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www.hydrol-earth-syst-sci-discuss.net/6/4813/2009/
doi:10.5194/hessd-6-4813-2009
© Author(s) 2009. This work is distributed
under the Creative Commons Attribution 3.0 License.
Calibration analysis for water storage variability of the global hydrological model WGHM
Deutsches GeoForschungsZentrum GFZ, Telegrafenberg, 14473 Potsdam, Germany
Abstract. This study contributes to an improved global simulation of continental water storage variations by calibrating the WaterGAP Global Hydrology Model (WGHM) for 28 of the largest river basins worldwide. Five years (01/2003–12/2007) of satellite-based estimates of total water storage changes from the GRACE mission are combined with river discharge data in a multi-objective calibration framework of the most sensitive WGHM model parameters. The uncertainty and significance of the calibration results is analyzed with respect to errors in the observation data. An independent simulation period (01/2008–12/2008) is used for validation. The contribution of single storage compartments to the total water budget before and after calibration is analyzed in detail. A multi-objective improvement of the model states is obtained for most of the river basins, with mean error reductions up to 110 km3/month for discharge and up to 24 mm of a water mass equivalent column for total water storage changes, as for the Amazon basin. Errors in phase and signal variability of seasonal water mass changes are reduced. The calibration is shown to primarily affect soil water storage in most river basins. The variability of groundwater storage variations is reduced at the global scale after calibration. Structural model errors are identified from a small contribution of surface water storage including wetlands in river basins with large inundation areas, such as the Amazon or the Mississippi. The results demonstrate the value of GRACE data and the multi-objective calibration approach for improvements of large-scale hydrological simulations, as they constitute a starting-point for improvements of model structure. The integration of complimentary observation data to further constrain the simulation of single storage compartments is encouraged.
Discussion Paper (PDF, 1906 KB) Interactive Discussion (Closed, 6 Comments) Final Revised Paper (HESS)
Citation: Werth, S. and Güntner, A.: Calibration analysis for water storage variability of the global hydrological model WGHM, Hydrol. Earth Syst. Sci. Discuss., 6, 4813-4861, doi:10.5194/hessd-6-4813-2009, 2009. Bibtex EndNote Reference Manager XML
