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Natural hazards often pose a considerable amount of social vulnerability which is the function of exposure, sensitivity and adaptation. Livelihood vulnerability assessment (LVA) benefits site-specific resilience building and disaster management. There are two popular indices of LVA – (1) the livelihood vulnerability index (LVI) of the Intergovernmental Panel on Climate Change (IPCC, 2007) and another method by (2) Hahn et al. (2009). The study intends to reveal the index that is more suitable to address the flood-induced livelihood vulnerability of the rural communities of the Mayurakshi river basin, India. To this end, the nature of exposure, adaptive capacity and sensitivity involving 35 parameters are measured mainly based on the primary data collected from a questionnaire survey executed over 2382 households spreading over 43 villages from five community development (C.D.) blocks. Moreover, the annual flood reports, district census reports, topographical maps, and satellite images are used as secondary data. The result shows that as per Hahn et al.’s LVI, Khargram (LVI- 0.41) is the most vulnerable block while Nabagram (LVI- 0.35) is the least vulnerable block. However, according to IPCC-LVI, Bharatpur-I has the highest LVI (0.02) and Burwan has the lowest LVI (-0.09). It is observed that exposure exhibits a strong positive correlation with IPCC-LVI and adaptive capacity also maintains a similar correlation with Hahn et al.’s LVI. Interestingly, Kandi is the most exposed block (score: 0.59) with a high adaptive capacity (score: 0.47) resulting in its exclusion from the high LVI category of both methods. This comparative performance assessment underscores the significance of the work before the decision-makers in preparing microscale disaster management plans.

Abstract Water pollution is a major concern for a decaying river. Polluted water reduces ecosystem services and human use of rivers. Therefore, the present study aims to assess the irrigation suitability of the Jalangi River water. A total of 34 pre-selected water samples were gathered from the source to the sink of the Jalangi River with an interval of 10 km and one secondary station’s data from February 2012 to January 2022 were used for this purpose. The Piper diagram exhibits that the Jalangi River water is Na+–HCO3 − types, and the alkaline earth (Ca2+ + Mg2+) outperforms alkalises (Na+ + K+) and weak acids (HCO3 − + CO3 2−) outperform strong acids (Cl− + SO4 2−). SAR values ranging from 0.35 to 0.64 show that water is suitable for irrigation and poses no sodicity risks. The %Na results show that 91.18% of water samples are good and acceptable for irrigation. RSC levels indicate a significant alkalinity hazard, with 94.12% of samples considered inappropriate for irrigation. PI findings show that 91.18% of water samples are suitable for irrigation. Apart from the spatial water samples, seasonal water samples exhibit a wide variations as per the nature of irrigation hazards. Gibbs plot demonstrates that the weathering of rocks determined the hydro-chemical evolution of Jalangi River water. This study identifies very little evaporation dominance for pre- and post-monsoon water. The analysis of variance (ANOVA) test illustrates that there are no spatial variations in water quality while seasonal variations are widely noted (p

River-road crossings are one of the basic infrastructures for rolling the wheels of development of the modern world facilitating connectivity and overcoming geographical obstacles. Their impacts on the hydro-geomorphology of the riverine landscape and the lotic habitat is a long concerning issue amongst scientists, planners and stakeholders. The construction of a new highway bridge over the Jalangi River commenced a few years ago, experiencing occasional halts and progressing at a notably sluggish pace. However, in 2022, the construction gained momentum and was completed in 2023. The study aims to evaluate the influence of the bridge and its construction procedures on the river’s channel morphology and turbidity. We gathered data on various structural aspects of the recently built highway bridge at Krishnagar spanning the Jalangi River, a dying distributary of the Padma River. This included assessments of channel geomorphology and information to water turbidity. To assess the impact of road crossing on channel geomorphology we applied tools of w/d ratio, channel efficiency and channel asymmetry (A*). At-a-station channel geomorphology of the river was drastically impacted by the structure of the bridge and its construction processes. As the river is a dying one, the impulse of road crossing felt to the downstream insignificant. The impact of road-river crossing on water turbidity appears significant at the construction site. Non-clearance of debris and soil from river beds and banks obstructed animal movement along the river banks. In like environments where robust data forms the foundation, it is recommended to pursue additional research to identify a mitigation strategy for the way forward.

Abstract In recent years groundwater contamination through nitrate contamination has increased rapidly in the managementof water research. In our study, fourteen nitrate conditioning factors were used, and multi-collinearity analysis is done. Among all variables, pH is crucial and ranked one, with a value of 0.77, which controls the nitrate concentration in the coastal aquifer in South 24 Parganas. The second important factor is Cl−, the value of which is 0.71. Other factors like—As, F−, EC and Mg2+ ranked third, fourth and fifth position, and their value are 0.69, 0.69, 0.67 and 0.55, respectively. Due to contaminated water, people of this district are suffering from several diseases like kidney damage (around 60%), liver (about 40%), low pressure due to salinity, fever, and headache. The applied method is for other regions to determine the nitrate concentration predictions and for the justifiable alterationof some management strategies.

