Fragipan controls on runoff generation: Hydropedological implications at landscape and watershed scales

The role of soils having a fragipan and/or strongly contrasting clay layer in generating surface runoff, especially in the context of variable-source-area hydrology at landscape and/or watershed scales, is poorly understood. If, as preliminary research results reported here from an east-central Pennsylvania experimental watershed are showing, surface runoff from fragipan soils can dominate a watershed's storm runoff response, it becomes imperative that hydropedologists develop tools to objectively, accurately, and routinely determine the location, extent, and hydraulic properties of these types of soils. Here, we illustrate the differing performance of non-fragipan and fragipan soils in producing surface runoff within an experimental watershed setting in east-central Pennsylvania (USA), demonstrating how soil mapping of fragipan conditions enhances our ability to portray the watershed's total hydrologic performance.