Unravelling watershed fluxes to detect emerging changes of the water balance

In a warming climate, atmospheric water vapour will increase, intensifying the global water cycle. However, this ”wet-get-wetter” and ”dry-get-drier” paradigm does not hold on regional scales and models seem to contradict observations. Furthermore, it is unknown whether modelled atmospheric moisture fluxes, entering and leaving the watersheds, are mass consistent with river discharge and sinks and sources such as aquifers, soil layers and surface waters. Consequently, observational evidence of the changing water cycle components is crucial for scrutinizing models. It is also essential to assess climatic water cycle trends which have far reaching ecological and socio-economic consequences, through the occurrence of heat waves, flooding, forest fires and water availability.

In this contribution, we introduce a 5 year research project, which was recently funded through the Vidi talent scheme programme of the Dutch Research Council. We will explain how we plan to use satellite gravimetry, radar altimetry, in a joint inversion scheme, to estimate water fluxes in and out of the watersheds of the North Sea region, and those of the Greater Horn of Africa. Furthermore, we’ll show how regional sea level change and vertical land motion will be consistently accounted for in the proposed estimation scheme.