Lower Gangetic Plain Research Articles

Ecological impacts on the distribution of Ganges River dolphin (Platanista gangetica) in the lower Gangetic plains and its conservation challenges

Despite threatened status, the Ganges River dolphin (Platanista gangetica) received insufficient attention in many habitats including the lower Ganges. In this study, through standardised monitoring programmes, we recorded the population and distribution of the species from a 100-km long stretch of the lower Ganges between January and December 2023. Important ecological parameters (e.g. fish abundance and water quality parameters) were also monitored to understand their effects on dolphin population in the river. Number of Ganges River dolphin varied over time (ANOVA: F11,88 = 10.9, p < 0.001) and space (F8,88 = 24.1, p < 0.001). Maximum number of dolphin was sighted in the month of August; whereas, the minimum was in February. Population of Ganges River dolphin was affected positively by fish abundance (LMM: F = 19.7, p < 0.001) and water transparency (F = 4.4, p = 0.042) and negatively by total dissolved solids (TDS; LMM: F = 13.5, p = 0.001). A range of challenges related to fishermen’s knowledge and attitude towards the Ganges River dolphin were identified. These include lack of awareness, high market demand and price for the species and negative attitude towards the species. Illegally harvested Vulnerable dolphins were sold only to produce dolphin oil to catch another Endangered fish species Clupisoma garua. The results of this study have conservation management applications and implications.

DNA Barcoding of Economically Important Fruit Flies (Diptera: Tephritidae) from the Lower Gangetic Plains of Eastern India

The Lower Gangetic Plains are India's central horticultural crop production regions. Fruit flies (Diptera: Tephritidae) are a significant insect pest that significantly hinders the effective crop production of various commercially valuable fruit and vegetable crops. Therefore, rapid and precise species identification techniques are essential to controlling, managing, and quarantining these pests. Furthermore, reliably identifying fruit flies is exceedingly challenging due to their striking resemblances in morphological characters. In this work, we investigated the effectiveness of mitochondrial cytochrome c oxidase I (COI) gene sequences for identifying seven fruit fly species, involving only the genus Bactrocera from the lower Gangetic Plains in eastern India. The sequences of the studied species showed 99%–100% similarity with sequences from within and outside the country. COI barcodes were able to distinguish between species, with K2P intraspecific genetic divergences ranging from 0-1% and K2P interspecific genetic divergences ranging from 3.65-28.46%, thus maintaining a proper barcode gap. Phylogenetic analyses were performed, and the results showed moderate to high supported monophyly among species. Therefore, COI barcodes have proven a highly successful alternative for quickly identifying fruit flies. This is also the first account of molecular identification of the previously reported tephritid fruit flies infesting fruits and vegetables in eastern India's agriculturally important lower Gangetic Plains.

Space–time clusters and co-occurrence of Plasmodium vivax and Plasmodium falciparum malaria in West Bengal, India

BackgroundMalaria, a prominent vector borne disease causing over a million annual cases worldwide, predominantly affects vulnerable populations in the least developed regions. Despite their preventable and treatable nature, malaria remains a global public health concern. In the last decade, India has faced a significant decline in malaria morbidity and mortality. As India pledged to eliminate malaria by 2030, this study examined a decade of surveillance data to uncover space–time clustering and seasonal trends of Plasmodium vivax and Plasmodium falciparum malaria cases in West Bengal.MethodsSeasonal and trend decomposition using Loess (STL) was applied to detect seasonal trend and anomaly of the time series. Univariate and multivariate space–time cluster analysis of both malaria cases were performed at block level using Kulldorff’s space–time scan statistics from April 2011 to March 2021 to detect statistically significant space–time clusters.ResultsFrom the time series decomposition, a clear seasonal pattern is visible for both malaria cases. Statistical analysis indicated considerable high-risk P. vivax clusters, particularly in the northern, central, and lower Gangetic areas. Whereas, P. falciparum was concentrated in the western region with a significant recent transmission towards the lower Gangetic plain. From the multivariate space–time scan statistics, the co-occurrence of both cases were detected with four significant clusters, which signifies the regions experiencing a greater burden of malaria cases.ConclusionsSeasonal trends from the time series decomposition analysis show a gradual decline for both P. vivax and P. falciparum cases in West Bengal. The space–time scan statistics identified high-risk blocks for P. vivax and P. falciparum malaria and its co-occurrence. Both malaria types exhibit significant spatiotemporal variations over the study area. Identifying emerging high-risk areas of P. falciparum malaria over the Gangetic belt indicates the need for more research for its spatial shifting. Addressing the drivers of malaria transmission in these diverse clusters demands regional cooperation and strategic strategies, crucial steps towards overcoming the final obstacles in malaria eradication.

