Cyclone and Storm Surge - Iczmpwb.org

Cyclone and Storm Surge - Iczmpwb.org Cyclone and Storm Surge - Iczmpwb.org

03.05.2015 Views

2.52 2. To reduce the average distance water needs to be transported during the periods the sluice is able to spill water. This means that the main body of the volume stored in the internal system should be located as close as possible to the gate. Many ponds and channel sections are used for fish breeding. Nets are used to prevent the fish to be washed away. These nets might reduce the discharge capacity of the canals significantly when they are stretched from one side of the canal to the other. Here is a conflict of interest. Zoning might offer a compromise. If fish breeding can be restricted to the far end sections of the canals or even better in special ponds, the reduction in the drainage capacity of the system might be limited. Zoning is not necessary if the velocity of the flow in the canals of the internal system is low (less than 0.15m/sec) when the sluices are spilling at full capacity. In any case it is advisable to avoid nets right in front of the inflow of the sluice gate.

Chapter Three Effect of Cyclones on Kolkata and Surroundings 3.1. Hazard on urban habitation zones due to tropical cyclones The most important urban conglomeration within the easy reach of tropical cyclonic storms is the State Capital Kolkata. Contiguous with Kolkata proper is a large urban area that includes what is called the Greater Kolkata, including the relatively newly developed township of Bidhan Nagar (also called Salt Lake) and the upcoming Rajarhat development area. Presently, the Kolkata Municipal Corporation Area measures around 187.33 sq. km. According to the 2001 Census, the population of this region is around 45,80,544 and the area is divided into 15 Boroughs and 141 wards. According to historical according, Kolkata developed around three villages – Sutanuti, Kolkata, and Gobindapur. These villages occupied the following present day regional demarcations: CHAPTER 3 Sutanuti Kolkata Gobindapur Chitpur, Baghbazar, Sobhabazar & Hatkhola Dharmatala, Bowbazar, Simla, Janbazar Hastings, Maidan & Bhowanipur The newer additions to the Kolkata municipality are the following: North South East Sinthi, Cossipore & Gughudanga Tollygunge, Khidderpore & Behala Salt Lake , Beliaghata & Topsia The city on the west is bound by the river Hooghly. As such, an intense rainfall as during a tropical cyclone over this region means a lot of runoff since much of the areas has been paved with little or no scope for natural infiltration. Ironically, the terrain of the land slopes from the west, at the edge of the river Hooghly, towards the east. Further east are the scattered salty marsh lands crisscrossed by the different tidal streams and channels that are connected to the Bay of Bengal to the south. The important creeks here are the Matla, Bidyadhari, Kultigong, Ichhamati, Raimangal, etc. Of course, a small portion of the city, mainly to the south and closer to the river Hooghly drains to the west. However, whether the eastern tidal creeks, or the river Hooghly to the west, both are prone to water level variations of the ocean: the Bay of Bengal, to be precise. This rise of water levels in the rivers is due to either only tidal variations or that coupled with

2.52<br />

2. To reduce the average distance water needs to be transported during the periods the sluice<br />

is able to spill water. This means that the main body of the volume stored in the internal<br />

system should be located as close as possible to the gate.<br />

Many ponds <strong>and</strong> channel sections are used for fish breeding. Nets are used to prevent the fish to be<br />

washed away. These nets might reduce the discharge capacity of the canals significantly when they<br />

are stretched from one side of the canal to the other. Here is a conflict of interest.<br />

Zoning might offer a compromise. If fish breeding can be restricted to the far end sections of the<br />

canals or even better in special ponds, the reduction in the drainage capacity of the system might be<br />

limited. Zoning is not necessary if the velocity of the flow in the canals of the internal system is low<br />

(less than 0.15m/sec) when the sluices are spilling at full capacity. In any case it is advisable to avoid<br />

nets right in front of the inflow of the sluice gate.

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