Study Area
Norheast Thailand, one of the distinct main
physiographic features of
Thailand, covers about onethird
of the total area of the
kingdom. It lies between the
latitudes of 14° and 19° N
and the longitudes of
101°and 106° E (Fig. 1).
Average rainfall varies from
1,000 m.m. in the southwest
to 2,000 m.m. in the
Northeast. The rainfall is
unevenly distributed during
the rainy season (May to
October), with over 80%
occuring during August and September.
Physiographically, the main area of the Northeast is
formed by the so-called Korat plateau and a part of the
central highland. The Phu Phan range lies in a
Northwest-Southeast direction, dividing the plateau into
two basins, the larger Korat basin to the south and the
smaller Sakon Nakhorn basin to the North. The two
basins are characterized by gently undulating alluvial
plain with scattered tree and patches of forest remnants.
Flood risk area in the Northeast is a result of large
rainfalls, the increased frequency and volume of surface
run-off, the rising levels of river bed and human
modification of land. The main rivers overflow their
banks frequently resulting in devastating floods.