Analysis And Extraction Of Soil And Water Loss Factors Based On RS And GIS--The Case Of Panzhihua City

Soil and water loss has resulted in a series of hazards, and it is the most serious environment problem in China. To precisely supply the type, intensity and distribution of soil and water loss in time is the principal basis for soil and water loss preservation, planning and decision-making.Recent years, the technologies of remote sensing (RS) and geographical information system (GIS) have developed rapidly and trended to be integrated and applied widely. Remote sensing supplies continuous information sources to environment surveying and monitoring in a large region. GIS is a powerful tool to management and analysis spatial data.In this paper, based on the original data of landsat-5 TM in 1988, landsat-7 ETM+ in 1999 and 1 ' 250000 topographic map as the main information sources, by the method of remote sensing digital image processing, the author has extracted leading factors of soil and water loss, such as vegetation cover, land-use type, gully density, parent materials of soil, and so on. On the basis of raster-to-vector contour line, digital elevation model (DEM) is got, then slope is calculated through DEM. Founding the standard for classification and gradation of soil erosion, by the spatial analysis of GIS, the author has proposed gradation index of soil and water loss of the study area, then gotten strength levels of soil and water loss of Panzhihua city. By comparing analyses between 1988 and 1999, the result are these: the whole area of soil and water loss has increased 1573.87km2, very slight loss area has reduced 1573.87km2, slight loss area has increased 1080.16 km2, moderate loss area has increased 298.39 km2, severe loss area has increased 133.03 km2, strongly severe loss area has increased 43.84 km2, violent loss area has increased 18.45 km2, the soil and water loss in Panzhihua city was showing in a worsened situation.It is feasible for analysis and extraction of soil and water loss factors based onRS and GIS. The following is the innovation and production in this paper:(1) Under being unable to obtain average erosion modulus situation, by the method of remote sensing digital image processing to extract leading factors of soil and water loss, such as vegetation cover, land-use type, gully density, parent materials of soil, and extract slope factor by applying topographic data, it is feasible in technology to research soil and water loss.(2) Founding the sector standard of the People's Republic of China standard for classification and gradation of soil erosion(SL 190-96), referring requirement of soil and water conservation technical specification, combining gradation calibration of soil and water loss factors, the author has proposed surface erosion gradation index of soil and water loss including vegetation cover, slope, gully density and land-use type factors, then gotten strength levels of soil and water loss of Panzhihua city.(3) Based on the geo-environment of Panzhihua city, the author has established a RS and GIS system from data collection-remote sensing digital image processing-extraction of soil and water loss factors-spatial analysis of GIS-gradation calibration and analysis of soil and water loss intensity, shown out the study technique route, method system and work flow of analysis and extraction of soil and water loss factors, which has reference value for surveying and dynamic monitoring of soil and water loss in the mountain area of China.