甘肃北山地区典型沟谷包气带土壤渗透特征研究

Characteristics of the Soil Permeability in a Typical Gully Aerated Zone of Beishan in Gansu Province

为研究作为高放废物处置库预选场址的甘肃北山地区典型沟谷包气带土壤渗透性,基于Guelph入渗仪测定了典型沟谷地带45个试验点不同深度的土壤饱和渗透系数,运用传统统计学分析试验结果,同时利用Arc GIS地统计学模块分析土壤饱和渗透系数趋势性和空间分布特征。结果表明:区内典型沟谷土壤饱和渗透系数均值为1.88×10^(-4)m s^(-1),变异系数为88%,总体上属中等变异;当土壤类型为高结构土时,随着试验深度的增加土壤饱和渗透系数逐渐减小;当试验深度为20 cm、40 cm和60 cm时,土壤饱和渗透系数沿经度和纬度方向无明显的分布趋势;在沟谷地带划分出的洪流径流路径中,距分水岭距离越远,土壤饱和渗透系数逐渐变小,即随着径流距离的增加,沟谷上游岩体内土壤饱和渗透系数大于沟谷中下游沟口和平滩土壤饱和渗透系数。

In order to study soil permeability in a typical gully aeration zone of Beishan in Gansu Province, the disposal site for high-level radioactive waste repository was selected. The saturated permeability coefficients of soil at different depths of 45 test locations in typical gully areas were determined by Guelph infiltration meter.Traditional statistical methods were used to analyze the trend and spatial distribution characteristics of soil saturation permeability coefficients by using the geostatistics module of ArcGIS software. The results showed that the average saturation permeability coefficient of soil in the typical gully was 1.88 × 10^(-4) m s^(-1), with a coefficient of variation of 88%, which belonged to moderate variation in general. The saturation permeability coefficient of high structured soil was decreased gradually with the increase of depth. At soil depths of 20 cm, 40 cm and 60 cm,the saturation permeability of soil had no obvious distribution trend along the longitude and latitude. The saturated permeability coefficient of soil became smaller with the increase of distance from watershed. Moreover, the saturated permeability coefficient of soil in the upper reaches of the gully was higher than that in the middle and lower reaches of the gully.