Quick Mapping of Soil Erosion Risks by Remote Sensing and GIS in East Java, Indonesia

要旨

This study demonstrated the use of Remote Sensing techniques and Geographic Information System (GIS) for assessing and mapping of soil erosion risk in East Java Province, Indonesia. A digital elevation model (DEM) derived from elevation contours combined with digital data on shuttle Radar Topographic Mapping-SRTM were used to calculate terrain parameters, such as slope and relief. The Landsat Thematic Mapper data were analysed to identify the existing landuse characteristics. The data of soil erosion factors such as soil erodibility, rainfall erosivity, slope steepness, type of landuse and management practices were scored and ranked according to their contribution to soil erosion risk. By means of GIS approach, a “weighted–summation” analyses of multiple input was performed to generate soil erosion risk map. The degree of soil erosion risk of certain areas was indicated by the total score resulting from summation of all soil erosion parameters. To verify the result of analyses, the ground truth and field data collection within representative sample areas were conducted. The results show that the degree of erosion risk was strongly related to the degree of rainfall erosivity, soil erodibility and slope steepness. It was found that about 43.1 % of the total areas were susceptible to erosion, ranging from moderate to high, and that 48, 6% of the intensive cultivated land were threatened by soil erosion. Agricultural production sustainability of sloping lands is strongly depended on the farm level management practices, such as by applied terracing, contour ploughing, strip cropping, etc.