Himalayan River System Research Articles

Late Miocene Uplift and Exhumation of the Lesser Himalaya Recorded by Clumped Isotope Compositions of Detrital Carbonate

AbstractThe Himalaya orogen evolved since the Eocene as the Tethyan‐, Greater‐, Lesser‐ and Sub‐Himalaya thrust sheets were uplifted and exhumed in sequence. Reconstructing the provenance of sediment in Himalayan River systems can inform on stages in the tectonic history of the orogen. Here, we analyze the oxygen, carbon and “clumped” isotope compositions of carbonate minerals from Himalayan bedrock, Ganga River sediments and Bengal Fan turbidite deposits. We demonstrate that river sediments consist of a mixture of Himalayan‐derived and authigenic calcite precipitated in the river system. The relative abundance and clumped isotope apparent temperatures of detrital calcite in turbidite deposits decreased between the Late Miocene and Pliocene, while chemical weathering intensity did not increase during this interval. Considered together, these results reflect the establishment of the Lesser Himalaya as an important carbonate sediment source for Himalayan rivers, driven by the uplift and exhumation of this thrust sheet.

Long-term changes and seasonal variability in the stream macrofauna of a Himalayan river system

Interpreting long-term variability in mountain stream ecosystems is challenging where potential causes such as climate change and altered land-use act simultaneously. The scarcity of historical data also limits research opportunity, especially at low latitudes. Here we assess the macroinvertebrate fauna of 12 Himalayan streams in Nepal covering an altitudinal gradient from 1500 to 3900 m asl using data from 1992, 2022 and 2023. We aimed to: 1) compare long-term change in richness and community composition over three decades to short-term seasonal variation, and 2) analyse long-term changes in relation to catchment properties. Rarefied richness decreased equally with altitude in 1992 and 2022, but was greater at most sites in 2022, with several new families detected. In contrast, no clear seasonal pattern was found. The 2022:1992 ratio in rarefied richness was positively correlated with catchment area and weakly with maximum catchment altitude, while the two highest and glaciated sites gained relatively more taxa than other sites. NMDS ordinations from rarefied Bray-Curtis dissimilarities showed considerable overlap in communities among the three datasets. Pairwise rarefied dissimilarities among all sites increased significantly with altitudinal distance between sites in 1992 while there was no such relationship in 2022. Dissimilarities between 1992 and 2022 samples showed a near-significant correlation with increased catchment vegetation cover as shown by NDVI. Our study is the first to document long-term variations in stream macroinvertebrate communities in Himalayan mountain streams, illustrating how some altitudinal patterns have remained stable through time while others appear to have weakened with links to global change.

Tracing hydrological, lithological and geothermal sources of Himalayan river system: a case study from the Teesta River Basin

Tracing hydrological, lithological and geothermal sources of Himalayan river system: a case study from the Teesta River Basin

Comparative Analysis of Gut Bacterial Communities in Fish and Shellfish of Great Himalayan River System

Comparative Analysis of Gut Bacterial Communities in Fish and Shellfish of Great Himalayan River System

Landscape evolution of the NW Himalayan rivers during the late Quaternary and their non-contemporaneity to the Harappan Civilization

A large perennial river system, the Ghaggar-Hakra, fed by the palaeo-Sutlej and palaeo-Yamuna Rivers from the west and east respectively, has been argued to have sustained the Bronze Age Harappan urban settlements (∼4.6–3.9 ka BP) in NW Himalayan foreland in India and Pakistan. However, it has been demonstrated by previous workers that palaeo-Sutlej was already defunct in this region by ∼8 ka, much before the peak of urbanism. In contrast, the evolutionary history of palaeo-Yamuna, a major feeder to the Ghaggar-Hakra River system, remains weakly documented and enigmatic. This knowledge gap limits our understanding of the influence of regional-scale hydrological conditions on the growth and eventual demise of the Harappan Civilization. Here, we present the high-resolution chronostratigraphic records based on 47 optically stimulated luminescence (OSL) ages from 6 cores (∼50 m deep) retrieved across the palaeochannels of the Yamuna. We document multi-storied sand bodies deposited by a mobile channel belt in a large alluvial fan system characterized by four possible stages of drainage reorganization and landscape evolution during the late Quaternary. It has also been inferred that a major eastward shift of the palaeo-Yamuna River occurred at ∼18 ka, predating both the westward shift of the Sutlej at ∼8 ka and the decline of the Harappan Civilization at ∼3.9 ka BP. Our chronostratigraphic data helps to understand the drainage reorganization of the Himalayan river systems during the late Quaternary in the NW Himalayan foreland and reaffirms the non-contemporaneity of the Harappan Civilization with a large river system.

