சென்னை வெள்ளம் ஒரு கருத்து சித்திர தொகுப்பு - தமிழீழச் செய்தியகம்
புதிய தலைமுறை தொலைக்காட்சி நகரமைப்பு விபரணம்:
குறிப்பு: ஒளி நாடா விபரணம் உரைக்கும் மையமான கருத்து; கடந்த 10 ஆண்டுகளில் எடுக்கப்பட்ட நகரமைப்புப் பணிகளே இவ் அனர்த்தத்துக்கு தனிக் குறிப்பான காரணமாகும்.
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இந்திய உலகமயத்துக்கு படுக்கை விரித்த, தமிழ் நாட்டு ஆளும் கும்பல்களின், சிசுவே-
2015 சென்னை வெள்ளம்!
புதிய ஈழப் புரட்சியாளர்கள்
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SUBMERGED
Thanks to the “Make in Chennai” boom.
WRITTEN BY Nityanand Jayaraman · Nov 18, 2015 · 08:15 am
CHENNAI FLOODS
Tamil Nadu Chief Minister J Jayalalithaa's response to the floods in Tamil Nadu is frightening. A report in NDTV quotes her as saying, “Losses are unavoidable when there's very heavy rain. Swift rescue and relief alone are indicators of a good government.” These words are intended to normalise a human-made disaster, and gloss over the pathology of urban development under successive administrations.
It is quite usual for politicians and civic officials to blame so-called unprecedented rains for the civic and humanitarian crisis each monsoon brings, and decouple development from disaster. But unprecedented rains occur quite regularly in Chennai. As a city on the high-energy coast facing the Bay of Bengal, Chennai is no stranger to heavy rains and cyclonic storms. Chennai has experienced particularly heavy rains roughly once every 10 years – 1969, 1976, 1985, 1996, 1998, 2005, 2015.
Sathyabama University was constructed in a water body on Old Mahabalipuram Road.
In fact, at 235 mm, last weekend's rainfall is not even the big daddy of big rains. The Nungambakkam rain gauge recorded 270 mm on October 27, 2005; 280 mm in 1969, and 450 mm in November 1976.
Even in 1976, Adyar overflowed its banks and invaded first-floor houses. But those were the days when Chennai was derided for being an overgrown village, an underdeveloped aspirant to metropolitan status.
Today, Chennai has a host of expensive infrastructure aimed at ushering in a “Make in Chennai” boom – a brand-new (though leaky) airport built on the floodplains of the River Adyar, a sprawling bus terminal in flood-prone Koyambedu, a Mass Rapid Transit System constructed almost wholly over the Buckingham Canal and the Pallikaranai marshlands, expressways and bypass roads constructed with no mind to the tendency of water to flow, an IT corridor and a Knowledge Corridor consisting of engineering colleges constructed on waterbodies, and automobile and telecom SEZs and gated residential areas built on important drainage courses and catchments.
MRC Nagar 2001, Google Maps
MRC Nagar 2015, Google Maps
With every invitation to Make in Chennai, the city is unmaking itself and eroding its resilience to perfectly normal monsoon weather events. The infrastructure of big commerce has replaced the infrastructure to withstand natural shocks.
The 2015 disaster was not just avoidable; it was a direct consequence of decisions pushed for by vested interests and conceded by town planners, bureaucrats and politicians in the face of wiser counsel.
The case of the Pallikaranai marshlands, which drains water from a 250-square-kilometre catchment, is telling. Not long ago, it was a 50-square-kilometre water sprawl in the southern suburbs of Chennai. Now, it is 4.3 square kilometres – less than a tenth of its original. The growing finger of a garbage dump sticks out like a cancerous tumour in the northern part of the marshland. Two major roads cut through the waterbody with few pitifully small culverts that are not up to the job of transferring the rain water flows from such a large catchment. The edges have been eaten into by institutes like the National Institute of Ocean Technology. Ironically, NIOT is an accredited consultant to prepare Environmental Impact Assessments on various subjects, including on the implications of constructing on waterbodies.
Other portions of this wetland have been sacrificed to accommodate the IT corridor. But water offers no exemption to elite industry. Unmindful of the lofty intellectuals at work in the glass and steel buildings of the software parks, rainwater goes by habit to occupy its old haunts, bringing the back-office work of American banks to a grinding halt.
The vast network of waterbodies that characterised Chennai can only be seen on revenue maps now. Of the 16 tanks belonging to the Vyasarpadi chain downstream of Retteri, none remain, according to Prof. M. Karmegam of Anna University.
Virtually every one of the flood-hit areas can be linked to ill-planned construction. The Chennai Bypass connecting NH45 to NH4 blocks the east flowing drainage causing flooding in Anna Nagar, Porur, Vanagaram, Maduravoyal, Mugappair and Ambattur. The Maduravoyal lake has shrunk from 120 acres to 25. Ditto with Ambattur, Kodungaiyur and Adambakkam tanks. The Koyambedu drain and the surplus channels from Korattur and Ambattur tanks are missing. Sections of the Veerangal Odai connecting Adambakkam tank to Pallikaranai are missing. The South Buckingham Canal from Adyar creek to Kovalam creek has been squeezed from its original width of 25 metres to 10 metres in many places due to the Mass Rapid Transit System railway stations. Important flood retention structures such as Virugambakkam, Padi and Villivakkam tanks are officially abandoned.
Capacity reduction
Before political rivalry between the two Dravidian parties brought it to a midway halt, an ill-advised Elevated Express freight corridor from Chennai harbour to Maduravoyal had already reclaimed a substantial portion of the Cooum's southern bank drastically reducing the flood-carrying capacity of the river.
