The hydrology thematic team organized an internal workshop from 29 to 30 November 2021, hosted by the University of Strasbourg, France. The meeting was held in a hybrid format (physically and by videoconference) due to the circumstances. It was followed by a visit on the field of several Rhine sites on 1 December 2021. The main objectives of the workshop were to discuss the different types of sensors and their pros and cons for the validation activities on inland water surfaces (rivers and lakes), to share the recent progress made by CNES on satellite altimetry data processing for hydrology, to evaluate the proposed locations of new calibration sites on the Garonne river, the Rhine river and the Po river, and to report and discuss possible difficulties identified to install new instruments, mainly due to the delivery of local authorizations.

The workshop was very fruitful and will be followed by other thematic meetings in order to refine the selection of sites and instruments and prepare the roadmap and the demonstration field campaigns.