Water Erosion Model Building And Its Application To Eutrophication Study

Water erosion caused by rainfall runoff is a difficult problem worldwide, the focal point of the research is generally focused on small-scale water erosion. China has a vast territory, at the same time, it has very severe soil erosion problem caused by water erosion, the impact of climate, topography, land use and surface materials. The degree of water erosion and erosion hazards of different parts are not same. Water erosion can be caused by surface runoff which can carry large amounts of sediment movement, then the sediment deposition left in lakes and reservoirs. This cause great harm to the water body. So the establishment of large-scale water erosion model and apply it to water erosion on Lake Eutrophication analysis has important theoretical significance and application value.This paper is supported by the geographic information system technology, combined with the U.S. soil general equations, utilized Ministry of Water Resources of remote sensing interpretation of raster data for model validationthe establishment of a large-scale water erosion model to simulate the status in2010. It indicated that the model has good applicability. The simulation results as follows:the total national water erosion is about6.697billion tons in2010. The maximum amount of the soil erosion contribution rate is moderate erosion from the point of view of the erosion level erosion,, it’s about34.20%of the total erosion. Second is the intensity of erosion and slight erosion. One is the amount of17.23%and the other is15.49%. The minimum is accounted for4.30%of the severe erosion. From slight erosion to severe erosion, the erosion area of each erosion level reduce with the erosion of the increased intensity. The area of the slight erosion and mild erosion accounted for85.47%, but it was only21.5%in the country’s total erosion. The extreme erosion and the severe erosion area though only1.21%of the total area, but it was14.07%in the total. The proportion of such regional erosion is much more than the proportion of the eroded area, we should focus on prevention. Most of the region is mountainous areas of the Loess Plateau and the southwest area.The model is applied to the analysis of lake and reservoir eutrophication, the outcome is as follows:(1) in Yunnan and Guizhou erosion intensity decreases gradually from northwest to southeast. In the three periods,1996-2000,2001-2005and2006-2010, the degree of erosion of the northwest mountains and the southern mountain are both the intensity level. Apparently, the northwest and south is the most severe water erosion areas. From three periods of erosion intensity classification map comparison, it can be obviously found that in1996-2000, the intense level is the smallest;2001-2005is the largest;2006-2010is less than the2000-2005slightly. So Yunnan and Guizhou have the most water erosion hazard areas in2000-2005.(2) during1996-2000to2001-2005, the Erhai Lake eutrophication mainly due to the excessive emission of man-made pollution sources, and natural sources, to a certain extent, speed up the Erhai lake eutrophication process. In2006-2010,the natural sources of pollution load is the main reason to increase the Erhai Lake eutrophication, so the proposal of soil conservation measures and control of chemical fertilizer loss is proposed.