Abstract
A satisfactory performance of hydrological models under historical climate conditions is considered a prerequisite step in any hydrological climate change impact study. Despite the significant interest in global hydrological modeling, few systematic evaluations of global hydrological models (gHMs) at the catchment scale have been carried out. This study investigates the performance of 4 gHMs driven by 4 global observation-based meteorological inputs at simulating weekly discharges over 198 large-sized North American catchments for the 1971–2010 period. The 16 discharge simulations serve as the basis for evaluating gHM accuracy at the catchment scale within the second phase of the Inter-Sectoral Impact Model Intercomparison Project (ISIMIP2a). The simulated discharges by the four gHMs are compared against observed and simulated weekly discharge values by two regional hydrological models (rHMs) driven by a global meteorological dataset for the same period. We discuss the implications of both modeling approaches as well as the influence of catchment characteristics and global meteorological forcing in terms of model performance through statistical criteria and visual hydrograph comparison for catchment-scale hydrological studies. Overall, the gHM discharge statistics exhibit poor agreement with observations at the catchment scale and manifest considerable bias and errors in seasonal flow simulations. We confirm that the gHM approach, as experimentally implemented through the ISIMIP2a, must be used with caution for regional studies. We find the rHM approach to be more trustworthy and recommend using it for hydrological studies, especially if findings are intended to support operational decision-making.
Highlights
Climate change impact research is currently moving onto the provision of climate projection services by impact models for use in developing adaptation strategies in various environmental sectors [1]
Based on a multi-model approach composed of four global hydrological models (gHMs) (DBH, H08, LPJml, and PCR-GLOBWB) and two regional hydrological models (rHMs) (GR4J and HMETS) driven by multiple forcing meteorological datasets over 198 large-sized North America (NA) catchments for the 1971–2010 period, this study aims at contributing to the ISIMIP2a topic for operational use purposes by: (1) assessing the gHMs’ performance in terms of simulating seasonal flow dynamics; (2) comparing the gHMs’ performance with that of the rHMs; and (3) based on (1) and (2), exploring the influence of the global driving datasets and catchment characteristics on gHM performance
This study presents a catchment-scale comparative evaluation of the performance of four gHMs driven by four global meteorological datasets against two rHMs driven by one global meteorological dataset using two statistical criteria, Taylor diagrams, and visual hydrograph comparisons
Summary
Climate change impact research is currently moving onto the provision of climate projection services by impact models for use in developing adaptation strategies in various environmental sectors [1]. Many worldwide initiatives have emerged from organizations and research centers, with the production and dissemination of information on projected climate change impacts on water resources through specific hydrological indicators. Such information is usually designed to cater to the needs of water and energy domain practitioners and is intended for use (and is sometimes used) in operational decision-making. Data suppliers and modelers have the responsibility of providing reliable and accurate information on the impacts of climate change on water as local adaptation measures stem from that. Such work normally makes use of a hydrological model calibrated and validated at the catchment under study
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