Dear Mr Shankar, What I mean ...

Dear Mr Shankar, What I mean by scientific dredging is that a scientific / technical assessment should be done whether we need the dredging of a river or not ? What is the purpose of dredging a river ? The rivers are natural drainage channels to carry water received from glaciers and/ or rainfall in catchment areas. The dredging of river is not going to add quantity of water in the river flow. But in Maharastra and Karnataka the dredging is being done / proposed for increasing the availability of water in rivers. This a incorrect. If there are obstructions in natural flow of water natural or man made, they need to be removed, in a way suggested by technical experts. But just deepening and widening of the river arbitrarily, is not going to help to increase the availability of water in the river. As regards dams, the soil strata in submergence area of a dam reservoir and dam section, needs to be impervious, so that the stored water does not percolate through the submergence area and the dam section. Otherwise the stored water in dam reservoir will percolate down and dam will be empty in a short time, making the dam reservoir useless. The silt/ sand collected in the submergence area should be removed in such a way that this process does not remove the impervious soil strata. However the best way to minimize the inflow of sand and silt in dam reservoirs , is to do afforestation in the catchment area. I hope I have replied your query. I shall welcome further questions if any.