Mapping Hazardous Condition of Soil Erosion through GIS Analysis for Effective Management of Land Resources of Vegetable Production Regions in West Java, Indonesia

摘要

Land use changes from forest, upland field or paddy field to vegetable field have been appeared recently in some parts of highland area of West Java Province in Indonesia, of which the elevation is around 1,000 meters above sea level. The study site of this research is located in the Lembang Sub-District, which is one of the representative vegetable production areas at the present, and is revealed such a land use change extensively. In the vegetable fields, the surface of soils would not be covered by vegetation or other materials for considerable duration of time in a year. This might accelerate the hazardous condition of soil erosion. In this study, the authors carried out a series of field survey, which consisted with measurement of rainfall, soil sampling and observation of land cover and topography. They also implemented the computer-based analysis of topographic maps, aerial photos and satellite remote sensing data. The results of field survey and computer-based analysis were used to estimatethe hazardous condition of soil erosion by applying the formula of USLE (Universal Soil Loss Equation) and to produce maps of potential hazard. USLE normally estimate the annual rate of soil erosion, however, in this study it was modified to estimate monthly rate of soil erosion. By calculating the amount of soil loss for the various case of cropping of vegetables, the authors could show the way to avoid the severe soil erosion by considering the timing of coverage of vegetation and occasionally happened heavy rainfall in the early period of rainy season.