poster: p2222-05 lake chad : present situation and possible future management
TRANSCRIPT
Foreword This study has been developed in a period when Boko Haram had not rea-ched its present activity, with thousands of murders and kidnappings around and in the Lake itself. The social and bio-physical elements presented hereunder may only apply in a peaceful socioenvironment.
Lake Chad is submitted to an increased demographic pressure in a context of long histori-cal hydrologic variability with no clear indication on the climate change impact over its basin. The challenge is to identify long term water management strategies.
The present state of the lake
In the recent past, after a rather wet period (1950-1970), the size of Lake Chad has decreased sharply as a result of the Sahel droughts (1970-1995) with occasional drying out of its northern basin before a partial recovery (1995-2015).
The inundated area of Lake Chad (in black) within the lake boundaries at the end of the wet period in 1973 (light grey). From NASA-Landsat data.
Most of the pessimistic declarations in the media about the future of Lake Chad originate from the dry 1980 situation. The present state of the lake, since the beginning of the 2000s, has been that of a moderately low water level, with large marshes and abundant natural resources exporting food in the surrounding region. Endogenous innovations in family agriculture and small scale water management have been the key for the adaptation of the local people to the lake's variability.
Small climate change vs high lake susceptibility to rainfall change
The recent IPCC-AR5 report has concluded with a great uncertainty that the rainfall change should be moderate over the Chari basin, but with no clear indication on the direction of the change. As the Lake is highly sensitive to the rainfall on its basin - a change in 10 % of the rainfall creates a 30 % variation of its area - there remains a great uncertainty on the future of the Lake and on the politics to be imple-mented to sustain the food production and the livelihood of the local people.
The need for an integrated basin-wide water management strategy
A project presently supported by the Lake Chad Basin Commission (LCBC) aims attransferring about 6.2 billion cubic metres per year from the Ubangui River, a tributary of the Congo River, to the Chad basin. This transfer would avoid a drying out of the northern part of the lake (home to about 0.6 million inhabitants) in case of severe drought but would not allow for a mitigation of the drought impact over the whole Lake Chad basin, presently home to 35 to 40 million people but foreseen to reach 80 million in 2040. Basin wide solutions should therefore be studied. Increasing agricultural water productivity and resilience to climate change may be usefully developed and popularized.
The proposed LCBC inter-basin transfer (Cima 2011)
ReferencesLemoalle J., Magrin G. (eds), 2014.– Le développement du lac Tchad : situation actuelle et futurs possibles. Marseille, IRD Éditions, , 215 p.+ USB 638 p.Magrin G., Lemoalle J., Pourtier R. (eds), 2015.- Atlas du lac Tchad. Paris, Passages, 226 p.
Contact:G. Magrin, UMR Prodig, Université Paris 1-Panthéon-Sorbonne [email protected]. Lemoalle, UMR G-Eau, IRD, Montpellier France [email protected]
Lake Chad : present situation and possible future management G. Magrin and J. Lemoalle
Lake Chad