Cyclone and Storm Surge - Iczmpwb.org

6.47
15. Ceriops tagal 0.22 0.40 0.50 0.61 1.72
16. Phoenix paludosa 0.40 0.55 0.70 0.85 1.05
17. Nypa fruiticans 0.50 0.60 0.76 0.95 1.20
6.5. Coastal erosion protection
The total length of coastal embankment in West Bengal is about 58 kms stretching from the Orissa-
West Bengal border west of Digha upto the Rasulpur river. It is maintained by the Irrigation and
Waterways Department, Government of West Bengal. The embankment protects the inundation of
inland habitated areas from the wrath of violent cyclonic storms and consequent storm surges.
However, the embankment is not very close to the sea at all places. At Chandpur, for instance, it is
so close to the sea that it has been eroded off along a considerable length. At places like
Shankarpur, the embankment is safe, but a large chunk of coastal shelter belt plantation of Casurina
trees have come under the threat of erosion by the dashing sea waves. The jetty at the same place
has been washed off, and at present some temporary measures have been taken by the Irrigation
and Waterways Department, to reduce the effect of the waves. At Digha, the erosion of sea beach
has been prevented from further recession by providing a very costly revetment using concrete
blocks. But just east of this section, there is severe erosion and a big patch of Casurina shelter belt
plantation is presently under threat of being wiped away. It may be noted that in the past couple of
decades, quite a good area of such plantation has already been devoured by the sea by repeated
wave action and enhanced wave dashes during cyclonic storms.
As such, the severely affected portion of the coastal embankment that is affected by erosion (and
enhanced during occurrences of cyclones) is estimated to be about 20 kms. This is because not all
coastline of West Bengal is affected by erosion. In fact, at Junput, there has been a lot of deposition
and the shoreline has shifted seawards over the years. Anyway, the reach that is affected by severe
erosion needs immediate attention, otherwise valuable land is likely to get lost due to shoreline
recession and consequent loss of human habitated land areas.
A possible solution to counter the sea face erosion is to provide a boulder revetment underlain with
geotextile, as shown in Figure 6-20. This design has been taken from the Manual on the use of Rock
in Hydraulic Engineering published by the Road and Hydraulic Engineering Division of the
Government of Netherlands. It has been tested in many locations along sea faces, though certain
other methods may also prove equally useful.