Chemical Nature of Hooghly (Ganga) River Water and an Assessment of their Impact on the Eco-Pedon System of Indian Botanic Garden, Howrah

The eco-pedon system of the protected premises of the Indian Botanic Garden, located along the river Hooghly in the lower gangetic plain in the district of Howrah, has been studied with a conservational point of view to understand the indiscernible phenomenon of the impact of the river water on the garden eco-pedo-chemical characteristics often submerged due to occasional tidal inundations of the river during the monsoons.It is experimentally revealed that a chemically dilute river water siphons off the mineral riches of the submerged soil system during flash floods. The intensity of mineral erosion is noted to be directly proportional to the periodic length of submergence of the soil system notwithstanding its natural revamping capacity.

Grasses of Indian Botanic Garden

In this paper 71 species of grasses belonging to 42 genera have been enumerated. Panicum elegantissimum and Polytrias amaura are new additions to Indian Flora. They have been collected from Indian Botanic Garden which falls under the Lower Gangetic Plains.

Analysing spatio-temporal drought characteristics and copula-based return period in Indian Gangetic Basin (1901-2021).

Uncertainty and uneven distribution of monsoonal rainfall and its consequences on crop production is a matter of serious concern in India, specifically, in theIndo-Gangetic plainregion. In this study, drought patterns were investigated through standardised precipitation index (SPI) of varying timescales, using the India Meteorological Department (IMD) precipitation data (1901-2021). We analysed the spatio-temporal pattern of different drought characteristics (frequency, duration, severity, intensity) of the Indian Gangetic basin using run theory. The bivariate copula method has been incorporated to combine two drought properties (severity and duration). Copula integrates multivariate distribution and considers the dependency rate among the variables. The five most widely used copulas from various copula families, elliptical (normal, t-copula) and Archimedean (Clayton, Gumbel, Frank), were estimated for modelling, and the best fit copula was selected. The study revealed that seasonal drought is more frequent and intense in the Upper and Middle Gangetic Plain, whereas annual drought is quite scattered in nature. It is worthy to mention that downward drought trends were observed in this agricultural belts significantly after 1965; specifically, in the Upper, Middle, and Trans Gangetic Plain regions. With increasing drought duration and severity, the drought return period raised, but the frequency decreased gradually. Most of the droughts characterised by less duration and severity occurred with a return period below 10years for the whole region. The major 100 + years return period droughts were to be found after 1960 and their frequencies were significantly higher after 2000. The most recent remarkable droughts with more than 100years of return occurred during 2008-2011 and 2016-2018 in the Upper and Middle Gangetic plains, whereas in the Lower Gangetic plain, a hundred-year return period drought was occurred during 2010-2013. This study provides agroclimatic-zones-wise significant information of drought characteristics and its nature of occurrence in the Indian Ganga Basin. The results enhance the understanding of drought management and formulation of adaptive strategies to mitigate the adverse impact of droughts.

Management of soil cover and tillage regimes in upland rice-sweet corn systems for better system performance, energy use and carbon footprints

This study investigates the effects of tillage and mulching regimes on rice-sweet corn systems in the lower Gangetic plains, focusing on region-specific and crop-specific impacts on soil-crop-environmental parameters. The experiment consisted of three levels of tillage: conventional (CT), minimum (MT), and zero (ZT), and four levels of mulching: live, leaf litter, paddy straw, and no mulching. The results show that ZT tillage resulted in higher bulk density (BD) compared to other treatments, despite an increase in soil organic carbon (SOC). Live and leaf litter mulching led to slight reductions in BD in the upper soil layers. CT resulted in net depletion of SOC whereas ZT registered a positive sequestration rate of 1.19 Mg ha−1 yr−1. Live and leaf litter mulching increased SOC sequestration by 42.6% and 38.8% compared to paddy straw mulching, respectively. Initially, ZT resulted in a 10.3% reduction in system productivity compared to CT, while MT yields were comparable to CT. However, mulching regimes consistently improved production by 16.4%–25.2% as compared to no mulch. ZT and MT were found to be more affordable than CT, with cost savings of 18.2% and 6.8%, respectively. ZT had the highest B: C ratio, indicating better economic efficiency. Among the mulching treatments, live mulching was the most economical. Both ZT and MT saved input energy by approximately 22.9% and 13.5%, respectively compared to CT. Live mulching resulted in the highest net energy and energy output. Compared to CT, ZT reduced carbon footprint (CF) by 41.5 and 22.2% in rice and sweet corn, respectively. MT scored midway between ZT and CT in all parameters. CT exhibited several limitations, including high input energy requirements, high cost of cultivation, poor economic efficiency, negative environmental impacts, and loss of SOC. ZT initially experienced yield reduction and lower net returns in the early years. Therefore, MT was identified as the best alternative in the initial years before transitioning completely to ZT, as it provided comparable yields to CT with better overall benefits. Among the soil cover regimes, live mulching was found to be the most favorable option across all dimensions.

