River close to the Tsingy de Bemaraha, Madagascar (20°00’S, 45°15’E).

Although rivers manage to penetrate the Tsingy de Bemaraha, a UNESCO World Heritage Site, it is otherwise a giant labyrinth of karstic needles covered by dry, tropical forest. In Madagascar, which suffers from chronic drought, the tree thousand odd streams and rivers constitute the most precious of resources. But given the country’s uneven and unreliable rainfall (varying from 150 inches [3,800 millimeters] annually in the northern regions to 15 inches [380 millimeters] annually in the western regions) and the absence of firm legislation to protect waterways from chemical and industrial pollution, water in Madagascar is not only a rare commodity but also a threatened one. Today, 95 percent of the country’s wastewater is returned to the earth without undergoing any prior treatment, and only 27 percent of the population has access to a network of drinking water (one of the worst records in the world). To assist places such as Madagascar, attending states at a 2005 international conference on Africa’s water and sewage issues pledged to extend drinking and water facilities to 80 percent of Africa’s population by 2015.