Abandoned quarries in Chennai could help augment water supply, study finds

Quarries hold hidden water potential for Chennai

A new study from Anna University has identified a possible lifeline for Chennai's water-starved landscape: its abandoned quarries. The research, conducted by the Institute for Ocean Management, found that many of these disused pits across the city could be turned into sources for augmenting the local water supply.

The study mapped 59 abandoned quarries in the Chennai metropolitan area. It assessed their depth, volume, and proximity to existing water distribution networks. The researchers believe these quarries, once treated, could serve as both storage reservoirs and recharge zones for the city's stressed aquifers.

Mapping the water stock

Each quarry was evaluated for its water-holding capacity. The study found that some of the deeper quarries could hold several lakh litres of water, enough to supplement supply for nearby neighbourhoods during dry months.

The water quality in these quarries, however, varies. Some have been polluted by dumping of construction debris and sewage. The study recommends a phased approach: first, clean and desilt the quarries, then treat the water to meet drinking water standards. It also suggests constructing recharge shafts to allow filtered water to percolate into the groundwater table.

Legal and logistical hurdles

One of the biggest challenges is ownership. Many quarries are on private land or are mired in litigation. The study calls for the Chennai Metropolitan Development Authority and the Greater Chennai Corporation to take the lead in identifying quarries that can be acquired or leased for public use.

A pilot project is proposed for two or three quarries in areas with acute water scarcity. The researchers estimate that the cost of cleaning and retrofitting a medium-sized quarry would be a fraction of what it costs to build a new desalination plant.

A long-term solution for water security

Chennai has faced severe water crises in recent years, with its reservoirs often running dry before the monsoon. The city has relied on expensive and energy-intensive desalination plants and water tankers that travel hundreds of kilometres. The quarry study offers a cheaper, more sustainable alternative that also helps manage stormwater runoff.

The report will be submitted to the state water resources department next month. Officials said the findings could be integrated into the city's next master plan for water supply.

If implemented, the quarry project could provide an additional 10-15 million litres of water per day for Chennai by 2028. The researchers caution, however, that this will require sustained political will and public cooperation.

For now, the study provides a roadmap. The next step is for the government to decide whether to turn these abandoned pits from hazards into assets.