Cyclone and Storm Surge - Iczmpwb.org

3.20
the ocean level as a result of storm surges. This causes flow accumulation in the drainage channels,
which in turn, causes backflow into the city.
The waterlogging problem may be ascribed to the typical geographical feature of the city being of
saucer type, the central portion being of lower elevatron and pumping is required to remove the
waterlogging as there is hardly any scope for gravitational drainage. The eastward drainage does not
pose much serious problems while the areas, viz. Amherst Street, Thanthania, Chitpur, Free School
Street, Camac Street, Sarat Basu Road where sewers have a north-south alignment have chronic
waterlogging problem. The inadequate road surface area of the city of only 6-8 percent aggravates
the waterlogging problem. The storm water from the buildings instead of draining into the sewers
through the yard gullies is discharged onto the inadequate road surface. Moreover, the gully pits on
the roads, through which the water should drain out are inadequate in number and often choked
owing to lack of maintenance. Further, rain washes solid waste to the mouths of gully pits, blocking
the free flow of water into them. Besides, the city sewer system has no separate dry weather and
storm weather flow arrangement thus resulting in major and minor underground trunk sewer lines
being badly silted up for absence of cleaning at regular intervals and this has made the reduction in
flowing capacity of storm weather flow considerably to the extent of about 30 percent.
3.14. Drainage of Bidhan Nagar (Salt Lake)
Salt lake is divided into three zones namely Sector I, Sector II, and Sector III which have different
topographical and consequential drainage features. While storm water of Sector I, and Sector II flow
into Kestopur Canal by gravitation, nearly 40 percent of the drainage of Sector III is effected by the
pumping station at DE-block and rest through gravitation flow into Eastern Drainage Canal. It can
easily be understood the vital part these two canals namely Kestopur and Eastern Drainage Canal
play in overall storm water management of Salt Lake. Since both these two canals originate from
Kolkata desilting of these two canals will contribute a lot for swift drainage of Salt Lake, in addition to
the benefit of Kolkata Municipal area.
It must be remembered that Bidhan Nagar was formed by filling up of low-lying marshy lands with
sand from the river Hooghly. Not all places of the reclaimed land was filled up the same extent.
Hence, certain portions of the township which are not that high suffer fromdrng congestion. Also, the
drainage channels of Kestopur Canal and the Eastern Drainage Canal have silted up considerably
from their original design sections, resulting in backflow of the township’s internal storm water
drainage.