Soil Erosion and Its Spatial Distribution in Majiagou catchment in the Hilly-gully Region of the Loess Plateau, China after Implementation of 'Grain for Green' Policy

摘要

Soil erosion in the hilly-gully regions of Loess Plateau has been very serious problem. In recent years, implementation of "Grain for Green" Policy has a fundamental impact on soil erosion. In order to understand the situation of soil erosion in this area, taking the typical hilly-gully regions in the Loess Plateau, Majiagou Catchment which lies in the north part of Shaanxi province as an example, based on land use filed survey and data in 2008, this study uses Soil erosion Classification Standards (SL-190-196) issued by the Ministry of Water Conservation to calculate the soil erosion modulus of the catchment and to analyze their spatial distribution. It is shown that soil erosion modulus in Majiagou Catchment was 5700 t/(km2.a) under the conditions of land use and land cover in 2008. The ratios of areas associated with different erosion levels to the whole Catchment present in normal distribution, where moderate erosion accounts for 53.65% of the total area of the catchment.Strong and light levels for 17.23% and 14.64% respectively and very strong, slight and extreme levels take less, for 4.16%, 1.12% and 9.2% respectively. The erosion distributions of the upper, middle and lower reaches of the catchment are effected greatly by the features of topography and geomorphology. In the upper and middle reaches, it matches well with the whole catchment in erosion distribution. While in the lower reaches, distribution that slight and strong levels take a great proportion and light and extreme levels less is indicated.