石羊河尾闾黏土质夹层结构土壤对降雨入渗的响应

为探明该种土壤结构如何影响降雨在土壤中再分配及其影响效果,采用自然降雨背景下的人工试验方法开展了黏土质夹层对降雨入渗影响效果的试验研究。结果表明:(1)降雨后经过相同时间水分再分布后的土壤末期含水率主要受控于降雨初期含水率、降雨入渗所能达到的最高含水率及其黏土夹层厚度;(2)黏土质夹层表层沙土土壤含水率在降雨条件下经过长期水分再分布后表现出黏土层厚度越小,表层含水率越低的特征;黏土层及黏土层下部的沙土层初始含水率越高,在降水初期水分增加量、增加速度以及水分流失量、流失速度与初始含水率具有一定的正相关关系。因此,黏土质夹层结构土壤阻滞水分入渗到植物难以利用到的深层,将水分固持于黏土层及黏土层上下部,在表层覆沙20 cm情景下,10,20,30 cm厚度的黏土质夹层以10 cm处理总体水分保持效果最好。

Response of Clay Interlayer Structure Soil to Rainfall Infiltration in the Lower Reaches of Shiyang River

An experimental study on the influence of clay interlayer on rainfall infiltration was carried out by artificial test method under the background of natural rainfall to find out the effect of soil structure on rainfall redistribution in the soil.The results show that:(1)after the same time of rainfall and redistribution of water,the water content of soil at the end of rainfall is mainly controlled by the water content at the beginning of rainfall and the highest water content that rainfall infiltration can reach,followed by the thickness of clay interlayer;(2)after long-term water redistribution under rainfall conditions,the soil moisture content of sandy soil on the surface layer of clay interlayer shows the characteristics that the smaller the thickness of clay layer is,the lower the surface water content is;the higher the initial moisture content of sand layer under the clay layer and the clay layer is,the more the water content increases,the increasing speed,the water loss,the loss speed.The soil with clay interlayer structure blocks the infiltration of water into the deep layer where the water is hard to be used by plants,and the water is held in the clay layer and the upper and lower part of the clay layer.It has the best effect as a whole for water retention in the 10 cm thick clay layer when the surface layer is covered with sand for 20 cm thick over 10 cm,20 cm and 30 cm thick clay layers.