How Do the Dynamics of Urbanization Affect the Thermal Environment? A Case from an Urban Agglomeration in Lower Gangetic Plain (India)

Urban growth and development has significantly affected urban heat island (UHI) due to urbanization. Particularly in the cities in developing countries, the assessment of UHI has emerged as one of the core research themes as it significantly affects the ecological environment and livability in cities. Thus, the assessment of UHI is crucial for climate mitigation and sustainable urban landscape planning. This study identifies the dynamics of landscape patterns and the impact of composition and configuration on the thermal environment in English Bazar Urban Agglomeration (EBUA), Eastern India, along the urban–rural gradient (URG) approach. Geospatial approaches and spatial metrics were employed to assess the impact of the landscape pattern on the thermal environment. Descriptive and inferential statistics have also been used to find the effects of landscape patterns on the thermal environment. The result has also been validated based on the location and correlation analysis. The built-up area increased by about 63.54%; vegetation covers and water bodies declined by 56.72% and 67.99% from 2001 to 2021. Land surface temperature (LST) decreased with increasing distance from the core of the city. LST declined by about 0.45 °C per kilometer from the core of the city towards the outside. LST had a positive correlation with IS and a negative correlation with green space (GS) and blue space (BS). The mean aggregation of the impervious patches was larger (73.21%) than the GS (43.18%) and BS (49.02%). The aggregation of impervious surface (IS) was positively correlated, and aggregations of GS and BS had a negative correlation with LST. Findings suggest that the spatial composition and configuration of the impervious surface, GS, and BS must be considered in landscape planning and design framework to make the city more livable.

Effect of Zinc Nutrition on Lathyrus (Lathyrus sativus L.) under Varying Sowing Dates in the Gangetic Plains

Background: In the lower Gangetic plains, which have typical short winters and Zn-deficient soil, identifying a temporally flexible sowing window with adequate Zn fertilization assumes importance to produce Zn-dense lathyrus in rice-based systems. The current study was conducted to evaluate the effects of sowing dates and Zn nutrition on growth, Zn enrichment and economics of lathyrus. Methods: The experiment was laid out in a split plot design with three replicates comprising two sowing dates (14th and 29th November) in main plots and eight Zn nutrition encompassing various Zn application methods and method-specific doses in the sub-plots. Result: Late sowing with foliar spraying of 1.0% ZnSO4 at pre-flowering and pod development stages significantly improved growth traits and yield, while fetching maximum economic benefits in lathyrus. Although sowing dates exerted no significant effect, foliar spraying with 1.0% ZnSO4 significantly improved Zn concentration in lathyrus seed (30.36 ppm). Hence, under inevitable late sowing conditions, lathyrus is an ideal choice when accommodated with adequate Zn fertilization since it is capable of sustaining adequate productivity and nutritive values under suboptimal conditions because of its ability to strike a balance between root and shoot growths.

Assessment of Spatio-temporal variability of climate in the lower Gangetic alluvial plain.

Global climate change is a cause of concern as extreme events have intensified in recent years, with increased floods and droughts also reported in the Lower Gangetic Plain (LGP). Assessments from Regional Climatic Models (RCM) cannot capture the local climate variability necessary for devising an action plan for climate risk mitigation. The present study aims to fill this gap by assessing the long-term local-scale climate variability using Modified Mann-Kendall (MMK) and Centroidal Day (CD) shifts for the Patna district, which can be extended to other districts in the LGP. The time series is split into two halves to account for changes due to urbanization in recent three to four decades. CD analysis shows a forward shift in the monsoonal and annual rainfall in recent decades. The variability in total rainfall has become more pronounced post-1985 during monsoon, postmonsoon, and winter seasons. An increase of 64.53mm (18.9%) in surface runoff and a strong correlation between built-up area and precipitation further cement the role of urbanization in local climate change. Despite a 5.74% decrease in monsoonal rainfall, a 3.51mm/day increase in rainfall intensity is observed during the monsoon. The implications of these variabilities have posed new challenges for the agricultural production and management of water resources and the interactions between groundwater and surface runoff.

