Only a Barrage Can Save! - The Ganga: Water Use in the Indian Subcontinent - page 91

Debesh Mukherjee cited a number of times that a sustained minimum flow of
40,000 cusecs, round the year, was absolutely necessary for the rejuvenation of the
Hooghly.
To sum up the problems of the Bhagirathi-Hooghly, as cited by Indian and foreign
experts:
a) Eastward shift of the main Ganga toward the Padma, which occurred in early
16th century, leaving the original course through the Bhagirathi. Shifting of
navigation through a ship canal, or shifting the port to Canning on the Matla
river, or navigation through the Jalangi and Mathabhanga, were no permanent
solutions;
b) Fall in the duration of flow from the Ganga to the Bhagirathi and gradual shifting
of the offtake point to downstream, leading to loss of headwater volume and
of depth;
c) Uncontrolled and excess entry of sand and silt in the Bhagirathi, resulting in
their deposition in the mouth and the bed;
d) Fall in the river's capacity and movement of tide-borne sand and silt upward
and their subsequent deposition in the bed which further reduced the capacity;
e) Increase in tidal range and flow-tide current, intensifying bores in the port area;
f) Increase in salinity in river water, making it unfit for human consumption and
damaging boilers and industrial machineries, located on the banks; ingress of
salinity in ground water, causing loss of agricultural yield;
g) Siltation over the bars and low-water crossings and shifting of navigation routes,
year to year, and loss of depth in navigation channels;
h) Optimum frequency and volume of dredging and non-availability of enough
land for disposal of dredged spoils; and
i) Decline in movement of deep-draft ships, in handling of import and export cargo
etc., affecting the economy of the country.
Remedial measures that were considered for counteracting the above were
as under:
i. Shifting of navigation channel through a ship canal and of the port;
ii. Dredging of the bars and crossings and also of the river-bed;
iii. Dredging of the offtake of the Bhagirathi and the bed of the entire river;
iv. River-training works; and
v. Provision of controlled and silt-free upland discharge, round the year.
As regards (i), shifting of the navigation channel or the ports not successful and
the proposal was abandoned at the initial stage.
As regards (ii), dredging could give only a temporary relief and with continuous
dredging, the root cause of deterioration could not be removed, because dredging
was optimum and there was not enough space ashore where dredged spoils (about
100 million cft) could be dumped, year after year.
As regards (iii), it was impossible to keep the Bhagirathi head active by dredging
for prolonged supplies, round the year, as the head of the river was not stable and
had shifted downward, several times, in the past. Besides, frequent changes in the