Research on Land Degradation in Jinhua-Quzhou Basin by Remote Sensing: A Case Study
金衢盆地土地退化遥感研究──以兰溪市上华试验区为例

Based on the criteria for assessment of land degradation two synthetic maps of land degradation in different periods (1950's and 1980's) are prepared by using aerial photos and with the help of GIS. It has been shown that due to the long history of economic development more than 64% of land were cultivated or used in the studied area. Various grades of degraded land caused by water erosion occupied only 36% of the total land: some 5. 11% of this are severely and very severely degraded, 7. 38% moderately and more severely degraded and the other 23. 43% slightly degraded and non-degraded. Since downslope zonation of soil, vegetation and erosional features is obvious from top to foot of hill, same situation happens to spatial variation of degraded land. It has been proved that severely and very severely degraded land characteristic of bared badlands were not formed in recent decades due to deforestation as it was commonly thought, but its history could been traced back to at least Ming and Qing Dynasties (350-650 years B. P.), even Tang, Song, Yuan and Jin Dynasties (650-1300 years B. P). During the last few decades the development of land degradation manifests itself as drastic reduction. of non-degraded land and parallel increase of slightly and moderately degraded land.