application of remote sensing and gis for flood risk

IRJC

International Journal of Social Science & Interdisciplinary Research

Vol.1 Issue 11, November 2012, ISSN 2277 3630

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APPLICATION OF REMOTE SENSING AND GIS FOR FLOOD RISK

ANALYSIS: A CASE STUDY OF KRISHNA AND TUNGABADRA RIVER

VALLEY

MR. SATHISH S*, DR. NAGENDRA H.N** & MR. RAVI G***

*Ph.D. Student,

** Associate Professor in Urban and Regional Planning,

*** Ph.d. student) at Institute of Development Studies,

University of Myosre,

Manasagangothri, Mysore-570006.

______________________________________________________________________________

ABSTRACT

River valley human settlements will be most effected by floods due to dependence of water

source and physical and social works. One effected floods will distribute life fabric for five to ten

years. This in turn changes migration pattern and relocation. Advances in remote sensing

technology and new satellite platforms such as ALOS (Advanced Land Observation Satellite)

sensors widened the application of satellite data. One of the many fields that these technologies

can be applied is to validate flood inundation models. For a long time flood extent from flood

inundation models were validated using the ground truth surveys which was not very much

reliable. In this study flood extent was extracted from satellite images available for one in 50

year flood event occurred on June 2008 in Krishna and Tungabhadra river valley in Karnataka.

Then that was compared with the flood extent derived from the flood extent obtained for the 50-

year rainfall using relevant models. Based on the flood extent and to develop, demonstrate and

validate an information system for flood forecasting, planning and management using remote

sensing data with the help of Flood Hazard Maps for different return periods (10, 20, 40, 50 and

100 years), Assess the population vulnerability and physical vulnerability of the lowest

administrative division subjected to floods, and using above results conduct a flood risk analysis

of the study area.

A comprehensive prediction model will mitigate the risk to a greater extent. Availability of

technologies such as Remote Sensing and GIS( Geographic Information Systems) gives more

reliable scenario to analyze and find solutions in policy framework. Post flood information

system is often random and patchy in its quality of data. Much of the physical observations and

extent of flood levels can be accurately modeled for effective analysis. Both the aspect of flood

risk and post flood evaluation has been studies in Krishna river valley topography plays a major

role in spreading the level of water which affects normal life.

KEYWORDS: Geographic Informatin System, Policy framework, flood forecasting, population

vulnerability, physical vulnerability.

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1. INTRODUCTION

Accurate and current floodplain maps can be the most valuable tools for avoiding severe social

and economic losses from floods. Accurately updated floodplain maps also improve public

safety. Early identification of flood-prone properties during emergencies allows public safety

organizations to establish warning and evacuation priorities. Armed with definitive information,

government agencies can initiate corrective and remedial efforts before disaster strikes

(Chapman and Canaan, 2001).

Sam U. Shamsi,(2002) in the report „GIS Applications in Floodplain Management‟ has conveyed

that GIS is ideally suited for various floodplain management activities such as, base mapping,

topographic mapping, and post-disaster verification of mapped floodplain extents and depths.

For example, GIS was used to develop a River Management Plan for the Santa Clara River in

Southern California. A GIS overlay process was used to further plan efforts and identify

conflicting uses along the river and areas for enhancing stakeholder objectives. A 1 inch = 400 ft.

(1 cm = 122 m) scale base map was created to show topography, planimetric features, and

parcels. Attribute data were entered into a separate database and later linked to the appropriate

map location. Six layers were created for flood protection related work: 100-year floodplain,

100-year flood way, 25-year interim line, existing facilities, proposed facilities, and flood

deposition. The lessons learned from this mapping project indicate that GIS is useful in capturing

and communicating a vast amount of information about the study area and the river. While the

use of GIS and the process to gather and record data were not without problems, the overall

value of GIS was found to overweigh those challenges (Sheydayi, 1999).

