A Cause Study And Module Simulation Of Gully Erosion In Black Soil Region

The black soil region, which is well known as the most important market grainproduction base of China, is suffered by the severely soil erosion due to the massreclamation in latest100years. As a result of soil degradation, the black soil layer inmuch area is become thinner. The safety of grain production in this area has beeneffect not only by lose of fertility of soil, but also the gully development. Gullies inblack soil region erode farmland and has been a threat of roads and residents.Moreover,the most importance is that it has not only affected the sustainabledevelopment of social economy,but also the food safety in China．The landdegradation of black soil region has draw a widely attention from the society inrecently years. Many research of erosion in black soil region were taken since1990s,most of which were focus on slope scale or small drainage scale, the monitor of gullyerosion is also less than10years in most cases. There is a lack of study in a regionscale and a long time period. Along with the remote sensing technique development, itis possible to use remote sensing images to monitor gully development in a large area.With the help of history images, it is possible to obtain historical information ofgullies in a long period.The data source of this study is Spot5image in2005and Corona image in1965,of which spatial resolution is2.5m and2.7m, respective. This paper derived gullydistribution data in1965and2005in KeBai region based on GIS and RS technology.With the help of field survey, the process of gully development was discussed. Therewere10factors be chosen to analysis gully risky in study area. Ten single thematicmaps (slope, aspect, slope shape, SPI, TWI, lithology, soil, precipitation, land coverand distance from nearest residential) were obtained and the analysis was takenbetween gully erosion and thematic maps. In order to estimate and validate gullyerosion susceptibility in study area, a bivariate statistical analysis was taken by using1965gullies, and the susceptibilities of gully erosion in2005of study area was taken.A Geomorphic Threshold Model was used to assess the risk of gully occurrence.Based on the analysis, a gully erosion suspecting division was applied in generalized black soil region. It represents a useful tool for sustainable planning, conservation andprotection of land from gully processes. The main work in the paper are as follows:(1) The result of field survey showed that gravity and lithology are two importantfactor of gully development. Based on field survey and gully image characteristicanalysis, the gully distribution map and density map were obtained. With the analysisof land use change map, the area which became to farmland was most suffered bygully erosion. Gully density in that area in2005was21times more than1965's. It isshowed that human activities play an important role in promoting gully erosion.(2) Gully erosion in black soil region is controlled by multiple factors such astopography, soil, lithology, climate, land cover and human activity. With theunivariate analysis of gully erosion and controlling factors, it is showed that there issignificant relationship between gully erosion in black soil region and multiplefactors.(3) The SA threshold analysis showed that there is an underground process ingully erosion development, and the critical slope is less than Loess Plateau.Gullyerosion susceptibilities analysis based on multiple factor showed that there is anacceptable accuracy by using historical gully distribution data and multiplecontrolling factors. Over80%gullies are correctly classified falling in high and veryhigh susceptibility classes. With the help of3D laser scanning software, the soil lossin study area caused by gully erosion was calculated. The result showed that morethan1000million m3of soil was eroded by gully erosion in study area and there is anurgent of treatment in black soil region.(4) A gully risk zoning was taken by using a variety of natural elements ingeneralized black soil area, Terraces and piedmont hills were identified as highsusceptibilities of gully erosion region. Finally, the countermeasures of soil erosion inblack soil area were discussed in different susceptibilities zone.