Ganges Research Articles

Dietary exposure of potentially toxic elements to freshwater mammals in the Ganga river basin, India

The threatened Gangetic dolphin (Platanista gangetica) and smooth-coated otter (Lutrogale perspicillata) occuring in the Ganga River Basin (GRB), are experiencing a decline in their population and distribution range owing to multiple anthropogenic pressures, including pollution by Potentially Toxic Elements (PTEs). Apex predators primarily encounter contaminants through dietary exposure. Yet, notable gaps persist in our understanding of the risks associated with the ingestion of PTE-contaminated prey for Gangetic dolphins and smooth-coated otters. In this study, we examined the occurrence and spatial variation of PTEs in the prey (fish) of both these riverine mammals across three major rivers of the Basin, while also evaluating the associated risk of ingesting contaminated prey. Our assessment revealed no statistical variation in bioaccumulation profiles of PTEs across the three rivers, attributable to comparable land use patterns and PTE consumption within the catchment. Zn and Cu were the most dominant PTEs in the prey species. The major potential sources of pollution identified in the catchment include agricultural settlements, vehicular emissions, and the presence of metal-based additives in plastics. Zn, As and Hg accumulation vary with the trophic level whereas some PTEs show concentration (Hg) and dilution (As, Cr, Pb and Zn) with fish growth. The Risk Quotient (RQ), based on the dietary intake of contaminated prey calculated using Toxicity Reference Value was consistently below 1 indicating no significant risk to these riverine mammals. Conversely, with the exception of Co and Ni, the Reference Dose-based RQs for all other PTEs indicated a substantial risk for Gangetic dolphins and smooth-coated otters through dietary exposure. This study serves as a pivotal first step in assessing the risk of PTEs for two threatened riverine mammals in a densely populated river basin, highlighting the importance of their prioritization in regular monitoring to reinforce the ongoing conservation efforts.

Identification of key habitats and conservation threats of the Ganges River dolphin (Platanista gangetica) of Bangladesh

Ganges River Dolphins (Platanista gangetica) are known to inhabit all major river systems in Bangladesh. However, comprehensive spatial records for this globally endangered aquatic mammal are notably scarce nationwide. Furthermore, their habitats are increasingly threatened due to excessive utilization of aquatic resources and their habitats by the growing human population. To allocate limited resources in safeguarding high-priority dolphin habitats, we conducted field surveys and arranged stakeholder consultations to identify key dolphin habitats and the conservation threats they face across Bangladesh. Through this process, we have identified 14 river segments as high-priority winter habitats for Ganges River Dolphins. These dolphins encounter both direct and indirect threats within their habitats. Direct threats include entanglement and occasional intentional killing for traditional medicinal purposes and as fish attractants. Indirect threats leading to habitat degradation comprise the construction of dams and barrages for upstream water extraction, increasing industrial pollution in river waters, overfishing, and alterations to river morphology caused by siltation and sedimentation. The heavy reliance of local communities on dolphin habitats, coupled with a lack of widespread awareness and insufficient conservation efforts, pose significant challenges to the future survival of Ganges River Dolphins in Bangladesh. Bangladesh J. Zool. 51(3): 253-266, 2023

Seasonal Variation, Diversity, and Composition of Planktons in the Ganga River

Plankton are important components of aquatic ecosystems because they contribute to primary production, which sustains fisheries and other ecosystem functions. The study was carried out over a one-year period at three Ganga River sites: Haridwar (Bhadrabad) site A1, Bijnor (Balawali) site A2, and Muzaffarnagar (Bairaj Ganga bridge) site. Bacillariphyceae made almost 65% of the phytoplankton at location A1 14% Chlorophyceae and 14% Cynophyceae. The zooplankton consisted of Protozoa (80%) and Cladocera (20%), with Ulvophyceae accounting for 7%. At location A2, the phytoplankton composition was Bacillariphyceae (79%) and Chlorophyceae (7%). ˃ Cynophyceae (7%). Ulvophyceae (7%), and zooplankton were Protozoa (80%), Rotifera (20%). At location A3, the phytoplankton mix shifted to Bacillariphyceae (70%). ˃ Chlorophyceae (18%) ˃ Cynophyceae (12%) and Protozoa (60%) Rotifera accounts for 40%. The Simpson diversity index (D) value for phytoplankton is 0.58, whereas for zooplankton, the value is 0.53. The mean plankton density at locations A1, A2, and A3 was 2059, 2959, and 3304 individuals per liter, respectively. Only dissolved oxygen in physicochemical characteristics correlated positively with plankton density; all other metrics correlated negatively.

