Tuesday, August 23, 2011

Nepal dams won't stop Indian floods

Joydeep Gupta in China Dialogue: “Every monsoon when there is a flood in Bihar, including this year right now, local politicians blame Nepal and the lack of dams there” For decades, Indian planners working to harness the waters of the Ganges and its tributaries have believed building dams in Nepal will save Bihar and eastern Uttar Pradesh from the floods that occur almost every year. A recent comprehensive study led by the World Bank says this belief is no more than a myth.

The belief was that there were substantial upstream reservoir storage possibilities in the Ganges basin that straddles India, Nepal and Bangladesh. But the Ganges Strategic Basin Assessment (SBA) coordinated by the World Bank and carried out by experts in the region has found that the largest 23 dams that have been conceived would only hold an additional 13 percent of the annual flow of water. The preliminary findings of the SBA have been presented to government officials in all three countries and were unveiled in public at the World Water Week in Stockholm.

The experts working with the South Asia Water Initiative (SAWI) coordinated by the World Bank found that in terms of flood control, there would be little basin-wide effect of upstream storage, and that effects were unlikely at the sub-basin level either. The models – developed by the Institute of Water Management in Bangladesh, the Indian Institute of Technology, Delhi and RMSI, a consultancy firm in India, and vetted by SAWI experts – showed that at the sub-basin level, the dams would reduce peak flows, but would not necessarily reduce floods. Most rivers in the basin are largely embanked, and local rainfall and embankment failures cause the most flooding, the study found....

Bihar flooding in 2008, shot by Sharada Prasad, Wikimedia Commons via Flickr, under the Creative Commons Attribution 2.0 Generic license

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