STUDY AREA
The study area is Khon Kaen, a province in the Northeast, and
locate between latitude 15° 40′ to 17° 5′ N and longitude 101° 45′ to
103° 10′ E (Fig. 1). It covers a total area of 10,886 sq km. (Office of
National Statistic, 2000). Average rainfall varies from 1,000 - 1,500
m.m. The rainfall is unevenly distributed during the rainy season (May
to October) with over 80% occuring during August and September.
Physiographically, the gently undulating areas were found in the
northern and western part of study area, central and soutern part were
low land to floodplain belong to main river. Main economic crops
include rice, sugarcane, and cassava.