CHENNAI: Chennai’s potential groundwater source, used by authorities to quench the city’s thirst during summer, is at risk with the Chennai Metropolitan Development Authority (CMDA) considering a proposal to open fragile aquifer recharge areas near the East Coast Road (ECR) for large-scale development by allowing a higher floor space index (FSI).
A CMDA panel is learnt to have studied the proposal and a decision is expected to be taken at a high-level meeting soon.
Unregulated development and large-scale tapping of groundwater have impacted aquifer recharge areas in and around Kottivakkam, Palavakkam, Neelankarai, Okkiam Thoraipakkam, Injambakkam, Karapakkam, Sholinganallur and Uthandi. Untouched for development from 1980 to 2007, the area was opened for partial development, following a plea from the tourism department, with a permissible FSI of 0.8. It was then argued that rainwater conservation through rainwater harvesting in buildings will preserve the groundwater.
But rather than monitoring the development in the region, authorities, including the CMDA and the Directorate of Town and Country Planning (DTCP), turned Nelson’s eye toward the unchecked growth in the area.
Earlier, the sandy nature of the area allowed for the penetration of rainwater. But with the built-up area in this aquifer zone along the coast seeing an increase of 15 per cent between 2004 and 2016, the groundwater potential has been decreasing as water could not percolate down, according to a research study by the Geology Department of Anna University.
‘Present land use, land cover indicate rise in settlements’
As per the Geological Survey of India study, the total potential of the aquifer from Thiruvanmiyur and Uthandi is 20 MLD. The present land use and land cover indicate the rise in settlements, which may impose over-exploitation. If the discharge is increased by 10 per cent it results in a maximum decline of groundwater level from 0.50 m to 1.00 m with a substantial increase of seawater intrusion as the groundwater level falls below sea level, according to Chennai Metro Water sources.
While it is not known why the CMDA wants to unlock the ECR stretch, key to Chennai’s water security, to pave way for high-rise buildings, Sekhar Raghavan, director of Rain Centre, said opening up of the fragile aquifer for development will be suicidal.
“They are killing the goose which lays the golden egg. This is aquifer region should be carefully handled. There is enough for our needs but not for our greed,” said Raghavan, one of the pioneers in rainwater harvesting.
Former Anna University professor of urban engineering K P Subramanian said any relaxation of development regulation parameters such as the FSI, coverage and the height in the aquifer recharge area of the ECR between Thiruvanmiyur and Mamallapuram will result in intense building activities.
“Building and parking area are impervious. Therefore, rainwater can’t percolate at the recharge zone. Potential consequences of such a situation are flooding, steadily declining water table and the intrusion of seawater into the sweet water. Ultimately, it will increase the release of greenhouse gases into the atmosphere contributing to climate change,” he said.
‘Suicidal to open aquifer for devpt’
While it is not known why the CMDA is pushing to unlock the ECR stretch to pave way for high-rise buildings, Sekhar Raghavan, the director of the Rain Centre, said opening up of the fragile aquifer region for development will be suicidal