The occurring

expanding and aggravating of soil erosion in the Changjiang river valley have taken a fairly long period of time. According to analysis of hisorical material

soil erosion in the valley was slight with dense vegetation before the 10th century. From 10 th century to 17 th century

the soil erosion area was expanded. Since mid 17th century

due to the sharp increase in population and excessive exploitation in the mountainous and hilly areas of the valley

soil erosion has been aggravated and become a serious environment problem. It was proved that the unreasonable exploitation of land resources by mankind is a leading factor causing soil erosion.