Environmental Engineering Reference
In-Depth Information
Table 1.3
Important rivers of Indian Sundarbans
Estuaries
Description
Hugli
It forms the western border of Indian Sundarbans
It is the main river of West Bengal and along with the Ganges and Bhagirathi rivers comprise a
national waterway
Most of the coastal industries of West Bengal are concentrated along the western bank of this river
Muriganga
It is a branch of the Hugli River
It
ows along the east of Sagar Island
Unique mangrove vegetation is found along the bank of this river
fl
Saptamukhi
It has its origin at Sultanpur
It is connected with the Muriganga (Bartala) branch of the Hugli River through Hatania
Duania
-
canal
Thakuran
It begins near Jayanagar in South 24 Parganas and has a number of connections with the Saptamukhi
It has perhaps earlier connected with the Calcutta canal through the Kultali and the Piyali rivers,
which exist today in a dying state
Matla
This river originates at the confluence of Bidyadhari, Khuratya and the Rampur Khal close to the
town of Canning in South 24 Parganas
Matla is connected to Bidya and ultimately
ows to the Bay of Bengal. The freshwater connection
and discharge to this river have been lost in the recent times
Salinity of the river water is relatively high (in comparison to Hugli or Muriganga) owing to
freshwater cut-off from the upstream region
fl
Bidyadhari
This was
ourishing branch of the Bhagirathi during the fteenth or sixteenth century, but now
serves only as a sewage and excess rainwater outlet from the city of Kolkata
The river bed is completely silted, and presently, it is almost in dying condition
fl
Gosaba
The waters of Matla and Harinbhanga (Raimangal) through a large number of canals from it
The river
fl
ows through the reserve forests
Harinbhanga
The river begins from Sahebkhali in North 24 Parganas and is connected with the Rampura khal by
Barakalagachi River and with the Gosaba River through the River Terobhanki
The Harinbhanga (also known as Ichamati and Raimangal) forms a natural demarcation between
India and Bangladesh
'
deep-water waves
'
c. The third division is ordinary gravity waves
with periods between 1 and 30 s. They are
composed of two types of waves, namely
a. A
is one in which the
ratio depth (d)/wave/length (l) is more than
0.5. Capillary waves belong to this category.
b. A
'
sea
.
d. The infra-gravity waves are generally long
period waves having periods between 5 min
and 12 h.
waves
'
and
'
swell waves
'
'
shallowwater wave
'
is one in which D/L is
are shallow water
waves even in the deepest portion of the ocean.
Another mode of wave classi
less than 1/20.
'
Tsunamis
'
'
Tsunamis
'
and
'
storm surges
'
cation is by the
belong to this division.
e. The ordinary tidal waves are astronomical
waves with
nature of controlling force.
a. The shortest of the waves, the capillary waves,
have a restoring force due to the surface
tension of water. When water has been dis-
placed, the force brings it back to normal
position due to surface tension.
b. In case of ultra-gravity waves and gravity
waves, gravity acts as the major restoring
force.
c. Gravity together withCoriolis force acts as the
restoring force in case of long-period waves.
xed time period of about 12 h
(semi-diurnal) and 24 h (diurnal).
f. The trans-tidal waves are those having peri-
ods greater than 24 h. Under this, the longer
period components of astronomical tides are
also included.
Waves can also be classi
ed on the basis of
the relationship of the waveform to the depth
of water.
