Browsing by Author "Jacob Noble"

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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
Hydrogeochemical characterization of groundwater in the shallow aquifer system of Middle Ganga Basin, India
(Elsevier B.V., 2023) Abhinav Patel; Shive Prakash Rai; Kossitse Venyo Akpataku; Nijesh Puthiyottil; Abhinesh Kumar Singh; Neeraj Pant; Rajesh Singh; Prashant Rai; Jacob Noble
Middle Ganga Basin (MGB) is lifeline for millions of inhabitants relying heavily on the groundwater. This has resulted in depletion of water quality and quantity at a very rapid scale. The present study has emphasized on hydrogeochemical evolution of groundwater in the Middle Ganga Basin, covering an area of 99,058 sq. km. Around 400 water samples were evaluated to determine the geochemical evolution of the shallow groundwater in MGB. The weighted average water quality index (WAWQI) shows 20.2% of the groundwater are unsuitable for drinking purposes. The Ca–HCO3 water facies dominates in northern region in the interfluves of Ghaghara and West Rapti rivers whereas more evolved water types such as Mg–HCO3, Na–HCO3 are found in the interfluves area of Ghaghara, Ganga, Yamuna, and Gomati Rivers. The occurrence of more mineralized water with increasing residence time in the flow direction suggests geogenic control and evolution follow the Chebotarev sequence. The saline water type is observed in and around the settlement reflecting the in-situ enrichment due to stagnation and anthropogenic activities. Hierarchical cluster analysis classified the regional groundwater data into three distinct major groups G1, G2, and G3. Factor 1 is attributed to anthropogenic inputs and associated with subgroup G2B and group G3. Factor 2 is attributable to the geogenic factors and is associated with subgroups G1A, G1B, and G2A. The various bivariate plots confirm the dominance of silicate weathering over carbonate weathering in the study area. Geochemical mass balance modeling suggests calcite and dolomite are in saturation to oversaturation conditions, restricting their further dissolution and primary silicate minerals controlling the groundwater chemistry. Our work reveals hydrogeochemical evolution on a regional scale in the shallow groundwater which will help to develop sustainable groundwater management strategies. © 2023 Elsevier B.V.
Refining aquifer heterogeneity and understanding groundwater recharge sources in an intensively exploited agrarian dominated region of the Ganga Plain
(Elsevier B.V., 2024) Abhinav Patel; Shive Prakash Rai; Nijesh Puthiyottil; Abhinesh Kumar Singh; Jacob Noble; Rajesh Singh; Dharmappa Hagare; U.D. Saravana Kumar; Nachiketa Rai; Kossitse Venyo Akpataku
Densely populated region of Ganga Plain is facing aquifer vulnerability through waterborne pollutants and groundwater stress due to indiscriminate abstraction, causing environmental and socio-economic instabilities. To address long-term groundwater resilience, it is crucial to understand aquifer heterogeneity and connectivity, groundwater recharge sources, effects of groundwater abstraction etc. In this context, present study aims to understand factors responsible for vertical and spatial variability of groundwater chemistry and to identify groundwater recharge sources in an intensively exploited agrarian region of the Ganga Plain. Interpretation of chemometric, statistical, and isotopic analysis categorises the alluvial aquifer into zone 1 (G1; ground surface to 100 m) and zone 2 (G2; >100 m-210 m). The group G1 samples are characterized by a wide variation in hydrochemical species, noted with pockets of F– and NO3– rich groundwater, and fresh to more evolved water types, while group G2 groundwater is characterized by a sharp increase in freshwater types and limited variation in their isotopic and hydrochemical species. The G1 groundwater chemistry is governed by soil mineralogy, local anthropogenic inputs (SO42-, Cl -, and NO3–), and manifested by multiple recharge sources (local precipitation, river, canal water, pond). The G2 group is dominated by geogenic processes and mainly recharged by the local precipitation. Geospatial signatures confirm more evolved water type for group G1 in northwestern region, while freshwater type covers the rest of the study area. Fluoride rich groundwater is attributed to sodic water under alkaline conditions and enriched δ18O values emphasizing role of evaporation in F- mobilization from micas and amphiboles abundant in the soil. The findings provide insight into potential groundwater vulnerability towards inorganic contaminants, and groundwater recharge sources. The outcome of this study will help to develop aquifer resilience towards indiscriminate groundwater extraction for agricultural practices and aim towards sustainable management strategies in a similar hydrogeological setting. © 2024 China University of Geosciences (Beijing) and Peking University
Spatiotemporal variability in stable isotopes of the Ganga River and factors affecting their distributions
(Elsevier B.V., 2021) Shive Prakash Rai; Jacob Noble; Dharmaveer Singh; Yadhvir Singh Rawat; Bhishm Kumar
Although the Ganga is an important fluvial system of India, the isotopic investigations of its water are limited and not reported for the whole length of the river. This limits the understanding of the hydrological processes of the river whose flow characteristics have been changed considerably over the years due to changes in the climate and land use/land cover patterns of the region. This study intends to fill this gap of data and knowledge. Hence, a robust isotope datasets were generated for a period of 2–3 years from 11 locations covering the entire length of the river (2250 km). These data were further analysed to study the controls on spatiotemporal patterns of river water isotopes and understand dominance of different hydrological processes affecting flow characteristics of the river in different reaches. The stable isotopes of oxygen and hydrogen in river water exhibited large spatial and temporal variation throughout the study periods. The most negative isotopic values (mean δ18O: −15‰ to −9.7‰) between 0 and 318 km in the mountainous region during pre-monsoon period attributes to the dominant glaciers melt contribution while the altitude effect in rainfall is mainly responsible during monsoon season. However, less negative isotopic values (mean δ18O: −9.7‰ to −4.3‰) between 318 and 1000 km correspond to the mixing of water from major tributaries. Other hydrological factors responsible for the increased isotopic values include evaporative enrichment and contribution of isotopically less negative groundwater. The observed relatively low isotopic values (δ18O: −4.3‰ to −6.9‰) in the downstream of 1000 km of the river are due to joining of tributaries originating from the Nepal Himalayas. Results substantiate that distinct isotopic values found in different reaches of the river are because of the variations in basin characteristics, hydro-meteorological processes, and water mixing. These findings would contribute in developing a better knowledge on hydrological behaviour of the Ganga River and help in taking appropriate measures for maintaining its sustainable flows. © 2021 Elsevier B.V.
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.