CoAuthors

Stéphane Calmant (LEGOS, IFCWS, IISc, Bengalore, India); Johary Andriambelosom (Institut et Observatoire de Géophysique d'Antananarivo (IOGA), Université d'Antananarivo, Madagascar); Ayan Fleischmann (IPH-UFRGS, Porto Alegre, Brazil); Cecile Dardel (GET, Université de Toulouse, CNRS, IRD, UPS, Toulouse, France); Marielle Gosset (GET, Université de Toulouse, CNRS, IRD, UPS, Toulouse, France); Daniel Medeiros Moreira (CPRM, Rio de Janeiro, Brazil); Vinicius Siqueira (IPH-UFRGS, Porto Alegre, Brazil); Thiago Santos (RHASA-UEA, Manaus, Brazil); Sakaros Bogning (Département de Sciences de la Terre, Université de Douala, BP 24 157 Douala, Cameroun); Taina Conchy (RHASA-UEA, Manaus, Brazil); Rodrigo Cauduro Dias de Paiva (IPH-UFRGS, Porto Alegre, Brazil); Walter Collischonn (IPH-UFRGS, Porto Alegre, Brazil); Joecila Santos da Silva (RHASA-UEA, Manaus, Brazil); Maxime Vayre (CLS, Ramonville St Agne, France)

A unique dataset of -Manning consistent- stage/discharge rating curves (RCs) was built at virtual stations (VSs) from the 27-day repeat cycle Sentinel3-A and 10-day repeat cycle Jason-3 missions. For this purpose, we used discharges simulated with the MGB hydrologic-hydrodynamic model and the satellite altimetry time series in several tropical and sub-tropical hydrological watersheds, including the Amazon and Maroni basins in South America and the Niger, Congo, Ogooue and Tsiribihina basins in Africa. The resulting RCs were used to get a priori information on the RC’s parameters at the newly released Sentinel3-B VSs.
Thus, we get a dense framework of RCs, ranging from less than ten (for the Tsiribihina basin) to hundreds (for the Congo and Amazon basins) of VSs per basin. The RCs validation was threefold: 1) a systematic validation of the rated discharge against simulated discharge in overlapping time period; 2) a validation against in-situ discharge was performed when available; and 3) field works provided some precious comparison between estimated depths and/or rating curve parameter and ground truth. Whenever possible and physically acceptable, time series in the close vicinity of each other were merged in order to increase the frequency of revisit.
Thanks to the operational status of the COPERNICUS Sentinel3-A&B and NASA/CNES Jason3 satellites, users are ensured to benefit from new observations of water height, hence from new estimates of depth and discharge, during the all mission lifetime, i.e. at least 15 years. Discharge information will shortly be released on the Hydroweb website (http://hydroweb.theia-land.fr/) under the form of the RC coefficients to be applied to the water surface elevation time series.