Luận văn Study on flood risk assessment in downstream area of Ke Go reservoir, Ha Tinh province

MINISTRY OF EDUCATION AND

TRAINING

MINISTRY OF AGRICULTURE AND

RURAL DEVELOPMENT

THUYLOI UNIVERSITY

STUDY ON FLOOD RISK ASSESSMENT IN DOWNSTREAM

AREA OF KE GO RESERVOIR, HA TINH PROVINCE

Tran Ngoc Huan

MSc Thesis on Intergrated Water Resources Management

Hanoi, 2015

MINISTRY OF EDUCATION AND

TRAINING

MINISTRY OF AGRICULTURE AND

RURAL DEVELOPMENT

THUY LOI UNIVERSITY

Tran Ngoc Huan

STUDY ON FLOOD RISK ASSESSMENT IN DOWNSTREAM

AREA IN KE GO RESERVOIR, HA TINH PROVINCE

Major: Intergrated Water Resources Management

THESIS OF MASTER DEGREE

Supervisor: Asso. Prof. Dr. Pham Thi Huong Lan

This research is done for a partial fulfilment of the requirement for

Master of Science Degree at Thuyloi University

This Master Programme is supported by NICHE – VNM 106 Project

Hanoi, 2015

Abstract

Flooding causes economic, social and environmental damages and life loss. This

fact increases the great attention on flooding by government, and science in many

countries around the world. As a country located in the tropical climate region,

Vietnam has been facing various water related disasters since ancient time,

particularly in central parts of Vietnam where featured by steep topography. In

recent years, Rao Cai river basin in Ha Tinh province is frequently flooded due to

climate change impact, rapid infrastructure and urbanization growth. This problem

caused serious damages to human life, properties, and social – economic

development activities…

Flood risk management is a new concept based on a proactive approach which

recently becomes a robust tool for reducing flood damage. Main contents of flood

risk management are flood risk assessment and flood preventive measures or flood

preventive planning. Flood risk assessment is key part in flood risk management.

Flood risk assessment is a function of three main variables: flood hazards,

vulnerability, and coping capacity. Understanding of flood hazards, vulnerability,

and coping capacity is the vital step for efficiency of flood risk assessment. Flood

risk management strategies have not been developed for Rao Cai river basin for

many years and there is no spatial planning approach for regional development.

This research aims at flood risk assessment for Rao Cai river basin based on the

new concept of flood risk management mentioned above. An incorporated

hydrological modeling approach for hazard assessment for Rao Cai river basin has

been adopted in this research. The research objective divides into three parts: (1)

Identification of flooding and potential reasons based on available natural, social

and economic data; (2) The second part involved flood simulation and inundation

mapping of events with chosen return periods using a MIKE package model (MIKE

UHM, MIKE 11, and MIKE 11 GIS).The model was calibrated and verified based

on the data series in October, 2010. A flood from 2^ndto 6^th, October 2010 was used

to calibrate the model. Another flood in October, 2010 (from 14^thto 19^th, October)

was used to verify the model. Results of calibration and verification were fit to

measured data. The flood simulations for selected return periods were generated for

200 and 1000 years corresponding to frequency of design and checking flood of Ke

Go reservoir. (3) Flood risk assessment is combined effect of flood depth (hazard

factor) and population density (vulnerability factor) by weighing factors for both of

them. As for the results, the research revealed that flood risk assessment is helpful

tool for flood risk management.

Flood risk maps were produced for the flood of 1000 year and 200 year return

period. The level of hazard and risk were determined for each community in Cam

Xuyen, Thach Ha and Ha Tinh city. These maps can be used for flood risk

management and mitigation planning for Ha Tinh province in general, Rao Cai river

basin in particular.

Declaration

I hereby certify that the work which is being presented in this thesis entitled, “Study

on flood risk assessment in downstream area in Ke Go reservoir, Ha Tinh

province” in partial fulfillment of the requirement for the award of the Master of

Science in Integrated Water Resource Management, is an authentic record of my

own work carried out under supervision of Asso. Prof. Dr. Pham Thi Huong Lan.

The matter embodied in this thesis has not been submitted by me for the award of

any other degree or diploma.

Date: February 15, 2015

Tran Ngoc Huan

Acknowledgements

I would like to express my sincere gratitude to my advisor Asso. Prof. Dr Pham

Thi Huong Lan for her guidance, suggestion and inspiration.

