Calibration of a Global Hydrological Model with GRACE Data

Abstract

Water mass variations from the GRACE satellite mission are an unprecedented data set for validation and calibration of large-scale hydrological models. We develop an efficient multi-objective calibration framework to incorporate time series of monthly measured river discharge and GRACE water storage variations into the parameter tuning process of the WaterGAP Global Hydrology Model (WGHM ). The calibration approach is applicable to large river basins worldwide. For the example of the Amazon river basin, simulation results improved for both objectives after calibration. The improvement is shown to be due to decreased flow velocities and, thus, larger and longer-lasting water storage in the surface water network of the Amazon. The results highlight the beneficial nature of GRACE for advancing hydrological models and for understanding water storage variations in the continental water cycle.