HR: 0800h
AN: H31A-0124    [Abstracts]
TI: Multi-objective calibration of a global hydrology model using GRACE water storage variations
AU: G\ddot untner, A
EM: guentner@gfz-potsdam.de
AF: GeoForschungsZentrum Potsdam, Telegrafenberg, Potsdam, 14473, Germany
AU: * Werth, S
EM: swerth@gfz-potsdam.de
AF: GeoForschungsZentrum Potsdam, Telegrafenberg, Potsdam, 14473, Germany
AU: Schmidt, R
EM: rschmidt@gfz-potsdam.de
AF: GeoForschungsZentrum Potsdam, Telegrafenberg, Potsdam, 14473, Germany
AU: Petrovic, S
EM: sp@gfz-potsdam.de
AF: GeoForschungsZentrum Potsdam, Telegrafenberg, Potsdam, 14473, Germany
AU: W\ddot unsch, J
EM: wuen@gfz-potsdam.de
AF: GeoForschungsZentrum Potsdam, Telegrafenberg, Potsdam, 14473, Germany
AU: Barthelmes, F
EM: bar@gfz-potsdam.de
AF: GeoForschungsZentrum Potsdam, Telegrafenberg, Potsdam, 14473, Germany
AB: The satellite gravity mission GRACE (Gravity Recovery And Climate Experiment) was launched in 2002. Since then, GRACE provides global maps of time variations of the Earth's gravity field. These gravity variations are directly linked to mass redistributions on the Earth's surface. Thus, various geophysical and climatologically- driven processes can be observed. In particular, GRACE observations of large-scale water storage changes provide a comprehensive data set to analyze the global water cycle and to validate and calibrate hydrological models. In this contribution, we present the first results on the calibration of the WaterGAP Global Hydrology Model (WGHM) based on surface mass variations derived from the current RL04 GRACE-only gravity field model time series generated at GFZ Potsdam (GFZ-RL04). WGHM models the continental water storage including the most important water storage components, i.e., soil, snow, groundwater and surface water. The model is forced by climate data at a 0.5 degree resolution and hitherto calibrated against observed river runoff at 1235 gauging stations world wide. The station-based calibration of WGHM results in locally fitted discharge data, but model accuracy may decrease with distance from the calibration stations and for other water flux components or storage compartments. Previous studies of measured (by GRACE) and simulated (by WGHM) seasonal variations of total water storage in large river basins partially show significant differences, especially for the seasonal amplitudes. Combining both the present station-based accuracy of the model in terms of river discharge and the integrative nature of the GRACE data with global coverage, more realistic and improved simulation results are expected from a multi-objective calibration approach. This denotes the evaluation of model parameters through their simulation performance against more than one model output objective. In this contribution, these objectives are river discharge and total water storage change from GRACE. The Dynamically Dimension Search (DDS) calibration method was extended for a multi-objective problem and used to improve WGHM parameterization. Results of the multi-objective calibration of WGHM against GRACE data are presented and improvements compared to a single- objective approach are highlighted. Furthermore, calibrations against a reduced GRACE signal containing only the dominant (annual, semi-annual, or longer) signal components were tested. The results reveal the innovative contribution of the GRACE satellite mission to the field of hydrological modeling.
DE: 1217 Time variable gravity (7223, 7230)
DE: 1800 HYDROLOGY
DE: 1846 Model calibration (3333)
DE: 1847 Modeling
SC: Hydrology [H]
MN: 2007 Fall Meeting