Toward improved regional hydrological model performance using a novel
soil data-informed calibration method
Abstract
Accurate soil moisture and streamflow data are an aspirational need of
many hydrologically-relevant fields. Model simulated soil moisture and
streamflow hold promise but numerical models require calibration prior
to application to ensure sufficient model performance. Manual or
automated calibration methods require iterative model runs and hence are
computationally expensive. In this study, we leverage the Soil Survey
Geographic (SSURGO) database and the probability mapping of SSURGO
(POLARIS) to help constrain soil parameter uncertainties in the Weather
Research and Forecasting Hydrological modeling system (WRF-Hydro) over a
central California domain. After calibration, WRF-Hydro soil moisture
exhibits increased correlation coefficients (r), reduced biases, and
increased Kling-Gupta Efficiencies (KGEs) across seven in-situ soil
moisture observing stations. Compared to four well-established soil
moisture datasets including Soil Moisture Active Passive Level 4 data
and three Phase 2 North American Land Data Assimilation System land
surface models, our POLARIS-calibrated WRF-Hydro produces the highest
mean KGE (0.67) across the seven stations. More importantly, WRF-Hydro
streamflow fidelity also increases especially in the case where the
model domain is set up with an SSURGO-informed total soil thickness.
Both the magnitude and timing of peak flow events are better captured, r
increases across nine United States Geological Survey stream gages, and
the mean Nash-Sutcliffe Efficiency across seven of the nine gages
increases from 0.19 in default WRF-Hydro to 0.63 after calibration. Our
soil data-informed calibration approach, which is transferable to other
spatially-distributed hydrological models, uses open-access data and
non-iterative steps to improve model performance and is thus
operationally and computationally attractive.