Dynamic changes in soil erosion intensity of a watershed - Taking the Kulietu river watershed as an example

The Liuhe River is one of the typical basins with serious soil erosion in Northeast China. The Kulietu River watershed is a sub-watershed of the Liuhe River basin. Taking Kuhetu watershed as an example, a system for soil erosion study by GIS (Geographic Information System) has been developed in this paper. Based on the data of remote sensing image, relief map and experimental data of the Liuhe River, this paper firstly selects landform, rainfall, soil, runoff, and soil and water conservation measures (mainly vegetal measures) as the environmental erosion factors to study the mechanism of soil erosion and set up a typical dynamic system for soil erosion in a watershed. Then, this paper analyses the dynamic changes of the eroded environment in the watershed by analyzing the sequential maps through GIS software ARC/INFO, and D-ARC/INFO (Dynamics ARC/INFO), developed by the writers. Many maps have been drawn by GIS to reflect the erosion situation of the watershed in different periods and different types, such as maps of soil erosion intensity, maps of soil erosion control, and maps of erosion intensity evaluation, etc. Moreover, on the basis of the above research work, the situations of soil erosion and environmental changes in the watershed during different periods are carefully studied by method of environmental dynamic analysis. Not only the natural factors but the human factors causing soil erosion are analyzed in this study. Finally, an erosion system for a watershed has been integrated to provide the scientific basis for comprehensive control in watersheds in Northeast China. The main conclusions are as follows(l) It is a comprehensive research work to study soil erosion in a watershed by the method of system dynamics to establish the dynamics model. Any study, if just from a single affecting factor, or a special time, will be all static and one-sided and can't reflect the relationship among various affecting factors. However, from systematic science and by method of dynamics, the research of erosion dynamic changes and processes in a watershed will be agreeable with the fact.(2) The D-ARC/INFO, developed in this research project, has preliminary merged some functions of systematic dynamics with special use of ARC/INFO, such as prediction, spatial analysis, which is quite helpful to predict the changes in soil erosion intensity.(3) This research result is quite helpful to soil control in a watershed for its powerful prediction function of soil erosion intensity. In fact, the data from the model agree very well with the observed data. So it is practical to spread this achievement to soil and water conservation in a wider region.