退耕还林还草工程实施对洛河流域土壤侵蚀的影响

退耕还林还草工程是中国实施的重要生态环境建设与保护工程，对区域植被覆盖及土壤侵蚀产生重要影响。以洛河流域（陕北黄土高原部分）为研究对象，利用流域通用土壤侵蚀方程（RUSLE），结合流域降雨、土壤类型、DEM、植被覆盖等数据，定量分析了2000—2010年退耕还林还草工程实施对流域土壤侵蚀的影响。结果表明:（1）洛河流域2000—2010年耕地面积减少，林地、草地面积增加，土地利用变化主要发生在2000—2005年；（2）洛河流域2000—2010年土地利用变化导致植被NDVI平均值增大，耕地变化区域植被NDVI值增加幅度高于耕地未变化区域，表明耕地变化区域植被NDVI增加对耕地区域总体植被NDVI值增加贡献较大；（3）降雨侵蚀力和退耕还林还草工程实施对土壤侵蚀具有明显的影响。受降雨侵蚀力增大影响，2000—2010年洛河流域土壤侵蚀呈增加趋势；不考虑降雨侵蚀力变化情况下，洛河流域土壤侵蚀呈减少趋势，反映出退耕还林还草工程实施对土壤侵蚀的减缓作用。

Impacts of Grain for Green Project on Soil Erosion in Luohe River Basin of Northern Shaanxi Province,China

Grain for Green Project (GGP) is an important ecological and environmental construction and protection engineering project in China, and it has great influence on vegetation cover and soil erosion. The Revised Universal Soil Loss Equation (RUSLE), together with precipitation, soil type, DEM and vegetation cover, was used to investigate the impacts of GGP on soil erosion from 2000 to 2010 in Luohe River Basin, northern Shaanxi Province, China. Results showed that: (1) farmland decreased while forestland and grassland increased due to GGP, and land use change mainly occurred from 2000 to 2005; (2) the increase of vegetation NDVI value induced because of land use change from 2000 to 2010 in Luohe River Basin, and the increase rate of vegetation NDVI in farmland changing area was higher than that in the unchanged area; (3) both rainfall erosivity and GGP implementation have the significant impact on soil erosion. The increase of soil erosion in Luohe River Basin during 2000—2010 mainly resulted from the increase of rainfall erosivity. If rainfall erosivity keeps constant, then soil erosion in the basin would decrease because of the effects of GGP on soil erosion.