Large Dams Worsening Floods in India?

Environmentalists say heavy flooding on the Indian sub-continent in 2006 may at least partly be the consequence of the many large dams ostensibly built to control natural water systems.

Activists and experts believe that the flooding resulted not from higher rainfall but from a failure to balance properly flood control with other objectives of big dams—irrigation and hydro-power. Flood control demands that dams allocate adequate space to receive flood surges, maximizing hydro-power potential means that water level in dams is kept as high as possible.

Dinesh Mishra, an engineer and convenor of the Barh Mukti Abhiyan (Campaign for Freedom from Foods) points to siltation rates at many dams that are much higher than original estimates. Silt buildup reduces the capacity of storage reservoirs to absorb flood flows.

But others, including Himanshu Thakkar, hydrologist and coordinator for the South Asia Network on Dams, Rivers and People (SANDRP), attribute this year's devastation to sheer mismanagement at large reservoirs on the Tapti, Narmada, Krishna, Godavari, Mahi and Sabarmati rivers. He agrees that reservoirs need to store water as protection against the possible failure of monsoon, but says the floods that ravaged Surat in the western state of Gujarat were preventable by earlier controlled releases of reservoir water.

Ravindranath, an activist with the environmental organization 'River Basin Friends' in the northeastern state of Assam, says nearly 160 dams are being planned in the region. Based on past experience, he worries that even relatively small dams can unleash destructive flash floods. But some of the planned dams will be massive in scale. The danger increases because the northeast has been witness to large-scale ecological destruction in the catchment areas due to illegal lumbering, quarrying and mining.

While floods were reported this year in ostensible drought-prone, water-deficit areas (such as Barmer district in Rajasthan), some of the nprmal surplus basins experienced drought-like conditions.

Bharat Dogra, “Environment-India: Large Dams Blamed for Floods,” Inter Press Service, 4 September 2006.Link: www.ipsnews.net/news.asp?idnews=34566.