Chennai and Rain – Perennial Problem

Chennai , formerly known as Madras, is the fourth  largest metropolitan area of India and the capital city of the Indian state of Tamil Nadu. Located on the Coromandel Coast of the Bay of Bengal, Chennai had a population of 4.2 million in the 2001 census within its municipal corporation. The urban agglomeration of Chennai has an estimated population over 8 million, making it one of the largest urban agglomerations in India.
Chennai's soil is mostly clay, shale and sandstone. Sandy areas are found along the river banks and coasts. Chennai lies on the thermal equator and is also coastal, which prevents extreme variation in seasonal temperature. For most of the year, the weather is hot and humid. 
The average annual rainfall is about 1,300 mm (51 inches). The city gets most of its seasonal rainfall from the north-east monsoon winds, from mid-September to mid-December. Cyclones in the Bay of Bengal sometimes hit the city. 
Chennai has the Marina Beach (second longest beach in the world) runs for 12 km along the shoreline of the city. 
Two rivers meander through Chennai, the Cooum River (or Koovam) through the centre and the Adyar River to the south. 
A third river, the Kortalaiyar, flows through the northern fringes of the city before draining into the sea at Ennore. 
The Buckingham Canal , 4 km (3 miles) inland, runs parallel to the coast, linking the two rivers. 
The Otteri Nullah, an east-west stream, runs through north Chennai and meets the Buckingham Canal at Basin Bridge. 
There are about 35 lakes and tanks of varying sizes, are located on the fringes of the city. 
If the rivers, lakes, ponds and tanks are utilized properly, along with the Buckingham Canal, the water logging and flood situation could be easily prevented.
Chennaites  face heavy rain and subsequent water logging for weeks after the rains. This despite the fact that Chennai has lots of natural facility to prevent this problem. Not in many metropolitan cities do you find 2 rivers, a canal connecting those rivers and numerous lakes. If most of the rain water are drained to these water bodies, or if there is a proper drainage system to facilitate the easy flow of water, then Chennai wouldn't face flood problems.
In many areas, the water had inundated into homes and shops to about 4 to 6 feet. Properties were lost and business were lost because of this flooding. 
This happens almost every year, and yet, the civic bodies don't have the intelligence and resource to solve this problem.
Years of inaction by the Chennai Corporation have allowed encroachments to settle down over the stormwater drains and the waterways leading to further blockage. 
Encroachments on waterways have been identified as one of the major causes of inundation during heavy rains, according to a flood mitigation strategies report commissioned by the Chennai Corporation.
A study by the Tamil Nadu Slum Clearance Board and the Public Works Department in 2002 and 2003 revealed that 31,540 families had been staying along the banks of the Adyar and the Cooum rivers as well as on the banks of the Buckingham Canal. 
According to Aarvee Associates report, more than 15,345 families stay on the banks of the Buckingham Canal during the said period, while 9,562 families live along the Cooum River and 6,624 live along the Adyar River. Canals across the city are choked with encroachments, preventing the flow of storm water. 
The government had also allowed construction of residential colonies in several catchment areas, like Adambakkam, Nanganallur, Alandur and Tirusulam.
The city has stormwater drains of about 950 km, about 100 km of which have been constructed in the recent years. The remaining 850 km are older drains that need to be regularly desilted. The civic body does not regularly desilt the drains as part of its pre-monsoon exercise. There are also demands to construct additional storm water drains in several areas to prevent water logging.

Chennai is one of the metros in India with chronic water problems which is dependent mostly on ground water supply.
In many parts of Chennai, the traditional wells had dried up years ago. People then resorted to drilling deep and installing bore wells. Some of these bore wells go as deep as 200 feet and more to find water. How long can we expect to get water from these bore wells without replenishing the water sources? Recharging the ground with rainwater helps to refresh the water resources.
Don't you think its ironic, that the city which faces water shortage, gets affected by water logging and flooding. 
  • Management of drainage lines for efficient water flow.
  • Management of surface water-flow to avoid surface ponding.
  • Properly and regularly desilt existing storm water drains, lakes and tanks.
  • Remove the encroached extension of Slum Clearance Board tenements, temples and hutments on the banks. 
  • In order to control the flood water, there has to be a diversion canals diverting storm water or waste water to discharge into the nearby river.
  • Effective Rain water storage solution in each and every building. If each building could store half of the rain water being drained into the road, flooding could be reduced by half.
  • Increase deep rooting vegetation for greater utilization of water from the soil
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Posted via email from Edward Anil’s Blog

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