ABSTRACT
The land suitability map in general is established based on individual crop which provides inadequate
information for land use planning. This evaluation is then formulated with objective of delineating units of land as
to their suitability for combining economic crops with regarding the legal conservation areas. The study area, Chi
watershed, covers extensively in Northeast Thailand with an area of about 49,500 sq km. The major economic crops
in the area are rice, sugar-cane, cassava and rubber tree. The suitability assessment for each crop was conducted
using the method as described in FAO guidelines. For each crop, land suitability unit was established using overlay
process of the defined theme layers or land qualities. As a result the suitability map with their associated class
attributes for rice, sugar-cane, cassava and rubber tree were carried out. In addition, the conservation areas in the
watershed were also digitally encoded in GIS database. Simultaneously, overlay process was then performed of the
suitability layers and conservation areas with selection criteria of identifying conservation area, highly and
moderately suitable classes. The resultant map obtained is a result of combination of defined suitability class of
combining crops and the conservation areas. The planning alternative that best matches land uses to the highly and
moderately suitable land areas was suggested with respect to the conservation area