Current state-of-the-art models typically applied at continental to global scales (hereafter called macro scale) tend to use a priori parameters, resulting in suboptimal streamflow (Q) simulation. For the first time, a scheme for regionalization of model parameters at the global scale was developed. We used data from a diverse set of 1787 small-to-medium sized catchments (10–10;000 km2) and the simple conceptual HBV model to set up and test the scheme. Each catchment was calibrated against observed daily Q, afterwhich 674 catchments with high calibration and validation scores, and thus presumably good-qualityobserved Q and forcing data, were selected to serve as donor catchments. The calibrated parameter sets forthe donors were subsequently transferred to 0.58 grid cells with similar climatic and physiographic characteristics, resulting in parameter maps for HBV with global coverage. For each grid cell, we used the 10 mostsimilar donor catchments, rather than the single most similar donor, and averaged the resulting simulatedQ, which enhanced model performance. The 1113 catchments not used as donors were used to independ-ently evaluate the scheme. The regionalized parameters outperformed spatially uniform (i.e., averaged calibrated) parameters for 79% of the evaluation catchments. Substantial improvements were evident for all major Koppen-Geiger climate types and even for evaluation catchments > 5000 km distant from the donors. The median improvement was about half of the performance increase achieved through calibration. HBVwith regionalized parameters outperformed nine state-of-the-art macroscale models, suggesting these might also benefit from the new regionalization scheme. The produced HBV parameter maps including ancillary data are available via www.gloh2o.org.

BECK Hylke;  VAN DIJK Albert I.J.M.;  DE ROO Arie;  MIRALLES Diego G.;  MCVICAR Tim. R;  SCHELLEKENS Jaap;  BRUIJNZEEL L. Adrian; 

2016-08-18

AMER GEOPHYSICAL UNION

JRC96130

0043-1397,   

http://onlinelibrary.wiley.com/doi/10.1002/2015WR018247/full,    https://publications.jrc.ec.europa.eu/repository/handle/JRC96130,   

10.1002/2015WR018247,