Population status and genetic assessment of mugger (Crocodylus palustris) in a tropical regulated river system in North India

For rewilding the depleted crocodylian populations in India, a targeted ‘one-species one area’ based conservation approach was adopted in the early-1970s. Suitable habitats were identified and designated as protected areas, specifically targeted to recover a particular crocodylian species. A ~ 610 km stretch of Chambal River in the Ganga River Basin was declared as National Chambal Sanctuary to restore the ‘Critically Endangered’ gharial (Gavialis gangeticus), where active management of mugger (Crocodylus palustris) was discouraged. In the present study, we examined the population trends, occupancy, and genetic status of mugger by conducting population monitoring and genetic assessment to understand the status of potentially competitive mugger in the Sanctuary. Our finding suggests that the mugger population has notably increased and colonised the Sanctuary. We observed a moderate level of genetic diversity in the mugger, which was relatively higher compared to the gharial in the Sanctuary. The rapid colonization of ecological generalist mugger raises concerns about potential competition with ecological specialist gharial threatening its long-term sustainability. Considering the coexistence dynamics between the species, it is essential to extend adaptive management strategies for mugger to ensure successful recovery of gharial population in the Sanctuary.

Occurrence and Composition of Fish Species in Three Different Locations of the Ganga River

The freshwater ecosystem's health and fish diversity depend on natural and human interventions. The present investigation was carried out for one year to observe the present physicochemical parameters, fish composition, and abundance with diversity at three selected locations, i.e., A1, A2, and A3. Physico-chemical parameters were exceptionally suitable, and the limnological conditions were favorable for the growth and survival of biodiversity. 39 fish species belonging to 8 orders and 16 families were recorded, and cypriniformes was the most predominant order, followed by siluriformes. Simpson's Diversity Index (D) at site A1 was D=0.73, site A2 D=0.82, and site A3 D=0.87. The highest diversity was found at site A3 and the lowest at site A1. The second most dominant catch of exotics in the landing has adversely impacted the Indian major carps. There should be proper regulations and guidelines for the production and disposal of effluents as well as excessive fishing of indigenous aquatic fisheries.

Spatio-temporal distribution and carcinogenic assessment due to potentially toxic elements in aquifer water of Ganga and Yamuna River basins, India

The spatial and temporal dispersion of potentially toxic elements (PTE) are evaluated for shallow groundwater samples of Delhi and Patna considering PTE pollution index (HPIPTE), evaluation index (HEIPTE), cancerous and non-cancerous effects, hazard coefficient index (HQI) and overall hazard index (HInc) considering fuzzy entropy weights and source identification is done through PCA. The evaluation of groundwater indicators as pH, TDS and PTE (As, Ni, Mn, B, Pb, Fe and Zn) indicated 6.67% and 3.33% of sampling stations exceeded the threshold limit, HPIPTE > 100 for arid and humid periods of Delhi, whereas 3.33% and 13.33% of sampling stations come under high contamination in the banks of the Ganga in arid and humid seasons respectively. The hazard coefficient index (HQI), only 18% and 21% of the specimens were in the grade of low pollution in both the seasons of Delhi and Patna. The trend of HQI is followed as, HQIAs>HQIPb>HQIFe>HQIMn>HQINi≥HQIZn>HQIB in Delhi region for both Young and elders in both seasons, while the sequence is followed as, HQIAs>HQIPb>HQIFe>HQIMn>HQIZn>HQINi>HQIB in the Ganga River basin area for elders and Young. The index (HInc) found 4 Young & 3 elders and 4 Young & 4 elders (Patna, arid and humid seasons) whereas 6 Young and 5 elders (Delhi, arid and humid seasons) affected as per the index per 1000 cases reported. The PC1 (As, Fe, Mn, and Pb) and PC2 (pH, As, Fe, and Pb) extracted from PCA pointed to the effects of evolution of contamination, hydrogeochemical reaction, disintegration of rocks, its dissolution, dispersion, and dilution in unconfined deep aquifers. Rapid depletion of groundwater table may cause the influx of As contamination in the shallow groundwater, whereas high Pb, Fe, Mn and Ni may be the reasons of nearby industries and improper waste disposal process. The findings and GIS mappings may put some light on the PTE over the Rivers which can help the local government and decision makers to formulate safe and protective bounds, to reduce the rate of contamination and to protect the water ecology and environmental system.

