Contemporary global hydrological (or land surface) models provide conflicting estimates of e.g. mean annual evapotranspiration or low, mean, and high flows in river basins, resulting in strongly differing estimates of current water availability or climate change impact on freshwater resources. The central objective of this project is to improve our understanding of global freshwater resources and obtain better estimates of continental water fluxes and storages.
To achieve these goals, 10 individual projects have been defined in the different research institutes (including GIS) to cover the required areas of expertise
Project 6: Estimation of river discharge and surface water storage from spaceborne data: full catchment coverage with optimal space and time resolution
Insufficient observational evidence of hydrological parameters at the global scale is a major impediment for progress in the hydrological modeling. As the data provision from in situ gauge networks is deteriorating, satellites come to the rescue. Although spaceborne sensors offer a synoptic and global view by their very nature, satellite products do have their own limitations in terms of accuracy, temporal resolution and spatial coverage. This project aims to greatly improve the observational database for two key hydrological variables, river discharge and surface water storage, by innovative modeling of results from satellite altimetry (water level) and satellite imagery (surface area).
The major research questions that we aim to answer within this project include:
- How can we modify the existing single-stem densification of altimetric measurements and make it work for an entire river basin?
- How can we methodologically improve the discharge estimation from multi-mission altimetry over full catchments?
- Can we quantify the amount of surface water storage change within total storage variations?
- How to deal with non-stationarity of surface storage and discharge?