Analysis on Impact Factors of Land Desertification in Lower Reaches of Tarim River in Past 50 Years

The quick process of desertification in the lower reaches of the Tarim River is obvious in the arid regions of the world,where all social sectors have pay more attention to,especially to its causes.Because of the irrational water-land resources use and biological resources exploitation in the past 50 years,the lower reaches of near 363 km from the DaXiHaiZi reservoir had been dry for 30 years,the groundwater level in these areas decreased from 3~5 m in 1950 to 8~12 m in 2000,resulting in the reduction of natural vegetation area year by year.Consequently the desertification area increased year after year,increasing from 12% in 1958 to over 90% of the total land area.The aridity degree of environment in the lower reaches of the Tarim River was strengthened.In the past 50 years,the regional precipitation and temperature wavely changed,not too strong to bring about great environmental change.The anthropogenic causes superimposed on climatic ones are the key reasons for eco-environment degrading and desertification developing in study region.