I would also like to acknowledge Dr. Vu Thanh Tu, Mr Duong Hai Thuan and Dr.

Bui Du Duong for their comments and suggestion.

I would like to thank the Hanoi University for Natural Resources and Environment,

Ministry of Natural Resources and Environment, Vietnam and NICHE – VNM

106 Project for the award of a scholarship and also Hanoi Water Resources

University for giving me the opportunity for this special study.

I also wish to thank members of the master thesis committee consist of Prof.Dr.

Nguyen Quan Kim (chairman), Asso.Prof.Dr. Mai Van Cong (examination),

Asso.Prof.Dr. Nguyen Mai Dang (examination), Dr Le Viet Son and Dr Dinh

Thanh Mung for their comments, examination, and corrections.

Finally, I would like to express my special appreciation to my friends and

colleagues for their supports, encourages and advices. The deepest thanks are

expressed to my family members for their unconditional loves.

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TABLE OF CONTENTS

CHAPTER 1 - INTRODUCTION...........................................................................1

1.1. Problem statement ............................................................................................1

1.2. Research objectives ..........................................................................................3

1.3. Scope of study...................................................................................................3

1.4. Structure of thesis .............................................................................................3

CHAPTER 2: LITERATURE REVIEW................................................................5

2.1. Concepts of flood risk, hazard and vulnerability..............................................5

2.2. Flood risk assessment .......................................................................................7

2.3. Previous studies in study are a ...........................................................................9

CHAPTER 3: DESCRIPTION OF STUDY AREA.............................................10

3.1. Physical characteristic s ...................................................................................10

3.1.1. Location of this basin ...............................................................................10

3.1.2. Topography condition s .............................................................................11

3.1.3. Hydro-meteorological characteristics ......................................................12

3.2. Social and economic characteristics ...............................................................16

3.2.1. Population.................................................................................................16

3.2.1. Rural area .................................................................................................17

3.3. Reservoir and current irrigation system..........................................................18

3.3.1. Overview of Ke Go reservoir ...................................................................18

3.3.2. Irrigation system.......................................................................................21

3.4. Flooding situation in downstream area...........................................................22

3.4.1. The flooding events occurred in 201 0 ......................................................22

3.4.2. The flooding events occurred in 201 2 ......................................................25

3.4.3. The flooding events occurred in 201 3 ......................................................26

CHAPTER 4: METHODOLOGY AND DATA USED .......................................28

4.1. General framework .........................................................................................28

4.1.1. Methods to flood risk assessment.............................................................29

4.1.2. Method for estimating design hyetograph................................................30

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4.1.3. Method for developing design hydrograph on lateral flow in downstream

............................................................................................................................31

4.1.4. Method for simulation floods corresponding to various return period ....31

4.1.5. Method for inundation mappin g ...............................................................31

4.2. Governing equation in MIKE packag e ...........................................................31

4.2.1. Rainfall runoff model (MIKE - Unit hydrograph model) ........................32

4.2.2. Hydrodynamic model (MIKE 11 HD) .....................................................33

4.2.3. Identification of inundation maps ............................................................34

4.3. Data used ........................................................................................................35

4.3.1. Data collection..........................................................................................35

4.3.2. Data analysis.............................................................................................36

CHAPTER 5: RESULTS AND DISSCUSIONS ..................................................40

5.1. The reasons cause the flooding in downstream area ......................................40

5.1.1. Climate change impacts............................................................................40

5.1.2. Infrastructure impact s ...............................................................................43

5.2. Flood hazard ...................................................................................................43

5.2.1. Rainfall runoff modeling ..........................................................................43

5.2.2. Flood modeling.........................................................................................50

5.2.3. Flood hazard maps....................................................................................58

5.3. Flood vulnerability..........................................................................................62

5.4. Flood risk in downstream area of the Ke Go reservoir...................................65

CHAPTER 6: CONCLUSIONS AND RECOMMENDATIONS ...................70

6.1. Conclusions.....................................................................................................70

6.2. Recommendations...........................................................................................71

REFERENCES........................................................................................................73

APPENDI X ..............................................................................................................76

Appendix 1: Frequency curve of maximum rainfall during 1 day of stations.......77

Appendix 2: Roughness coefficien t .......................................................................81

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LIST OF TABLES

Table 3- 1 Lists of meteorological station s ...............................................................12

Table 3- 2: The average of monthly rainfall at Ha Tinh station from 1975 - 2010 ..14

