Dynamic changes of soil erosion in the Chaohu Watershed from 1992 to 2013

With the help of GIS and RS technology, and based on remote sensing image data,DEM data, soil type data and relevant statistical data, we use the modified universal soil loss equation(RUSLE) as the evaluation model to determine the relevant parameters of the model,to calculate the soil erosion modulus in Chaohu Watershed from 1992 to 2013, and to analyze the spatial and temporal dynamic changes of soil erosion intensity in this region. The soil erosion area in Chaohu basin is mainly distributed in the NE-SW direction. Slight, mild,moderate, intense, strong and severe erosion accounted for 93.46%, 6.25%, 0.68%, 0.19%,0.01% and 0.01% of the total watershed area respectively. The largest erosion area was paddy field, accounting for 64.42% of the total watershed, followed by woodland(20.98%) and urban and industrial land(10.36%), which was based on micro erosion and mild erosion mentioned above. From 1992 to 2006, the soil erosion modulus decreased from 510.70 t/(km2· a) to 129.79t/(km2· a), falling by 74.59%, while the vegetation cover increased from 37% to 47.80%. The change of soil erosion area was obvious: mild(8.93%), moderate(2.33%), intense(1.32%),extreme(0.09%) and severe erosion(0.05%) were reduced to 4.74%, 1.39%, 0.28%, 0.02% and0.01%, respectively, while slight erosion increased from 87.88% to 94.16%. However, the slight erosion reduced to 93.46%, and the slight erosion had a worsening trend in 2013. From1992 to 2013, the soil erosion modulus increased from 129.79 t/(km2· a) to 149.44 t/(km2· a), an increase of 15.14%, meanwhile the vegetation cover rate decreased from 47.80% to 45.15%.