Considering the land resource as a national asset the development, exploitation of the resource
should be visionary in the context of sustainable use. A large number of farmers in Thailand the
immediate problems of today cost of living override any consideration of the future. They are
geared to safety and utilize minimum inputs for subsistence. Soil erosion control may be of
importance in terms of sustainable development but it is not immediate need of the farmers. Soil
conservation should be then put forward by the government. With the budget constraint, priority
should be given to the high risk areas of erosion. For years a number of government organizations
have realized the soil erosion problems and the conservation measures have continuously
implemented. When trying to implement the conservation of soil it is necessary to have spatial
information of soil erosion risk within the areas. For the past few decades the experiments on the
study of soil erosion were conducted in a number of aspects to quantify the amount of soil loss.
There exists no update of overviews of spatial soil erosion. The accumulation of scientific
knowledge in the United States and in the humid tropics has made it possible to do this with the
Universal Soil-Loss Equation (USLE) (Wischmeier, W.H. et al., 1987; Lal, R., 1976). Earlier study
conducted by Mongkolsawat et al. (1994) provided the methodology for soil erosion mapping with
USLE and GIS in which the result was reliable for the small area of watershed. It still exists some
limitations particularly the calculation of slope length factor in the context of spatial boundary. In
addition the potential source of the soil erosion risk potential is in selecting the factor values
assigned. Even though in Thailand the soil erosion map or “Erosview” provided by Land
Development Department (LDD,2001) in digital form, it is likely to be based on empirical and
discrete study. However the approach to our study will provide an alternative on the basis of theory,
updated spatial data and the use of availability of GIS software for the slope length calculation and
the factors integration. The objectives of this study were then to explore the methodology for spatial
modeling of soil erosion risk and to provide the soil erosion risk in the Northeastern Thailand.