Assessment of the tube-well water quality: A micro-level case study from Lower Gangetic Plain (LGP) in North 24 Parganas district, West Bengal, India

The purpose of this study is to investigate the quality of tubewell water (TW) in Barasat-I (Community Development Block) under North 24 Parganas District of Lower Gangetic Plain (LGP), West Bengal, India with respect to suitability for drinking purpose. This is the first micro-level ground water related study in this region. In total twenty (20) groundwater (GW) samples from tube-wells at different locations of nine (09) Gram Panchayats (GP) were collected and analyzed. The results have been compared with the Indian standard (IS) for drinking water based on eight parameters, such as pH, total dissolved solids (TDS), total suspended solid (TSS), conductivity, total alkalinity (TA), total hardness (TH), chloride (Cl), and arsenic (As). Moreover, TDS (50%) and Total Hardness (TH) (90%) were found to be above the desirable limit. However, pH, Chloride, has been found to be within the permissible limit. This micro-level study revealed that high contamination with arsenic of GW has been identified on the middle to eastern side of Barasat-I. As is found to be above acceptable limit at 70% sampling points. Therefore, rural people of the eastern side of the Barasat-I are prone to a higher risk of black-foot disease due to higher level of As. Overall, the groundwater in this block is not suitable and fit for direct drinking. It needs treatment to minimize pollution or contamination, where regular monitoring and analysis is recommended to determine the extent of contamination in the other parts of LGP. The findings of this study will be beneficial to manage and control ground water vulnerability in micro-level for water scientists, policy makers, and researchers as well in sustainable way and must be achieved by 2030.

Assessment of the tube-well water quality: A micro-level case study from Lower Gangetic Plain (LGP) in North 24 Parganas district, West Bengal, India

Assessment of the tube-well water quality: A micro-level case study from Lower Gangetic Plain (LGP) in North 24 Parganas district, West Bengal, India

Fish diversity decline in the lower Gangetic plains: a victim of multiple stressors

Fish diversity decline in the lower Gangetic plains: a victim of multiple stressors

Photothermal Quotient-An Effective Thermal Index for Evaluation of Lentil (Lens culinaris L.) Phenology and Yield in the Lower Gangetic Plains

Background: Sowing time and variety-specific genetics influence the phenological development of lentil (Lens culinaris L.), affecting its heat and solar energy utilization for attaining satisfactory yield. The present study was conducted to assess how the different thermal indices behaved in explaining variation in phenology and yield components with corresponding effects on yield of lentil varieties grown under varying sowing dates. Methods: The experiment comprised of four sowing dates in the main plots and five lentil varieties in the sub-plots, laid out in a split-plot design replicated thrice. The phenology, yield components and yield were recorded. The computed thermal indices and correlation and regression analyses were used to assess their effects on yield traits and yield. Result: Sowing after 7th November reduced lentil yield by 13.6-22.5 kg ha-1 day-1 and 0.9-2.1% ha-1 day-1 on absolute and relative basis, respectively. The varieties WBL 77 and HUL 57 were less sensitive to temperature fluctuations resulting in stable yield performance under varying thermal regimes. Despite significant influence of temperature on yield traits, growing degree days explained 82.0-89.0%, while photothermal quotient (PTQ) explained 92.0-96.0% of the total variation in yield. PTQ emerged as a reliable yield predicting thermal index and might be used for breeding climate-smart lentil varieties.

Discharge-driven rapid bank-erosion and its impact on sediment budgeting in the lower Gangetic plains

Discharge-driven rapid bank-erosion and its impact on sediment budgeting in the lower Gangetic plains

Growth, Grain Yield and Soil Nutrient Status of Kharif Rice (Oryza sativa L.) as Influenced by Integrated Nutrient Management in Lower Gangetic Plains

A field experiment was conducted during the Kharif season of 2019 at Instructional Farm, BCKV, Jaguli, Nadia (West Bengal) to study the Growth, yield, and soil nutrient status of Kharif rice (Oryza sativa L.) as influenced by integrated nutrient management under lower Gangetic plains in a Randomized Block Design (RBD) having three replications. Outcomes revealed that rice plots fertilized with NPK@125% of RDF(100:50:50 kg/ha) + FYM@ 5 t/ha +vermicompost @2.0 t/ha recorded the highest plant height, elongation rate dry matter accumulation, crop growth rate and no. of tillers per hill. The maximum grain (5.25 t/ha) and straw yield (5.84 t/ha) as well as soil nutrient status after harvest of Kharif rice was recorded with NPK@125% of RDF (100:50:50 kg/ha)+FYM@ 5 t/ha+ Vermicompost @2.0 t/ha followed by NPK@ 80:40:40 kg/ha + ZnSO4@25 kg/ha which is 53.72% higher over control.

