Enhancing the representation of water management in global hydrological models

Abstract. This study enhances an existing global hydrological model (GHM), Xanthos, by adding a new water management module that distinguishes between the operational characteristics of irrigation, hydropower, and flood control reservoirs. We remapped reservoirs in Global Reservoir Dam (GRanD) database to 0.5∘ spatial resolution Xanthos so single lumped reservoir exists per grid cell, which yielded 3790 large implemented unique operation rules for each type, based on their primary purposes. In particular, hydropower have been treated as previous GHM studies, while here, we determined via optimization maximizes long-term production. conducted simulations using enhanced validated monthly streamflow 91 river basins, where high-quality observed data were available. A total 1878 (296 486 1096 others) out are located basins part our reported results. The Kling–Gupta efficiency (KGE) value (after management) is ≥ 0.5 0.0 39 81 respectively. After module, performance improved 75 worsened only 7. To measure relative difference explicitly representing (as commonly done other GHMs), use normalized root mean square error (NRMSE) coefficient determination (R2). Out 296 reservoirs, NRMSE > 0.25 (i.e., considering represent moderate difference) over 44 % when comparing both simulated releases storage time series two simulations. suggest correctly GHMs could important implications understanding freshwater resource challenges at regional-to-global scales. modeling framework will allow analysis future development from coupled human–earth system perspective.