The last 30 years have seen a sharp decline in hydrological databases around the world, particularly in Africa. Spatial altimetry makes it possible to complete the in situ measurement network in order to densify data and ensure better hydrological monitoring.
The Surface Water and Ocean Topography (SWOT) programme is a French-American Earth observation satellite with contributions from UKSA and CSA that by 2021 will monitor water level variations of major streams, such as lakes and rivers, estimate runoffs from rivers and monitor ocean levels.  The SWOT mission uses a new, as-yet untested technology: wide swath altimetry. This development constitutes a real technological breakthrough which aims to provide measurements with an unprecedented precision and to improve our understanding of the water cycle. Although SWOT is mainly a scientific satellite, it offers a great potential for the development of new applications and services with significant economic and societal impacts.
As part of the Future Investment Program, CNES* has set up a preparatory programme, the SWOT-Downstream programme. Its goal is to develop products tailored to end-users’ needs integrated into existing or future services, and to prepare water stakeholders for the use of these new data from space. In Hydrology, the SWOT-Downstream programme focuses on preparing the hydrology user community by sharing simulated SWOT datasets. It also shares multisensory hydrology derived products, such as soil moisture, water levels, land cover, etc., supports and promotes scientific work in space hydrology, and associates customers and service providers in the development of new applications. Most SWOT-Downstream activities will be gathered in a global “Water Database” portal (see figure below).
A working group has been set up to demonstrate all the space data capabilities in hydrology. The Congo basin is the first pilot site. Applications in development include monitoring the Congo water level and discharge and forecasting navigation and hydropower capacity as well as a water information system. All of this work covering the Congo basin is financed by AFD and CNE.