Variability and pattern of surface moisture on a small-scale hillslope in Liudaogou catchment on the northern Loess Plateau of China

The variability and structure of surface soil moisture along a hillslope is still poorly understood on the northern Loess Plateau of China. In this study, a field experiment was conducted on a small-scale hillslope in Liudaogou catchment and aimed to characterize the pattern of upper 15 cm soil moisture. During the experimental period, mean soil moisture on the hillslope was dominated by an antecedent rainfall event. The values of mean moisture were positively proportional to the antecedent precipitation amount and then decreased during the next dry-down period. The variance of surface moisture decreased with increasing mean moisture. The spatial patterns of surface moisture could be separated into four groups by the structures of surface moisture along the hillslope during the experimental period. Rainfall property and soil response to rainfall jointly exerted some control on the spatial patterns of surface moisture. Gradient, soil bulk density, and surface rock fragment content contributed little to the patterns of surface moisture along the hillslope.