Delhi govt’s Palla floodplain project enters fifth phase

The Palla floodplain extends along 25km of the Yamuna and contains aquifers that are perennial sources of drinking water for Delhi

The Delhi government’s irrigation and flood control (I&FC) department on Tuesday kicked off the fifth round of the Palla floodplains reservoir project, officials aware of the venture said.

The reservoir project is designed to recharge the city’s groundwater table by harvesting floodwaters from the Yamuna during the monsoon season by increasing the percolation rate of groundwater. (HT Archive)

The Palla floodplain extends along around 25km of the Yamuna north of Wazirabad, and contains aquifers that are perennial sources of drinking water for Delhi. The reservoir project is designed to recharge the city’s groundwater table by harvesting floodwaters from the Yamuna during the monsoon season by increasing the percolation rate of groundwater. This groundwater, officials said, can then be extracted for use during the lean summer months.

The first four rounds of the pilot project were carried out over the last four years through a 26-acre pond on the floodplains of Palla at the Delhi-Haryana border near Sungarpur, and in the long run, the I&FC department plans to create a 1000-acre recharge pond.

A government official associated with the project said an analysis of the findings of the first four rounds shows that there has been a considerable rise in the groundwater level, and that the pilot reservoir is facilitating additional groundwater percolation.

“The project is designed to raise the groundwater levels along the floodplains by capturing excess monsoon rainwater through a series of excavated ponds to increase the water availability. Millions of gallons of water used to run off into the river, and the project is being used to trap the rainwater and increase the levels of underground water,” the official said.

“A 26-acre pond has been created on the floodplain site and 33 piezometers (an instrument used to measure the pressure of groundwater) have been installed to ascertain the quantum of rise in groundwater levels. The land has been leased at the rate of ₹94,328 per acre, and the government spends around ₹52 lakh on the project every year,” the official said.

Officials said that when upscaled to a larger area, the reservoir will also help moderate the floods to a certain extent.

An assessment report by the I&FC department said that the reservoir area was submerged for 14 days in 2019, 19 days in 2020, 24 days in 2021 and 30 days in 2023. “The average water table rise between the pre and post monsoon period in 2021 was 0.5-2.5 metres, while the rise was 0.7-2m in 2022,” the report said.

The government estimates that the pilot reservoir led to ground water recharge of 2,280,000 cubic metres in 2022 alone.

Environmental activist Diwan Singh, who organised the Yamuna Satyagrah to rejuvenate the river and other water bodies in the Capital, said, “The floodplains get naturally recharged as sand in these areas have a high percolation rate. But this extraction must be carried out in sustainable limits.

Singh said he was of the opinion that the sand bed in floodplains should not be disturbed to a large extent as sand also is the part of ecology of the river system.