Experimental investigation of the efficiency of stone revetment for different temporal variations with the static water condition

Abstract The objective of this study is to determine the optimum size of stone revetment for different water standing durations and critical drawdown rates for 80% height of flood. The model bank was constructed using soil sourced from the Parlalpur ferry ghat of the Ganga River in Kaliachak, West Bengal, with a field density of 1.5 g/cc achieved by maintaining a 10% moisture content (MC) in the model bank soil. The model river bank was prepared considering Froude (F) similitude having a distorted depth scale of 1/20 and a linear scale of 1/200. In this study, effective stone sizes (D10) – 2.3, 3.22, 4.58, 6.31, and 8.84 mm – were used. These stone sizes were investigated in conjunction with three water standing durations: 15, 30, and 45 min. The bank slope was prepared at 1V:1.5H, and a drawdown ratio of 80% was maintained. The effectiveness of stone revetment size was analysed in terms of the percentage loss of stone revetment and the percentage loss of the model bank's cross-sectional area. The outcomes of this study indicate that the 6.31 mm stone size exhibits optimal performance.

Conservation planning for Gangetic dolphin (Platanista gangetica) in smaller rivers of the Ganga River Basin, India

The complex and dynamic networks of river system, vital for the maintenance of biodiversity and ecosystem services, are under pressure due to human-induced water stress disrupting ecological processes. Recognition of the importance of rivers as source of life though has led to efforts towards protecting large rivers, nevertheless the conservation and management of smaller rivers remained mostly neglected, creating significant gaps in ecological restoration initiatives. In the present study, we assess the distribution and population status of Gangetic dolphin (Platanista gangetica) in the small rivers in the Ganga River Basin for integrating it into the basin wide river conservation strategy. We observed that the Gangetic dolphin inhabited most tributaries and sub-tributaries of the Ganga River, with a naïve occupancy rate of Ψ̂ = 0.68 ± 0.04 (mean ± SE) having 606 ± 142.77 (mean ± SE) individuals and accounts for 15% of the total Gangetic dolphin population in the Basin. The results of N-mixture and MaxEnt models demonstrate that channel depth, presence of meanders and water discharge were key predictors of distribution in these rivers, and the proximity to confluences were identified as a critical predictor. About 54% (620 km) of 1150 km of the surveyed river stretches exhibited suitability for dolphins in the Basin, indicated by a probability distribution score of ≥0.50. Combining this data with the available information, we delineated a total of 2850 km stretch covering entire Ganga River System suitable for Gangetic dolphins within the Basin. Notably, the 620 km of suitable stretches identified in smaller rivers represent 22% of the overall suitable stretches across the entire basin. These stretches were translated to conservation priority stretches for systematic conservation planning involving various stakeholders for improved river conservation in the Basin.