Table 3- 3: Monthly discharge of Ke Go reservoir from 1957 - 2010......................15

Table 3- 4: Population pattern...................................................................................16

Table 3- 5: Land use..................................................................................................17

Table 3- 6: Technical parameters of reservoir ..........................................................19

Table 3- 7: Parameters of junction work items .........................................................19

Table 3- 8: Technical parameters of Irrigation channels system ..............................21

Table 3- 9: Statistic of damages caused by rainfall and flood at Ha Tinh city, Thach

Ha and Cam Xuyen district occurred from 14 October to 19, October, 2010 ..........24

Table 4- 1 Database used for research ......................................................................36

Table 5 - 1: Result of frequency analysis of maximum daily rainfall ......................44

Table 5 - 2: Value of design rainfall distribution of Ha Tinh, Ky Anh and Huong

Khe stations during 1 day corresponding to difference frequency (daily rainfall) ...44

Table 5 - 3: Sub-catchment of Rao Cai river basin and weighting factors of

meteorological statio n ...............................................................................................46

Table 5 - 4: Parameters of UHM in MIKE RR model of Ke Go catchment.............47

Table 5 - 5: Different in peaks of observed and simulated discharge for calibration

mode at Ke Go reservoir ...........................................................................................48

Table 5 - 6: Different in peaks of observed and simulated discharge in verification

at Ke Go reservoir .....................................................................................................48

Table 5 - 7: Parameters of UHM - SCS for Rao Cai’s sub -catchments....................50

Table 5 - 8. Runoff link of sub-catchments into river network in MIKE 11 model .53

Table 5 - 9: Monitoring points for the calibrating and verifying hydraulic model...53

Table 5 - 10: Results of flood simulation form 2^ndOct to 6^thOct, 2010 for

calibration of MIKE 11 HD model ...........................................................................55

Table 5 - 11: Results of flood simulation from 12 Oct to 18 Oct- 2010 ...................57

Table 5 - 12: Maximum water level corresponding to design and checking flood of

Ke Go reservoi r .........................................................................................................57

Table 5 - 13. Designed flooding hazard level scale for the downstream of the Ke Go

reservoir.....................................................................................................................58

Table 5 - 14. Flood hazard areas for flood event in 2010 .........................................60

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Table 5 - 15. Flood hazard areas corresponding to design and checking flood........62

Table 5 - 16. Criteria of vulnerability map derived from population density for the

downstream of the Ke Go reservoir ..........................................................................63

Table 5 - 17. Criteria of vulnerability map derived from population density for the

downstream of the Ke Go reservoir ..........................................................................65

Table 5 - 18. Flood risk map for the downstream area of Ke Go catchment in flood

in October, 2010........................................................................................................65

Table 5 - 19. Statistic table of flood risk of different floods.....................................68

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LIST OF FIGURES

Figure 3- 1: Map of study are a ..................................................................................10

Figure 3- 2: Topography of Rao Cai river basin in ASTER global DEM ................11

Figure 3- 3: Hydro-meteorological station network of Rao Cai river basi n .............13

Figure 3- 4: The average of monthly rainfall at Ha Tinh station from 1975 - 201 0 .14

Figure 3- 5: Monthly discharge flow into Ke Go reservoir ......................................16

Figure 3- 6: The spillway of Ke Go Reservoir, there are two arc gates ...................19

Figure 3- 7: The Emergency spillway of Ke Go reservoir........................................19

Figure 3- 8: Flood at Ha Tinh city in October, 2010 ................................................23

Figure 3- 9: Percentage of damages in terms of money for various categories

occurred from 14^thto 19^th, October, 2010 .................................................................25

Figure 3- 10: Flood at Ha Tinh city in October, 2012 ..............................................26

Figure 3- 11: Inundation in the downstream of Ke Go reservoir in June 2^nd2013...27

Figure 3- 12: Flood in Ha Tinh city in October, 2013 ..............................................27

Figure 4 - 1: Illustration of the research methodology..............................................29

Figure 4 - 2: Mass flow rate in and out of an elementary control volume................34

Figure 4 - 3: MIKE 11 GIS Input and Outpu t ...........................................................35

Figure 4 - 4: Inflow of Ke Go reservoir in October, 2010 ........................................37

Figure 4 - 5: Inflow of Ke Go reservoir in October, 2013 ........................................37

Figure 4 - 6: Water level at Phu and Hoi Bridge station in October, 2010...............38

