Hydropedology In Seasonally Dry Landscapes: The Palouse Region Of The Pacific Northwest Usa

The Palouse region of the Pacific Northwest USA provides a unique opportunity to study relationships between soil morphology and hydrologic processes. Regionally east-west gradients in mean annual precipitation and temperature generally account for spatial variability in major soil types. However, at the hillslope scale, the steep topography of the Palouse induces unique microclimates leading to extreme variability in effective precipitation. Argillic and fragipan horizons in the north-facing, wetter, microclimates lead to seasonal perched water and rapid subsurface lateral flow accelerating the eluviation of clays in albic Esoil horizons and driving variable source area hydrology. Soil slips (i.e. rapid mass wasting events) below deep snow drifts and long-term loss of top soil as a result of excessive erosion through runoff and tillage processes both are involved in positive feedback mechanisms that drive the hydrology of the landscape. Development of this conceptual understanding of Palouse region hydropedology has had profound implications for generating effective solutions to regional erosion, water quality, and groundwater recharge problems.