Aquifer recharge area down by 250 acres in 8 years, sets off alarm

Study says urban development eating into no-development zone along Thiruvanmiyur to Uthandi coast in Chennai, will affect groundwater recharge, leading to seawater intrusion
Image used for representational purposes only
Image used for representational purposes only

CHENNAI: Setting off water security concerns in Chennai, the aquifer recharge area on the southern coast from Thiruvanmiyur to Uthandi, classified as a ‘No-development Zone’,  has seen a decline of 250 acres between 2011 and 2019.

According to the interim report presented by the Centre for Urbanisation, Buildings & Environment (CUBE) to Chennai Metropolitan Development Authority (CMDA), the ‘No Development zone’  decreased from 1,739 acres in 2011 to 1,495 acres in 2019.

Claiming that this could be due to the dwindling open land and agricultural land and the rise in the built-up area, the study points out that such changes will result in a reduction in the recharge of groundwater resulting in a lowering of the groundwater table followed by seawater intrusion.

“The area of built-up land witnessed substantial growth, expanding from 2344.6 acres (13.1%) in 2002 to 4326.1 acres (24.2%) in 2013, and further increasing to 5162.2 acres (28.8%) in 2023,” the report said.

The ‘No Development Zone’ highlights the significance of preserving aquifers in their natural state, free from any development activities. Currently, the permissible developments in the zone include non-high-rise buildings up to a height of 9 metres.

The buildings include residential, professional consulting offices, schools, shops, parks, cottage industries, storage facilities, hostels, assembly halls, transportation depots, and various public utility buildings. The development parameters such as plot extent, frontage, floor space index (FSI), plot coverage, and height are regulated based on the type of development and location.

CMDA has asked CUBE to carry out the study as it plans to revisit the ‘Development Rules’ for the aquifer recharge area. The idea is to evolve the measures for protecting aquifers by integrating groundwater recharge and rainwater harvesting mechanisms in the planning permissions for developments. Through this, CMDA intends to analyse the effect of the existing developments and future development on the aquifer recharge area along the southern coast of the Chennai Metropolitan Area (CMA) from Thiruvanmiyur to Uthandi.

The interim report of CUBE has highlighted that there is no need to change the development regulations till 2033. “The existing population in the aquifer recharge area which is 4.9 lakh is only 61.9% of its maximum holding capacity, which is 8 lakh. There is still significant room for population growth and development while adhering to existing regulations,” the report said.

The report also said for the villages from Kottivakkam to Uthandi, the current water supply is 8.8 MLD for 2023, whereas the demand as per the current population is 55 MLD. And with maximum densification, the requirement would be 77 MLD. This means only 15% of the current population can be catered to with a metro-water supply and the rest of the population will be dependent on other sources, including groundwater.

The ongoing urbanisation needs to balance economic development with the preservation of open spaces, agricultural resources, and natural ecosystems, the report added.

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