Floods are probably the most recurring, widespread, disastrous and frequent natural hazards of

the world. India is one of the worst flood-affected countries, being second in the world after

Bangladesh and accounts for one fifth of global death count due to floods. Total geographic area

India is 328.7millian hectares, in which about 40 million hectares nearly 1/8th of India‟s

geographical area is flood-prone.19

Along with this India has the highest occurrence of natural disasters in south-east Asia with

about 85 percent of the country liable to be affected by one or the other disaster viz. avalanches

cyclone, drought, earthquake, flood, landslides, etc. There are also many environmental hazards,

spontaneous or human-induced related to the natural forest or soil cover or over-exploitation of

agricultural land. Of these about 63 percent of the total agricultural area is drought prone, while

area devastated by annual or flash floods is estimated to be about 12 to 15 percent of the area.

The long coastline and the coastal areas are exposed to one or two pre or post monsoon cyclones

every year. More than 50 percent of India‟s geographical area is vulnerable to seismic or

geodynamical activity of varying intensity. These natural hazards are so frequent and so

devastating that these affect the economic development. Social stability gets severely disturbed

and inflicts untold human miseries leading to health hazards.

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Although the occurrence of such disasters cannot be prevented or regulated, the proper

application of scientific knowledge based on past experience can minimize the economic and

health consequences of the population.

INTRODUCTION:

The natural hazards can be listed as avalanches and landslides in Himalayas, cyclones in coastal

areas, drought in rain-scarcity areas, earthquakes in seismic and tectonic activities affected areas

and floods in heavy rainfall area. Hence effect of these hazards causes damages at various

degrees to an extent of disaster, the phenomena of these kinds of disaster due to flood demands a

systematic study.

Disaster means a catastrophe, a calamity or mishap, a grave occurrence, which causes a serious

disruption of the functioning of a society, causing widespread human, material or environmental

losses exceeding the ability of the affected society to cope using only its resources.

A Flood is defined as the overflow of areas that are normally submerged with water or a stream

that has broken its normal confines or has accumulated due to lack of drainage. Floods are

among the most common and destructive natural hazards causing extensive damage to

infrastructure, public and private services, the Environment, the economy and devastation to

human settlements. The flood has different types, they are; River flood, Coastal flood, urban

flood, storm flood etc these may be flash flood or slow onset flood.28

B. Normal floods are expected and generally welcomed in many parts of the world as they

provide rich soil, water and a means of transport, but flooding at an unexpected scale (damaging

flood) and with excessive frequency causes damage to life, livelihoods and the environment.

Over the past decades, the pattern of floods across all continents has been changing, becoming

more frequent, intense and unpredictable for local communities, particularly as issues of

development and poverty have led more people to live in areas vulnerable to flooding. The

Fourth Assessment Report (2007) of the Intergovernmental Panel on Climate Change (IPCC)

predicts that „heavy precipitation events, which are very likely to increase in frequency, will

augment flood risk‟. These floods will affect life and livelihoods in human settlements in all

areas, e.g., coastal zones, river deltas and mountains. Though there were continuous efforts to

mitigate flood and its effects on victims.

C. Floods by nature become a complex event and caused a range of human vulnerabilities,

inappropriate development planning and climate variability with the exception of flash floods,

whose scale and nature are often less certain. Hence it requires more comprehensive studies

about flood to formulate appropriate strategies to mitigate flood and its impacts.

NEED FOR THE STUDY

Floods are an endemic problem in India. The National Commission on Floods, more commonly

known by its Hindi name „Rashtriya Barh Aayog‟, in 1980 estimated that about 40 mha of area is

flood-prone. This was later revised to 33.5 mha. On an average, 7.5 mha Area is affected by

floods in any one year, in some or other part of the country. Large flood events capture the

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Public attention. Inundations in Mumbai in July 2005, Surat in August 2006, Bihar in August

2008 due to breach in Kosi embankments, Karnataka in October 2009 are some of the flood

events in the recent past that have resulted in considerable discussion in the public space. Every

major flood event is immediately followed by a flood of a different kind – „scholarly‟ articles

analyzing the flood event and the current flood management paradigm. Almost all such articles

say more or less the same thing. some studies says the flood is described as man-made, the

technology based flood management paradigm is declared as all wrong, the technocrats are

admonished for thinking that they can concur the nature and finally, it is asserted that our

ancestors had mastered the art of living with floods, which we should also adopt.