Genetic characterization of minor carp (Labeo gonius) from Indian rivers revealed through mitochondrial ATPase 6/8 and D-loop region analysis: implications for conservation and management

India is the habitat of many freshwater fish species that make a significant contribution to endemism. However, the native species population is declining at a very fast rate due to pollution, habitat loss or degradation, new species introduction, hydrologic alterations, and overfishing. The minor carp, Labeo gonius, is one of the important fish species in the Indian river systems and holds enormous potential in culture fisheries. Therefore, the precise status of population structure is a prerequisite for the management of the species. In the present study, we assessed the potential of mtDNA ATPase 6/8 and D-loop regions as markers to determine the genetic diversity and phylogeography of L. gonius from Indian rivers. We have selected five major Indian rivers for investigation which could represent geographically distant populations of the studied fish. A total of 210 ATPase 6/8 sequences (842 bp) and 203 D-loop region sequences (683 bp) of L. gonius from the five major Indian rivers were submitted to NCBI. Results revealed that ATPase 6/8 has 17 haplotypes and 70 polymorphic sites with an overall haplotype diversity of 0.560 ± 0.036 and nucleotide diversity of 0.00347 ± 0.00. Furthermore, D-loop analysis revealed 58 haplotypes, 67 polymorphic sites, 0.954 ± 0.006 overall haplotype diversity, and 0.01914 ± 0.00 nucleotide diversity. The hierarchical AMOVA analysis indicated that a high proportion of the genetic variation (76.46% and 70.22% for the D-loop and ATPase 6/8 regions, respectively) was attributed to among-population variation under gene pool-1 (considering all the stocks from Ganga, Brahmaputra, Teesta, Narmada, and Mahanadi as a single pool). Furthermore, in gene pool-2, samples were divided into two groups: group 1 (Himalayan rivers)—Ganga, Brahmaputra, and Teesta; and group 2 (peninsular rivers)—Narmada and Mahanadi. Genetic variations in the D-loop and ATPase 6/8 regions were found among populations within groups at 70.65% and 53.48%, respectively. Haplotype network analysis revealed that there were significant differences in distributions and frequencies. The observed unique haplotypes might be useful for differentiating the stocks. In brief, the present study suggested that the D-loop and ATPase 6/8 regions are potential markers and represent a significant contribution to the genetic characterization of the minor carp L. gonius from major Indian rivers. Moreover, the L. gonius population along the east coast especially in the Himalayan rivers (Ganga, Brahmaputra, and Teesta river basin) is found to be genetically more diverse. The results would provide a scientific basis for the assessment of fisheries resources and management of this important species.

Population genetics of the critically endangered three-striped turtle, Batagur dhongoka, from the Ganga river system using mitochondrial DNA and microsatellite analysis

The three-striped roofed (Batagur dhongoka) is a semi-aquatic turtle that belongs to family Geoemydidae. Due to anthropogenic pressure, it has been facing an intense decline of over 80% in its distribution range in the past 50 years. It is considered as 'Critically Endangered' so effective conservation strategies are needed to protect the species by determining their genetic diversity and population genetic structure. This study investigates the genetic diversity, population structure and demographic pattern of B. dhongoka from two Turtle Rescue and Rehabilitation Centre established near Ganga river using mitochondrial cytochrome b (Cyt b: 1140 bp) ; control region (CR: 451 bp) and ten nuclear microsatellite loci. mtDNA results show low levels of nucleotide diversity (π = 0.0022) in B. dhongoka haplotypes and provide evidence for a low substitution rate. The demographic pattern estimated by the Bayesian skyline plot (BSP) analysis indicates historical stability followed by growth in the effective population size, with a recent reduction in population size from ~ 2 thousand years ago. The microsatellite findings show a moderate level of observed heterozygosity (Ho: 0.49). Bayesian-based clustering analysis revealed weak genetic structures in B. dhongoka and presence of admixed assignations suggesting close genetic relationships. These findings shed light on B. dhongoka's genetic status and underline the necessity of comprehensive rehabilitation and relocation programs and conservation and management techniques to ensure the species' long-term survival. In order to ensure the effective protection and conservation of B. dhongoka, the Government of India has taken a proactive measure by incorporating it into Schedule I of the Wildlife (Protection) Act, 1972, as amended in 2022.