The Spatial and Temporal Disparity of Fish Assemblage and Its Association with Environmental Factors Through Multivariate Statistical Analysis in Jammu and Kashmir's Himalayan River System.

The goal of this study was to explore the dynamics of the environmental components with fish species assemblages in the Ravi and Chenab rivers of the Himalayan river system during the study period from "July 2020 to June 2021".. To examine the relationship between fish species and environmental parameters, multivariate statistical analyses including canonical correspondence analysis, principal component analysis and cluster analysis were applied to data from fish species. ANOSIM and SIMPER were used to determine whether fish assemblage varied with seasons or streams and to identify the fish species that contributed to this variation between the sampling sites. To study the effect of environmental factors on fish species richness, multiple regression analysis was used. Fish species belonging to 30 species and 12 different families (Cyprinidae, 66.6%) were recorded from three study sites (Bhini, Jhajjar and Chadwal streams) with Chadwal (34.3%) having the most ichthyofaunal population. Hillstream fish species dominated the Bhini stream, while catfish species dominated the Jhajjar stream. The Chadwal Stream was home to a diversity of fish species due to its vast fishing grounds. The values of free carbon dioxide (FCO2), bicarbonates (HCO3-), and habitat structure showed significant variations (p<0.05). The Shannon-Wiener (H'), Simpson dominance, and Margalef index values of fish communities were high. Differences in environmental parameters in each sampling site influenced the fish population in the present study. Our findings showed that environmental factors influenced species composition and provided evidence for the dynamic interaction between environmental variables and fish assemblage in the Ravi and Chenab rivers.

Evidence for paleo-continental margin and folding of relic fragment of oceanic lithosphere, northeast Indian subcontinent

The processes of continental breakup, reassembling of landmasses, and huge deltaic sediment depositions contribute to reconfiguring the Earth's surface. Here, we show a classic example of contiguous structures of paleo-continental margin on the eastern Indian Shield and an ancient fragment of the oceanic lithosphere beneath Bangladesh. In the present work, we collated gravity data from Bangladesh and adjoined parts of the Indian shield and the northern Bay of Bengal to decipher rocks' nature and long-term behavior. The gravity map illustrates N-S oriented alternate bands of ∼150 km wide positive and negative anomalies in the Bangladesh region, besides showing signatures of prominent geomorphic features such as the Shillong Plateau, Sylhet Trough, Burmese Arc, etc. The crustal models reveal the presence of paleo-continental margin segments on the eastern edge of the Singhbhum craton and south of the Shillong Plateau, ∼150 km wide folded oceanic crust beneath Bangladesh, and a low slab dip of the subducting Indian plate beneath the Burma platelet. The inferred continental margin evolved after the breakup occurred between the Rajmahal-Sylhet Line and continental fragments (Elan Bank and southern parts of the Kerguelen Plateau) at about 120 Ma. Subsequently, the sediments carried by two great Himalayan river systems were excessively deposited on the margin and over an older fragment of the oceanic lithosphere, resulting in the progradation of the Bengal delta towards the ocean. The oceanic crust beneath Bangladesh was folded with approximately 150 km wavelength as the compressive stress regime is locally operative due to the eastward moment of the Indian plate and westward propagation of the Indo-Burman Wedge.

