Geoscience Reference
In-Depth Information
Table 8.3
Analysis of the driest part of the lean season flow
Percentage share
between March and
May
Share of flow between
March and May
Tot a l flow
between
January and
June (Mm
3
)
Tot a l flow
between
March and
May (Mm
3
)
Ganga
down-stream
(Mm
3
)
River
Bhagirathi
(Mm
3
)
Ganga
down-
stream
Percent
of flow
River
Bhagirathi
Year
1
2
3
4
5
6
7
8
1975
31,020
10,590 (E)
30
9,500 (E)
1,090 (May
only)
90
10
1976
43,500
17,460 (E)
40
9,500 (E)
7,960
54
46
1977
36,560
16,660 (E)
46
9,500 (E)
7,160
57
43
1978
49,300
17,480 (E)
35
9,500 (E)
7,980
54
46
1979
42,330
20,140
48
12,350
7,790
61
39
1980
32,500
11,400
35
7,280
4,120
64
36
1981
37,380
16,310
44
9,910
6,400
61
39
1982
46,300
18,180
39
10,910
7,270
60
40
1983
33,020
13,960
42
8,470
5,490
61
39
1984
61,370
14,400
23
8,610
5,790
60
40
1985
32,270
12,710
39
7,630
5,080
60
40
1986
40,360
16,510
41
9,900
6,610
60
40
1987
35,580
13,710
39
8,220
5,490
60
40
1988
35,740
14,110
39
8,480
5,630
60
40
1989
45,200
15,300
34
8,120
7,180
53
47
1990
40,110
16,490
41
7,980
8,510
48
52
1991
43,960
14,470
33
7,250
7,220
50
50
1992
28,870
11,230
39
4,950
6,280
44
56
1993
28,670
11,920
42
5,610
6,310
47
53
1994
33,780
12,130
36
4,510
7,620
37
63
1995
43,370
14,050
32
6,280
7,770
45
55
Average
56
44
The total flow is being shared between the downstream Ganga and the River
Bhagirathi since 1975, as shown in Table 4.6 (Chapter 4), the average flow ratio
being 92:8. Of this, the flow during driest months - March to May - is quite
insignificant. Leaving 1975, the flow is shared as per ratio, shown in columns 7
and 8 of Table 8.3. Dividing the total period in two parts - from 1976 to 1987 and
from 1988 to 1996, the percent share in the first part ranged from 64:36 in 1980 to
54:46 in 1976 and 1978 with an average of about 59.4:40.6 and that in the second
part ranged from 53.47: in 1989 to 37.63 in 1994 with an average of about 46:54.
Considering the total lean-season flow, as shown in column 2 of Table 8.3, the per-
cent flow during the three driest months varied from 23% in 1984 to 48% in 1979
with an average of about 38%, which has been shared between the two, as shown in
the table.
Distribution of the total lean-season flow, as shown in Table 8.4, is about 10% of
the total annual flow of the river. This flow has been between Ganga downstream
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