China is country with vast population and scarce cultivated land per capita.About 33% of the arable land was eroded by wind、water、frost、gravitation and engineering forces.In order to investigate the soil erosion condition and protection measures of the cultivated lsand the soil erosion survey was done by intepretating TM imagery of 1995 and 1996 in China.Landsat TM imagery was composed,projected,rectified and interpreted to get the 1∶100000 vector data of the national land use and the soil erosion map with the help of field investigation,topography,vegetation,soil quality,and soil erosion map.The provincial maps were collected into the national ones.The soil erosion was classified into water erosion,wind erosion,frost erosion,gravitation erosion and engineering erosion in terms of the national standard issued in 1996.The soil erosion intensity was classified into six grades. About 75.05% of Chinese cultivated land was dry hand and 24.95% was paddy field.The soil erosion of the dry land was more serious than that of the paddy field.About 42.48% of the dry land was eroded while 7.96% of the paddy field was eroded.Totally,33.15% of the cultivated land was eroded.The water force erosion took up 88.43% of all the eroded cultivated land and the wind erosion was about 11.08%. The eroded cultivated land by water forces was mainly located in Sichuan,Heilongjiang,Gansu,Shaanxi,Inner Mongolia,Yunnan,Shanxi,Guizhou and Chongqing.They concentrated in the Loess plateau,Yungui plateau and Sichuan mountain area.In Chongqing municipality,Guizhou,Sichan and Gansu Provinces the eroded percentage was more than 80%.That of Shaanxi,Yunnan,Ningxia,Inner Mongolia,Fujian and Shanxi was more than 51%.The water eroded dry land in Heilongjiang took up about 38.14% of that of Chinese cultivated land because its dry land was large.The highly serious water erosion located mainly in Loess plateau and Yunan,Guizhou,Sichuan,Fujian and Jiangxi mountain area.The acreage of the wind eroded dry land was located in Inner Mongolia,Jilin,Heilongjiang,Hebei,Henan,Xinjiang and Gansu Provinces which took up about 91.66% of the national wind erosion.Inner Mongolia was the most serious area by the wind erosion and the eroded percentage was more than 36.
1%.The percentage of Jilin、Ningxia、Xinjiang and Hebei Provinces was more than 7%. More mountain and hill areas were distributed in Sichuan,Yunnan,Guizhou,Anhui,Heilongjiang,Guangxi,Hubei and Zhejiang and were the main water erosion areas in China.The water eroded paddy field was more than 10% in Yunnan,Guizhou and Sichuan Provinces.The wind eroded paddy field in Heilongjiang took up about 55.12% and Liaoning was 9.2%,Hubei 7.83%,Jilin 7.35%,Inner Mongolia 6.52%.The wind eroded areas were located in Northern China.In Inner Mongolia the wind eroded paddy field was about 9.12%. The frost erosion happened in the coldest areas including Inner Mongolia,Tibet and Qinghai which took up about 82.77%、16.76% and 0.34% of Chinese frost erosion acreage respectively.Engineering erosion was caused by mining,quarrying,building and other activities.The engineering erosion in dry land was the most serious in Guangdong Province whose percentage took up 58.01% and Heilongjiang was 14.21%.The enginering erosion in paddy field in Guangdong was about 59.29% of China and Fujian was 15.39%.A great amount of cultivated land was converted into urban、 rural settlements and the construction land.The engineering erosion extended without agricultural field protection measurements.The gravitation in Guangdong was most serious with the rapid development of cities.In Chongqing municipality and Hunan Province the slope cultivated land caused the gravitation erosion. From above we could draw the conclusion that the dry land of the water erosion was most serious in China.There was a strong relationship between the soil erosion and the ecological background.In order to study the relationship,SEI(Soil Erosion Intensity Index)and EI(Ecological Environ