The SWOT mission : a milestone in CNES hydrology program

Water scarcity is a major global challenge, exacerbated by climate change and extreme events. While ground-based measurements remain essential, they are often limited by geographical and financial constraints. Satellite observations complement these efforts, providing essential data across vast areas with consistent spatio-temporal sampling; an essential resource for effective water management.

The French space agency CNES has been actively engaged in space-based hydrology for several decades, building on a robust 30-year partnership with NASA. Among its most notable recent advancements is the launch of the Surface Water and Ocean Topography (SWOT) mission in December 2022, marking a true revolution in hydrology. With its wide swath and high-resolution altimetry, SWOT provides unprecedented coverage and accuracy in monitoring water heights at the global scale. The first results have exceeded expectations, demonstrating remarkable success.

One of the key strategies at CNES for hydrology is the integration of satellite data within a global Earth Observation system approach. The Data Terra research infrastructure is central to this vision, offering a platform for sharing and processing data from various missions. A key component of this is the THEIA platform, which focuses on continental surfaces, including hydrology through hydroweb.next thematic hub. This hub provides access to SWOT data alongside numerous other sources. The SWOT downstream program has been a key success, from fostering a strong science team over the years to developing new applications tailored to various end users.

Looking towards the future, CNES is making substantial investments in the next generation of space-based hydrological observations, including the S3NG-T (Sentinel-3 New Generation - Topography) mission within the Copernicus program, which will build upon the wide swath concept pioneered by SWOT.