Browsing by Author "Suneel Kumar Joshi"

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Hydrochemical evolution of groundwater in northwestern part of the Indo-Gangetic Basin, India: A geochemical and isotopic approach
(Elsevier B.V., 2023) Shive Prakash Rai; Kossitse Venyo Akpataku; Jacob Noble; Abhinav Patel; Suneel Kumar Joshi
The present study aims to understand the hydrochemical evolution of groundwater in the Ghaggar River Basin, representing a zone of excessive abstraction of groundwater in the northwestern Indo-Gangetic Basin. The study comprises a regional scale and high-resolution sampling of groundwater during pre- and post-monsoon seasons of 2013 and their analyses for major ions, δ18O, δ2H, and 3H. Variation in hydrochemical and isotopic data is found both in spatial and vertical scales. The significant vertical variation of TDS, NO3− and K+ allowed the classification of the aquifer system into two major groups: shallow (depth < 80 m bgl) and deep (depth > 80 m bgl). The depthwise variations of δ18O and δ2H support this categorization of the aquifers. The Ca-HCO3 and Ca-Mg-Na-HCO3 water facies with higher values of 3H in the proximal part of the basin characterize recharge areas under humid conditions. The dominance of Mg-Na-HCO3 and Na-HCO3 facies in shallow and deep aquifers in central part of the basin, illustrate the intermediate to advanced stages of hydrochemical evolution in the system. Dominance of brackish Ca-Mg-Cl-SO4 and Na-Cl-SO4 water types in the discharge areas is due to the prevailing geological conditions and anthropogenic activities. Geochemical modelling supports the reverse cation exchange and mixing during lateral and vertical flows, weathering of silicate minerals, dissolution of crustal salts, and evaporative enrichment are the natural processes governing the evolution of groundwater chemistry along the flowpaths. The developed process-based conceptual model will aid in the formulation of a suitable plan for groundwater resource management in the region. © 2023 China University of Geosciences (Beijing) and Peking University
Identifying moisture transport pathways for north-west India
(John Wiley and Sons Ltd, 2023) Suneel Kumar Joshi; Sudhir Kumar; Rajiv Sinha; Shive Prakash Rai; Suhas Khobragade; M. Someshwar Rao
The isotopic composition (δ18O and δ2H) of precipitation is widely used as a moisture source tracer. In north-west India, the δ18O, δ2H and D-excess values of precipitation correlate mainly with air temperature; however, the moisture sources of water vapour are unclear. Therefore, we collected daily precipitation isotope data (n = 425) from 13 rain gauge stations in northwest India in 2013. We established a regional meteoric water line (MWL) for northwest India and local MWLs for all 13 rain gauge stations separately. We observed an altitudinal gradient of about 0.11‰/100 m in slope and about 1.22‰/100 m in intercept from the western to the northeast part of the study area. The isotopic composition of precipitation shows spatial and temporal variability across the study area. We found higher Deuterium excess values during winter (December–February) and lower during the monsoon season (July–September), which may be associated with the different moisture sources, namely, the Bay of Bengal, Arabian Sea and Westerly disturbances. Our results suggest local moisture recycling may also occur during the study period. The present study can enhance the knowledge of the isotopic evolution of precipitation and moisture sources in northwest India. © 2023 John Wiley & Sons Ltd.
Modelling water levels of northwestern India in response to improved irrigation use efficiency
(Nature Research, 2020) Shashank Shekhar; Suman Kumar; A.L. Densmore; W.M. van Dijk; Rajiv Sinha; Manoranjan Kumar; Suneel Kumar Joshi; Shive Prakash Rai; Dewashish Kumar
The groundwater crisis in northwestern India is the result of over-exploitation of groundwater resources for irrigation. The Government of India has targeted a 20 percent improvement in irrigation groundwater use efficiency. In this perspective, and using a regional-scale calibrated and validated three-dimensional groundwater flow model, this article provides the first forecasts of water levels in the study area up to the year 2028, both with and without this improvement in use efficiency. Future water levels without any mitigation efforts are anticipated to decline by up to 2.8 m/year in some areas. A simulation with a 20 percent reduction in groundwater abstraction shows spatially varied aquifer responses. Tangible results are visible in a decade, and the water-level decline rates decrease by 36–67 percent in over-exploited areas. Although increasing irrigation use efficiency provides tangible benefits, an integrated approach to agricultural water management practice that incorporates use efficiency along with other measures like water-efficient cropping patterns and rainwater harvesting may yield better results in a shorter period. © 2020, The Author(s).
