The Polambakkam Lake : A Thangal-Eri Water Story

பண்டயகால தமிழகத்தில் 47 வகையான நீர்நிலைகள் இருந்திருக்கின்றன. 

ஆறு நிரம்பி ஏரி,

ஏரி நிரம்பி கண்மாய்,

கண்மாய் நிரம்பி கரணை,

கரணை நிரம்பி தாங்கல்,

தாங்கல் நிரம்பி ஏந்தல்,

ஏந்தல் நிரம்பி ஊரணி,

ஊரணி நிரம்பி குளம்,

குளம் நிரம்பி குட்டை.

அன்றோ குட்டை நிரம்பியது!

ஆனால் இன்று?

நீர்நிலைகளின் வகைகளை பட்டியலிடுவது ஒருபுறம் இருக்கட்டும், இன்றைய காலத்தில் நம் நீர்நிலைகளை பார்க்கக் கூட முடியாது. அதிசயமாக ஒரு ஏரியும் தாங்கலும் ஒன்றாக இணைந்த பொலம்பக்கம் ஏரியை நாங்கள் கண்டுள்ளோம். அதனை பற்றி விளக்கும் வலைப்பதிவுதான் இது. 

Let’s recall some of the localities in Chennai- Iyyappanthangal, Ekkatuthangal, Retteri and Ponneri. What do these names denote? A thangal or a lake that once thrived as a huge water body in the region. With rapid urbanization and overpopulation, we have turned these precious water bodies into irregular terrains with high-raised apartments and concrete roads.

From Poonthangal, Periyathangal, Puthuthangal, Panayanthangal, Karanaithangal, Rajanthangal, Thazhanthangal to Uzhavarkeni Thangal, E.F.I’s eco restoration of thangal in Tamil Nadu has been extensive.

Check out how E.F.I’s Rajanthangal Lake Restoration is beneficial to the local community:

The Polambakkam Lake

This time, we are bringing you the astounding story of Polambakkam Lake. A large water body that is both a thangal and a lake (eri), which feeds hundreds of acres of farm fields in the district of Chengalpattu.

Situated 95 kms south to the capital city of Chennai, the Polambakkam Lake spreads across an area of about 175 acres. As part of an interconnected lake system, the Polambakkam lake is a crucial water body that is connected with the outlet of the Karumpirai Lake. This means that the lake’s water retention capacity is crucial to ensure the smooth flow of water to other lakes and ponds in the area. 

Sadly though, the Polambakkam Lake was in a deteriorated state due to excessive silt deposit and a lack of definitive boundary in its foreshore region. The lake was heavily infested with invasive plant species such as Prosopis juliflora, Ipomea carnea, and other thorny shrubs, compromising the lake’s capacity to store water. The inlet channel, which is crucial for supplying water to the lake, faced encroachment threats. Additionally, elevated roads and buildings constructed on the foreshore obstructed surface water runoff from flowing into the lake’s deeper areas.

E.F.I’s Restoration Efforts

Given its vast expanse, the lake was strategically segmented into six zones to ensure efficient execution of restoration efforts. A series of activities ranging from deweeding, desilting, construction of nesting islands, recharge pits and percolation trench are being carried out in the Polambakkam Lake. 

  • Deweeding: Invasive plant species such as Prosopis juliflora and Ipomea carnea covered the lake surface. Prosopis juliflora spreads rapidly and significantly reduces groundwater levels due to its deep tap roots. Thus hindering the growth of native vegetation. Therefore, a total of 75.39 acres was deweeded across 5 zones in the lake and a 1830 m of weeds were cleared on the bund to promote a healthy ecosystem with enhanced biodiversity. 
  • Desilting: Desilting is the process by which accumulated silt is removed from the surface of a water body. Over time, accumulated sediment reduces the volume of water a lake can hold. Desilting helps restore this capacity, ensuring the lake can adequately store water during rainy seasons and mitigate flooding risks. By increasing the water volume, desilting can also help maintain healthy water levels during dry periods. The Polambakkam Lake was desilted at an average depth of 2 ft for an expanse of 14 acres.
  • Bund Construction: Construction of bunds is essential for the lake to maintain water levels, especially during dry periods. A dual embankment with primary and secondary bund was made to enhance the lake’s structural integrity and to clearly demarcate its boundaries. Primary bund of 2356 meters was strengthened and secondary bund of 593 meters was constructed.
  • Construction of Islands: Using the excavated silt, nesting islands were created to enhance the biodiversity of the lake and provide a place for aviary and territorial species to thrive in. By providing a safe and undisturbed space, nesting islands can significantly increase bird reproduction, which is necessary to enhance habitat diversity. 
  • Recharge Pits: Recharge pits are structures that are deeper than the average depth of the lake bed. By contributing to a higher groundwater table, recharge pits can help maintain healthy water levels in the lake, especially during dry seasons. They enhance groundwater percolation and the overall water storage capacity.

After Restoration

With E.F.I’s restoration efforts, the Polambakkam Lake has been transformed into a water paradise. As a healthy aquatic ecosystem, the lake supports all life forms and is a vital source of water for the nearby farmlands. The thangal-eri has now become a significant biodiversity hotspot that can be boasted about by future generations. 

Take a look at the wide expanse of water in the Polambakkam Lake:

Volunteer for India and her Environment with E.F.I

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