抄録
Massive flooding in the Chao Phraya River basin, Thailand, in 2011 has caused great damage on the most parts of the country. In order to identify inundated areas due to large-scale floods like that in 2011, analysis of the satellite data is an effective way to understand both overall and detailed situation of inundation. In this paper, we proposed a method to estimate inundated areas utilizing data from two kinds of satellite, HJ-1A and ENVISAT, with different resolutions and spectral bands. In this method, the water surface in some local areas was extracted from HJ-1A data, by which the threshold value of ASAR image of ENVISAT was adjusted so that the inundated area matches with the result of HJ-1A. Then, the inundated area in a larger sample domain was estimated by the ENVISAT data. The result indicated that the inundated areas spread over paddy fields along with time, but they were limited to these low elevation zones. In another domain, we found that inland areas located far from rivers were largely inundated, which is probably due to the water storage in paddy fields, while previous estimation did not detect these areas.