Remarkably, all these causes were listed out by the government's own officials at a seminar on waterways organised by the Chennai Metropolitan Development Authority in 2010. But there seems to be many a slip between enlightened understanding and enlightened action.
The Second Masterplan prepared by the Chennai Metropolitan Development Authority glibly authorises built-up spaces with no regard to hydrology. In the Ennore region, the authority has reclassified waterbodies, intertidal zones and mangrove swamps as “Special and Hazardous Industries” and handed it over to the Kamarajar Port Ltd.
In Ponneri, a town in a rural part of Chennai Metropolitan Area, developers are executing Chennai Metropolitan Development Authority-approved plans with no regard to drainage. Last weekend, Ponneri received 370 mm of rain – 135 mm more than Chennai did. While it suffered from flooding, damage to property and life was not high. Ponneri is slotted to be developed as a Smart City. But will our dumb engineers be able to build a smart city?
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http://scroll.in/article/769928/chennai-floods-are-not-a-natural-disaster-theyve-been-created-by-unrestrained-construction
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Chennai's vanishing waterbodies
A.SRIVATHSAN, K.LAKSHMI
Ghost of waterbody:Maduravoyal lake is one of the many waterbodies on the city fringes that have shrunk owing to encroachments and inadequate maintenance.— Photo: Maheshwar Singh
Ghost of waterbody:Maduravoyal lake is one of the many waterbodies on the city fringes that have shrunk owing to encroachments and inadequate maintenance.— Photo: Maheshwar Singh Of 650 extant two decades ago, only a fraction remains; water shortages, flooding a direct consequence
About two decades ago, a research project by the Centre for Environmental and Water Resource Engineering, IIT Madras estimated that about 650 waterbodies existed in the Chennai region.
More than half of them were located south of River Adyar. At present, as the second Master Plan for Chennai indicates, only a fraction of them exists. Most of the waterbodies within the city have vanished and only a few remain in the immediate periphery.
According to records of the Water Resources Department (WRD), the area of 19 major lakes has been shrunk from a total of 1,130 hectares to nearly 645 hectares and hence reduced their storage capacity.
M. Kaarmegam, former director of the Centre for Water Resources, Anna University, said: “There were 16 tanks downstream of Retteri called Vyasarpadi chain of tanks. Kodungaiyur tank was one among them. Now, there is no sign of them. There was also a tank in Thirumangalam area.”
Maduravoyal Lake, which was once spread across 120 acres has now shrunk to 25 acres. Encroachments and misuse of lake bed were the reasons, he added.S. Narayanan, treasurer of Kazura Garden Residents' Welfare Association, Neelankarai, recalled that there were over 13 waterbodies in the area until a few decades ago. “Many of them have been encroached upon and buildings have come up. There are only two lakes now. Even a pond in our colony has been encroached,” he said.
The consequence of this rapid loss of waterbodies has not only reduced the extent of collective water harvesting, but also severely impacted flood management within the city. The principal cause of local flooding in many areas, it emerges, is the mismanagement of waterbodies and impairment of linking canals.
For instance, the Virugambakkam drain, which was 6.5 km long and drained into the Nungambakkam tank, is now present only for an of extent of 4.5 km. The remaining two km stretch of the drain is missing. Nungambakkam tank was filled and built.
This along with the loss of Koyambedu drain has resulted in the periodic flooding of Koyambedu and Virugambakkam areas.
This phenomenon is now repeating in the suburbs. The surplus channels connecting various waterbodies in western suburbs such as Ambattur and Korattur have been encroached upon. The waterbody in Mogappair has almost disappeared. Lake beds often serve as make shift dumping yards and cesspool. This has resulted in inundation of neighbouring localities.
The Veerangal Odai that connects the Adambakkam lake with Pallikaranai marsh ends abruptly after 550 m from its origin and the remaining part is not to be seen. This causes inundation in places such as Puzhithivakkam and Madipakkam.
S. Mohan, professor, Environment and Water Resources Engineering, IIT Madras, cautions that loss of waterbodies and channels not only induced flood but also increased saltwater intrusion. As a thumb rule, he said, every one metre of water-head in a water body can push sea water laterally by 40 meters.
The waterbodies thus function like a protective ring. But for the presence of Buckingham Canal, saltwater would have intruded further west and affected more residential areas, Mr. Mohan explained. Restoration and proper maintenance of the tanks are critical to Chennai's future, he emphasised.
Some of the tanks, because of negligence have silted at the rate of 2 to 3 mm every year and some have been lost due to encroachments.
A way forward would be to create a scientific inventory of waterbodies and delineate flood zones within the city. The flood zone will have to be identified based on the location of the waterbodies, natural drains, water shed area and it has to be a no building zone, said Mr. Mohan.
According to sources in the WRD, only 19 of the 29 existing major waterbodies can be restored. Others such as the Ullagaram, Adambakkam, Thalankanacheri, Mogappair and Senneerkuppam tanks cannot be restored, they say. The case of lost water channels is even worse, they have totally disappeared.
All is not lost say the officials. The waterbodies in Madhavaram and Korattur can be fully restored. The water resources along with that in Ambattur and Porur could be used as storage points as they would have a capacity of 600 million cubic feet of water.
Once rejuvenated, the 19 waterbodies would have a combined storage capacity of 1,000 mcft. At present, the city reservoirs have a storage capacity of 11,000 mcft, officials of the Water Resources Department said.
The department is also in the process of improving the waterways and surplus courses and creating straight cut canals from various waterways to the Cooum under the Jawaharlal Nehru National Urban Renewal Mission. This could substantially improve flood management within the city, officials added.
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வெள்ள அனர்த்த வீடியோ பதிவுகள்;இரண்டு
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