Comparison of ecosystem services provided by an urban and a riverine wetland: a multi-scale evaluation from lower Gangetic plain, Eastern India.

Wetland ecosystems (WE) are considered the most productive ecosystems on the globe which provide a range of basic and critical ecosystem services (ES) to humans. However, WE are constantly being degraded because of a poor understanding of social benefits at a local level and the lack of recognition of economic values for ES at sub-national and national levels. This study aims to compare a peri-urban wetland with a riverine wetland from lower Gangetic plain, Eastern India, to identify the bundle of ES based on its perceived importance from multiple perspectives at a local level. Participatory research tools have been employed (i.e., key informant interviews, household survey, and field observation) for data collection. Based on rapid assessment of wetland ecosystem services (RAWES) approach, a priority ranking analysis was used to examine ES. A Mann-Whitney U test was performed to find out significant differences in RAWES approach between riverine and peri-urban wetlands. Multiple regression model (MRM) was also performed to explore the impact of socio-demographic factors towards the perception of WES. Results showed that (i) the utilizations of WES largely vary between riverine and peri-urban wetland; (ii) provisioning and regulating ES were attributed relatively higher importance by the people of riverine and peri-urban wetlands in comparison to other ES; (iii) as per RAWES approach, the ESI value for riverine wetland was higher (0.58) than the peri-urban wetland (0.44) indicating the higher importance and dependence on WES; and (iv) population growth, expansion of settlement, climate change, and agricultural expansion were attributed as significant drivers of WE change (particularly for urban wetland). This study suggests the much-needed policy interventions and future pathways of research for developing effective measures to ensure livelihood sustainability of the dependent communities and to sustain (active) the ecosystem health of riverine and peri-urban wetlands.

Sacred green spaces in semi-urban areas sustain more birds than its adjacent areas: A study from lower Gangetic plains, West Bengal, India

Abstract With rapid urban expansion and flourishing real estate sector, remaining green patches in many sub-urban/peri-urban areas are facing immense threat and/or being destroyed. We therefore, explored the avian abundance and richness of green spaces around temples (sacred sites) and compared them with adjoining green spaces without religious places (control sites). The species richness and abundance in sacred sites (12.16 ± 0.65 species; 25.54 ± 1.176 individuals) was significantly higher than control sites (6.31 ± 0.77 species; 20.04 ± 1.4 individuals). The compositions of avian communities of sacred sites were significantly different and the presence of temple positively influenced the species richness. GLMM also revealed that the species richness was positively influenced by the distance to building and tree cover area and not influenced by distance to road, areas of water body, bare land. Our findings indicate that the green spaces around the sacred places have greater avian diversity in semi-urban areas, and could be prioritized for the conservation of avian diversity. Generating local support could be relatively easier due to traditional, religious and/or cultural belief against tree felling around the places of worship.

Integration of RS-GIS with Frequency Ratio, Fuzzy Logic, Logistic Regression and Decision Tree Models for Flood Susceptibility Prediction in Lower Gangetic Plain: A Study on Malda District of West Bengal, India

Integration of RS-GIS with Frequency Ratio, Fuzzy Logic, Logistic Regression and Decision Tree Models for Flood Susceptibility Prediction in Lower Gangetic Plain: A Study on Malda District of West Bengal, India

Immature stages of Culicoides innoxius Sen & Das Gupta and pupa of C. huffi Causey (Diptera: Ceratopogonidae) from India

Both larval and pupal stages of Culicoides innoxius Sen & Das Gupta and pupal stages of C. huffi Causey are described and illustrated. All specimens were collected from the Lower Gangetic plains of West Bengal. Larvae of C. innoxius were obtained from rotten banana stem, while a single pupa of C. huffi was collected from an irrigation channel associated with the rice agroecosystem. A pictorial pupal key of the species of the genus reported from India is provided.