资源环境科技发展态势分析平台

The redistribution of hillslope soil water during and after rainstorms is affected by soil properties and topography. Therefore, understanding how soil-terrain attributes affect the soil volumetric water content (VWC) distribution under various catchment storages is a prerequisite for accurate hydrological modeling. Herein, the relationships between soil-terrain attributes and soil VWC were examined in a steep (average slope = 60%), forested, zero-order catchment. Detailed topography, soil properties and runoff, and high frequency (6-min) soil moisture data observed from July 2016 to November 2017 were employed along with resampled VWC data in three time-steps (daily, hourly, and 6-min intervals) for correlation analysis between soil-terrain attributes and measured VWC. The results showed that daily aggregated data overlooked the highly heterogeneous flow conditions under dry-wet transitions, leading to a constantly high correlation between VWC and the topographic wetness index (TWI). In comparison, the 6-min data captured short-lived flow processes, highlighting that, in reality, VWC-TWI correlations fluctuated frequently as a function of catchment storages and precipitation characteristics, with four wetting patterns identified. Under wet-dry transitions, the VWC-TWI correlations increased significantly (from 0.3 to 0.6) as the hillslope gradually drained of lateral subsurface water. Soil water behavior consists of diurnal oscillations superimposed on a declining trend, which demonstrates the existence of unsaturated flow and which contributed to the increase in the strength of the correlations. Finally, through correlation analysis of all drying (n = 4) and wetting (n = 45) periods, we found that soil-terrain attributes and VWC correlations can be used to identify the dominant soil water processes in various catchment storages.

This article is protected by copyright. All rights reserved.