Flood risk assessment for Indian sub-continental river basins

Abstract. Floods are among India's most frequently occurring natural disasters, which disrupt all aspects of socio-economic well-being. A large population is affected by floods, which leave their footprints through human mortality, migration, and damage to agriculture and infrastructure, during almost every summer monsoon season in India. Despite the massive imprints of floods, sub-basin level flood risk assessment is still in its infancy and requires advancements. Using hydrological and hydrodynamic models, we reconstructed sub-basin level observed floods for the 1901–2020 period. Our modeling framework includes the influence of 51 major reservoirs that affect flow variability and flood inundation. Sub-basins in the Ganga and Brahmaputra river basins witnessed substantial flood inundation extent during the worst flood in the observational record. Major floods in the sub-basins of the Ganga and Brahmaputra occur during the late summer monsoon season (August–September). While the Beas, Brahmani, upper Satluj, upper Godavari, middle and lower Krishna, and Vashishti are among the sub-basins influenced by the presence of dams on downstream flood dynamics, the Beas, Brahmani, Ravi, and lower Satluj sub-basins are the most impacted by floods and the presence of dams. Bhagirathi, Gandak, Kosi, lower Brahmaputra, and Ghaghara are India's sub-basins with the highest flood risk. Our findings have implications for flood risk assessment and mitigation in India.

Phosphorus distribution in the water and sediments of the Ganga and Yamuna Rivers, Uttar Pradesh, India: insights into pollution sources, bioavailability, and eutrophication implications.

River nutrient enrichment is a significant issue, and researchers worldwide are concerned about phosphorus. The physicochemical characteristics and phosphorus (P) fractions of 36 sediment and water samples from the Ganga (Kanpur, Prayagraj, Varanasi) and Yamuna (Mathura, Agra, Prayagraj) rivers were examined. Among the physicochemical parameters, pH exceeded the permissible limit in Ganga and Yamuna River water and sediment samples. Electrical conductivity (EC) and alkalinity were within the permissible limits, whereas total nitrogen (TN) exceeded the limit in Yamuna water. The analysis of phosphorus fractions indicated the dominance of inorganic phosphorus (IP) (76% in Ganga and 96% in Yamuna) over organic phosphorus in both rivers, suggesting the mineralization and microbial degradation as major processes responsible for transforming OP to IP. The positive correlation of pH with IP, AP (apatite phosphorus), and NAIP (non-apatite inorganic phosphorus) explains the release of inorganic phosphorus under alkaline conditions. The correlation between total organic carbon (TOC), TN, and organic phosphorus (OP) indicated the organic load in the rivers from allochthonous and autochthonous sources. Phosphorus released from river sediments and the concentration of phosphate in overlying river water show a positive correlation, suggesting that river sediments may serve as phosphorus reservoirs. The average phosphorus pollution index (PPI) was above one in both rivers, with relatively higher PPI values observed in the Yamuna River, indicating the contamination of sediment with phosphorus, indicating the contamination of sediment with phosphorus. This study revealed variations in the P fractionation of the sediment in both rivers, primarily as a result of contributions from different P sources. This information will be useful for applying different mitigation techniques to lower the phosphorus load in both river systems.

Genetic diversity, spatial connectivity, and population structure of Asian silurid catfish Wallago attu (Bloch and Schneider, 1801) in the Ganga River System: insights from mitochondrial DNA analysis.

