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Thursday , 23rd September 2021

Recharge Structures

Section: Hydrogeology pages are not under access control

Sustainability of Sources – Success Stories Recharge Through Defunct Bore Wells, Karukurichi Village, Namakkal District, Tamilnadu.

A research and development project to facilitate recharge to deep-seated fracture system through defunct bore wells (deep bore wells, which have become defunct due to lowering of water table )have been taken as pilot project study. The village taken for this project is Karukurichi habitation belongs to Puduchatram block, Namakkal district of Tamilnadu. The population of the habitation is 2310 as per 1991 census. This habitation comes under partially covered category and the level of supply is 30 LPCD.

There are 4 bore wells and one open well in the habitation, which are used as Source for drinking water purpose. Apart from this, there are around 12 irrigation wells in the vicinity of the habitation. The yield from the only power pump source is also not sustainable during summer since the water level is deep and the quantum of recharge by natural means to the fracture system is not sufficient.

As the defunct bore wells are deep and terminate in the fracture system the present attempt would likely recharge the fracture system and improve the ground water potential of the area.

The methodology adopted in the pilot study includes the Identification of observation wells to monitor the hydrological characteristics before and after the intervention, detailed Geophysical survey in a grid patterns to ascertain different fracture system, electrical logging of the defunct bore wells to ascertain the exact fracture depths and providing infra structure to convert the defunct well as recharge well.

The defunct bore wells were subjected to flushing to make it fit for recharge by removing the silt accumulated over the years. Telescopic trench around the bore well has been excavated and the MS casing pipe removed from the bore well and a new PVC pipe has been attached to the bore well. Perforated slots were provided and the trench excavated is backfilled with coarse sand, followed by 12 mm blue metal up to a thickness of 05. m and second layer of sand filter for a thickness of 0.5 m provided which is followed by the second layer of blue metal of 1.0 m to 20mm filled up to the ground level.

A storage tank of capacity 210 Cu.m. is created nearby and the surface runoff water harvested in the tank and is allowed to percolate to the defunct borewell through a recharge shaft.

The impact analysis reveals that the water level in the wells maintained within 10-12 m bgl unlike 38 – 42 m in the earlier years. Pumping hours have been considerably reduced since the and Sustained water supply in the village is ensured. Agricultural wells with a rise in water level have facilitated increased agricultural activities. Quality of the source water has been considerably improved in respect of TDS and other parameters. It has been reduced 15 % compared with the TDS of earlier years.