Using multi-temporal remote-sensing data to estimate 2011 flood area and volume over
Chao Phraya River basin, Thailand
Preesan Rakwatin a , Thudchai Sansena a , Nat Marjang b & Anusorn Rungsipanich a
a Geo-Informatics and Space Technology Development Agency, Lak Si, Bangkok, 10210, Thailand
b Department of Water Resources Engineering, Kasetsart University, Chatuchak, Bangkok, 10900, Thailand
*Corresponding author. Email: This email address is being protected from spambots. You need JavaScript enabled to view it.
Version of record first published: 05 Sep 2012
1. Introduction
Thailand’s worst flood in 50 years occurred during the 2011 rainy season. This flood inundated 65 of Thailand’s 77 provinces. Over 14 million people were affected between July and December, and 756 people were killed. Flood waters raged from Chiang Mai in the North to the capital city Bangkok. The Thai government has estimated the flood damage at US $41.2 billion. Severe flooding critically impacted Thailand’s agricultural and industrial sectors.
Continuous heavy rain caused the 2011 severe flood. The accumulated rainfall during January–October was 1647 mm, which is 42% higher than the 30-year average. The rainfall pattern was also unusual. Heavy rainfall started in June at the beginning of rainy season and continued until mid-October. There were five intense tropical storms that exacerbated the already serious situation: Haima, in June, which caused flash floods in Northern and Northeastern Thailand; Nock-Ten, in July, and Nesat, Haitang and Nalgae, in September.
Although the country has extensive drainage systems, most of them were near to or over capacity. The efficiency of many drainage canals was reduced because they were blocked by water hyacinth, dumped waste and human-built structures. The influence of high tides in the Gulf of Thailand slowed drainage. High tides raised the river level to as high as 2.6 m above mean sea level, which is higher than the city’s concrete floodwall of 2.5 m.
Land subsidence and land-use change are other problems that make flooding hard to solve in the central region. Bangkok and its vicinity are sinking at the rate of 2–3 cm per year (Aobpaet et al. 2009). Deforestation and urbanization not only increase the rate and volume of flood run-off but also cause soil erosion and landslides (Petchprayoon et al. 2010).
Remotely sensed imagery plays an important role in providing up-to-date information that is spatially accurate and captures a wide area with frequent, repeated observations. The Geo-Informatics and Space Technology Development Agency (GISTDA) analyses satellite imagery directly received from its ground receiving station as well as elsewhere to create satellite image maps for the government’s Flood Relief Operation Center (FROC) on a daily basis. These satellite image maps are now freely available online for public use at http://flood.gistda.or.th.
In this letter, we describe flood monitoring and estimate flood volume for the Chao Phraya River basin using multi-temporal remote-sensing data during the great flood of 2011.
Remote Sensing Letters
Vol. 4, No. 3, March 2013, 243–250
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