Agreements & MOUs - The Ganga: Water Use in the Indian Subcontinent - page 208

Table 10.15 Mean navigable depths over five different bars below Calcutta up to Hooghly point
during lean season

Year Roypur Phalta Ninan Nurpur Eastern gut

1 2 3 4 5 6

1974 4.40 3.50 4.40 3.90 4.35

1975 4.70 4.40 5.35 4.25 4.15

1976 4.30 4.00 4.35 3.70 4.60

1977 4.80 3.80 4.50 4.00 4.20

1982 4.90 4.65 5.00 4.35 3.75

1987 5.00 3.90 3.85 3.35 3.50

1992 5.05 3.60 4.15 3.80 3.75

1996 4.50 4.40 5.20 4.00 3.65

1997 4.55 4.35 4.95 3.80 2.50

1998 4.90 4.15 4.50 4.70 3.50

1999 5.40 4.75 4.10 3.75 3.25

Table 10.16 Available mean depth in days for ships navigating the port area round the year

Navigable depth
(m) <3.0 m

Navigable depth (m)
3.0-3.50 m

Navigable depth (m)
3.51-4.0 m Year (July-June)

1 2 3 4

1984-1985 17 194 154

1985-1986 31 181 153

1986-1987 36 206 123

1987-1988 152 214 −

1988-1989 36 268 61

1989-1990 3 209 153

1990-1991 15 228 122

1991-1992 34 332 −

1992-1993 91 243 31

1993-1994 20 253 92

1994-1995 118 234 13

1995-1996 224 141 −

1996-1997 184 181 −

1997-1998 132 233 −

1998-1999 127 238 −

on the waterway, the tides from the sea dissipate their energy in forming a wave with
a high column of water and moving upstream. In the Hooghly, they rise two to three
metres high and hazard the movement of ships and damage jetties, mooring bits,
sea-walls etc. Few river estuaries in the world experience such phenomena. Before
the barrage came up, the Hooghly used to have tidal bores of varying intensity,
throughout the year. Afterward, the frequency of bore tides came down because of
continuous upland flow, as shown in Table 10.17. The percentage of their occurrence
fell to five after the barrage was commissioned from 50 before it.