Since 2005, LEGOS together with the "NASA Surface Water Working Group" (USA) have developed an international partnership in this field of hydrology from space, and proposed a dedicated space mission - known as "WatER" (Water Elevation Recovery) to study continental surface waters.

This mission objective is to measure river, lake and flooded area water levels (and their spatio-temporal derivatives), using a new technical concept: interferometric altimetry (see Alsdorf and Lettenmaier, 2003, and Alsdorf et al., 2004, Alsdorf et al., 2007).

PSince 2005, LEGOS together with the "NASA Surface Water Working Group" (USA) have developed an international partnership in this field of hydrology from space, and proposed a dedicated space mission - known as "WatER" (Water Elevation Recovery) to study continental surface waters.

Interferometric altimetry provides two-dimensional images over swaths of ~50x50 km and horizontal resolution of the order of 100 m (Enjolras et al., 2005, Thesis of V. Enjolras), whereas conventional altimetry provides point data along profiles several tens or hundreds of km apart.

Furthermore, this technology overcomes conventional altimetry problems, namely spurious reflections due to dry soils, vegetation and relief.

During his thesis, V. Enfolras analyzed in detail the performances of a mission of interferometric altimetry in wide mown for the continental hydrology.

LEGOS organised workshops in November 2004 (Toulouse), March 2005 at ESRIN and July 2005 at CNES Paris, to coordinate the European and American scientific collaboration around the WatER mission.