Potential of SWOT for Monitoring Water Volumes in Sahelian Ponds and Lakes

Manuela Grippa (1) , Cyprien Rouzies (1) , Sylvain Biancamaria (2) , Denis Blumstein (2) , Jean-Francois Cretaux (2) , Laetitia Gal (1, 3) , Elodie Robert (1) , Marielle Gosset (1) , Laurent Kergoat (1)

1 GET - Géosciences Environnement Toulouse
2 LEGOS - Laboratoire d'études en Géophysique et océanographie spatiales
3 UMR LISAH - Laboratoire d'étude des Interactions Sol - Agrosystème - Hydrosystème

Small water bodies play a pivotal role in Sahel, as a critical source of water for livestock and people, and providers of important ecosystems services. Monitoring, modelling and better understanding their hydrological behaviour is therefore a key issue. The future Surface Water and Ocean Topography (SWOT) satellite mission will bring a resolution and spatial coverage breakthrough, allowing the estimation of water levels and volumes in small water bodies worldwide. This study assesses the potential of SWOT for monitoring water volumes in Sahelian ponds and lakes. This is done by analysing SWOT-like synthetic data produced using a SWOT simulator developed by NASA-JPL. For the Agoufou lake, water levels were retrieved with an accuracy better than 4 cm, while slightly worst results were obtained for the Zalam-Zalam lake, that has a more elongated shape. In addition, data from the Global Precipitation Mission Dual-frequency Precipitation Radar have been also employed to investigate the backscattering coefficient variability in the same radar frequency band (Ka-band) as SWOT. We have found that, in the study region, the contrast between water and land, dependent on soil type, soil moisture, and wind conditions, is sometime quite small which can be challenging for water masks estimation. Overall, the first application of the SWOT simulator over the Sahel has shown the good potential of SWOT for monitoring the seasonal variability of water levels and volumes in this region.

Mots clés: SWOT; inland water; Sahel; lakes

Domaines: Hydrologie; Ingénierie de l'environnement; Traitement du signal et de l'image [eess.SP]

Manuela Grippa, Cyprien Rouzies, Sylvain Biancamaria, Denis Blumstein, Jean-Francois Cretaux, et al.. Potential of SWOT for Monitoring Water Volumes in Sahelian Ponds and Lakes. IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing, 2019, 12 (7), pp.2541-2549. ⟨10.1109/JSTARS.2019.2901434⟩. ⟨hal-02272484⟩