黄土高塬沟壑区小流域雨季末期土壤水资源状况及其空间分异

Soil Water Resources and Their Spatial Differentiation in a Small Watershed on the Loess Tableland-Gully Region at the End of Rainy Season

为了阐明雨季末期黄土高塬沟壑区小流域土壤水分状况,以王东沟小流域为例,用烘干法测定了不同地形和利用方式组合下6 m深度的土壤含水量,测定时间为2019年11月上旬。结果表明:(1)塬面不同树龄苹果园0—2.6 m土壤湿度较高且无显著差异,其平均值为21.6%,2.6—6 m土壤平均湿度随树龄增加而减小,到26 a时降至15.3%。塬面26 a苹果园与农田0—6 m平均湿度分别为17.8%,19.9%。下坡位、梁顶和上坡位的26 a苹果园0—0.8 m土壤湿度都较高,而0.8 m以下随深度呈现出递减趋势,0—6 m平均土壤湿度分别为:16.7%,15.1%,14.0%。各地形刺槐林地0—1.5 m的土壤湿度随着深度的增加逐渐减小,塬面刺槐林地1.5 m以下保持在15%左右,而下坡位、梁顶和上坡位均低于13%。(2)塬面和下坡位0—6 m土壤平均湿度表现出农田>26 a苹果园>刺槐林地的特征,梁顶和上坡位表现出荒草地>农田>26 a苹果园>刺槐林地的特征。研究结果对于深入认识黄土高原小流域土壤水资源的分异特征,推进农业生产和植被建设具有重要意义。

In order to clarify the soil water status in various combinations of landform and land use in the Loess Plateau at the end of rainy season,this study selected Wangdonggou watershed where located in the loess tableland-gully region,and then measured 0—6 m soil water content(SWC)by oven drying method in early November,2019.The results showed that:(1)the SWC of 0—2.6 m soil depth was relatively high,averaged 21.6%,and there was no significant difference in orchards with different apple tree ages on the tableland;the average SWC of 2.6—6 m soil depth decreased with the increase of apple tree age,and dropped to 15.3% at orchard age of 26;the average SWC of 0—6 m depth were 17.8% and 19.9%in the apple orchard with the age of 26 and farmland on the tableland,respectively.The average SWCs of 0—6 m depth in the apple orchards with the age of 26 were 16.7%,15.1%,14.0% at the downslope,ridge-top and upslope,respectively,and showed a decreasing trend with depth below 0.8 m;In the forests of Robinia pseudoacacia,the SWC gradually decreased with the increase of depth above 1.5 m,and the SWC below 1.5 m depth was about 15%at the tableland,less than 13% at all of the downslope,ridge top and upslope;(2)the SWCs of 0—6 m depth at the tableland and downslope decreased in the order:farmland>apple orchard with the age of 26>Robinia pseudoacacia forest,and the ones at the ridge top and upslope decreased in the order:grassland>farmland>apple orchard with the age of 26>Robinia pseudoacacia forest.These results are of great significance for understanding the differentiation characteristics of soil water resources in small watersheds of the Loess Plateau and promoting agricultural production and vegetation construction.