Risk Wise

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e-Flood Map: flood damage

assessment in Thailand

Geo-Informatics and Space Technology Development Agency

ocated in the tropical zone, Thailand has suffered from

several tropical storms every year. During mid-2006, the

Pra Pirun and Chang San depressions caused damages

nationwide, with catastrophes in some large areas. It started

with heavy rainfall which caused massive landslides in Utaradit,

a province in northern Thailand, where hundreds of people were

killed, thousands were physically and psychologically impacted,

and their relatives and properties were lost. Subsequently,

massive water mass from the north overwhelmed agricultural

areas in the central part of Thailand. In order to protect the

Bangkok metropolitan, a massive amount of water was drained

into paddy fields in surrounding areas, which became inundated

for several months. Human beings, livestock and crops all

suffered from this deluge.

The Geo-Informatics and Space Technology Development Agency

(GISTDA) is a public organization that has played an active role in

implementing and supporting the use of geo-informatics technolo-

gies for disaster risk management, including flood. As the main

distributor of satellite imageries and a major GIS/RS application

agency of Thailand, GISTDA has proved the value of Earth observa-

tion data to the field of disaster management. Throughout the long

period of the 2006 flooding, GISTDA dedicated its resources to serve

the needs of local governmental officers for up-to-date data which

was crucial for their work. The flooded areas were interpreted from

various available satellite imageries using automatic classification

together with manual checking. Data was provided to end users daily

in the form of paper maps, digital satellite images, and GIS (vector)

data of flooded areas. This daily work lasted for over four months,

and since then, GISTDA has been the main responsible supporter of

ready-to-use Earth observation data for flood management.

Due to the extensive period of flooding and the burden on farmers

whose farms were inundated in order to protect the City of Bangkok,

it was necessary that the Government provide compensation for each

farmer and for suffering people. The calculation for compensation is

based on the number of days that each area was inundated. GISTDA’s

e-Flood Map project was then initiated to serve such a purpose, as

well as to monitor the flooded area. The developed solution requires

lots of work and intensive GIS analysis. The project’s results are not

limited to valuable information about the total amount of days each

administrative region and each land use type was affected by the flood;

the relevant data collected in the database can also be beneficial for

many other applications. e-Flood Map DVDs containing flood statis-

tics, study reports, summarized figures, satellite images, GIS data of

the flooded area and a software application that enables users to

examine the data were distributed to end users nation-

wide.

The e-Flood Map Project is considered a major and

resourceful flood risk management project using Earth

observation systems. Results from the project play a

crucial rule not only in the process of compensation,

but also in the process of rehabilitation at local level.

Furthermore, distributed data from the project is

useful for a vast number of user communities includ-

ing researchers, students, politicians, farmers and

bankers. It also offers an excellent opportunity for

Mosaicked False Colour Composite Landsat Imagery

with Inundated Data of 2006 in Thailand

Data from the e-Flood Map project is distributed to a number of

end users

Source: GISTDA