The Ganga River System (GRS) is a biodiversity hotspot, its ecological richness is shaped by a complex geological history. In this study, we examined the genetic diversity, spatial connectivity, and population structure of the Asian Silurid catfish, Wallago attu, across seven tributaries of the GRS. We employed three mitochondrial DNA (mtDNA) regions: cytochrome c oxidase subunit I (COXI), cytochrome b (Cyt b), and control region (CR). Our comprehensive dataset encompassed 2420bp of mtDNA, derived from 176 W. attu individuals across 19 sampling sites within the seven rivers of GRS. Our findings revealed high gene diversity (Hd:0.99) within W. attu populations. Analysis of Molecular Variance (AMOVA) highlighted that maximum genetic variations were attributed within the populations, and the observed genetic differentiation among the seven populations of W. attu ranged from low to moderate. Network analysis uncovered the presence of three distinct genetic clades, showing no specific association with seven studied rivers. Bayesian skyline plots provided insights into the demographic history of W. attu, suggesting a recent population expansion estimated to have occurred approximately 0.04million years ago (mya) during the Pleistocene epoch. These results significantly enhance our understanding of the genetic diversity and spatial connectivity of W. attu, serving as a vital foundation for developing informed conservation strategies and the sustainable management of this economically valuable resource within the Ganga River System.

Simulation of the Hydraulic Model HEC-RAS Coupled with GIS and Remote Sensing to Study the Effect of River Cross-section Width in Detecting Flood-prone Areas

Abstract Flooding is one of the extreme hydrological phenomena. It is a recurring natural disaster that causes loss of life and property in many parts of the world, particularly during the monsoon season. It is important to address such issues for local government and policymakers to manage the flood properly. One such flood management activity is to develop a flood-prone area that depicts the spatial and temporal extent of flood accurately. The integration of the Hydrologic Engineering Centre - River Analysis System (HEC-RAS) model and geospatial tools have emerged as a crucial approach for identifying and mapping flood-prone areas. The successful application of the HEC-RAS model generally depends on the topographical data, which represents the channel and floodplain geometry. In floodplain geometry, discrete cross-sections play a vital role to develop the floodplain map, particularly in the flat topographical region. To extract these data it needs a high-quality digital elevation model (DEM), such as light detection and ranging (LiDAR). However, due to a lack of high-resolution topographical data, flood hazard mapping in developing countries is rare. In common practice, the centerline of the river is considered the flow path for the channel. The orientation of the cross-sections is perpendicular to this line and extends to reach the limits of the floodplain. But, it is difficult to define the limits and it may depend on the magnitude of the flood. Hence, in this study, the HEC RAS model coupled with ArcGIS has been applied to the Ganga River, which traverses through the Bihar state of India to study the effect of cross-sectional width to define the floodplain. The Bihar state is facing substantial hardships from annual flooding events with approximately 16.5% of India’s flood-prone area. The extreme flood values for 5, 10, and 25 years of return period have been determined and the influence of the three different cross-sectional widths to mapping the floodplain has been investigated. This novel perspective adds dimension to the understanding of flood dynamics and its implications for flood risk assessment. In this analysis, it has been observed that, with an increase in the width of the cross-section, the floodplain area also getting increased. In this topographical region, keeping a fixed flow path will underestimate the flood-prone area. The width of the flow path depends on the topography of the region and the river flow. The outcomes of this analysis provide valuable insights into the flood-inundated areas for the specified return periods, enabling the identification and prioritization of flood-prone zones.

