Dynamic change of soil retention function and evaluation on its economic value in mountainous area of Upper Huaihe River Basin

The mountainous area of Upper Huaihe River had carried the National Grain for Green Project and Water and Soil Conservation Demonstration County Project into execution from the year of 1995 to 2000.Based on the data of soil erosion in this study area at the year of 1995 and 2000,by adopting GIS technology,integrating with methods of gridding and interpolation,this paper analyses the dynamic change of soil erosion quantity in per-pixel and economic value of soil retention function.The results showed that:(1) The area of the Upper Huaihe River in mountainous area is about 2.6×104 km2.The area and soil erosion quantity of farmland,forestland and grassland are higher than that of other ecosystems.(2) The quantity of soil erosion had decreased 152.85×104 t in study area from 1995 to 2000.(3) The regions where soil erosion modulus are high mainly distributed in southeast of study area,and this distributing status has a strong correlation with terrain factors and climate.(4) Land where soil retention value has increased and its amplitude are bigger than the decreased and its range in mountainous area of Upper Huaihe River from 1995 to 2000.(5) The total economic value of soil retention had increased 1001.86×104 Yuan in study area.The values of soil retention in most cities and counties of study area have increased in varying degrees.