risk Assessment

The basis of effective and efficient risk management is risk analysis and

assessment (Merz et al., 2007). Huang (2005) pointed out that in the past, flood

risk assessment used to be based on statistical risk-analysis approaches which

focus on the study of flood defence systems using probabilistic design. Such

methods provide risk assessment to support long-term planning such as dike

. construction which is usually applied for large spatial scales. This approach does

not usually involve complex hydraulic computations beyond 1-0. In recent times, a

collection of flood risk assessment methodologies have been developed by

simulating the consequence using physically-based numerical simulation models

22

for inundation modelling, which calculates the damage caused by individual flood

events. This method provides the consequence of the impact associated with a

particular flood event, and involve computations in 1-D and beyond. Often such a

method is used for short-term operation such as the operation of a retention basin

during flooding.

Gilard (2002) proposed the "inondabilite" method to assess the flood risk

based on estimating the two components of risk - vulnerability and hazard - from

synthetic hydrological model called flow-duration-frequency (QdF). This method

was applied in several basins in France of areas from 20 up to 1 ,000 km square.

Gilard (2002) found that the method has helped decision makers in designing

better policies for flood management. Furthermore, a new trend in modern risk­

based analyses in Integrated flood management systems shows an increasing

relyianc on the tools and capabilities of computing machines and mathematical

modeling (i.e. algorithms). This was a natural consequent of the global trend in

employing evolutionary computing in wide range of applications in hydrological

sciences and by which a new thrust of discipline has emerged - hydroinformatics

(Savic and Khu, 2005). Digital mapping is one successful endeavor used in

hydroinformatics for flood forecasting and communicating flood risk to different

concerned parties (Aibaneseb et al., 2008). Since map~ give a more direct and

stronger impression of the spatial distribution of the flood risk than other forms of

presentation (verbal description, diagrams), they are valuable for presenting and

assessing the local flood situation, and they provide information for many

applications in flood defense and disaster management (Merz et al., 2007; De

Bruijn and Klijn, 2009).

23

I.

II.

Ill.

Today, various flood damage estimation methods are in use in several

countries around the world. However, there is no standardization of such

methodology, and different organizations are using various methods without any

national consensus. To date Malaysia does not have a standard procedure or

methodology to assess damages caused by flood that comes yearly as a mere

repetition (Neging, 2004 ). Therefore, there is a need for adopt different flood risk

assessment approaches to achieve sustainable river management for the sake of

effective planning on short- and long-term bases.

2.3 Hydroinformatics

Abbott et al. (2005) defined hydroinformatics as "the application of

information, computation and communication technologies in the various fields of

hydroscience and engineering''. They argued that ·the term per se rooted on- the

recent developments in computer-based applications in the field of hydrology.

Hydroinformatics has recently developed from computation to communication and

soon become able to interconnect the communication-enhancing technologies with

the social aspects of development (decision-makers, stakeholders, public, etc.)­

thus it increasingly becomes a sociotechnology. According to Savic and Khu

(2005), the tools and algorithms emerged by the evolutionary computing

techniques of hydroinformatics have allowed for the follow,ing features:

Utilizing multiple solutions instead of a single solution;

Synthesizing new solutions from previous ones, and

Modifying previous solutions to accommodate changes

24