|
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.
Go to: Chapters
— Site Images — Powerpoints
— Posters
|
AFRICA'S LAKES
Chapter 3 - Challawa Dam |
 |
 |
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.
| |
