Reconstruction of Historical Atmospheric-Hydrologic Data by a Hydro-climate Model for a Sparsely Gauged Watershed

A lack of observations within watersheds can make the production of streamflow data via hydrologic models a big challenge. Authors propose a methodology to reproduce historical atmospheric-hydrologic data at the desired fine time-space scales for a sparsely gauged watershed by means of a hydro-climate model, entitled “WEHY-HCM (Watershed Environmental Hydrology Hydro-Climate Model)”. The WEHY-HCM enables coupling of a regional climate model such MM5 (fifth generation mesoscale model) and WRF (weather research and forecasting model) as an atmospheric module, with a process-based hydrologic module (WEHY). To investigate the reliability of WEH-HCM, the WEHY-HCM is set up over a sparsely gauged watershed and the spatially downscaled reconstructed atmospheric data to a 3-km horizontal grid resolution with an hourly time increment, is obtained from NCAR/NCEP global reanalysis data (reanalysis I). Hydrologic simulations by WEHY-HCM were applied to the Upper Putah Creek watershed based on the reconstructed atmospheric data and the estimated WEHY model parameters. The simulation results of WEHY-HCM were evaluated by means of statistical tests for both calibration and validation periods. The results of statistical tests performed using observed and simulated values indicated that the model performance can be considered as exhibiting an acceptable accuracy during both calibration and validation periods. The spatial maps of the evapotranspiration rate and runoff volume showed that the WEHY-HCM can represent a sparsely gauged watershed with unique topography well. This study found that the WEHY-HCM can be a useful tool to simulate the hydrologic processes in a sparsely gauged watershed.