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GANGA U/S
FLOW 10%
D/S
6%
GANGA U/S
FLOW 6.2%
D/S
4.7%
a) January to June
(Lean season flow)
b) January, February & June
(Lean Season Flow)
GANGA U/S
FLOW 3.8%
D/S
2.3%
c) March to May
(Lean Season Flow)
Fig. 8.4 Schematic line diagram showing the percentage lean season flow distribution in Ganga
and Feeder canal
Reduction of Discharge
According to S. C. Majumdar, maximum flood discharge, as computed from the
readings of the Ganga was 2.48 million cusecs at Farakka in 1913. The lowest level
there was R.L. + 57.7 feet, or 17.59 m, the lowest bed-level being about + 21 feet
(6.4 m) and the highest flood level at R.L. 83.2 feet (25.37 m). From available
records, though the minimum flow in a very bad year might be of the order of
50,000 cusecs, or 1,416 cumecs, the average flow that should matter, even in the
driest months, is much higher. After verifying records of 5 years at that time, he
mentioned that the average discharge at Farakka on monthly basis varied between
299,000 and 79,000 cusecs, i.e., 8,465 and 2,237 cumecs, in the dry season, from
November to May and between 1,615,000 and 175,000 cusecs, or 45,725 and 4,955
cumecs, in the monsoon months, from June to October.
Debesh Mukherjee, the Chief Engineer and later the first General Manager of
the Farakka Barrage Project, is on record that in 1952 and 1953 the dry season
flow of the Ganga at Farakka went down to 40,000 cusecs (1132.5 cumecs); this
was the minimum there since 1948. Therefore, contrary to earlier assessments, it
has been found that the lean-season flow at Farakka would be 40,000 cusecs, or
even less. According to the Government of India report, 'Preservation of the Port
of Calcutta, 1961', the lowest level, recorded at Farakka on 6th February 1958 was
R.L. + 52.15 feet (15.9 m) from the gauge discharge curve at the time, the minimum
discharge was 55,000 cusecs (1,557 cumecs).
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