GLOBALIZATION AND METAL REPOUSSÉ CRAFT OF VARANASI: CHALLENGES AND OPPORTUNITIES

Varanasi, on the Ganges River in India, is recognized for its old crafts and culture. Metal repoussé is one of several art forms that reference millennia-old aesthetics and methods. Varanasi metal repoussé had problems and possibilities with globalisation. This abstract explores Varanasi's metal repoussé craft's complex relationship with globalisation, its problems, and potential for sustainable expansion. Globalisation has benefited and hurt Varanasi crafts like metal repoussé. Artists may present their work abroad with greater connection and market access, boosting economic and cultural interchange. Globalisation causes loss of authenticity, mass-produced replacements, and artisan exploitation for profit. Metal repoussé artists in Varanasi battle to preserve their skills and creations despite progress. Globalisation might destroy ancient traditions. Customers want quicker, cheaper goods; therefore, craftspeople must decrease their quality and authenticity requirements to compete. Globalisation has commercialized craft, turning it into commodities. Commercialization devalues each piece's work, ability, and cultural relevance, exploiting artists who are already suffering. Despite these constraints, globalisation may reinvigorate Varanasi's metal repoussé craft. One solution is using digital networks and technology to reach more people while retaining creative expression. Handicrafts are respected more because internet markets and social media allow craftspeople to exhibit their work, engage with buyers, and share their story. Collaborations with cultural organisations, historians, and designers may modernize and experiment with methods. Craftspeople may attract more customers and stay up with the market by incorporating new ideas and design features while keeping their trade. Varanasi craftsmen may benefit on the rising demand for environmentally and ethically manufactured goods by presenting their products as cultural heritage and sustainability. Craftspeople may attract socially conscious clients by emphasising local resources, eco-friendly processes, and fair trade. In today's globalized world, the Varanasi metal repoussé craft has many obstacles but also many potentials for development and creativity. Collaboration, technology, and historical preservation help craftspeople participate in the global market.

Methyl red biodegradation by novel halophilic Lactiplantibacillus plantarum SS-AU1 isolated from river Ganges

Methyl red biodegradation by novel halophilic Lactiplantibacillus plantarum SS-AU1 isolated from river Ganges

Assessing the water quality of River Ganga in Varanasi, India, through WQI, NPI, and multivariate techniques: a comprehensive study

Abstract In the present research water quality from nine different sampling points (S1–S9) from the River Ganga at Varanasi was examined for different water quality parameters, and multivariate statistical analyses were carried out. Subsequently, several indices, such as water quality index and Nemerow pollution index (NPI), were calculated. The results indicated that the Ganga River at Varanasi had high levels of coliform concentrations, altered pH, and elevated dissolved oxygen/biochemical oxygen demand and chemical oxygen demand values. The weighted arithmetic water quality index values revealed that sites S8, S9, and S2 were the most polluted and unfit for bathing and drinking. Most of the sampling sites have NPI values greater than 1 for several parameters, indicating high levels of pollution. The study revealed that the water quality is poor for bathing and drinking at most of the sites throughout the year. In addition, the upstream water quality assessment revealed that water quality was good compared with the heavily contaminated downstream region. This knowledge can be useful for environmentalists, policymakers, and water resource managers to develop strategic plans to preserve the cultural and aesthetic worth of the Ganga River in the future.

Seasonal variation of surface water quality and streamflow in Rispana: A tributary of Ganges river, India

AbstractTo evaluate the seasonal changes in quality and quantity of river Rispana (a tributary of river Ganges—Dehradun region of India) water quality index (WQI) was calculated at four major locations by using the weighted arithmetic method. Sixteen samples in all were taken throughout the pre‐monsoon (April 2022), monsoon (July 2022), post‐monsoon (November 2022), and the Winter season (January 2023). The major parameters, namely, temperature, dissolved oxygen (DO), pH, electrical conductivity (EC), and total dissolved solids (TDS), E‐coliform, sulphate, total alkalinity (TA), total hardness (TH), and biochemical oxygen demand (BOD) were considered for calculation of WQI. The WQI varied from minimum 44.53 (good) at site 1 – Kairwaan Gaon during monsoon season to maximum 302.69 (unfit for drinking) at site 4 – Mothrowala during the pre‐monsoon period. In 75% samples quality of water was unfit for domestic purpose and the contributing factors are DO, BOD, and Coliform which exceeds permissible limit in all samples. The major factors attributed for decline in the Rispana water quality are discharge of sewage, commercial sites effluent, and urban runoff. Pre‐monsoon, monsoon, post‐monsoon, and winter had average total coliform levels of 1849.6, 2419.6, 2419.6, and 1546.25, respectively, in MPN units. The average value of E‐coli for the four season vary from 1306.8 to 1888.1 MPN. The pollution load (physico‐chemical parameters and bacteriological factors) increases as the river Rispana flows to downstream in urban locations. Streamflow was observed as very lean except monsoon season (~1500 cfs) due to more extraction of Rispana's fresh water in upstream and unplanned changes in its catchment basin; thus establishes an extensive decline in availability of fresh water sources (Domestic use) in downstream Dehradun city area. In monsoon season, more streamflow (rain water influx) maintains the WQI also in good‐moderate category. The land use/land cover – LULC analysis in Rispana basin area, depicted 71% enhancement in urbanization (24.16%–41.55%) takes place in 15 years’ span (2003–2017). The study establishes the potential causes (natural and anthropogenic) for Rispana deterioration and provides a baseline (quality index) for aquatic and ecological rejuvenation of its watershed by executing a proper management strategy with people participation. This work contributes discernments for effective water resource management to address the smart city objectives and sustainable development goal‐SDG:6, urban and municipal authorities must take cognizance for revival of this domestic water resource.