Figure 5 - 1: Annual rainfall change on the Rao Cai river basin from 1975 – 2005 41

Figure 5 - 2: Changing of maximum rainfall of Ha Tinh statio n ..............................42

Figure 5 - 3: Inflow of Ke Go reservoir and actual rainfall 2013 .............................43

Figure 5 - 4: Rao Cai watershed sub-basin schematizations and Thiessen polygon

weighting computation of mean rainfall of sub-catchment in Rao Cai river basin ..45

Figure 5 - 5: Parameters of UHM in MIKE RR model of Ke Go catchment ...........47

Figure 5 - 6: Observation and simulation of hourly discharge of Ke Go reservoir

from 2 Oct to 6 Oct – 2010 for calibration model ....................................................47

Figure 5 - 7: Observed and simulated hourly discharge of Ke Go reservoir from 14

Oct to 19 Oct – 2010 – Verification..........................................................................48

Figure 5 - 8: Flood at Ke Go reservoir in 16 October 201 3 ......................................49

Figure 5 - 9: Hydraulic calculation network in downstream of Ke Go reservoir .....51

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Figure 5 - 10: Storage capacity of floodplain in downstream...................................52

Figure 5 - 11: Calculated and measured water level at Cau Phu (2^ndto 6^thOctober,

2010)..........................................................................................................................54

Figure 5 - 12: Calculated and measured water level at Cau Ho (2^ndto 6^thOctober,

2010)..........................................................................................................................55

Figure 5 - 13: Calculated water level and measured water level at Cau Phu(12 Oct to

18 Oct- 2010) ............................................................................................................56

Figure 5 - 14: Calculated water level and measured water level at Hoi Bridge (12

Oct to 18 Oct- 2010) .................................................................................................56

Figure 5 - 15. Some typical picture to determine flood hazard threshold.................60

Figure 5 - 17. Flood hazard map of 0.5% design flood even t ...................................61

Figure 5 - 18. Flood hazard map of 0.1% design flood even t ...................................62

Figure 5 - 19: Frequency distribution of population of study area ...........................63

Figure 5 - 20: Frequency distribution of population density of study area...............63

Figure 5 - 21: Vulnerability map in Rao Cai river basin ..........................................64

Figure 5 - 22. Designed risk level for the downstream of the Ke Go reservoi r ........65

Figure 5 - 23. Flood risk map for the downstream area of Ke Go river basin of flood

in October, 2010........................................................................................................66

Figure 5 - 24. Flood risk map for 0.5% design floo d ................................................67

Figure 5 - 25. Flood risk map for 0.1% checking floo d ............................................68

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LIST OF ARCONYM

Ha Tinh Committee for Flood and Strom prevention and Control and

HCFSCS

Search and Rescue

CCFSC

UHM

RR

Central Committee for Flood and Storm Control

Unit Hydrograph Model

Rainfall Runoff

HD

Hydraulic Dynamic

SCS

Soil Conservation service

VHDIC

DEM

Vietnam Hydro-meteorological Data and Information Center

Digital elevation model

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CHAPTER 1 - INTRODUCTION

1.1. Problem statement

In recent years, the situation of flooding and tropical becomes more and more

severe, especially in Vietnam’s Central provinces. With the rain increasing quickly

both in quantity and intensity, many large floods as well as deforestation in the

upstream appears. Besides, there is also the impact of the socioeconomic

development, such as the process of rapid urbanization, infrastructure construction

(roads, channel systems), which are factors hindering the flow of water and

increasing damage caused by floods. Unsafe reservoirs contain a high risk.

According to the Steering Committee for Flood and Storm Control Central, in 2013,

floods and typhoons have caused 264 deaths and 800 injured people, about 12,000

collapsed and damaged houses, and the loss of more than 300,000 ha of rice, 2

broken irrigation dams, etc. The estimated total material damage amounted to

approximately 25,000 billion dongs (2013), 16.000 billion dongs (2012) and 12.000

billion dongs (2011) (Hoai, 2013). It is undeniable that the effects of climate change

have a significant impact on the weather in recent years and cause significant

damage both to people and property.

