Lake Chad was once the sixth largest lake in the world, but prolonged drought and increased water use have shrunk the lake dramatically. It now spans less than a tenth of the area it covered in the 1960s. Back then, the lake covered about 25,000 square kilometers, an area the size of the U.S. state of Vermont. Now it’s smaller than Rhode Island.
The fluctuations in lake water levels have stabilized in recent years, but it is still a dynamic environment. Social conflicts and insecurity in the region make it difficult to monitor water levels with ground-based measurements. Satellite imaging has therefore been crucial to monitoring the changes to the lake, especially with the infrared bands on Landsat sensors, which make it easier to distinguish water and vegetation.
These Landsat images show the overall transition of Lake Chad from open water to wetland. The desert appears tan, wetlands are green, and open water is blue.
The black and white 1963 image is from the film-based Argon reconnaissance satellite program, declassified in the 1990s.
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Thanks to Jean-Claude Olivry of ORSTOM for his assistance.