Application of Geo-CA and GIS in the Dynamic Monitoring and Simulation of Soil Erosion in the Loess Hilly-gully Regions

It is very important to dynamically simulate and predict the development and evolutionary process of soil erosion.Based on integrating the remote sensing image and revised universal soil loss equation(RUSLE),in this study the values of soil erosion amount in loess hilly-gully regions in the Weigou Watershed during the period from 1998 to 2004 are calculated.Then a map of soil erosion intensity is obtained according to the classification of soil erosion intensity,and the relationship between soil erosion and its background including elevation,slope,aspect and land use types is revealed.On which a geographic cellular automata model is developed based on the integration of GIS and RUSLE,and the spatial evolution of soil erosion deuring the period from 2004 to 2010 is simulated using this model.The results of the simulation are as follows:(1) The model is effective to simulate soil erosion evolution at macroscopic and microscopic scales;(2) Average annual soil erosion amount in the Weigou Watershed was decreased from 1998 to 2010,and the proportion of soil erosion in the regions with serious soil erosion(the sediment is higher than 10 000 t/(km2·a)) is higher than 60% of total in the watershed,so these regions are important in controlling soil erosion;(3) The soil erosion in the watershed in 2004 was 9 242.5 t/(km2·a),and soil erosion is serious in the regions with slope varying in a range of 15°~25°,south aspect,elevation varying in a range of 1 800~1 900 m a.s.l. It is estimated that the total area and amount of soil erosion in the study area in 2010 will be reduced to 120.65 km2 and 1.21×106 t respectively.