As flood dynamics are more complex understanding flood management requires study of

hydrology, open channel hydraulics, and river morphology. Amongst those who comment on

flood Management studied on floods have found some solution for efficient flood management

and mitigate flood along with further studies on lakes and rivers have symbiotic relationship in

term of exchange of water inflow and outflow.3

However Reliable and precise estimation of floods is critical for efficient flood management and

surface water planning. Hydrologists use catchment and hydrological data to establish regional

relationships between mean annual flood and various catchment and rainfall characteristics. The

relationship is used for predicting floods of different return periods.

Historically many human settlements were along the rivers but people chose the highest possible

points thus minimizing chance of floods. But with increasing population of the cities, settlements

had to occur at lower and lower levels and closer to river thus increasing chances for floods. This

had happened in many Indian settlements. At the time when dam was built perhaps rivers had

good carrying capacity and later on downstream as settlement encroaches the river catchments

and their natural watercourses have caused flood.(5th WSEAS Int. Conf. on environment,

ecosystems and development, (2007)).

Floods are a naturally occurring hazard that becomes disasters when they affect human

settlements. The magnitude and frequency of floods is often increased as a result of the following

human actions.

Settlement on flood plains contributes to flooding disasters by endangering humans and their

assets. However, the economic benefits of living on a floodplain outweigh the dangers for some

communities. Pressures from population growth and shortages of land also promote settlement

on floodplains. Floodplain development can also alter water channels, which if not well planned

can contribute to floods. Urbanization also contributes to urban flooding in four major ways.

1. Roads and buildings cover the land,

2. Preventing infiltration so that runoff forms Artificial streams.

3. The network of drains in urban areas may deliver water and fill natural channels more

rapidly than naturally occurring drainage, or may be insufficient and overflow.

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4. Natural or artificial channels may become constricted due to debris, or obstructed by

river facilities, impeding drainage and overflowing the catchment areas.

Deforestation and removal of root systems increases runoff. Subsequent erosion causes

sedimentation in river channels, which decreases their capacity intern causes flood during rainy

season. Failure to maintain or manage drainage systems, dams, and levee bank protection in

vulnerable areas also contributes to flooding.

The flash flood common in many regions results from the outbreak of dammed lakes. These

dammed lakes can break resulting in flash flood. Hundreds of lives and millions of rupees worth

of property and investment in high-cost infrastructure are lost in the region every year due to

landslides, debris flows, and floods, along with the destruction of scarce agricultural lands. In the

last decade floods killed many persons and affected billion people worldwide. And the number

of events as well as deaths is increasing significantly higher in Asia than elsewhere, and among

all water-induced disasters this number is much higher for flash floods .

The Government of India (GOI) has been spending large amount of money on flood control, its

main focus is on irrigation. GOI has launched „National Flood Control Program‟ in 1954 and set

up the “Rashtriya Barh Ayog” (RBA), “National Flood Commission”, in 1976 to evolve a

coordinated, integrated and scientific approach to the flood control problems in the country and

to draw out a national plan fixing priorities for implementation in the future. The RBA in its

report in 1980 identified flood prone districts in many states of India including Karnataka and

also extended services by proposing strategies to mitigate impact of flood. It is interesting to note

that despite of these efforts, India is still repeatedly witnessing massive flood hazards

Under the concepts of integrated development many dams were built. Dams in India and

anywhere else are made for different purposes including power generation, irrigation, flood

prevention, land reclamation, and water diversion. Given the multiple objectives of dams, dam

management and food control involves different stakeholders with different interests and

responsibilities, but these efforts makes the flood control related decision making a complex

process. This has become a quite common phenomenon in every states of India, including

Karnataka which has been no exception as far as sufferings inflicted by natural and man-made

hazards are concerned. The state has been frequented by cyclones, floods, droughts, landslides,

subsidence and occasional earthquakes. Progressive trends of any region are controlled to a large

extent by the requirements of the inhabitants, agriculture, industries, transportation,

communication, education and Culture, which generally form the vulnerability attributes.

