Unraveling the hydrology and sediment balance of an ungauged lake in the Sudano-Sahelian region of West Africa using remote sensing

Abstract. The presence of ephemeral ponds and perennial lakes in the Sudano-Sahelian region West Africa is strongly variable space time. Yet, they have important ecological functions societies are reliant on their surface waters for lives livelihoods. It essential to monitor understand dynamics these assess past, present, future water resource changes. In this paper, we present an innovative approach unravel sediment balance Lac Wégnia, a small ungauged lake Mali near capital Bamako. uses optical remote sensing data identify shoreline positions over period 22 years (2000–2021) then attributes heights (WSHs) each observation using bathymetry. We novel methodology quantitatively analyze deposition erosion patterns at lakeshores beds. method therefore represents significant advancement previous attempts remotely African drylands, since it considers not only changes depth explain recent declining trends areas, but also storage capacity. At recognize silting tributaries lake, overall, processes dominant threaten persistence because progressive through natural levee outlet. This factor contributes 66 %±18 % decreasing WSH trend, while 34 dry-season level explained by increasing evaporation from possibly falling groundwater tables. Due reservoir capacity WSHs even wet season spite positive rainfall patterns.