Hilsa fisheries in India: a socio-economic analysis of fishers in deltaic Ganga region of river Hooghly

Hilsa (Tenualosa ilisha) is a premium table fish in the eastern and some parts of the north-eastern region of India, especially for the Bengali community, contributing uniquely to the societal and economic significance of artisanal fisheries of the country. The major distribution of the fish species in India lies in the Bhagirathi–Hooghly component of the Ganga River system. The aim of the study was to examine if traditional Hilsa fisheries in India are sustainable as the livelihood of artisanal fishers in light of the socio-economic conditions of Hilsa fishers in West Bengal. Structured socio-economic surveys were conducted with 402 fishermen from the upper stretch of river Hooghly to its lower stretch (300 km) in West Bengal during 2020–2021. The average monthly income of the Hilsa fishers in the lower stretch of river Hooghly (Godakhali) (₹25,000–30,000/USD 301–361) was higher than that in the upper stretch at Farakka (₹10,000–15,000/USD 120–180). However, fish species other than Hilsa are generating significantly higher returns for 56% of fishers in the Hooghly district; 40% of Hilsa fishers in South 24 Parganas and Murshidabad (Farakka) districts are engaged in non-fishery activities for livelihood. There are significant differences between Hilsa fishers with other fisheries as secondary occupations and those with non-fishery activities as secondary occupations in terms of socio-economic characteristics. These imply that Hilsa fisheries are profitable as a continued traditional livelihood, but it alone is not sufficient enough to support the livelihood of the artisanal fishers. This indicates the threatened economic sustainability of the Hilsa fisheries sector at present. Considering the high market demand for Hilsa in the eastern and north-eastern regions of India and the market complexities, more significant investments need to be channeled into the Hilsa fisheries of the northern Bay of Bengal region. Such investments encompass a wholesome approach, including more governmental initiatives for conservation and management.

Agricultural drought response to meteorological drought over different agro-climatic zones of the Ganga River basin

Abstract Drought directly impacts the agricultural ecosystem, thus causing significant threat to regional and global food security. Investigating the occurrence and propagation patterns of drought events is crucial for its better understanding and mitigation. The study investigates different agro-climatic regions of the Ganga River basin from 2001 to 2020 to quantify meteorological drought using the Standardized Precipitation Index (SPI). Additionally, the assessment of agricultural drought was conducted using the Standardized Soil Moisture Index (SSMI) and Normalized Difference Vegetation Index (NDVI). For understanding the propagation dynamics of drought, Pearson Correlation Coefficient (PCC)-based approach was employed to compute the propagation time between meteorological and agricultural drought types. Stronger correlations were observed between SPI and SSMI compared to SPI and NDVI anomaly, highlighting the direct connection between precipitation and soil moisture. The results of the present study show that the time for propagation ranges within 1–11 months across the Ganga basin as inferred from the maximum PCC values between the SPI and SSMI time series. The propagation rate from meteorological drought to agricultural drought varied from 29.03 to 73.33% among different agro-climatic regions. The insights gained from this analysis on propagation time and rate can inform policymakers in formulating appropriate measure.