Forest Pattern On Regulation Of Erosion And Sediment Processes Of Watershed In Loess Area

Soil erosion is a major factor of causing environmental degradation. For a long time, human irrational utilization of natural resources is destroying the vegetation and thus leads to serious erosion. As a result, increasing erosion reduces land productivity, soils' fertility and water capacity, and etc., which turn to further deteriorate the ecological environment. Soil erosion in the loess area relates to low vegetation cover rate in this region.As the most important ecological system on the earth terrain, forest plays its specific function in hydrological ecology via forest crown, dense shrubs and grasses under trees, litters and soils. Moreover forest has roles in protecting head waters, purifying water quality, conserving soils and water and reducing natural disasters through its interaction with soils, air and water. More often in China, assessment on forests' conservation ability is based on single indicator, i.e. forest cover rate. Recently, rational distribution of forests has been paid much attention, but researches on relationship between forest pattern and erosion and sediment is not much although there are many progresses in studying relations between forested slope and non-forested slope or forested watershed and non-forested watershed. Therefore, it is significant to have studies on effects of forest pattern on soil erosion.The thesis is based on study on relationship between forest pattern and erosion and sediment processes, carried out in four watersheds of Luergou, Luoyugou, Qiaozidonggou and Qiaozixigou in Tianshui City of Gansu Province. The study covers the following aspects:1. A space and attribute database is established based on 3S technologies. To do this, long term data pertaining to rainfall, runoff, sediment in the above watersheds collected by Tianshui Experimental Stations of Soil & Water Conservation was analysed, plus field investigations, observations and experiments.