Science & Technology

IIT Madras Researchers Propose Rapid Groundwater Recharge technology

:- An open agricultural well near Ayankulam in Thisayanvilai Taluk of Tirunelveli was widely reported to be recharging an estimated 1,500-2,500 litres of water every second for several weeks without overflowing

 

Researchers of Indian Institute of Technology (IIT) Madras have proposed implementing a rapid groundwater recharge technology for combined flood and drought mitigation near Ayankulam village in Thisayanvilai taluk of Tirunelveli District, Tamil Nadu.

A proposal for this project has been submitted to the Tirunelveli District Administration, which had requested IIT Madras to study this phenomenon.

An open agricultural well in Ayankulam was widely reported to recharge an estimated 1,500-2,500 litres of water every second for several weeks without overflowing. The recharge water for this well was from the excess overflow of an adjacent minor irrigation tank due to the record monsoon rains in Nov-Dec 2021.

The well became a local attraction and was called a “miracle well” since typical wells would fill and overflow in a matter of hours at such recharge rates. Local villagers have been practicing this ad-hoc method of well recharge during episodic intense monsoon years for several decades. They claim that this practice increased the local water table in a 10-15 [km] radius from the well.

The region surrounding this village is considered a dry belt with hot summers. Many small land-holding farmers have abandoned their farming practices and work as labourers in larger farms or other labour-based occupations. Being close to the coastal zone, several agricultural and domestic wells in the region suffer from saltwater intrusion due to excessive pumping and lowering of groundwater levels. Even extending the agricultural water availability by a few months each year can  positively impact the livelihoods of these farmers.

A team led by Dr. Venkatraman Srinivasan, Assistant Professor, Department of Civil Engineering, IIT Madras, visited the site to investigate this phenomenon and explore the potential of this well and possibly other wells in the region for use as rapid aquifer recharge during monsoon floods for storage and withdrawal during the dry summer months.

The IIT Madras Team suggested implementing a ‘Rapid Recharge Technology,’ which, when developed, can bring several potential benefits to the region like mitigate floods and droughts, it can filter and clean water when managed appropriately and would also create a subsurface dam for water storage without evaporation loss.

Explaining the potential of this pilot project, Dr.Venkatraman Srinivasan, Assistant professor, Department of Civil Engineering, IIT Madras, said, “This is a win-win situation for all stakeholders. The excess water which causes devastating floods and would otherwise empty into the ocean is being channelled to recharge the groundwater for storage and retrieval in the dry summer months.”

Currently, while groundwater recharge is practiced only during episodic(about once every 4-5 years) extreme flood events in one well, it is possible to design a system that can recharge the aquifer annually (every monsoon season) through multiple injection well systems. Such a system of annual aquifer recharge will facilitate sustainable water use in the dry summer months. Further detailed studies are required to develop and optimize this flood and drought mitigation technology.

 

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