The Ke Go reservoir, located on the Rao Cai river in Cam My commune, in

the Cam Xuyen district of the Ha Tinh province, about 20 km from Ha Tinh city to

the West, is selected as a case study. The reservoir is located on one of the larger

rivers of Ha Tinh province: the catchment area to the Ke Go hydrological station is

230 km²with the total length is 27 km. The Rao Cai area to estuary is 892 km²,

including the whole Cam Xuyen district, Ha Tinh city and a part of Thach Ha

province. The Ke Go reservoir has the particularly important task to irrigate 20,896

ha of arable land of the two districts of Thach Ha and Cam Xuyen, to supply water

for Ha Tinh city and for industry, combining power generation, fish growth and

flood control for the downstream. This is the largest irrigation headworks system of

the central Vietnam and is constructed for a long time.

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The flood risk research and assessment

has particularly important

implications for the prevention and mitigation of natural disaster. Firstly, flood

hazards as part of the management of flood risk can be understood as the probability

that flood prone areas will be inundated for a given time period with a specific

return period (Alkema, 2007). Flood modeling is a relatively new approach, which

is used in many countries for flood hazard and risk assessment. Flood hazard and

risk based spatial planning must be applied to flood prone areas (Pender, 2007).

Measures of flood control aimed at lowering the vulnerability of people and their

property, also include a list of means, i.e. river engineering works, such as dams,

levees, embankments, and/or river training works, such as retention polders (Klijn,

2009). Traditionally, management on flood risk focuses on preventing floods by

river training and dykes system. There are several disadvantages to this approach,

such as dyke break caused by erosion or overtopping of the embankment.

Nowadays alternative and more resilient management strategies are applied in many

countries in the global (Bruijn, 2005). The Decision Support Systems (DSS) are

supposed to be a robust tool for flood risk management; DSS is not only meant for

experts, as it is a new trend to represent the final output of the experts’ research in

way to meet the decision makers’ skills and requests (Klijn, 2009). However, for

many countries DSS is unfeasible, due to the lack of data and techniques as well as

experts, and the country of Vietnam is no exception.

Actually, there is little research on flood risk assessment in Vietnam, for

instance in the case of the Ke Go Catchment there has been only one study that has

focused on the effects of flood scenarios to downstream areas without any detailed

assessment information about the level of risk that can cause for people to have the

mitigation measures in place (Thai et al., 2011). The research of the topic ―Study on

flood risk assessment in downstream area of Ke Go Reservoir – Ha Tinh province‖

will be a useful tool for decision-makers in view of spatial planning and future risk

assessment for the region.

3

1.2. Research objectives

General objective: Flood risk assessment in the downstream of the Ke Go

reservoir, Ha Tinh province, to have measures in preventing and controlling

damage due to floods for study area.

The specific objective of this research can be determined as:

- Analyzing potential reasons cause flooding in the study area to have accurate

estimation and suggestion for this research and local authority.

- Understanding the flood risk assessment method to choose a suitable method

apply for the study area.

- Generating flood risk maps of the downstream of the Ke Go reservoir based

on hazard maps corresponding to flood scenarios and vulnerability maps to

estimate risk level for each area. Based on local authority can determine

where should emergency action being concentrated or having prepare plans

and measures when flooding.

1.3. Scope of study

This study focuses on considering population density and flooding depth to assess

flood risk in the downstream area of the Ke Go reservoir.

1.4. Structure of thesis

The thesis structure includes 6 chapters. The brief explanation of those chapters is

as followed:

Chapter 1 introduces problem statement of the research, the object of the research

and scope of study.

Chapter 2 reviews several studies about concept of flood risk, hazard and

vulnerability, flood risk assessment methods and some previous researches relate to

study area.

4

Chapter 3 reviews the physical characteristics as well as social and economic

characteristics of the study area. The chapter also indicates the Ke Go reservoir and

current irrigation system and flooding situation in recent years.

Chapter 4, the general framework of this research will be mentioned including both

methods and theory. Besides, the data collected during the research was

summarized and analyzed.

Chapter 5 shows results corresponds the research objective about potential reasons

caused flooding and flood risk assessment based flood hazard and vulnerability

factors on the maps. MIKE package model setup, calibration and validation are

described.

Chapter 6 focuses on the main findings and recommendations for further studies

and local authority.