Strongly heterogeneous patterns of groundwater depletion in Northwestern India
(Elsevier B.V., 2021) Suneel Kumar Joshi; Sanjeev Gupta; Rajiv Sinha; Alexander Logan Densmore; Shive Prakash Rai; Shashank Shekhar; Philippa J. Mason; W.M. van Dijk
Northwestern India has been identified as a significant hotspot of groundwater depletion, with major implications for groundwater sustainability caused by excessive abstraction. We know relatively little about the detailed spatial and temporal changes in groundwater storage in this region, nor do we understand the interplay of factors controlling these changes. Groundwater managers and policymakers in India require such information to monitor groundwater development and make strategic decisions for the sustainable management of groundwater. Here, we characterise high-resolution spatio-temporal variability in groundwater levels and storage change across northwestern India through analysis of in situ measurements of historical groundwater level data. We note a slow gain in groundwater storage of + 0.58 ± 0.35 km3 for the pre-monsoon and + 0.40 ± 0.35 km3 for the post-monsoon period between 1974 and 2001. However, from 2002 to 2010, groundwater storage was rapidly depleted by −32.30 ± 0.34 km3 in the pre-monsoon and −24.42 ± 0.34 km3 in the post-monsoon period. Importantly, we observe marked spatial heterogeneity in groundwater levels and storage change and distinct hotspots of groundwater depletion with lateral length scales of tens of kilometers. Spatial variability in groundwater abstraction partially explains the depletion pattern, but we also find that the sedimentological heterogeneity of the aquifer system correlates broadly with long-term patterns of groundwater-level change. This correlation, along with the spatial agreement between groundwater level change and water quality, provides a framework for anticipating future depletion patterns and guiding groundwater monitoring and domain-specific management strategies. © 2021 The Author(s)
Tracing the isotopic signatures of cryospheric water and establishing the altitude effect in Central Himalayas: A tool for cryospheric water partitioning
(Elsevier B.V., 2021) Neeraj Pant; Prabhat Semwal; Suhas Damodar Khobragade; Shive Prakash Rai; Sudhir Kumar; Rajendra Kumar Dubey; Jacob Noble; Suneel Kumar Joshi; Yadhvir Singh Rawat; Harish Chandra Nainwal; Sunil Shah; Aditya Mishra; Rajeev Saran Ahluwalia
This study focuses on the isotopic characterization of cryospheric water and quantification of different components contributing to Alaknanda River (major tributary of the Ganges River system) at its place of origin near snout of the Satopanth Glacier. A detailed understanding of various sources/flow components contributing to the river is useful for water resource management under changing climate scenario and helpful in risk assessment due to natural hazards in the headwater catchments, Extensive fieldwork was conducted, and water samples were collected from the river, snow, glacial ice, rain, lakes, and supraglacial channels of Satopanth Glacier Basin during the ablation period of 2017 and analysed for δ18O, δ2H, and 3H along with electrical conductivity. The results helped to establish the spatio-temporal and altitudinal variability in isotopic signatures of rain, snow, and ice in Satopanth Glacier Basin. The altitudinal effect in δ18O of pre-monsoon and monsoon rainfall is −0.13‰ and −0.41‰ per 100 m rise in elevation, respectively. Snow samples show depleting isotopic trend with an altitude effect of −0.43‰ in δ18O per 100 m rise in altitude. However, snowpack samples show an enrichment with time indicating post-depositional isotopic fractionation. The contrasting isotopic gradient in debris covered and non-debris covered ice are −0.9‰ and +3.4‰ per 100 m rise in elevation, respectively. These results divulge the spatial as well as temporal variation in cryospheric waters and these variations are used to derive the isotopic signatures of snow melt, glacier melt, and rain water. The results of hydrograph separation show that the snow melt, ice melt and rain water contribute about 33%, 49% and 18% respectively, to the discharge of Alaknanda River during the ablation period. Tracer based hydrograph separation indicates that the snow melt contribution dominates in river discharge during the initial ablation period. River discharge is a mixture of snow melt, glacier melt and rain water during July and August, while there is a dominance of glacier melt during end of the ablation period. The results of the present study highlight the importance of accounting the spatial and temporal variability in tracer signatures of cryospheric water for quantifying the contributions of snow and ice melt in a river originating from glacerised area. © 2021 Elsevier B.V.
Understanding groundwater recharge processes in the sutlej-yamuna plain in nw india using an isotopic approach
(Geological Society of London, 2021) Suneel Kumar Joshi; Shive Prakash Rai; Rajiv Sinha
The isotopic composition of water has been widely used to investigate groundwater dynamics and recharge processes. In the present study, we have analysed the isotopic composition of groundwater, and of Sutlej River, Yamuna River, Ghaggar River and canal water from the Sutlej-Yamuna plain in NW India. We document spatial and depth-related variations in δ18 O and deuterium excess (d-excess) values of groundwater in three zones based on topography and slope (zones I–III) from NE to SW. In Zone I, precipitation is the main recharge source for groundwater, as indicated by the isotopic values. We infer mixed recharge from precipitation and irrigation return flow in Zone II. Zone III records depleted δ18 O and higher d-excess values in most of the groundwater samples, suggesting active recharge from canals. Further, we have calculated the contribution of canal water in groundwater using the hydrograph separation approach and have also quantified the uncertainty in its estimation. We note significant spatial and depth-related variability in the canal water contribution to groundwater recharge. The canal contribution is as high as 83 + 10% at 18 m below ground level (bgl) in Zone III, and as low as 5 + 3% at 43 m bgl in Zone II. The present study provides the baseline data on recharge processes in NW India, which is critical for developing sustainable management strategies for groundwater resources in this region. © 2020 The Author(s).