by C.T. Pope
Once the third-largest source of freshwater in Africa, Lake Chad is disappearing according to new satellite images — putting millions of people in four Central African countries at risk of losing their primary water supply.
The vast shallow lake, with a surface area equivalent to Lake Erie only 40 years ago, is now one-twentieth its previous size. The region surrounding the basin continues to suffer from intense, long-standing drought choking-off the lake’s water supply.
Historically, the lake has varied greatly in volume due to its shallow bottom and large surface area. In the dry season, Lake Chad becomes mostly a large marsh, which then recharges on average to a 5 feet (1.5 meters) deep lake with the return of the monsoons. At its documented peak, the lake was only about 23 feet (7 meters) deep.
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The shrinking lake has had a substantial impact on the local populations, as entire communities have switched from a fishing-lifestyle to one of farming and agriculture. Local communities that once ringed the shores of the lake are now isolated villages — miles from water — and these populations have literally begun farming the now-dry lake bottom. Much like the drying of Uzbekistan’s Aral Sea, the impacts are far-reaching and complex.
Jonathon Foley and Michael Coe of the University of Wisconsin, Madison, found that while the drought has caused significant declines in water levels, human factors are mostly to blame for the present levels.
In their paper, published in the Journal of Geophysical Research, Foley and Coe concluded that increased demands on the water resources flowing into the lake, and withdrawals from the lake itself, have prevented Lake Chad from returning to its pre-sixties size.
As the Sahara slowly encroaches on the lake, the local populous has come to depend on the rivers flowing into the basin more and more. The diversion of this water to support a population of some nine million herdsman, farmers and fishermen has exacerbated the effects of drought.
In an interview with National Geographic, Foley warned that “[t]he problem is expected to worsen in the coming years as population and irrigation demands continue to increase. It shows how vulnerable our water resources can be.
“There are enough people in the world now that we need to start planning and looking at fresh water as a finite resource or we’re going to be in trouble. We don’t get any more.”
Plans are in the works to divert water from the Congo River to the River Chari, which flows into Lake Chad, and revitalize the lake. The ambitious project would construct some 60 miles of canals and pump water uphill toward Lake Chad, but it is unclear when the diversion project would begin or who would fund it.
Lake Chad, which lies on the boarders of the African nations of Chad, Cameroon, Niger and Nigeria, supports a vast ecosystem of waterfowl, crocodiles, fish, shore birds, and grazing animals.
The recently released satellite images combined with older images (see graphic) show the desertification occurring in the Lake Chad basin. All images were compiled when the lake was at its seasonal peak.
References and Additional Resources:
Africa: Atlas of our Changing Environment (UNEP)
EarthShots: Satellite Images of Environmental Change (USGS)
Shrinking African Lake Offers Lesson on Finite Resources (National Geographic)
Slow death of Africa’s Lake Chad (BBC)
Shrinking of Lake Chad: Tale of Human Abuse, Climate Change (Global Policy Forum)