Study on Spatial and Temporal Changes of Soil Erosion in Yuexi County,Anhui Province

Soil erosion data at four selected temporal periods,i.e,soil erosion intensity maps of 1958,1983,1992 and Landsat TM of 2004.Soil erosion intensity maps of 2004 is interpreted from TM imagery.Making use of the ArcGIS software,soil erosion intensity maps at different periods are served as overlay analysis.In order to analyze area conversion of soil erosion intensity at different periods and changes of soil erosion degree.Based on Markov model,dynamic evolution of soil erosion is forecasted in Yuexi county.Main conclusions are as follows:(1)Soil erosion status in Yuexi county had experienced stages of rapid deterionration to gradual recovery from 1958 to 2004.Soil erosion had aggravated continually from 1958 to 1983.Intense soil erosion had taken place and water area had decreased.Soil erosion status was restoring gradually from 1983 to 1992.Intense soil erosion disappeared.Soil erosion was to be in the recovery stage from 1992 to 2004.Ecological environment was clearly better.(2)Different types of soil erosion were mutually transformational at different times.(3)Unchanged area of soil erosion degree had experienced descending to ascenting in Yuexi county from 1958 to 2004.Increasing area of level of soil erosion degree enlarged observably after that it descended gradually,and yet descending area of level of soil erosion degree declined and then climbed up.(4)Predicting results basing on Markov model shows that soil area of slightly erosion shall be increasing to 64 221 hm2 if current soil erosion status goes on maintaining at the end of 2016,and that soil area of midderate erosion will be descending,soil area of serious erosion will be increasing in local area but its changes are unconspicuous.Soil area of deposition type shall be descending eminently and waters area shall be diminishing.Soil erosion status will be tending toward better on the whole.