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Africa's Lakes
Atlas of Our Changing Environment
Nambia Desert
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Increasing concern as to how human activities impact Africa's lakes has led to documentation and quantification of the lakes and the environmental changes taking place. Through a combination of ground photographs, current and historical satellite images, and narrative based on extensive scientific evidence, this publication illustrates how humans have altered their surroundings and continue to make observable and measurable changes to Africa's lakes and their environment.


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AFRICA'S LAKES
Chapter 3 - Challawa Dam
27 Nov 1990 image 19 Oct 1999 image
Challawa Dam, Nigeria
The Challawa Gorge Dam, completed in 1993, is the second largest of the 23 dams along the rivers in Nigeria's Hadejia-Jama'are River Basin. Although the dam has improved the water supply for irrigation, it has also ruptured the fragile natural balance along this stretch of water. When it rains heavily, the river can break its banks and flood farms and land upstream from the dam. Areas downstream, meanwhile, do not receive enough water to maintain the wetlands bordering the river. Under these conditions, the soil dries out and overgrazing occurs, which in turn leads to wind erosion of the topsoil. These satellite images provide a comparison of the area before and after the dam's construction. The 1999 image shows the degree to which flooding upstream impacts the landscape, and how the lack of water downstream negatively affects riverine wetlands and cropland. The colour of the water in the flooded area is also indicative of high-sediment content.
Africa's Lakes cover

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