As the uncertainty over the monsoon increases, and the groundwater levels fall to ‘critical’ category (as classified by the Central Ground Water Board), Delhi government has proposed to create an underground reservoir that can store an estimated 37,000 million gallons of rainwater.
The CGWB’s critical category indicates that the groundwater resources are largely stressed in the region, and hence, immediate actions should be taken to manage the resource sustainably. The proposed project will be carried out along the Yamuna floodplain in the northwest of Delhi’s Palla on a 1000-acre land. If the underground reservoir successfully stores the proposed amount of water, it is said to be enough to meet the city's water supply shortfall even during peak summer.
Authorities and the government is confident that the project has the potential to meet the shortfall during the city’s peak summer. The Yamuna floodplains consist of alluvial soil with a high percolation rate of 6-9m per day and the Delhi government is planning to rent this land from the farmers who are cultivating crops across the area. According to a report in The Times Of India, a 100 crore budget has been allotted for groundwater conservation projects.
As there are no well-established storage facilities except a few natural aquifers, about 280 million cubic metres of water is lost every year during the monsoon in Delhi. Therefore, the new project aims to create small ponds that will be built across the 20 km stretch from Palla to Wazirabad.
Announcing the pilot project, Chief Minister Arvind Kejriwal assured that these ponds would be completely eco-friendly and the water will be able to reach these ponds only when there is flooding in the river Yamuna. There has been an average of 18 flooding cycles in river Yamuna each year yielding about 3,700 million gallons of water.
Forecasts suggest that the southwest monsoon is likely to arrive in Delhi within the next two days after a long delay. Generally cloudy skies with very light rains or thunderstorms are forecast across Delhi till Friday. The increasing uncertainty over the timing and intensity of the monsoon has posed a significant threat to water security in many large cities across the country. Chennai, Delhi, and Bengaluru have been facing the risk of ‘Day Zero’ as early as 2010. Day zero is when cities run out of the water and the supply is shut off.
Speaking to the Times of India, Ankit Shrivastava, technical advisor of Delhi Jal Board suggests that there is potential in retrieving water from Yamuna’s flooding and storing it in the floodplain. The demand-supply gap in Delhi ranges from 250 to 300 million gallons of water per day, according to Shrivastava, if they manage to preserve good amount of water the extraction of only 100 million cubic metres will be enough to meet one month’s water demand.
The state cabinet meeting led by Arvind Kejriwal that approved the project also made rainwater harvesting mandatory in all the government buildings.
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