黄土区坡地和坝地土壤电阻率分布特征及应用

土壤水分的准确高效测定是土壤水文学研究的重要基础,以土壤电学性质为基础的电阻率成像法(ERT)为土壤水分信息获取提供了新的技术手段.为探究E RT在黄土区土壤水文过程研究中的可行性,利用高密度电法仪测定了陕北六道沟小流域典型坡地和坝地剖面土壤电阻率(ρ),分析了不同土地利用方式下ρ二维分布特征,探讨了E RT在黄土区土...

Distribution and Application of Soil Electrical Resistivity in Slope Land and Check Dam in the Loess Region

【Objective】Soil moisture is one of the most important factors for plant growth and solute transport in arid and semi-arid areas. An accurate and effective measurement of profile soil moisture is a critical issue of soil hydrology. The technology of electrical resistivity tomography(ERT) based on soil electrical properties provides a new geophysical method for measuring soil moisture content in the profile, which has been widely applied in the studies of soil water dynamics, groundwater recharge and root-water interactions in many regions in the world. However, little is known yet about the applicability of ERT to monitoring soil moisture or groundwater in the loess area, and the lack of information on profile soil resistivity(ρ) as affected by land use inhibits progress of the research on hydro-geophysics. This study was conducted to(1) explore characteristics of profile ρ,as affected by land use and slope position, in slope land and dam land in the northern part of the Loess Plateau,(2) determine effects of slope position and land use type on ρ and(3) examine applicability of ERT to monitoring soil moisture and groundwater dynamics in the loess area. 【Method】 Profile ρ in slope lands and dam land, different in land use type(including cropland,natural grassland, artificial grassland and caragana shrubland) was measured with a high-density ERT(Advanced Geosciences,Inc.) in the Liudaogou catchment in the northern part of the Loess Plateau. Variation of profile ρ with land use type and slope position was analyzed with ANOVA.【Results】Results show that land use type and slope position had significant effects on ρ in slope land. In terms of mean profile ρ, lands different in land use type followed an order of caragana shrubland > artificial grassland > natural grassland > cropland. Furthermore, mean profile ρ was the lowest in the bottom of the slope, followed by the middle and top of the slope. These findings suggest that profile ρ was closely related to soil moisture condition. Profile ρ in the dam land exhibited obvious horizontal and vertical variation in distribution. Vertically, ρ displayed a curve of high-low-high from the top to the deep loess layer, and the upper boundary of the low-resistance zone was consistent with the table of shallow groundwater in the dam land, while horizontally, profile ρ was closely related to land use type and geological position. Compared with the head dam land, the tail dam land had a low-resistance zone significantly thicker and penetrating the high-resistance zone in the shallow soil layer, which may be ascribed to crops’ lower water consumption.【Conclusion】Spatial distribution of profile ρvaries significantly with land use type and slope position in the loess area. The geophysical method of ERT is recommended for monitoring and studying spatial and temporal characteristics of dry and wet conditions of soil profiles different in land use type,as well as shallow groundwater dynamics in the loess area of China. It can also be used to study relationships between precipitation, vegetation, soil moisture and groundwater, particularly for areas thick in sediment deposits.