5

CHAPTER 2: LITERATURE REVIEW

2.1. Concepts of flood risk, hazard and vulnerability

 Flood risk

In the series of document ―Living with Risk‖, the International Strategy for Disaster

Reduction (ISDR) of United Nation describes risk is ―the probability of harmful

consequences, or expected losses, resulting from interactions between natural or

human-induced hazards and vulnerable conditions‖ (UN, 2004). This definition

emphasizes relevant vulnerabilities through that risk can be also defined as a

function of hazard and vulnerability. Risk is defined:

Risk = Hazard × Vulnerability

Emphasis to risk retention, Asian Disaster Reduction Center (ADRC, 2005)

mentioned flood risk as a function of probability of loss and loss:

Risk = probability of loss × loss

Focus on the resilience capacity of society against to risk, ADRC in the report of

―The role of local institutions in reducing vulnerability to recurrent natural disasters

and in sustainable livelihoods development ‖developed a new term of risk generally,

particularly flood which is illustrated in the function below:

Hazard x vulnerability

Risk =

Capacity of societal system

Generally, the term of flood risk is variable according to the purpose of particular

research. In this research, flood risk is understood as being a function of a

probability of a specific flood event and vulnerability of societal systems.

 Flood hazard

According to Baas.S, et al (2008) and United Nations (2004) hazard can be

determined as ―potentially damaging physical event, phenomenon or human activity

6

that may cause the loss of life or injury, property damage, social and economic

disruption or environmental degradation‖. Hazards have different origins: natural

(geological, hydro-meteorological) or can be provoked by humane (environmental

degradation and technological hazards). Each hazard is characterized by its location,

frequency and probability of occurrence in a specific region within a specific time

and magnitude. The investigation of assessment of hazard is associated to study of

physical aspects and phenomenon of the given hazard through collection and

analysis of historical records, this process is defined as assessment of hazard

(Geohazards, 2009). Aspects of exposure and vulnerability are not considered in the

hazard term, since it focuses on the event or physical situation (Tamar, 2010).

Flood hazard is a function of: flood magnitude, depth of water and

velocities, water rise rate, duration, evacuation problems, and population size at risk,

land use, flood awareness and warning time (CSIRO, 2000). Flood hazard

categories reflect the flood behavior across the floodplain and can be represented by

four degrees of hazard: low, medium, high and so high. Above mentioned hazard

categories are subdivided as qualitative flood hazard categories and is very useful

for local communities and decision makers. Also quantitative manner of

representation of flood hazard are very important for mitigation planning purpose as

well as for risk assessment because they allow quantitative determination of the

frequency and magnitude of flood (Tamar, 2010).

 Flood vulnerability

Vulnerability is an essential part of risk study and it refers to the susceptibility of

people, communities or regions to natural or technological hazards (Kumpulainen

2006). Vulnerability can be understood as the degree to which people are

susceptible to loss, damage, suffering and death in the event of a disaster.

Vulnerability also encompasses the idea of response and coping, since it is

determined by the potential of a community to react and withstand a disaster (Trinh,

2009).

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Vulnerability is also seen as the extent to which a person, group or socioeconomic

structure is likely to be affected by a hazard (Twigg, 2004). The author moreover

insists that the observable part of vulnerability is the emphasis on physical or

material aspects (Trinh, 2009).

Flood analysis mainly focused on physical characteristics of flood (such as flooding

depth, flooding extent…) without socio-economic vulnerable assessment. Tu and

Trinh (2009) indicated a new approach in developing flood map is to assess the

vulnerability to flood of community and economic sectors in flood-affected area

that is an effective tool for integrated flood management. Economic flood damage

evaluation can estimate for tangible and intangible damages such as building,

products, and health damage. Damage level correspond to subjects is scientific basis

to determine subject has high, medium or low vulnerability to have suitable

measure. In general, flooding depth is the most characteristic in damage estimation.

Damage magnitude strongly depends on the flooding depth, damage functions are

developed as depth-damage curve relationship (Tu, 2009).

2.2. Flood risk assessment

Floodplain analysis and assessment of flood risk are important steps in

management of flood risk to identify appropriate mitigation activities for reducing

flood damages to human health, economic activity…

As a result of hazard assessment any special aspect of given hazard can be

mapped, this provide information on hazard distribution in spatial dimension (Bell,

1999). The flood hazard maps provide users with information addressing to spatial

and temporal probabilities of the floods (FEMA, 2010). Flood hazard mapping is

defined as one of the main steps in management of flood risk (Plate, 2002) and can

be considered to be the important tool for different issues: local planning, risk

assessment as they provide the information about past or possible hazards to local

communities and decision makers. Maps of flood hazard illustrate the intensity of

flood situation and probability of occurrence. The most important indicator for