Chemical weathering and Sr flux from the silicate lithology dominated fluvial system: Insights from major ions, dissolved Sr and 87Sr/86Sr of the Teesta headwaters, Sikkim Himalaya

Weathering and erosion in Himalayan river systems have an important role in global geochemical cycles and elemental distribution among various reservoirs. The present study has investigated major ions, Sr concentrations and Sr isotopes (87Sr/86Sr) in dissolved loads of the Teesta River System (TRS), which is located in the lower reaches (Sikkim Himalaya) of the Brahmaputra basin and covers ∼2% of the later. The above mentioned chemical analyses in the TRS have been studied to (i) quantify chemical weathering fluxes, (ii) decipher sources of Sr and 87Sr, (iii) assess lithological controls on dissolved components and (iv) test the fidelity of 87Sr/86Sr as a direct proxy for silicate weathering. The dissolved 87Sr/86Sr in the TRS ranges from 0.73269 to 0.85452 (mean ∼0.76) which is more radiogenic compared to that of the Ganga (∼0.73) and the Brahmaputra (∼0.74) at their outflow, indicating the importance of the TRS in Sr isotopic evolution of global ocean water. A positive correlation between Sr and SO42− concentrations in the TRS water indicates the sulfuric acid (H2SO4) mediated weathering in its catchment. Our study suggests carbonate lithology as a chief source of dissolved Sr to the river, whereas 87Sr is mainly derived from silicates, vein calcites and calc-silicates. Poor correlation between dissolved 87Sr/86Sr and silicate weathering indices ((Na*+K)/TZ+, SiO2/TDS, silicate cationic weathering rate (Xsil)) suggests either weathering of non-silicate rocks (carbonate, vein calcite, calc-silicate) and/or incongruent weathering (preferential 87Sr release) control dissolved 87Sr fluxes. The dissolved Sr and 87Sr flux to the Bay of Bengal (through the Brahmaputra River) have been estimated to be 1 × 107 moles/yr and 7.1 × 105 moles/yr, respectively which are 0.03% of the global riverine supply to the oceans.

Multivariate morphometric variability in freshwater prawn populations of Macrobrachium dayanum (Hendersen, 1893) from Himalayan river system, India

Macrobrachium dayanum is one of the most nutrient rich and economically important prawn species found in Chenab and Ravi rivers, the most important rivers of Northern Himalayan river system. An approach was undertaken to explore the intraspecific variations among different populations of M. dayanum from three different rivers Gho Manhasa stream (Chenab river), Taragarh stream and Mastpur stream (Ravi river). For the present study, 22 morphometric characters were subjected to multivariate analysis and out of which ten morphometric characters showed significant variations as revealed by the results of univariate ANOVA (p < 0.5). The outcome of principal component analysis accounted for 82.75% of the total variability among populations and canonical variate analysis indicated that 74.04% of the individuals were correctly classified after cross validation based on the significant differences in the morphometric characters for best separating groups. Cluster analysis revealed that three populations of M. dayanum could be grouped in two clusters indicating the possibility of occurrence of two stocks, which might demand different assessment and management strategies for distinct populations while designing management programmes for their sustainability. Moreover, molecular data will be helpful to assess the differentiation of the two stocks.

Exploring prevalence of potential pathogens and fecal indicators in geographically distinct river systems through comparative metagenomics

