紫色土旱坡地土壤水分时空分布特征

以三峡库区紫色土旱坡地径流小区为研究对象,分析了春季农田土壤水分时空分布特征及坡位对土壤水分动态变化的影响,结果表明:观测期间属干旱年份,3个小区土壤水分都表现出近似双"S"型曲线的变化趋势,土壤水分的时间变异性与同期降水量存在一定的相关性,但雨量及雨强的增大易形成坡面不饱和径流,不利于降水向坡地土壤水分的转化,以0~40 cm土壤平均贮水量以横坡耕作小区最大,其保水能力和蓄水能力优于顺坡耕作;对照地小区和横坡耕作小区随土壤深度增加其含水量变化程度越小,顺坡耕作小区则呈相反的变化趋势;小区不同土深土壤平均含水量都呈现上坡<中坡<下坡的变化规律,以顺坡耕作小区的增幅最大。

THE TEMPORAL AND SPATIAL DISTRIBUTION PROPERTIES OF SOIL-WATER IN PURPLE SOIL ON DRY SLOPELAND

An experiment was conducted on run-off plots on a hill slope in the Three Gorges Reservoir Region to study the temporal and spatial distribution properties of soil water in the farmland and the effects of slope on the dynamic variation in soil water.The fluctuation of soil water in all the 3 plots could be described with a double S-shaped curve and the time-variance of soil water appeared,to some extent,correlated with the rainfall at the same period.Increase in rainfall and its intensity was favorable for the formation of unsaturated runoff and disadvantageous to the transformation of the rainfall into soil water on the sloping land.The average water storage capacity in the 0~40 cm soil layer was maximum on the cross-plowing plot,i.e.water conservation and storage capacity of the cross-plowing plot was better than that of the straight-plowing plot.Variation degree of soil water content diminished with increase in soil depth on the check plot and the cross-plowing plot,while a reverse tread was noticed on the straight plowing plot.The average water content of deep soil in different plots presented a similar trend,i.e.upper slope > medium slope > lower slope.The amplitude was maximal on the straight plowing plot.