Only a Barrage Can Save! - The Ganga: Water Use in the Indian Subcontinent - page 92

Ganga and their effect on the offtake of the Bhagirathi precluded such possibilities,
as the head condition depended on the disposition of the parent river. The offtake
had shifted from Dhulian to Suti and then to Geria and at present is at Raghunathpur,
further down. These shifts were due to natural closure of old offtakes and creation of
new, leading to gradual diminishing of head water supply, in frequency and volume,
from the Ganga owing to alluviation at the head and the bed of the Bhagirathi.
The angle, formed between the Ganga and the Bhagirathi at the offtake gradually
changed to obtuse and finally got closed, creating a new head, downstream. It was
not practicable, nor was it attempted, to peg a favourable offtake at a particular
place and therefore, dredging of the offtake for facilitating entry of head water was
not practicable.
As regards (iv), river-training works in the Bhagirathi and the Hooghly used to
have very local effects and could not help maintain the deep navigation channel in
the river course, especially when water-level in the river fell between 25 and 30 feet
in the dry season. The cost of such works was also very high and the tasks were
hazardous; besides, these alone could not maintain the channel, unless supplemented
by head-water supply, round the year.
Regarding (v), controlled diversion of upland discharge from the Ganga was
the only practical solution to resuscitate the Bhagirathi-Hooghly. This alone could
reduce siltation in the bed near Calcutta port area and over bars and crossings,
decrease salinity in river and ground water, bores and tidal ranges and increase nav-
igation, the river's capacity and port activities etc. Such diversion was possible only
through a barrage on the Ganga at a suitable location with provision of gates to head
up water. With such discharge, it would be possible to prolong the freshet period
and moderate sharp and freshet peaks which cause heavy sand movements and bank
erosion. The historical background and elaborate studies by experts as well as by
concerned institutions and committees across a century favoured the construction of
a barrage to save Calcutta port and revive the economy of two Bengals and of India
as a whole.
The need for improving head-water supply was even more urgent, considering
the interception of the floods in the Damodar and the Mayurakshi by dams, con-
structed much earlier. Though they intercepted coarse sand and silt, flowing from
above, which could otherwise intrude into the Bhagirathi-Hooghly, they substan-
tially reduced freshet discharge, increase silt deposition and weakened tidal flows
and intensified bores and sand movement with flow-tides.
Farakka Barrage Project
Although the need for a barrage at Farakka was felt for a long time, it could not be
constructed by the British Indian government in Delhi. Only after Independence in
1947, the free government conceived it with the following objectives:
a) For perennial head-water supply from the Ganga into the Bhagirathi-Hooghly,
particularly in the dry season, to reinforce the capacity of the ebb flow, to scour
residual silt during flow-tide to revitalize Calcutta port, enable it handle more
cargo and to reduce cost of dredging and port installations;