Microbial communities are considered as vital members to reflect the health of a riverine system. Among them, pathogenic and fecal indicators imply health risks involved with potability of river water. The present study explores the diverse microbial communities, distribution pattern of potential pathogens, and fecal indicators between the geographically distinct Himalayan and Peninsular river systems of India. It also inquires into the environmental factors associated with community variance and distribution pattern of microbial indicators. The application of high-throughput amplicon sequencing approach unveiled significant demarcation (p < 0.004, Anosim R = 0.62) of samples suggesting unique microbial diversities in these two river sediments. Random forest analysis revealed Desulfobulbulus, PSB_M_3, and Opitutus in Himalayan, while DA101, Bacillus, and Streptomyces in the Peninsular as significant contributors to develop overall dissimilarity between the river systems. Permutational multivariate analysis of variance and co-occurrence network analysis were used to study the relationships between microbial taxa and environmental factors. Amongst the various studied environmental parameters, pH, K, Ca, Mg, Ba, and Al in the Himalayan and salinity, Na, temperature, and Th in the Peninsular significantly influenced shaping of distinct microbial communities. Furthermore, the potential pathogenic genera, including Flavobacterium, Clostridium, Arcobacter, Pseudomonas, and Bacillus were highly prevalent in both the river systems. Arcobacter, Clostridium, Acinetobacter, Bacteroides, and Caloramator were the prominent fecal indicators in these river systems. Our findings provide salient information about the crucial role and interplay between various environmental factors and anthropogenic influences in framing the microbiome of the distinct river systems in India. Moreover, assessing potential pathogenic and fecal indicators suggest the public health risk associated with untreated sewage discharge into these water sources. The detection of various F/S indicators and potentially pathogenic bacteria in Himalayan and Peninsular river systems emphasize the urgent need for future monitoring and management of major riverine systems in India.

Human impact on river planform within the context of multi-timescale river channel dynamics in a Himalayan river system

Rivers are dynamic landscape features which are often altered by human activity, making it difficult to disentangle human impact on geomorphic change from natural river dynamics. This study evaluated the human impact on river planform change within the context of short- and long-term river channel dynamics in the Himalayan Sutlej and Beas Rivers, by (i) systematically assessing river planform change over centennial, annual, seasonal and episodic timescales; (ii) connecting observed changes to human-environment drivers; and (iii) conceptualising these geomorphic changes in terms of timescale-dependent evolutionary trajectories (press, ramp, pulse). Landsat imagery was used to extract components of the post-monsoon active river channel (1989–2018), using the modified Normalized Differences Water Index to identify the wet river area, and visible red to determine active gravel bars. Findings were compared with a historical map to represent the pre-dam period (1847–1850) and with data on potential driving factors of change (discharge, climate and land cover). River planform characteristics changed significantly over all timescales, exhibiting strong spatiotemporal variation between and within both rivers. Dam construction likely caused channel narrowing and straightening at the centennial scale (press trajectory). In the Sutlej, this process has continued over the last 30 years, likely enforced by the cumulative effect of water abstraction and climatic changes (ramp trajectory). In the Beas, the pattern of change in river planform metrics was less pronounced over the same period and more variable along the length of the river, possibly linked to different dam operations that maintain a higher degree of flow variability and peak flows (press trajectory). High local erosion rates caused by aggregate mining (episodic) in the Sutlej were also observed (pulse trajectory). Expressed as evolutionary trajectories, the observed responses to human activity confirm the importance of legacy effects of human impact on river systems, and stress the dependency on spatial and temporal scales to determine trajectories of change. The multi-timescale assessment and conceptualisation provide insights into different dimensions of human impact on river planform change, which is pivotal to developing holistic management strategies.

Climate Change and Its Possible Impact in Groundwater Resource of the Kankai River Basin, East Nepal Himalaya

Increasing evidence of changing climate patterns is being observed, and the impact of this change on groundwater has a direct impact on the livelihood and economy of the region. The research focuses on the impacts of global temperature increase and changing precipitation on the groundwater resources of part of the Himalayan river system. The spatial and temporal variations of the hydro-meteorological data of the Kankai River Basin in East Nepal were analyzed using non-parametric Mann–Kendall tests and Sen’s Slope methods, whereas CanESM2 was used to predict the future precipitation scenarios, and an attempt has been made to evaluate the possible impacts on groundwater systems in the region. The temperature shows a significant warming trend (0.14–0.64 °C/decade); however, the precipitation trends suggest remarkable variation mostly at higher elevation. The average annual precipitation suggests a decrease of 1.82 mm/year and a similar decrement has been projected for the future. The groundwater in the region has been influenced by the changing climate and the condition may further be exaggerated by reduced recharge and increased evapotranspiration. This understanding of the impacts and climate scenarios will help the planners with better adaptation strategies, plans, and programs for a better society.

