Deep Drilling for Groundwater in Bengaluru, India: A Case Study on the City’s Over-Exploited Hard-Rock Aquifer System

Tejas Kulkarni, Matthias Gassmann, C. M. Kulkarni, Vijayalaxmi Khed and Andreas Buerkert
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Tejas Kulkarni: Hydrology and Substance Balance, University of Kassel, 34125 Kassel, Germany
Matthias Gassmann: Hydrology and Substance Balance, University of Kassel, 34125 Kassel, Germany
C. M. Kulkarni: Kiran Consultants, Bengaluru 560010, Karnataka, India
Vijayalaxmi Khed: Department of Agricultural Economics, University of Agricultural Sciences, Bengaluru—UASB, Bengaluru 560065, Karnataka, India
Andreas Buerkert: Organic Plant Production and Agroecosystems Research in the Tropics and Subtropics—OPATS, University of Kassel, 37213 Witzenhausen, Germany

Sustainability, 2021, vol. 13, issue 21, 1-20

Abstract: Over-exploitation of groundwater in India’s fastest-growing metropolis, Bengaluru, has resulted in wells being bored to unprecedented depths in a crystalline-rock aquifer. However, key questions about sustainability of this extraction process remain unaddressed due to the complexity of monitoring. Using primary surveys, this study looks at the spatio-temporal evolution of the wells on a city scale, finding that catchments with deficient water infrastructure have deeper wells. To maintain yields, well with depths >400 m are drilled, especially since 2000, leading to unsustainable groundwater extraction. Camera inspections in 54 wells at Electronic City in 2016 and 2017 revealed that water levels in the majority of the wells remained lower at depths <100 m, although some wells had deeper water levels at depths >250 m. Analysis of δ 18 O and δ 2 H signatures of groundwater samples at all depths followed the local meteoric water line indicating recent recharge, implying that drilling deeper only increases the borehole volume and does not tap into newer water sources. Water levels in deeper wells may stabilize at lower depths, are subject to high spatial variability, density of drilling, and high connectivity in upper zones. Given the interconnectedness between shallow and deeper aquifers, our research shows that increasing borewell depths could be a good indicator for falling aquifer water levels. This study fills an important gap in peri-urban, intermediate-scale aquifer conceptualizations across different land uses and provides further evidence for the difficulties of reliable groundwater monitoring in the over-exploited hard-rock aquifers of Bengaluru city.

Keywords: groundwater monitoring; Bengaluru; hard-rock aquifers; environmental isotopes; India (search for similar items in EconPapers)
JEL-codes: O13 Q Q0 Q2 Q3 Q5 Q56 (search for similar items in EconPapers)
Date: 2021
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (1)

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