干旱内流区尾闾绿洲土壤积盐的动态特征

 运用遥感与GIS技术,结合地统计学方法研究了三工河流域下游阜北绿洲近23 a来表层土壤(0～20 cm)盐分动态特征及其主导因素。结果表明:①研究区景观类型间相互转换频繁,区域绿洲化进程的同时,荒漠化也在加重,并且绿洲化进程强于荒漠化; ②通过对1982年和2005年土壤盐分的理论模型拟合,符合指数模型,并且,F检验达到极显著水平; ③Kriging插值及其与同期的绿洲景观类型图进行叠加运算表明,在自然和人为作用下,区域土壤盐化程度加重,高盐区面积增加,低盐区面积减少,土壤盐分在20 g·kg-1以上的分布面积增加了15.36%,而在5～10 g·kg-1范围减少43.85%; ④水库输水灌溉是引发区域地下水位抬升的直接因素,间接导致土壤盐渍化程度的加重。

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.