Soil Erosion Is Influenced by Grain for Green Policy in Loess Plateau Area of Northern Shaanxi, China

Abstract

Grain for Green Policy (GGP), one of China’s important ecological construction and protection policies, have been made remarkable achievements since implementation in 1999. The purpose of this work is to assessment of soil erosion influenced by GGP, which implementation is lead to great change of land use and vegetation cover, using RUSLE model on the basis of land use, MODIS NDVI, DEM and precipitation data in Loess Plateau area of northern Shaanxi, northwest of China. Result showed: (1) GGP implementation in northern Shaanxi was mainly during 1999-2003 and the area of returning farmland in the period accounted for 81.28% of the total area from1999 to 2008. (2) Farmland in northern Shaanxi and slope >25o was decrease 4.94% and 4.84%, respective ly, while grassland was increase 4.04% and 4.05%, respectively. The change of decreasing farmland and increasing grassland was mainly from 2000 to 2005 in northern Shaanxi and slope >25o. (3) Farmland was convert into woodland and grassland, which leaded to increasing of vegetation NDVI. Especially, the vegetation NDVI value of farmland in slope >25o was increase larger than whole area of northern Shaanxi from 2000 to 2010. (4) The change area of soil erosion in northern Shaanxi and slope >25o was decrease in 1 degree, while was increase in other degrees from 2000 to 2010. But when recalculated by rainfall erosivity in 2000, the change area of soil erosion in northern Shaanxi and >25o was increase in 1 degree, while was decrease in other degrees from 2000 to 2010. Vegetation cover change induced by GGP was reduce soil erosion, but due to rainfall erosivity increased, soil erosion was show increase trend in northern Shaanxi and slope >25o.