Inconsistency, or A Conspiracy? - The Ganga: Water Use in the Indian Subcontinent - page 113

d) Sudden reduction in discharge in the months of high tide would not leave much
time to dredge the channel to enable ships come and go from Calcutta port.
e) The salinity in water in the port area would be much more than it would have
been if 40,000 cusecs flowed into the river, round the year.
These adverse effects of reduced flow, as predicted by experts, Calcutta port and
the Government of West Bengal before and during the construction of the bar-
rage, have almost come true over three decades afterward. Though the deposit of
silt and sand in Calcutta port area and in some stretches has reduced considerably,
they have settled in the reach between Falta and Haldia and blocked the navigation
channel near Haldia port. Bore tides have increased in frequency, near Kolkata and
below. Water supplied to south Kolkata has turned brackish, though salinity reduced
markedly soon after the upland discharge began to be diverted from the barrage
in 1975. Thus, the improvement which was foreseen with 40,000 cusecs of upland
flow into the Bhagirathi-Hooghly, round the year, has not been a reality because of
reduced discharge.
Probable Causes of Reduction
As shown in Table 4.6, the total flow at Farakka and its distribution in the lean and
monsoon periods varied from 0.248 million Mm 3 in 1992 to 0.54 million Mm 3 in
1978. Of this, the total lean-season flow, from January to June, is quite insignificant,
compared to that between July and December, the ratio, ranging from 1:5.06 (1979)
to 1: 12.74 (1975). From the period from July to December, four monsoon months -
July to October - are separated, when the flow is about 85% of the total. Such erratic
flows make it very difficult to plan and implement any water resource development
project. Almost the entire monsoon flow and much of the dry-season flow go to the
sea without any use. Thus, diversion of a part of the flow into the River Bhagirathi
for the benefit of Calcutta port and of the people of West Bengal cannot be construed
as wastage, as alleged by some people in Bangladesh.
The flow in the Ganga for 20 years between January and June, from 1975 to 1995,
is charted in Table 4.6 (Chapter 4). The total available flow at Farakka and the per-
cent share between the river downstream and the Feeder Canal is shown in Table 8.2.
The average percent share of the flow in 21 years comes to 91.63 and 8.37, or 92
and 8, respectively. The average annual flow in the river between 1975 and 1996 is
about 0.39 million Mm 3 , against which the share of the River Bhagirathi is about
32,000 Mm 3 ; the remaining water flows downstream. The ratio of annual discharge,
shared between the Ganga downstream and the River Bhagirathi in those 20 years,
was maximum (88.1:11.9) in 1992 and minimum (94.4:5.6) in 1980, except in 1975,
the year of commissioning of the barrage. The average flow ratio is about 92.8. The
highest flow at Farakka was about 0.54 million Mm3 in 1978 and that in the River
Bhagirathi was 34,890 Mm 3 in 1990.
The driest part of the lean season flow is segregated and analysed. This is shown
in Table 8.3. The average percentage share of flow between the Ganga and the River
Bhagirathi in 21 years in the lean season of March to May is 56 and 44 respectively.