Water monitoring is a basic need of human kind, equally shared by all societies. Now, satellites offer a brilliant complement to the traditional in‐situ monitoring, rapidly and dramatically decreasing worldwide. IRD has been involved over a decade in collaborating with researchers in Southern (developing and emerging) countries to promote the study of the continental water cycle using space born information. Among the technologies so available, satellite altimetry has offered since the mid‐90’s a continuous monitoring of water level in particular in the large tropical watersheds. This technology will experience a dramatic improvement in the 2020’s with the launch of the CNES/NASA SWOT mission in October 2021, the biggest scientific project of these agencies in Earth Observation for the decade. It will provide a full coverage of all the water bodies on Earth at the 100m spatial resolution and twice a month of temporal resolution. Because it will rely on a breakthrough technology (wide swath SAR Interferometry in Ka band) the mission will need an extensive calibration and validation (CalVal) program. On the French side, this task is devoted to IRD owing to its historical know‐how in hydrology and its ability to conduct projects in the Tropical Band, where the largest rivers flow. All the teams participating to the GDRI are already involved in this key phase of the SWOT mission through their responsibility on managing “SWOT Gold Sites” where intense CalVal activities are to be conducted from now to the post‐launch phase, in 2022. The fact that Southern teams are involved in the preparation of one the major scientific satellite mission is of primarily importance to increase their visibility in the scientific community, a great opportunity for their students to join this community and an opportunity for the teams and Laboratories to propose better services to their national water management institutions. Today, IRD is the “meeting point” of these Southern teams, spread around the word. The purpose of the SCaHylab GDRI is to give these teams an opportunity to build their own network for long term South‐South and South‐Intermediate collaboration, to share expertise and skills, and moreover, to share students and trainings in view of co‐publications.