IIT- Madras designs plan to ‘inject’ dam’s surplus water into ground to prevent seawater intrusion

Using the hydro-geology of dry Thisaiyanvilai region of the district, IIT – Madras has proposed to ‘inject’ excess water getting discharged from Nambiyar dam during the monsoon into the ground through good number of open wells through ‘Rapid Recharge Technology’ which is expected to provide credible and everlasting solution to seawater intrusion into the land.

An open agricultural well in Aayankulam near Thisaiyanvilai in the district became a ‘picnic spot’ for the locals during the last monsoon as this ‘mysterious well’ did not overflow even though it was recharged with an estimated 1,500 - 2,500 litres of water every second for several weeks. Any ordinary well would have got filled-up and would have overflowed in a matter of hours at such recharge rates. The recharge water for this well was from nearby Nambiyar Dam due to the record monsoon rains in November last.

 Local villagers have been practicing this ad-hoc method of well recharge during intense monsoon. They claim that this practice increased the local water table in 10 to 15 km radius from the well.

 On getting information about this ‘mysterious well’, District Collector V. Vishnu and Speaker M. Appavu visited the well and Mr. Vishnu roped in a team from IIT – Madras to inspect the well and to suggest the measures for recharging wells in this coastal region through this well.

 A team led by Dr. Venkataraman Srinivasan, Assistant Professor, Department of Civil Engineering, IIT - Madras, camped at the site on December 2 and 3 last to investigate this phenomenon and explore the potential of this well and other wells in this region for use as ‘rapid aquifer recharge’ during monsoon for storage and withdrawal during the dry summer.

 The team has suggested implementing ‘Rapid Recharge Technology’ that include mitigating flood and drought, creating a subsurface dam for water storage without evaporation loss, distributing water automatically and equitably throughout the region, filtering and cleaning water when managed appropriately and preventing and reversing saltwater intrusion in coastal aquifers.

 Dr. Venkataraman Srinivasan said the unique hydro-geology of this region allows the implementation of this rapid aquifer recharge. In most other places, wells do not sustain such high injection rates and would easily overflow.