Because of the high population density and concentration of industrial and agricultural activities

across Karnataka, risk or vulnerability to natural or man-made disasters is particularly high. With

increasing developmental activities in high-hazard zones, e.g. the coastal regions, the

vulnerability scenario appears to be worsening with time.

But recently flood caused in the north Karnataka region have attracted the professionals on the

cause of flood and flood victims. The devastating floods of 2009 in Karnataka almost swept

away 13 Districts. These floods created havoc in this affected region, resulting in immense

destruction of human life, property and crops.

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Most members of these communities are laborers, peasants and artisans belonging to backward

or scheduled castes. Many of them work on meager daily wages and debt bondage is their way of

life. When affected by the floods, they lost employment or their most valuable and often only

asset, the household.

Moreover, the disaster had a stark impact on the children, many of whom lost parents and other

family members. They were in a very fragile environment that negatively impacted their

physical, mental, and psychosocial development, and existing resources did not adequately meet

their needs. Also there were no such sincere efforts to comprehend the position life of flood

victims. No comprehensive study has been done in the above aspect generally human settlement

development and its future expansion. Very little effort is made to plan for the probable floods;

most of the studies are in disaster management and after flood emergency effort planning. Which

involves the immediate disposal of budget and implementation of measures unscientifically?4

Dileep Mavalankar , Amit Kumar Srivastava (2008) .

Hence a systematic approach is needed to understand the causes and consequence s of flood and

formulate effective measures against flood hazards.

STUDY AREA

In general most of the human settlements in Karnataka were established very near to the main

river course and other water bodies with less knowledge of probable disasters. This study will

investigate in a designated area of recent floods experienced in flood affected villages in Raichur

district of northern part of Karnataka under Krishna and Tungabhadra river basin.

In the recent devastating floods of October 2009 almost swept away 13 Districts of Karnataka

state i.e. Belgaum, Bijapur, Dharwad, Gadag, Haveri, Karwar, Gulgarga, Bidar, Raichur, Bellary,

Koppala, Bagalkote and Davangere. These floods created immense destruction of human life,

property and crops. It left a trial of death and destruction with lakhs of people losing their

belongings and their lives severely disrupted. The most destructive floods washed out several

villages on the river banks, 6.55 lakh houses were devastated and crops in over 22 lakh hectares

were inundated. 229 peoples lost their lives and 7882 live stocks perished. A total of 4292

villages were affected in various degree have caused a loss of over an estimated amount in

rupees 18,500 crores that include both public and privately- owned properties. In the post flood

measures about 345 villages were proposed to relocate with other kind of relief measures for less

affected villages.

Table showing the names of district and number of villages to be relocated:

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The delineated area of study has been chosen to get proper representation of various types of

conditions of flood damage. The Raichur district has both Krishna and Tungabhadra basin on

either side. This will give ample scope for recommendation and study the varied conditions

existing for flood mitigation proposals.9

S tudy area prof i l e;

LOCATION & HISTORY: Raichur district is situated in north eastern part of Karnataka state. It

falls in the northern maiden region, between 15º 33‟- 16º 34‟ North latitudes and 76º 14‟- 77º 36‟

East longitudes and also between the two major rivers namely the Krishna and the Tungabhadra.

The district is bounded on the north by Gulbarga on the east by the Mahbubnagar district of

Andhra Pradesh. Administrative divisions of the district are shown in Fig.1.

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Fig 1. Location Map

Figure 2. A schematic diagram of the Krishna River basin, showing all proposed inter-basin

water transfers in and out of the basin (black lines with numbers) together with flow measuring

points (stations) for which some observed flow data were available for the study. Link numbers

are circled and correspond to the overall NRLP numbering system. Station numbering is for

identification purposes only. Due to the low quality, short records or inappropriate location

relative to the link points, only a few of the shown stations are usable. These include record at

station 3 (Krishna at Agraharam) and part of the record at station 1 (Krishna at Vijayavada).

