川中丘陵区小流域土壤侵蚀空间分异评价研究

Soil Erosion Distribution of a Small Watershed in the Hilly Area of Central Sichuan Basin

将地理信息系统(GIS)技术Arc/Info与通用土壤流失方程(USLE)相结合进行了小流域土壤侵蚀量的估算。以盐亭农田生态系统国家野外科学观测研究站内的截流村小流域(简称截流村小流域)为研究对象,依据实地调查资料及地形、土地利用、土壤和植被等数据,建立了小流域空间数据库,利用GIS的栅格数据空间分析功能,将小流域空间离散化为10 m×10 m的栅格,在栅格内根据合适的USLE因子算法进行了土壤侵蚀量估算,进而对小流域内土壤侵蚀强度空间分异和小流域内侵蚀量进行了统计分析。结果表明,截流村小流域年均输沙模数为1244.7 t/(km2.a),侵蚀强度属轻度;坡耕地占流域面积的44.17%,年均土壤侵蚀模数为2195.0 t/(km2.a),其侵蚀总量占流域总侵蚀量77.93%,表明坡耕地是该小流域水土流失的策源地,小流域水土流失治理的关键是实现流域内坡耕地的合理利用。同时对于林地和小于10°坡耕地的侵蚀模数结果与相关研究仅相差19.8%和4.4%,证实了该模型的准确性和可靠性。

Jieliucun watershed in the hilly area of central Sichuan Basin was chosen as the typical study area. Based on field survey, geographic information system （GIS） software and Arc/Info, geographical database of the watershed, including digital elevation model （DEM）, landuse, soil and vegetation, was built. The watershed was divided into some uniform grids（10 m × 10 m） in accordance with the GIS＇s function of raster spatial analysis. Integrated with GIS, Universal Soil Loss Equation （USLE） was applied to predict the amount of soil erosion in the watershed after studying the reasonable method for calculating factor values of USLE. Results show that the annual average mount of soil erosion is 1 244.7 t/（km^2·a）, which is in the category of lightly eroded area. Sloping land covers 44.17% of the total area, but the amount of its soil erosion accounts for 77.93% of that in the watershed. The study demonstrates that sloping land is the major source of soil loss, and therefore rational sloping land use is the key to soil loss control. The case study of Jieliucun watershed indicates that the model is reliable compared with other related studies.