Enhancing production and flow of freshwater ecosystem services in a managed Himalayan river system under uncertain future climate

Future climate change will likely impact the multiple freshwater ecosystem services (fES) provided by catchments through their landscapes and river systems. However, there is high spatio-temporal uncertainty on those impacts linked to climate change uncertainty and the natural and anthropogenic interdependencies of water management systems. This study identifies current and future spatial patterns of fES production in a highly managed water resource system in northern India to inform the design and assessment of plausible adaptation measures to enhance fES production in the catchment under uncertain climate change. A water resource systems modelling approach is used to evaluate fES across the full range of plausible future scenarios, to identify the (worst-case) climate change scenarios triggering the greatest impacts and assess the capacity of adaptation to enhance fES. Results indicate that the current and future states of the fES depend on the spatial patterns of climate change and the impacts of infrastructure management on river flows. Natural zones deliver more regulating and cultural services than anthropized areas, although they are more climate-sensitive. The implementation of a plausible adaptation strategy only manages to slightly enhance fES in the system with respect to no adaptation. These results demonstrate that water resource systems models are powerful tools to capture complex system dependencies and inform the design of robust catchment management measures. They also highlight that mitigation and more ambitious adaptation strategies are needed to offset climate change impacts in highly climate-sensitive catchments.

Link between climate and catchment erosion in the Himalaya during the late Quaternary

Few studies using geochemistry of sediments from plains and delta of the Himalayan river system have reported contrasting results on the shift in erosion of different lithotectonic units, across the strike of Himalayan orogen, in response to changes in the intensity of Indian summer monsoon (ISM) and glacial cover during the late Quaternary. Here we present records of the 143Nd/144Nd (εNd) and 87Sr/86Sr ratios and δ13C of sediment organic matter (δ13CSOM) in bulk sediment samples from two ~45 m long alluvial cores, collected from a paleo-Sutlej channel (in Sirhind, Punjab) at an upstream connection of a large river (Ghaggar-Hakra) with present-day Sutlej River in NW India. The isotopic variations are compared with the available proxy records that document changes in the ISM and Himalayan glacial extent. Significant covariation in down-core profiles of εNd (−14.1 to −22.2) and 87Sr/86Sr (0.72251–0.79456) reveals changing contributions of sediment derived from the Higher and Lesser Himalaya end-member sources in the catchment. Higher εNd (and lower 87Sr/86Sr) during early marine isotope stage (MIS) 1 and late MIS3 reflects increased contribution from the Higher Himalaya as a result of receding glacial cover as well as intense ISM that penetrates into the interior of the Higher Himalaya during warm periods. The δ13CSOM varies from −28.5‰ to −21.3‰ and shows a 5–7‰ increase from colder MIS2 to warmer early MIS1, implying an increase in C4 plant abundance during the same period in response to intensification of the ISM in the post last glacial maximum period. These variations in sediment provenance and vegetation pattern thus highlight the pronounced influence of climate on distribution of erosion and vegetation types in the NW Himalaya.

Counter-intuitive influence of Himalayan river morphodynamics on Indus Civilisation urban settlements

Urbanism in the Bronze-age Indus Civilisation (~4.6–3.9 thousand years before the present, ka) has been linked to water resources provided by large Himalayan river systems, although the largest concentrations of urban-scale Indus settlements are located far from extant Himalayan rivers. Here we analyse the sedimentary architecture, chronology and provenance of a major palaeochannel associated with many of these settlements. We show that the palaeochannel is a former course of the Sutlej River, the third largest of the present-day Himalayan rivers. Using optically stimulated luminescence dating of sand grains, we demonstrate that flow of the Sutlej in this course terminated considerably earlier than Indus occupation, with diversion to its present course complete shortly after ~8 ka. Indus urban settlements thus developed along an abandoned river valley rather than an active Himalayan river. Confinement of the Sutlej to its present incised course after ~8 ka likely reduced its propensity to re-route frequently thus enabling long-term stability for Indus settlements sited along the relict palaeochannel.

