The urban sprawl continues to occupy more space and, in the process, waterbodies shrink. With increasing population density and monsoons going awry, cities find themselves heading towards water-related crises.
The city, which teeters between floods and droughts, continues to lose out on its water resources due to mismanaged urbanisation and encroachments. The systematic destruction of waterbodies comes in the wake of the massive 2015 floods and years of drought thereafter.
The most recent case being Thamaraikeni lake, Sholinganallur, which has shrunk in size from 152 acres to 26 acres. The lake remains vulnerable as a portion of it has been reclassified in terms of land use to put up a police station.
This is one of the many waterbodies in and around the city that are being slowly destroyed by the urban sprawl. According to the audit report of the Comptroller and Auditor General of India, 2017, the built-up area in the Chennai metropolitan area has grown from 90.88 sq. km. in 1979, to 541.14 sq. km. in 2016. On the other hand, the water spread area of lakes and ponds has shrunk from 100.98 sq. km to 91.31 sq. km. in the past 40 years.
HOW TO READ THE IMAGES & GRAPHS
In each satellite image below, the area marked in red points to the extent of that lake in 1973 and the waterbody below depicts the actual lake extent as of 2018. The roads that criss-cross and the buildings built over the red area were once part of the lake which were later enroached upon. The graph below the maps shows the extent of select waterbodies* in 1954 and 2016. For instance, the Pallikaranai wetlands have shrunk from 15,000 acres in 1954 to just 1,500 acres in 2016.
Key to recharge
Protection of waterbodies plays a key role in sustaining groundwater recharge and preventing urban flooding, note experts. Jayaram Venkatesan, convener of Arappor Iyakkam, a non-governmental organisation, said many lakes also faced the threat of ‘legalised encroachments’ with reclassification of land use. He claimed that the State government did not have the authority to reclassify land use of waterbodies.“Lakes are major rainwater harvesting structures, and need to be classified as ecological hotspots. Several of them continue to be sewage cesspools. The Tamil Nadu Protection of Tanks and Eviction of Encroachments Act, 2007, that emphasises demarcation of boundaries and eviction of encroachments, has not been implemented effectively,” he added.
Though the integrated Cooum River Eco-restoration Project is on, tackling sewage pollution in the waterway remains a major challenge. Sources in the Water Resources Department note that the river in city limits continues to receive industrial effluents and sewage in several areas such as Greams Road and Chintadripet.The department has nearly finished work of desilting the waterway in the city.
But, restoration is not complete without plugging of sewage outfalls. Experts note that building sewage treatment plants along the river bund will only be an immediate solution and will not help in arresting new sewage outfalls. There is a need for concerted efforts by the government and people to save the city’s waterways.Chief Minister Edappadi K.Palaniswami on Thursday announced in the State Assembly that a comprehensive policy would be formulated for use of recycled water in industries and prevention of pollution of waterbodies.
Recycled water
Recycled water is indeed the solution to creating a resilient and drought-free water supply scenario, said experts. L. Elango, professor, Department of Geology, Anna University, said in hydrogeological terms, Chennai is not the best location for groundwater overextraction. Pollution of rivers would lead to groundwater contamination in adjacent areas.“We need a multi-pronged approach to reduce water stress — restoration of waterbodies, augmentation of surface water partly with release of treated sewage into rivers and use of recyled water,” he said. Citing an Anna University study, he said recycled water could contribute to nearly 30% of the city‘s water needs by 2030.
In a bid to tackle apathy towards waterbodies, the State government must form a lake development authority with a dedicated force to protect waterbodies as rainwater harvesting sources, according to Arun Krishnamurthy, founder, Environmentalist Foundation of India. “Lakes are encroached upon for development of infrastructure too. They must be declared as protected zones and government must invest in creating water literacy and take severe action against offenders,” he added.
