Automatic Extration Method of Stable Slope Angles of Water Level Change Region Based on DEM

The average low water level, water level change region, average flood level of natural river respectively exist many similar characteristics with the low water level, regulating water level (i.e. water level fluctuation band), the highest design flood level of reservoir operation period. Stable slope angles under low water level, in water level change region and above flood level in different rock-soil bodies have great significance to the prediction of bank collapse in reservoir operation period. Based on high-resolution aerial images in dry seasons and DEM (digital elevation model), using GIS component development technology, the paper developes a method to get stable slope angles of water level change region, which has some advantages such as high degree of automation and fast speed in achieving data in a large scale, therefore, underwater stable slope angles can be computed by discount, and the stable slope angles above water can be achieved through the similar method. Compared with the traditional method such as survey or statistical method, it greatly reduces the fieldwork, and according to the regions which human beings cannot reach in current conditions, it also can get detailed data, and it can get enough sample data for comparison and statistical analysis in different rock or soil bodies, so it can provide more dependable data for prediction of bank collapse of reservoir back zones.