Hydropedological functional units: a novel and accurate catchment-scale characterization of soil hydrology

Identifying patches with similar soil moisture patterns across a landscape over time is critical for upscaling ecohydrological processes, improving landscape and ecosystem models, and effective land management. We developed a novel way of delineating functional units with similar topographic, pedogenic, and hydrological properties, called Hydropedological Functional Units (HFUs), at the Susquehanna Shale Hills catchment in central Pennsylvania. The main goal of this study was to develop HFUs and compare its performance with two previously established methods, soil precision series (Order I soil survey) and landform units, for prediction of solum soil moisture storage across the landscape. We used a principal component analysis and a fuzzy clustering technique to integrate multiple data sources from a variety of ground based and remote sensing techniques for developing HFUs. Our results showed that HFUs performed better (cross-validation R-square = 0.88) than the precision soil survey (R-square = 0.85) and landform units (R-square = 0.47) in predicting solum soil moisture storage patterns. This study provides a unique approach to integrate multiple data sources, including remote sensing and geophysical data, and a new tool to inform poorly represented hydropedological processes in current landscape and ecosystem models.