World's Water Storage Capacity Shrinking as Dams Silt Up

BONN, Germany, December 4, 2001 (ENS) - The reservoirs of the world are losing their capacity to hold water as erosion brings silt down to settle in behind dams, the chief of the United Nations Environment Programme (UNEP) warned today.

Speaking to the Bonn International Conference on Freshwater, UNEP Executive Director Klaus Toepfer said that siltation is reducing the capacity of the world's reservoirs to hold water, a result that is hastened by the clearcutting of forests.

"The issue of dams can arouse strong passions on both sides," Toepfer told the delegates. "Some people are very much in favor of building dams and others are vehemently against. However, what we are talking about here is the state and fate of the existing stock of dams and reservoirs on whose waters billions of people depend for not only irrigation and drinking water, but also for industry and the production of hydroelectricity."

Dam at Long Quig Xia, China (Photo courtesy Traveler's Field Guide)

In response, UNEP has launched a new Dams and Development Project (DDP), to address siltation and other serious environmental effects of dam development.

Based in South Africa, the Dams and Development Project, known as the DDP Unit, is a follow up to the work of the World Commission on Dams, publisher of an in-depth report on the environmental impact of large dams in November 2000.

The new DDP Unit has secured funding and pledges of over $2.5 million from the governments of Germany, the Netherlands, Sweden, Switzerland and the United Kingdom. Sustainable management of reservoirs will take a central role in its work.

None too soon for Rodney White, author of "Evacuation of Sediments from Reservoirs" and a fellow of the Institution of Civil Engineers. White is warning the world's leaders to pay more attention to the capacity of the world's dams to hold water.

"The loss of capacity of the world's dams should be of highest concern for governments across the globe, and at the moment I do not believe this issue is commanding the attention it deserves," White said.

Located near several faults capable of generating large magnitude earthquakes, California's Casitas Dam has just been upgraded to higher earthquake resistance standards. (Photo courtesy U.S. Bureau of Reclamation)

In view of the "threat of global warming," Toepfer urged the planting of forests across the globe. "We must act to reduce the loss of forests and to re-afforest cleared areas as part of a comprehensive strategy of watershed management of the world's river systems," he said.

"There will always be natural levels of erosion that will contribute to a loss of water storage capability," Toepfer acknowleged, and called on engineers to provide "technical solutions that offer environmentally friendly ways of extending the lives of the world's reservoirs."

Jeremy Bird, interim coordinator of the DDP Unit, said next week, a meeting in Prague, Czech Republic, they would be looking at how to improve the performance of reservoirs and dams across a wide range of functions from agriculture to power generation.