The Lake Chad hydrology under current climate change - PubMed (original) (raw)

The Lake Chad hydrology under current climate change

Binh Pham-Duc et al. Sci Rep. 2020.

Abstract

Lake Chad, in the Sahelian zone of west-central Africa, provides food and water to ~50 million people and supports unique ecosystems and biodiversity. In the past decades, it became a symbol of current climate change, held up by its dramatic shrinkage in the 1980s. Despites a partial recovery in response to increased Sahelian precipitation in the 1990s, Lake Chad is still facing major threats and its contemporary variability under climate change remains highly uncertain. Here, using a new multi-satellite approach, we show that Lake Chad extent has remained stable during the last two decades, despite a slight decrease of its northern pool. Moreover, since the 2000s, groundwater, which contributes to ~70% of Lake Chad's annual water storage change, is increasing due to water supply provided by its two main tributaries. Our results indicate that in tandem with groundwater and tropical origin of water supply, over the last two decades, Lake Chad is not shrinking and recovers seasonally its surface water extent and volume. This study provides a robust regional understanding of current hydrology and changes in the Lake Chad region, giving a basis for developing future climate adaptation strategies.

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Conflict of interest statement

The authors declare no competing interests.

Figures

Figure 1

Figure 1

(a) Location map of the Lake Chad Basin (~2.5 × 106 km2) with the delimitation of the conventional basin, the Quaternary aquifer (orange), and the Chari-Logone Basin (black). (b) The study area with ENVISAT/SARAL satellite altimeter ground-tracks (yellow), Topex-Poseidon/Jason ground-tracks (red), locations of six VSs (red triangles), and locations of N’Djamena and Chagoua gauge stations (blue stars). a was generated by QGIS Version 3.10.2), and b was generated by Google Earth Pro Version 7.3 (

https://www.google.com/earth/

).

Figure 2

Figure 2

Time series (top) and anomaly (bottom) of surface water extent of the northern pool (blue), southern pool (red) and Lake Chad (green), for the 2001–2018 period. The trends are also plotted.

Figure 3

Figure 3

Top: monthly variation of GRACE-derived TWS (black), SWS of Lake Chad (blue) and its southern pool (green), groundwater (red), and root zone soil moisture (cyan). Bottom: monthly time series of in situ discharge at the N’Djamena gauge station.

Figure 4

Figure 4

Top: comparison between in situ and satellite derived water height collected from Hydroweb (

http://hydroweb.theia-land.fr

), and simulated data over the southern pool of Lake Chad. Bottom: Annual precipitation at four gauge stations within the Lake Chad basin.

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