Assessing soil erosion in inaccessible mountainous areas in the tropics : the use of land cover and topographic parameters in a case study in Thailand

Land degradation processes in hilly areas are often directly related to land cover changes. At the same time, many hilly areas in the tropics are inaccessible and thus lack proper data. As a result, data scarcity is a crucial problem when trying to assess soil erosion. In this paper a method is described showing the use of digital elevation, remote sensing and field measurement techniques for deriving necessary land cover parameters as required for erosion modeling. The study shows that correction of topography-induced illumination variation in remote sensing data helps improve classification accuracy while field measurements help in accurate estimation of cover factor. Similarly, the incorporation of DEM-derived parameters such as upslope catchment area and flow direction network in erosion modeling helps not only to improve the estimation of soil losses but also to identify the dominant erosion process active in the area. This makes the formulation of sound conservation measures for minimizing soil losses and reducing off-site erosion effects in low lying areas much easier.