Continental water storage plays a key role in the Earth’s water, energy and biogeochemical cycles. The total continental water storage is composed of a variety of storage compartments, including water storage on vegetation surfaces, in the biomass, in the unsaturated soil or rock zone, as groundwater, snow and ice, and in surface water bodies such as rivers, wetlands, natural lakes and man-made reservoirs. Since the ground-based observation network is not dense and comprehensive enough to allow for assessing water storage change within all its compartments over large areas, hydrological models are fundamental tools for quantifying the hydrological cycle on the continents.

Since March 2002 the satellite mission GRACE allows for the first time to estimate total continental water storage change at large scales. The principal goal of CEMIG is the consistent assimilation of satellite-based and in-situ observations into the global hydrological model WGHM (WaterGAP Hydrological Model), which is carried out by a cooperation of DGFI, the Institute of Astronomical and Physical Geodesy (IAPG) of the Technical University Munich (TUM) and the Helmholtz Center Potsdam - GFZ German Research Centre for Geosciences.

In particular the project aims at the following tasks:

1. Set-up of an appropriate mathematical formulation and joint estimation of improved parameters in the global water balance model WGHM from a suite of satellites and in-situ data.
   

2. Improved time series of continental water mass variations from simulations with WGHM after integration of observation data, using enhanced process formulations and parameters for selected regions.

3. Consistent observation- and model-based spatio-temporal partitioning of continental water mass variations among different storage compartments.