Delhi govt to continue Palla floodplain project to recharge groundwater

The groundwater table in the Palla floodplains has increased by 2 metres due to the pilot project and the government will increase the recharge capacity of the project from 812 million gallons to 20,300 million gallons soon.

The Delhi government has decided to continue the Palla floodplain project, which aims to recharge the city’s groundwater table by harvesting floodwaters from the Yamuna river during the monsoon, for the fourth year, officials said on Thursday.

Image for representation only. (Sakib Ali/ HT)

In 2019, a 26-acre pond was created near Sangarpur in Palla to assess the impact of floodwater collection on groundwater recharge during the monsoon. According to a government official, an average of 812 million gallons of groundwater has been recharged every year since the project was set up. Deputy chief minister Manish Sisodia, who reviewed the project with officials of the irrigation and flood control department on Thursday, said that the Palla project was created to store flood water so that the accumulated water can be used throughout the year to improve the groundwater level.

He added that the groundwater table in the Palla floodplains has increased by 2 metres due to the pilot project and the government will increase the recharge capacity of the project from 812 million gallons to 20,300 million gallons soon.

“While about 812 million gallons of groundwater have been recharged at present, 20,300 MG of groundwater will be recharged by increasing the area to 1,000 acres. This project will prove to be a great example not only for Delhi but for the drought-stricken and water-stressed states of the entire country,” he said.

The Palla project is spread across 40 acres. According to DJB officials, a study conducted during the pre-monsoon and post-monsoon seasons in 2020 and 2021 found that the groundwater recharge from this project is moving towards the city from the Yamuna river, thereby increasing the groundwater level of the entire city.

The three key findings of the study, a copy of which has been seen by HT, say that one, the groundwater is moving from the river towards Alipur; two, the groundwater level improvement in the pond area over three years is higher compared to areas away from the pilot site; and three, the project shows a higher level of groundwater recharge than extraction--the groundwater table was recharged by 2.9MCM in 2020 and 4.6MCM in 2021.

“The final report of Palla pilot has been submitted to Central Ground Water Commission and Upper Yamuna River Board for their approval. We will also approach NGT before expanding the size of the recharge pond to 1,000 acres,” a DJB official said. Officials said DJB used various tubewells and rannery wells to extract groundwater from the area and augment the city’s water supply. “The average combined annual extraction of water from Palla is around 3.6 million cubic metres (MCM) while the study has found that the excavation has increased groundwater by 3.75MCM. The groundwater recharge is more than the annual extraction,” the official claimed.

According to the government, data from the last decade suggests that on an average, 18 flooding cycles take place in the Yamuna floodplains every season when water levels go above 208m. With each cycle yielding 2,100 million gallons (MG) of water, it had been originally estimate that over 37,800MG water will be stored in the Palla project. Delhi has a demand-supply gap of 300MGD and DJB officials said that the excess water will be used in peak summer demand days in June. “Sub surface storage in sand beds towards Alipur is akin to a glass tumbler filled with sand to be used for temporarily storing water and extracting it later,” an official explained.

Manoj Misra, the convener of the Yamuna Jiye Abhiyan, a consortium of NGOs and individuals which has been working for the Yamuna’s revival for more than a decade, said that the project will not interfere will river ecology. “They should now carry out a pilot project in areas beyond the embankment. That area beyond the channel will lead to even more benefits and north-south movement of groundwater recharge,” he added.