Changing controls of soil moisture spatial organization in the Shale Hills Catchment

Modeling hydrological processes often requires the identification of dominant controls on soil moisture spatial organization under different climatic conditions at various soil depths. In this study, we utilized a four-year database consisting of soil moisture measurements at 106 locations from near-surface down to 1.1 m depth across a forested catchment in central Pennsylvania, USA. Our objectives were to 1) compare the spatial organization of soil moisture within different soil–landform units and its temporal persistence at different depths under varying catchment wetness conditions and 2) investigate correlation strength between soil moisture content and 11 soil–terrain attributes and the temporal change of such correlation. Our results showed that the catchmentʹs near-surface ( 0.3 to 1.1 m) soil moisture organization, however, exhibited increasing temporal persistence with depth, and subsoil moisture above the catchment-wide average was concentrated within convergent landforms under both wet and dry conditions. Topographic wetness index, slope, depth to bedrock, and percent (by weight) clay and rock fragment were significant (p  0.3 to  0.3 to  0.7 m) becomes more temporally persistent and is primarily a function of both topography and soil depth.