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A study of various types of flood and their characteristics in general will be required to

understand the characteristics of flood in the villages of Raichur district under Krishna and

Tungabhadra river valley region. This study will be carried out from secondary sources.

However primary survey will be conducted

1. To study the characteristics, causes and impact of flood affected villages in the study area

2. To study the efficacy of existing Post flood rural planning and development strategies

for the flood affected villages in the study area.

As the government has intervened in the planning and development processes in the flood

affected regions some secondary information will also be available, the same will be used to

understand the characteristics, causes and impact of flood. Based on the research study effective

Post flood rural planning and development strategies will be proposed for the type of flood

which generally prevailed in the study area.

To understand the causes for flood in the villages a detailed study will be carried out on the flood

phenomena in the study area by referring to its past recorded information. Also a field survey

(general enquiries and observation) will be conducted to study effects of flood on the village

settlements. The effect of flood has been studied categorically in terms of its implications on

social, economic and physical structure of villages.

A set of data will be collected regarding the planning measures that have been undertaken during

the flood and on the post effects of flood. Based on the data analysis and literature case studies,

some planning suggestions were proposed for the effective rehabilitation processes of a flood

affected villages.

The study will be carried out by collecting data, from both primary and secondary sources:

Detailed mapping of the settlement pattern and topographic features for delineating the

study area.

Hydrology and geological information to identify the flood zones, major drainage system

of the region and other aspects related to select the proposed area for rehabilitation.

Causes of the flood and their effects on socio-economic and physical structure of the

village.

Data that can support identification of problems in the planning measures under taken by

the concerned authorities and their efficacy in attaining the requirements of the flood

victims.

Three Methods of GIS Linkage

According to a literature review of GIS applications in computer modeling conducted by Heaney

et al. (1999) for the U.S. Environmental Protection Agency (EPA), Shamsi (1998, 1999) offers a

useful taxonomy to define the different ways a GIS can be linked to computer models. The three

methods of GIS linkage defined by Shamsi (2001) illustrated in Figure 2 are:

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1. Interchange method

2. Interface method

3. Integration method

Interchange Method

The interchange method employs a batch processing approach to interchange (transfer) data

between a GIS and a computer model. In this method, there is no direct link between the GIS and

the model. Both the GIS and the model are run separately and independently. The GIS database

is pre-processed to extract model input parameters, which are manually copied into a model

input file. Similarly, model output data are manually copied in the GIS to create a new layer for

presentation mapping purposes. This is often the easiest method of using a GIS in computer

models, and it is the method used most at the present time. Using GIS software to extract

floodplain cross-sections from DEM data or runoff curve numbers from land use and soil layers

are some examples of the interchange method.

Interface Method

The interface method provides a direct link to transfer information between the GIS and the

model. The interface method consists of at least the following two components:

1. A pre-processor, which analyzes and exports the GIS data to create model input files; and

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2. A post-processor, which imports the model output and displays it as a GIS layer.

The interface method basically automates the data interchange method. The automation is

accomplished by adding model-specific menus or buttons to the GIS software interface. The

model is executed independently from the GIS; however, the input file is created, at least

partially, from within the GIS. The main difference between the interchange and interface

methods is the automatic creation of a model input file.

U.S. Army Corps of Engineers HEC-GeoRAS software is a good example of the interface

method. Developed as an ArcView GIS extension, GeoRAS allows users to expediently create

input data for their HEC-RAS models. Additional GeoRAS information is provided below.

Integration Method

GIS integration is a combination of a model and a GIS such that the combined program offers

both the GIS and the modeling functions. This method represents the closest relationship

between GIS and floodplain models. Two integration approaches are possible:

1. GIS Based Integration: In this approach, modeling modules are developed in or are called

from a GIS. All the four tasks of creating model input, editing data, running the model,

and displaying output results are available in GIS. There is no need to exit the GIS to edit

the data file or run the model. EPA's BASINS software is a good example of this method.

