黄土高原沟壑区农田土壤水分动态变化分析

Dynamic Change of Farmland Soil Water in the Loess Tableland Gully Region

以黄土高原沟壑区径流小区为研究对象 ,分析了雨季、旱季缓坡农田土壤水分动态变化以及坡位对农田土壤水分动态变化的影响 ,结果表明 :雨季、旱季农田土壤水分动态变化趋势相同 ,但浅层 (10～ 30 cm )土壤水分变化幅度较大 ,尤其是降雨产流时 ;土壤水分的补偿和恢复主要取决于雨强适中、历时长且雨量大的降雨过程 ,与土壤前期水分剖面特征、作物覆盖度以及作物耗水特性密切相关 ,而坡度几乎没有影响 ;坡位对农田土壤水分动态变化也有一定的影响 ,观测期末雨季、旱季土壤蓄水增量为坡上 <坡中 <坡下 。

Based on the field data of runoff plots in the Loess tableland gully region, the dynamic change of farmland soil water was analyzed during rainy and dry time respectively, and the effects of slope position on soil water change were discussed. The results showed that the dynamic changes of soil water in every layer were similar, but the shallower the depth was, the bigger the change trend of soil water was, especially after runoff took place. The compensation and resumption of soil water was primarily dependent on the precipitation with reasonable intensity and long time, and had a close relation with the previous soil water profile, crop cover ratio and water consumption characteristic, but the effect of slope gradient could be omitted. The slope position had a small effect on the dynamic change of soil water, and the increase of soil water for 10~50 cm layer during rainy time and 10~60 cm layer during dry time was in the order of top<middle<foot. In addition, the stored water in the middle and lower parts was larger than that in the upper part of the farmland.