Geoscience Reference
In-Depth Information
Table 8.4
The distribution of total lean season flow (January-June) between Ganga downstream
and River Bhagirathi
Share between
Percentage share
Tot a l flow
between Jan and
June (Mm
3
)
Ganga
downstream
(Mm
3
)
River
Bhagirathi
(Mm
3
)
Percentage
of total flow
Ganga
downstream
River
Bhagirathi
Year
1
2
3
4
5
6
7
1975
31,020
7
27,500
3,520
(May and
June)
88.7
11.3
1976
43,500
11
27,430
16,070
63.1
46.9
1977
36,560
8
21,380
15,180
58.5
41.5
1978
49,300
7
33,060
16,240
67.1
32.9
1979
42,330
9
26,270
16,060
62.1
37.9
1980
32,500
7
22,000
10,500
67.7
32.3
1981
37,380
10
23,230
14,150
62.1
37.9
1982
46,300
12
31,520
14,780
68.1
31.9
1983
33,020
9
19,890
13,130
60.2
39.8
1984
61,370
15
46,870
14,500
76.4
23.6
1985
32,270
7
19,070
13,200
59.1
40.9
1986
40,350
11
24,670
15,680
61.1
38.9
1987
35,580
9
22,080
13,500
62.1
37.9
1988
35,740
9
22,670
13,070
63.4
36.6
1989
45,200
14
29,450
15,750
65.1
34.9
1990
40,110
10
23,290
16,820
58.1
41.9
1991
43,960
12
28,270
15,690
64.3
35.7
1992
28,870
12
14,480
14,390
50.1
49.9
1993
28,670
8
15,710
12,960
54.8
45.2
1994
33,780
9
17,570
16,210
52.0
48.0
1995
43,370
12
26,650
16,720
61.4
38.6
and River Bhagirathi as shown in columns 4 and 5. The percentage share is shown
in columns 6 and 7 which varied from 76.4:23.6 (1984) to 50.1:49.9 (1992) with an
average of about 62:38 without considering the year 1975. Thus, the flow through
the downstream Ganga is only 6% and that through the River Bhagirathi is only
4%, approximately. The salient points below emerge from an analysis of the flow
through the Ganga at Farakka.
i. The average annual flow through the Ganga at Farakka between 1975 and 1995
was about 0.39 million Mm
3
, of which the canal carried about 32,000 Mm
3
and the remaining water flowed through the river downstream, the average
ratio being about 8:92.
ii. The peak discharge at Farakka occurred on 6th September 1980; its intensity
was 73,054 cumecs, or 2.58 million cusecs. That year, the discharge in the
river which was above 56,635 cumecs, or 2 million cusecs, continued for a
maximum period of 30 days (Table 4.6).
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