Browsing by Author "Rajiv Sinha"

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Geo-electric resistivity evidence for subsurface palaeochannel systems adjacent to Harappan sites in northwest India
(2013) Rajiv Sinha; G.S. Yadav; Sanjeev Gupta; Ajit Singh; S.K. Lahiri
It has been proposed that a major palaeo-river channel course, the Ghaggar-Hakra, flowed in the interfluve between the modern Yamuna and Sutlej rivers in the western Ganges basin during the Late Quaternary. This palaeochannel course has been associated with extensive Bronze-age Harappan civilisation archaeological sites that are located with the channel. The abrupt abandonment of urban centres at ~3500BP has been explained as a consequence of river diversion, although alternative explanations for cultural decline have also been offered. A major problem with earlier interpretations has been that little information exists on the geology of the palaeochannel system. Electrical resistivity soundings were used to map the large-scale geometry and architecture of the palaeochannel system. A thick and extensive sand body is present in the subsurface in parts of north-western Rajasthan, Haryana and Punjab. The dimensions of the palaeochannel bodies imply that these are the deposits of a large river system, though detailed sedimentological analysis is necessary to validate this. Two of the resistivity transects are close to important Harappan sites, Kalibangan and Kunal, suggesting a possible link to archaeological site distribution. However, detailed chronological constraints are required to establish such links. Nevertheless, this study reports the first geophysical evidence for the subsurface geometry of the palaeo-Ghaggar-Hakra river system. © 2012 Elsevier Ltd and INQUA.
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).
Operational 500 m surface soil moisture product using EOS-04 C-band SAR over Indian agricultural croplands
(Indian Academy of Sciences, 2024) Dharmendra Kumar Pandey; Prashant Kumar Srivastava; Rucha Dave; Raj K. Setia; Ompal; Rajiv Sinha; Muddu Sekhar; Manish Parmar; Shubham Gupta; Deepak Putrevu; Raghav Mehra; V. Ramanujam; Bimal Kumar Bhattacharya; Raj Kumar
Surface soil moisture (SSM) at high spatial resolution is an essential land parameter for agricultural applications like irrigation mapping, scheduling, crop water stress assessment, etc. However, available satellite derived soil moisture products are inadequate for meeting the requirements of agricultural applications due to coarse scale soil moisture (~10–40 km). In this article, we developed an operational framework for first of its kind sub-km (~500 m) operational soil moisture product over India by utilizing ISRO’s EOS-04 C-band synthetic aperture radar (SAR) data based on active-passive approach. The potential of EOS-04 SAR for sub-km scale is demonstrated and tested over major cropland sites covering highly heterogeneous and dynamic crop conditions in different agro-climatic regions over India which shows a good agreement with in situ datasets with mean ubRMSE, ranging from 0.051 to 0.078 m3/m3. © (2024), (Indian Academy of Sciences). All rights reserved.
SARS-CoV-2 Infection in Children with Idiopathic Nephrotic Syndrome: A Multicentric Study
(Springer, 2023) Sanya Chopra; Sumantra Raut; Rajiv Sinha; Abhishek Abhinay; Archana Thakur; O.P. Mishra; Menka Yadav; Abhijeet Saha
A multicenter retrospective study was conducted to assess the clinical spectrum of 30 severe acute respiratory syndrome coronavirus (SARS-CoV-2)-positive children with idiopathic nephrotic syndrome. Difficult to treat nephrotic syndrome was found to be a high-risk group with a high incidence of acute kidney injury and mortality. © 2023, Indian Academy of Pediatrics.
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)
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).