Expert suggests silt-free barrages

A perennial flow of ‘bathing quality’ water is ensured through a self-purification process. Mr. Rao’s plan prefers building these barrages on the main river itself as it is virtually impossible to construct storage reservoirs elsewhere on the Gangetic plains or in the ecologically fragile Himalayan hilly regions.

September 22, 2014 01:33 am | Updated November 12, 2016 01:34 am IST - HYDERABAD:

A U.N. consultant and engineer has come up with a cost-effective plan for Ganga rejuvenation by building 25 silt-free barrages within the river system to dilute the waste and to maintain a continuous flow of fresh water.

T. Hanumantha Rao, former Engineer-in-Chief of the A.P. Irrigation department and U.N. consultant to 22 countries told The Hindu that his ‘Ganga rejuvenation plan,’ involved construction of barrages from Haridwar to Farakka, one below the other in such a manner that the stored water of the lower barrage touches the upstream one.

This would render the entire river a long reservoir limited to storing flood water within the flood zone of the river without submerging any village. A perennial flow of ‘bathing quality’ water is thus ensured through a self-purification process that takes care of waste water flowing into the river either directly or from dysfunctional sewage treatment plants, which has been the biggest challenge so far. His project is expected to be presented to Prime Minister Narendra Modi shortly.

The Central Pollution Control Board had estimated that 4800 million litres per day of waste flowed into the Ganga in 2013. This works out to 1,964 cubic feet per second (cusecs) requiring a fresh water discharge of about 19,640 cusecs for its dilution by 10 times. This is required essentially during the dry period of four months as flood flows take care of the dilution in the remaining eight months.

Mr. Rao’s plan prefers building these barrages on the main river itself as it is virtually impossible to construct storage reservoirs elsewhere on the Gangetic plains or in the ecologically fragile Himalayan hilly regions. A design innovation proposed in the barrages is that the bottom of the radial gate starts from the river bed apron level and is kept open to allow free normal flows and to wash down the silt. The water stored upstream in each barrage is released downstream to provide enough water for dilution of waste inflows.

There will be no siltation upstream of barrage as each vent will function as scouring sluice.

Besides purifying the Ganga basin, the project has advantages such as big ship navigation, hydro power generation, large-scale fishing for Hilsa and other species, assured environmental flows and conservation of mangrove of the wetlands, he says.

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