2. Model Based Integration: In this method GIS modules are developed in or are called from

a computer model. Computation Hydraulics Int.'s (http://www.chi.on.ca/) PCSWMM GIS

software is a good example of this method.

Because development and customization tools within most GIS packages provide relatively

simple programming capability, the first approach provides limited modeling power. Because it

is difficult to program all the GIS functions in a floodplain model, the second approach provides

limited GIS capability. Applications are being developed to connect HEC-HMS and HEC-RAS

models in a single ArcView GIS environment that would allow users to move easily from a

DEM to a floodplain map within a single program (Kopp, 1998).

Conclusion:

Remote sensing data accumulated from past ten years and GIS data base of command area will

give accurate progressive and environmental aspects for the best use for framing policy

decisions. The study area of Raichur district has both Krishna and Tungabhadra river valley with

both posing different set of information‟s for specific policy framework in terms of settlement

pattern and maintenance of post flood social economical and infrastructure fabric.

One of the main aim of study is to take accurate decisions on future settlement pattern in order to

avoid disaster effect in present river valley. Many efforts for disaster management by providing

housing solution in upland locations have failed to bring a change in the social fabric because of

locational disadvantage.

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Funding and mitigation efforts are mostly aimed at physical infrastructure shifting, which are not

used by the recipients. Flood aid and finance spread over years to rehabilitate will not be

effective to get desired expected satisfaction. Study suggest the redevelopment of settlements in

existing locations with emphasis on rapid flood evacuation and built infrastructure at higher floor

levels on existing settlements.

Flow and direction of water can be rapidly drained by creating infrastructure for the purpose.

Study observes the extreme conditions occur only during first and second week of august during

later part of the monsoon. It happens only for four to six days and disaster occurs in first four

hours of the peak period. Drainage takes more than a week to clear because of natural plain

lands. Many newly built houses have elevation of plinth raised to one meter to greatly mitigate

flood water at its highest peak time. Drafting the flood maps and implementing the decisions on

safe flood levels will be one of the most technical and managerial skills to be learnt in these

disaster experience. Remote sensing and GIS will be of immense use in framing policy guide

lines.

References:

1. Chapman, J. B. and W.D. Canaan (2001). "Flood Maps are Key to Better Flood Damage

Control." CE News, March 2001, 58-60.

2. Dileep Mavalankar , Amit Kumar Srivastava (2008) Lessons from Massive Floods of

2006 in Surat City: A framework for Application of MS/ORTechniques to Improve Dam

Management to Prevent Flood , Public Systems Group Paper presented at: Third National

Conference on Management Science and Practices (MSP) 2008 held at IIM Ahmedabad,

organized by ORSI Ahmedabad Chapter, Dated March 22-24, 2008.

3. Kopp, S. (1998). "Developing a Hydrology Extension for ArcView Spatial Analyst." Arc

User, Esri, April-June 1998, 18-20.

4. Sam U. Shamsi(2002), Ph.D., P.E. GIS Applications in Floodplain Management, report.

5. Shamsi, U.M. (1998). "ArcView Applications in SWMM Modeling." Chapter 11 in

Advances in Modeling the Management of Stormwater Impacts, Edited by W. James,

Vol. 6. Computational Hydraulics International, Guelph, Ontario, Canada. 219-233.

6. Shamsi, U.M. (1999). "GIS and Water Resources Modeling: State-of-the-Art." Chapter 5

in New Applications in Modeling Urban Water Systems, Edited by W. James,

Computational Hydraulics International, Guelph, Ontario, Canada, 93-108.

7. Shamsi, U.M. (2001). GIS and Modeling Integration. CE News, Vol. 13, No. 6, July

2001, p 46-49.

8. Sheydayi, A. (1999). "GIS Facilitates River Management Plan Development." Watershed

& Wet Weather Technical Bulletin, WEF, January 1999, 10-12.

9. The Fourth Assessment Report (2007) of the Intergovernmental Panel on Climate Change

(IPCC)(4) 5th WSEAS Int. Conf. on environment, ecosystems and development,

Tenerife, Spain, December 14-16, 2007 306

application of remote sensing and gis for flood risk

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