Total organic carbon transport by the Alaknanda River, Garhwal Himalayas, India

Transport and fate of organic carbon by the fluvial system play a significant role in the global biogeochemical cycle of carbon. Previous studies show that the transportation of modern organic carbon from the Himalayan River system accounts for 10–20% of the total global flux to the oceans. Till date, no study has been published which dealt with the transport of organic carbon in the headwaters of the Ganga River. The Alaknanda River is a headwater stream of the Ganga, which flows in the Western Himalayas of India. Water and freshly deposited channel sediment samples were collected during the months of March 2014 and August 2014 and analysed for dissolved organic carbon (DOC), particulate organic carbon (POC) and channel organic carbon (COC). The observed variability of organic carbon concentration was correlated with factors such as discharge, physiography and suspended sediment concentration (SSC). The results show that seasonal erosivity in the basin influences its DOC concentration and physiography, thus acting as a key parameter which controls transportation, oxidation and residence time of the organic matter. The allochthonous input of sediments from the erosional activities is the major source of organic carbon. At Devprayag, Alaknanda contributes 66% of the total DOC flux carried by the Ganga River. The comparison with the previously published values indicate that due to differences in physiography and chemical weathering rate, the Ganga River transports organic carbon mainly as a dissolved load in its upstream and predominantly as POC down the Himalayan foothills.

Environmental and spatial characterisation of an unknown fauna using DNA sequencing – an example with Himalayan Hydropsychidae (Insecta: Trichoptera)

Summary Ecological studies of freshwater biota in understudied regions are often obstructed by poor taxonomic knowledge. We posit that molecular tools can help alleviate this issue and present an example where we combined molecular tools, environmental data and ecological statistics to investigate the distribution and community ecology of an unknown fauna of hydropsychid caddisflies along altitudinal gradients in four Himalayan river systems of Central and Eastern Nepal. A total of 484 larval specimens from 34 tributaries were examined. Phylogenetic analysis of the mitochondrial cytochrome c oxidase I (COI) and the nuclear ribosomal RNA 28S were used to delineate molecular operational taxonomic units (MOTUs) applying three analytical methods: general mixed Yule‐coalescent (GMYC) model, Automatic Barcode Gap Discovery (ABGD) and Bayesian Phylogenetics and Phylogeography (BPP). Spatial distributional patterns and potential differences in ecological niches among MOTUs were statistically tested using regression and correlation approaches. Further, we examined the data for signs of non‐random structure in MOTU communities. MOTU diversity within the family of Hydropsychidae was generally high but varied across evaluated gene fragments and slightly among delineation methods. Yet, the subsequent evaluation of environmental and spatial drivers and resulting distributional patterns were highly consistent among the different MOTU estimates. Within each river system, we found community composition varied greatly along the altitudinal gradients, with many MOTUs associated with specific altitudinal ranges. Prevalent MOTU turnover at the river system scale indicated high β‐diversity in the hydropsychid community leading to high degrees of regional endemism. In the Langtang river system, we found fewer MOTU co‐occurrences than expected by chance. These results highlight the utility of DNA‐based approaches using variable genetic markers (mitochondrial or ribosomal nuclear) for primary biodiversity assessment of poorly studied groups or regions. Our study further shows that DNA‐based biodiversity measures are suitable for downstream applications, such as exploring fundamental questions in stream ecology.

