EVALUATING THE IMPORTANCE OF REGOLITH HETEROGENEITY ON CATCHMENT HYDROLOGY IN GARNER RUN, SUSQUEHANNA SHALE HILLS CRITICAL ZONE OBSERVATORY, PENNSYLVANIA, USA

Soil hydrologic properties determine how water, solutes, and sediment move through the near surface environment and serve as important input parameters for watershed-scale hydrologic models. While robust methods exist for characterizing the hydrologic properties of homogeneous, fine-grained soils, it is less clear how to incorporate rocky soils into critical zone models. Here we analyze the influence of regolith heterogeneity on catchment hydrology in Garner Run, a sandstone subcatchment of Shavers Creek in the Susquehanna Shale Hills Critical Zone Observatory, Pennsylvania. As a result of Pleistocene periglacial modification, Garner Run exhibits a strong heterogeneity in surface cover ranging from clay-rich soils to unvegetated boulder fields, which is not well captured by existing soil maps. Using a combination of new high-resolution maps of surface cover, field measurements of hydrologic properties, and preliminary model runs using the Penn State Integrated Hydrologic Modeling System (PIHM), we evaluate model sensitivity to spatial heterogeneity in regolith cover characteristics of sandstone landscapes in central Pennsylvania. Our results have implications for the interpretation of local measurements of soil moisture in such landscapes, and for the application of large scale soil maps in hydrologic models of upland landscapes.