Writing on the wall

Excessive groundwater extraction is triggering subsidence in the Indo-Gangetic plain

- VIVEK KUMAR SAH

ALL RESIDENTIAL in Kapashera societies extract groundwater. But we never thought it could lead to the sinking of our land," says Rajesh Gera, president of Surya Vihar Housing society in southwest Delhi, which is less than 10 km from the Indira Gandhi International Airport.

In 2014, one of the pillars in the parking lot of the society developed cracks. By 2019, the crack had widened so much that the entire building could have collapsed. This June, when Down To Earth (DTE) visited the society, Gera showed the repaired crack, which had reached more than 1.5 m in height. "We initially ignored it and then blamed the builder for poor construction. Now we know it is happening due to land subsidence triggered by excessive groundwater extraction," he says.

Residents tell DTE that apart from the threat of a collapse, they are also seeing the groundwater levels declining rapidly. In early 2000, the society had four borewells at a depth of 200 m. By 2020, two of them had dried up.

Shagun Garg, who is currently at the University of Cambridge, UK, had established the link between groundwater extraction and land subsidence in Delhi in 2020. He had found that land subsidence at Kapashera was happening at a rate of 17 cm per year, or roughly the length of a smartphone. Garg came to this conclusion after he monitored the land subsidence rate at four locations in the National Capital Region in 2014-16, in 2016-18 and in 2018-20. Apart from the residential society, he found subsidence at Fun and Food waterpark in Surya Vihar, and at Raja Nahar Singh International Cricket Stadium and Piyush Mahendra Mall in Faridabad.