Are the Himalayan glaciers retreating

The Himalayan mountain system to the north of the Indian land mass with arcuate strike of NW-SE for about 2400 km holds one of the largest concentration of glaciers outside the polar regions in its high-altitude regions. Perennial snow and ice-melt from these frozen reservoirs is used in catchments and alluvial plains of the three major Himalayan river systems, i.e. the Indus, Ganga and Brahmaputra for irrigation, hydropower generation, production of bio-resources and fulfilling the domestic water demand. Also, variations in the extent of these glaciers are understood to be a sensitive indicator of climatic variations of the earth system and might have implications on the availability of water resources in the river systems. Therefore, mapping and monitoring of these freshwater resources is required for the planning of water resources and understanding the impact of climatic variations. Thus a study has been carried out to find the change in the extent of Himalayan glaciers during the last decade using IRS LISS III images of 2000/01/02 and 2010/11. Two thousand and eighteen glaciers representing climatically diverse terrains in the Himalaya were mapped and monitored. It includes glaciers of Karakoram, Himachal, Zanskar, Uttarakhand, Nepal and Sikkim regions. Among these, 1752 glaciers (86.8%) were observed having stable fronts (no change in the snout position and area of ablation zone), 248 (12.3%) exhibited retreat and 18 (0.9%) of them exhibited advancement of snout. The net loss in 10,250.68 sq. km area of the 2018 glaciers put together was found to be 20.94 sq. km or 0.2% (±2.5% of 20.94 sq. km).

Study of solute sources and evolution of hydrogeochemical processes of the Chhota Shigri Glacier meltwaters, Himachal Himalaya, India

This study was carried out from 2003 to 2007 to understand the hydrogeochemical processes and the solute sources of the meltwaters of the Chhota Shigri Glacier, Himalaya. The meltwater is almost neutral to slightly alkaline in nature: bicarbonate and sulphate are the dominant anions, while calcium and magnesium are the dominant cations. Bicarbonate is found to be derived from carbonate weathering and partly from silicate weathering. Rock weathering followed by precipitation are the main controlling factors that influence the meltwater chemistry of this region. The relatively high values of pCO2 reflect a higher rate of solubility in comparison to release of excess CO2 gas to the atmosphere. The presence of active hydrogeochemical processes and sediment–water interaction results in excess solute transport through the meltwater to the Chandra River that feeds the Chenab, one of the great Himalayan river systems, and ultimately flows into the ocean. This study is the first of its kind to understand in detail the hydrogeochemical process and resultant solute load transport in this Himalayan glacier. Citation Sharma, P., Ramanathan, A.L., and Pottakkal, J., 2013. Study of solute sources and evolution of hydrogeochemical processes of the Chhota Shigri Glacier meltwaters, Himachal Himalaya, India. Hydrological Sciences Journal, 58 (5), 1128–1143. Editor Z.W. Kundzewicz

Exploring the temporal change in provenance encoded in the late Quaternary deposits of the Ganga Plain

Temporal analysis of Sr isotopes in soil carbonates and Sr and Nd isotopes in silicate fractions has been carried out in a sedimentary core (Kalpi core; 50m long) raised from the southern bank of the Yamuna river, Ganga Plain, India. The aim of the study is to constrain sediment provenance through comparison with the modern Himalayan and peninsular river systems' water and bank sediments. Sr isotopic data in soil carbonates (0.71874 to 0.71410) and SrNd isotopic data in silicate (0.72865 to 0.74544 and −13.9 to −17.2, respectively) vary significantly with depth and are indicative of both Himalayan and peninsular sources for sediments in the southern Ganga Plain. The positive correlation between 87Sr/86Sr ratio and 1/Sr in soil carbonate and the negative correlation between 87Sr/86Sr and εNd in silicate confirm mixing of sediments from these sources. Variations of 87Sr/86Sr ratios in soil carbonates show that at ~80 and 45ka the Himalaya acted as the major source of sediments in the southern part of the Ganga Plain. The gradual decrease in 87Sr/86Sr ratios after 80 and 45ka indicates change in source to peninsular India which is also supported by limited Sr and Nd isotope data in silicates. The change in sediment provenance corresponds well with the available climatic record and is suggestive of strong climatic control in sediment supply with high supply from the Himalaya during the interglacial period and peninsular sediments during glacial period.