Groundwater expert Shashank Deshpande explains to residents the designs of a percolation pond.
Groundwater expert Shashank Deshpande explains to residents the designs of a percolation pond.

Civic Sanskriti: Why groundwater is an invisible, but crucial resource

The Pune Municipal Corporation (PMC) has taken up a unique project to revive a water percolation pond in Handewadi, in southeast Pune
By Sanskriti Menon
UPDATED ON FEB 24, 2021 04:30 PM IST

The Pune Municipal Corporation (PMC) has taken up a unique project to revive a water percolation pond in Handewadi, in southeast Pune. This spot is right at the gate of the Dada Gujar Madhyamik Vidyalaya. The pond itself was perhaps made as a village tank several decades ago with support from Dada Gujar. The pond revival and redesign is being done by PMC with technical advice from ACWADAM, and participation of Mission Groundwater, a civil society initiative.

Rainwater from Handewadi flows into this percolation pond. Two newly constructed filtration pits will screen out leaves and rubbish flowing in with the rainwater. In addition, three small springs bring water naturally percolating in the surrounding area into the pond. Two recharge shafts are constructed to direct the pond water into the aquifer below, that is rock layers with numerous cracks and air bubbles that retain water.

The project is expected to be ready before the monsoon this year, as informed by PMC engineer Shramik Shevte, who took the initiative for the project. The recharged groundwater is likely to benefit several housing societies and commercial enterprises with borewells using water from this aquifer.

Managing groundwater in cities

Percolation tanks and recharge pits are common in watershed development projects across rural India. However, cities too need to take up watershed and groundwater management in a scientific, systematic manner, and quite urgently for many reasons.

First, the increasing population in Pune directly increases the demand for water. Thousands of housing societies have borewells. Dr Himanhsu Kulkarni, director of ACWADAM, estimates that nearly 20% of Pune’s water needs are met by groundwater. Though PMC’s 24x7 water supply project is expected to distribute water more equally across the city through new pipelines which will also curb leakages, the dependence on groundwater may not go away.

Second, erratic rains are common with climate change and we might not get enough of rain in some years. Dam water stocks may not be enough in drought years.

Third, climate change may also lead to heavy rains and without appropriate physical structures. Floodwaters can cause damage as well as just run off very rapidly without much percolation. Instead, with stream restoration and groundwater recharge structures created, floodwater run-off speed can be reduced and percolation increased.

Fourth, a more just approach is needed than bringing water from further and further away, such as in the Bhama Askhed project. Increasing urban demands can deprive farming and other rural communities of their water resources.

Pune should wisely manage the water it draws from the existing dams as well as the resource it is literally sitting upon – groundwater. Improved groundwater management requires good information about the resource, as well as appropriate rules and programmes for groundwater recharge and use.

Unlike rivers and streams that are visible in the cityscape, extensive studies are needed to map underground aquifers.

Studies show that Pune’s current plot-based rainwater harvesting voluntary programme should change to a comprehensive area-based approach. Protecting open vegetated areas like Bavdhan and Vetal tekdi, which are natural recharge zones, should be a priority. Recharge structures should be set up at places where the rock structure is such that it would hold water, as in Handewadi.

Further, the concretisation of streams and nallahs should stop. Corporators sometimes promote nallah concretisation mistakenly believing it helps the neighbourhood. In fact, concretisation is more likely to cause flash floods and reduce groundwater recharge. Instead, discretionary funds could be used to restore nallahs as natural streams.

We also need new rules to govern use of groundwater in cities.

The Handewadi project should spur a larger public initiative on groundwater in Pune. The government, technical agencies like the Central Ground Water Board and GSDA, experts like ACWADAM, and the public will need to collaborate, deliberate and innovate to develop sustainable, participatory groundwater management in Pune.

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