Percolation pond with recharge shaft as a method of managed aquifer recharge for improving the groundwater quality in th
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Ó Indian Academy of Sciences (0123456789().,-volV)(0123456789( ).,-volV)
Percolation pond with recharge shaft as a method of managed aquifer recharge for improving the groundwater quality in the saline coastal aquifer M C RAICY and L ELANGO* Department of Geology, Anna University, Chennai 600 025, India. *Corresponding author. e-mail: [email protected] MS received 4 February 2019; revised 1 August 2019; accepted 7 November 2019
The deterioration of groundwater quality has become a serious problem for the safe drinking water supply in many parts of the world. Along coastal aquifers, the saline water moves landward due to several reasons even though significant rainfall is available. The objective of the present study is to investigate the impact of a combined recharge structure including a percolation pond and a recharge shaft in improving the groundwater quality of the surrounding area. The area chosen for this study is Andarmadam, Thiruvallur district of Tamil Nadu. As a part of the study, a suitable site was selected for the construction of a percolation pond based on preliminary Beld investigations in 2012. Three piezometers were also constructed near the percolation pond to investigate the impact of the structure on groundwater recharge. Further, a recharge shaft was added to this structure in 2013 to overcome the clogging issues at the pond bottom and to enhance the recharge. The impact of the percolation pond on groundwater was assessed by comparing the periodical groundwater level Cuctuations with rainfall in the area. The Cuctuations in groundwater level near the percolation pond show variations before and after the construction of recharge shaft. The amount of water recharged through the percolation pond during the water year 2012–2013 was estimated as 250–300 m3. The volume of recharge was calculated to be increased more than twice after the construction of recharge shaft inside the percolation pond, on the assumption that recharge through the pond surface remained almost same as before. The dilution of ionic concentration in water was three times higher after the construction of recharge shaft. The long-term groundwater quality in the surrounding area of the pond improves gradually with time. The total dissolved solids (TDS) decrease considerably with time due to the dilution of dissolved solids in water with the fresh water recharging into the aquifer. The Wilcox diagram of most of the water samples after the construction of the recharge structure fall in the excellent to good category, indicating improvement in irrigation water quality. Keywords. Percolation pond; recharge shaft; salinity; coastal aquifer; recharge; groundwater quality.
1. Introduction The deterioration of fresh water resources by saline intrusion (Schroter et al. 2005; Werner et al. 2013) has become a global issue which aAects the coastal water quality and threatens the sustainable water
supply to the coastal communities (Cassardo and Jones 2011; Gain et al. 2012). Even though several expensive technological solutions are avail
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