Seasonal and spatial characterization of soil moisture and soil water tension in a steep hillslope.

Highlights • Soil moisture and soil water tension showed seasonally different characteristics at a steep hillslope. • The distribution of soil moisture characteristics curve was different between spring and autumn seasons. • The soil moisture transfer process was seasonally evolved from spring to autumn. Abstract Understanding variations in soil moisture and soil water potential is important for describing hydrological processes at the hillslope scale. An intensive field campaign to measure soil moisture, soil water potential, and rainfall events was performed at many locations and depths to obtain seasonal and spatial distributions of hydrometric measurements along steep hillslopes. Soil moisture and soil water tension analysis showed seasonally distinctive features in statistics and probability distributions. The relationship between soil moisture and soil water tension was explored to characterize seasonal and spatial variations. The recession slopes of soil moisture at several given points of the relationship were also seasonally different. The Brooks and Corey model and the van Genuchten model were used to estimate parameters for the measured data to explain the spatial and seasonal variations. Soil water storage analysis not only indicated that lateral flow tends to be abundant at greater depths but also revealed a seasonal trend in development of subsurface flow in the downslope direction. The combined impact of topography and vegetation determined the seasonal differences in hydrometric responses along the hillslope locations. [ABSTRACT FROM AUTHOR]