Parameter regionalization of a monthly water balance model for the conterminous United States
- 1US Geological Survey, Colorado Water Science Center, Denver Federal Center, P.O. Box 25046, MS 415, Denver, Colorado, 80225, USA
- 2US Geological Survey, National Research Program, Denver Federal Center, P.O. Box 25046, MS 413, Denver, Colorado, 80225, USA
- 3US Environmental Protection Agency, Office of Water (4503-T), 1200 Pennsylvania Ave., Washington, DC, 20004, USA
Abstract. A parameter regionalization scheme to transfer parameter values from gaged to ungaged areas for a monthly water balance model (MWBM) was developed and tested for the conterminous United States (CONUS). The Fourier Amplitude Sensitivity Test, a global-sensitivity algorithm, was implemented on a MWBM to generate parameter sensitivities on a set of 109 951 hydrologic response units (HRUs) across the CONUS. The HRUs were grouped into 110 calibration regions based on similar parameter sensitivities. Subsequently, measured runoff from 1575 streamgages within the calibration regions were used to calibrate the MWBM parameters to produce parameter sets for each calibration region. Measured and simulated runoff at the 1575 streamgages showed good correspondence for the majority of the CONUS, with a median computed Nash–Sutcliffe efficiency coefficient of 0.76 over all streamgages. These methods maximize the use of available runoff information, resulting in a calibrated CONUS-wide application of the MWBM suitable for providing estimates of water availability at the HRU resolution for both gaged and ungaged areas of the CONUS.