© ESAAn ESA Envisat image of Lake Chad, a freshwater lake located in central Africa
High flying satellites, which have already proven their mettle in delivering television programs, cell phone calls and views of our neighborhoods (thank you, Google Earth), can also locate potable water in countries such as Niger where droughts have made it scarce, the European Space Agency (ESA) announced this week.

The agency said satellites had successfully pinpointed 90 locations in western Niger where, based on satellite images taken between 1993 and 2007, drinkable surface water was likely to be; the Regional Center of the Permanent Interstate Committee for Drought Control (AGRHYMET) confirmed the satellites were right in all cases. AGRHYMET is a Niger-based agency formed in 1974 to gather information about food availability and the management of water and other natural resources in the Sahel, the region in Western Africa that forms the border between the Sahara desert to the north and the less arid forests to the south.

"Permanent and semi-permanent water body monitoring is an essential resource for rangeland activities and irrigated agriculture areas in the semi-arid zone," Issifou Alfari, head of AGRHYMET's water resources management and desertification division, said in a statement. "We are very happy with the project's scope and outcome, as we believe this source of information will be fundamental for water management activities."

ESA captures images of the Sahel via its European Remote Sensing (ERS) and Envisat satellites as part of the agency's WADE (Water resources Assessment using Synthetic Aperture Radar in Desert and arid lands in West African Ecosystems) project. The agency launched WADE in 2006 to map sub-surface, man-made water structures and surface water to help African nations find and manage their use of limited water supplies and, in November, installed WADE software in AGRHYMET's facilities in Niger's capital, Niamey.

ESA has made its space technology available since 2002 at no cost to African nations to help them avert possible water shortages. Its Tropospheric Emission Monitoring Internet Service (TEMIS) likewise provides free data about the atmosphere and environment to help nations worldwide assess air pollution problems.

Niger's water problems have been well documented. Scientific earlier this month reported about a resurgence of polio in that country, as well as several other west African nations. (In 2008 there were 1,618 documented cases of polio worldwide, 788 (nearly 50 percent) of them in neighboring Nigeria, which borders Niger to the south.) Polio is easily transmitted in areas with poor sanitation systems where drinking water is contaminated with sewage and human waste. A 2005 drought in Niger left millions facing starvation.