Groundwater recharge and age‐depth profiles of intensively exploited groundwater resources in northwest India

Abstract

Intensive irrigation in northwest India has led to growing concerns over the sustainability of current and future groundwater abstraction. Environmental tracers and measurements of groundwater residence times can help quantify the renewal processes. Results from 16 paired locations show the interquartile ranges for residence times in shallow alluvial groundwater (8-50 m deep) to be 1-50 years and significantly less than those from deeper groundwater (76-160 m deep) at 40-170 years. The widespread occurrence of modern tracers in deep groundwater (>60% of sites had >10% modern recharge) suggests that there is low regional aquifer anisotropy and that deep aquifers are recharged by a significant component of recent recharge via vertical leakage. Stable isotope and noble gas results at all depths conform to modern meteoric sources and annual average temperatures, with no evidence of significant regional recharge from canal leakage in this study area close to the Himalayas.

Groundwater quality in the alluvial aquifer system of northwest India: New evidence of the extent of anthropogenic and geogenic contamination

“…The 157 regional groundwater piezometric head decreases and flattens in a NE-SW direction (CGWB, 158 2007), with little or no regional flow within the central and SW part of the study area. Recent 159 groundwater dating work has shown that the regional groundwater flow is now highly modified 160 by vertical leakage due to both shallow pumping for irrigation and and abstraction at depth for 161 drinking water (Lapworth et al, 2015). Regionally the groundwater recharge is dominated by 162 meteoric rainfall (Lapworth et al, 2015), however in close proximity to surface water sources 163 including canal leakage and surface water exchange have been shown to be important (Rao et 164 al., 2017).…”

“…Recent 159 groundwater dating work has shown that the regional groundwater flow is now highly modified 160 by vertical leakage due to both shallow pumping for irrigation and and abstraction at depth for 161 drinking water (Lapworth et al, 2015). Regionally the groundwater recharge is dominated by 162 meteoric rainfall (Lapworth et al, 2015), however in close proximity to surface water sources 163 including canal leakage and surface water exchange have been shown to be important (Rao et 164 al., 2017). Irrigation in this region is both from shallow groundwater sources and the Bist-Doab 165 canal system diverted from the Sutlej River.…”

“…A recent study by Lapworth et al (2015) in NW India highlighted the low regional aquifer anisotropy through the use of modern residence time tracers (chlorofluorocarbons), and traced modern recharge from local meteoric sources using stable isotope ratios of O and H. This study showed that the shallow (0-50 m) and deeper (>75 m) aquifer system is actively recharged and renewed by local meteoric sources, and that the intensive pumping for municipal drinking water supplies from (>100 mbgl) induces vertical leakage from the shallow aquifer (Lapworth et al, 2015). This induced recharge may reduce aquifer depletion, but the presence of modern tracers within the shallow and deeper parts of the aquifer system suggests that this groundwater is perhaps regionally vulnerable to vertical contaminant migration from either anthropogenic or geogenic sources.…”

Security of Deep Groundwater in the Coastal Bengal Basin Revealed by Tracers

“…These include the relative importance of site‐specific, borehole‐ scale problems due to casing breaks at abstraction well sites (I. Choudhury et al, ) and aquifer‐scale vulnerabilities (Hoque et al, ) to contamination from shallow groundwater and the long‐term impacts of intensive pumping at depth (Khan et al, ; Knappett et al, ; Michael & Khan, ; Zahid et al, ). The presence of modern tracers (e.g., tritium and chlorofluorocarbons (CFCs)) in deeper groundwater systems (typically >150 m) has been attributed to deep pumping in the BAS and in many other aquifer systems globally (Jasechko et al, ; Lapworth et al, ; McMahon et al, ; Samborska et al, ) yet considerable uncertainty remains about the scale and nature of this pumping‐induced contamination. Here we present new evidence from multiple tracers drawn from dedicated, depth‐specific piezometers and actively pumped wells in the BAS, the world's largest deltaic aquifer system, to assess pumping‐induced recharge processes within the deep fresh BAS.…”

Assessment of Variation in Water Quality Index (WQI) of Groundwater in North Goa, India

“…For this, a groundwater monitoring network should be designed and planned scientifically in the study area 12 . The water level should be analysed quantitatively for proper planning [13][14][15][16][17][18][19] .…”