Lake Chad in Central Africa provides water to around 30 million people in four neighbouring countries, but it has lost 90 percent of its surface area in the last 100 years.

Environmentalists are warning of impending human and ecological disaster in the Sahel region if nothing is done to stop the disappearance of the lake.

Al Jazeera's Mohammed Vall reports, in the second part of our Thirst series on water, from Lake Chad.