On the Usefulness of Hydrologic Landscapes for Hydrologic Model Calibration and Selection

Abstract:

Hydrologic Landscapes (HLs) are units that can be used in aggregate to describe the watershed-scale hydrologic response of an area through use of physical and climatic properties. The HL assessment unit is a useful classification tool to relate and transfer hydrologically meaningful information between different watersheds without access to streamflow time series. A revised HL classification scheme was developed for over 10,000 assessment units (the fundamental unit of area for an HL) within the Pacific Northwest (PNW; Oregon, Washington, and Idaho). Aggregation and validation of the PNW HL assessment units to the watershed-scale was then completed for the PNW through use of clustering approaches and the hydrologic response as defined by hydroclimatic signatures. A result generated from this study was that the HL assessment units with greater moisture surplus or deficit formed a stronger connection between watershed-scale PNW HL and hydrologic response. The next step was to investigate the usefulness of the information contained within the PNW with regard to hydrologic modeling calibration and model structure selection. The hypothesis that we set forward for this study is that hydrologic response, as inferred and derived from the HL assessment units, is helpful for the structural identification and calibration of hydrologic models. A selection of streamgage stations and their associated watershed area across the PNW were modeled with lumped and semi-distributed modeling structures. The resulting model calibration and parameter space exploration leads to the identification of assessment unit types that are more hydrologically influential to the overall hydrologic functions of the watershed.