A Turbulent Devbhumi
Abstract: The deafening roar of the mighty Ganga, nearly three times its normal width, transporting boulders and earth from the majestic Himalayas must be experienced to be believed. Framed at one end by the span of the Ram Jhoola the muddy waters trundled down as black clouds gathered strength in the background. Soon golden spotlights through the dark clouds were obliterated as the River turned into a boiling cauldron.

The author is a practicing paediatrician in Delhi.

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An anabranch is a section of a river or stream that diverts from the main channel or stem of the watercourse and rejoins the main stem downstream. Local anabranches can be the result of small islands in the watercourse. In larger anabranches, the flow can diverge for a distance of several kilometres before rejoining the main channel.

The percentage of fish moving toward a dam’s turbine units that are diverted away by a fish guidance device, such as a submersible traveling screen.

Measure of the volume of water which a structure can pass or measure of the volume and flow of water within a watercourse.

A penstock is a sluice or gate or intake structure that controls water flow, or an enclosed pipe that delivers water to hydraulic turbines and sewerage systems. It is a term that has been inherited from the technology of wooden watermills.

The dam whereby the natural flow and elevation drop of a river are used to generate electricity. No large reservoirs are built for water storage in such projects.

Having a total catchment area of 61642 Sq.Km, Indira Sagar Project is the mother project for the downstream projects on Narmada Basin with largest reservoir in India, having 12.22 bm3 storage capacity.

An opening at a low level from a reservoir generally used for emptying or for scouring sediments and sometimes for irrigation releases.

A spillway is a structure used to provide for the controlled release of flows from a dam or levee into a downstream area. Spillways release floods so that the water does not overtop and damage or destroy the dam.

The tail race tunnel or channel are provided to direct the used water coming out of draft tube back to the river. Tail race is designed in such a way that water hammer is minimized when water leaves the draft tube.

A basin constructed to dissipate the energy of fast-flowing water from an outlet. Also known as stilling box.

In hydrologic terms, a graph showing the relation between the surface area of the water in a reservoir, the corresponding volume, and elevation, is the area-capacity curve.

Surge tank signifies a reservoir which mitigates pressure variations due to rapid changes in velocity of water. It absorbs the water hammer effects due to rapid start or closure of the turbine.