Dynamics of Soil Salt Accumulation in Oasis at Lower Reaches of an Inland River Basin

The dynamics of soil salt content in topsoil(0~20 cm) and its major causes were studied in Fubei region on the oasis at the lower reach of the Sangong river watershed with a combination of methods in geostatistics,GIS,and RS.The results revealed that: ①Transitions between landscape types were frequent.Both the processes of oasis development and desertification were being intensified,and the former was faster than the later.②The spatial variation in soil salinity was best fitted by exponential model in 1982 and 2005,with F-test showing high level of confidence.③Mapping of soil salinity by Kriging and its comparison with landscape maps at the same period showed that the area of soil salinization was increased,and the degree of soil salinization was higher in 2005 than in 1982.The area of soil salt content being more than 20 g·kg-1 had increased by 15.36%,but the area of soil salt content within 5~10 g·kg-1 had decreased by 43.85% in 2005 than that in 1982;④Agricultural irrigation with water from reservoir was the major cause directly resulted in the rise of groundwater table,and then indirectly lead to soil salinization.