Abstract Determining the degree of high groundwater arsenic (As) and fluoride (F−) risk is crucial for successful groundwater management and protection of public health, as elevated contamination in groundwater poses a risk to the environment and human health. It is a fact that several non-point sources of pollutants contaminate the groundwater of the multi-aquifers of the Ganges delta. This study used logistic regression (LR), random forest (RF) and artificial neural network (ANN) machine learning algorithm to evaluate groundwater vulnerability in the Holocene multi-layered aquifers of Ganges delta, which is part of the Indo-Bangladesh region. Fifteen hydro-chemical data were used for modelling purposes and sophisticated statistical tests were carried out to check the dataset regarding their dependent relationships. ANN performed best with an AUC of 0.902 in the validation dataset and prepared a groundwater vulnerability map accordingly. The spatial distribution of the vulnerability map indicates that eastern and some isolated south-eastern and central middle portions are very vulnerable in terms of As and F− concentration. The overall prediction demonstrates that 29% of the areal coverage of the Ganges delta is very vulnerable to As and F− contents. Finally, this study discusses major contamination categories, rising security issues, and problems related to groundwater quality globally. Henceforth, groundwater quality monitoring must be significantly improved to successfully detect and reduce hazards to groundwater from past, present, and future contamination.

Abstract The elevated concentrations of heavy metals in soil considerably threaten ecological and human health. To this end, the present study assesses metals pollution and its threat to ecology from the mid-channel bar’s (char) agricultural soil in the Damodar River basin, India. For this, the contamination factor (CF), enrichment factor (EF), geoaccumulation index (Igeo), pollution index, and ecological risk index (RI) were measured on 60 soil samples at 30 stations (2 from each station, i.e., surface and sub-surface) in different parts of the mid-channel bar. The CF and EF indicate that both levels of char soil have low contamination and hence portray a higher potential for future enrichment by heavy metals. Moreover, Igeo portrays that soil samples are uncontaminated to moderately contaminated. Further, pollution indices indicate that all the samples (both levels) are unpolluted with a mean of 0.062 for surface soils and 0.048 for sub-surface soils. Both levels of the char have a low potentiality for ecological risk with an average RI of 0.20 for the surface soils and 0.19 for the sub-surface soils. Moreover, Technique for order preference by similarity to ideal solution (TOPSIS) indicates that the sub-surface soils have lower pollution than the surface soils. The geostatistical modeling reveals that the simple kriging technique was estimated as the most appropriate interpolation model. The present investigation exhibits that reduced heavy metal pollution is due to the sandy nature of soils and frequent flooding. However, the limited pollution is revealed due to the intensive agricultural practices on riverine chars. Therefore, this would be helpful to regional planners, agricultural engineers, and stakeholders in a basin area.

AbstractThe increasing soil erosion (SE) and the associated problems for society, economy, and environment sparked a lot of interest in estimating and mapping SE at different basin scales. The estimation of SE exhibits that SE ranges from 10 to 50 t ha−1 yr−1, with a mean SE of 20 t ha−1 yr−1. The very steep slopes account for 54.21% of total soil loss. The SRB areas where soil loss rates are >10 t ha−1 yr−1 are considered the target areas which account for 27% of the study area and 96% of the soil loss). The high SY is concentrated only in the first-order basins located in a higher slope zone in the northern part of the river. Besides, basin morphometry (basin shape, relative relief) and anthropogenic activities (agricultural land) are retained in the PSLR model as significant factors contributing to SY in the entire river basin.

AbstractOne of the most important aspects of the ‘sub-tropical’ monsoon-influenced environment is the issue of ‘soil erosion’ and its related ‘land degradation’. On the other hand, the climate in this area has become quite extreme. According to this viewpoint, it is important to research a future ‘soil erosion’ scenario in front of the probable effects of climate change and land use change. For the objective of assessing the extent of soil erosion in this area, this study took into account both the USLE and the RUSLE. Compared to the USLE that has been validated, RUSLE has a comparatively greater quantitative efficiency. In RUSLE, the ‘very high’ (>20) and ‘high’ (15–20) ‘soil erosion’ zones tend to be associated with the ‘north-western, western, south-western, and southern’ regions of the river basin. The ‘soil erosion’ that will occur in the future has been estimated by taking into account the projected rainfall, land use and land cover (LULC). ‘Soil erosion’ has increased from the previous time to the projected time. Predicted R factor values for SSP 585 range from 399.92 to 493.72. In addition, a growing erosion tendency associated with increased shared socio-economic pathways (SSPs) has been found.

Study region: The Damodar Fan Delta, West Bengal, India. Study focus: The depletion of groundwater resources worldwide is escalating due to its profuse demand for drinking, irrigation, domestic, and industrial uses. Overexploitation of groundwater in a subtropical fan delta region with rapid population growth like the Damodar Fan Delta in India is of great concern for sustainable mapping, monitoring, and managing water resources. During 2000–2020, the Damodar Fan Delta portrayed an increase in semi-critical community development blocks, implying a decline in groundwater level. To this end, the present study intends to show the groundwater level dynamics including its future prediction, using machine learning algorithms based on the seasonal groundwater level data from 2013‐14 to 2020‐21 for 30 wells. New hydrological insights for the region: Post-monsoon kharif and rabi depicted a higher fall rate in the groundwater level compared to the pre-monsoon and monsoon periods. Future predictions using the best-fit model indicated an increasing trend in the depth of groundwater levels in the future (2025–26). The extreme gradient boost regressor appeared to be the best model, while the decision tree regressor was the worst performer. The major controlling factors of groundwater level dynamics were decreasing rainfall and increasing groundwater abstraction due to population growth and increased demand for irrigation, domestic, and industrial water.

Anthropogenic interventions in the form of dams and barrages often alter the fluvial functionality and eco-geomorphological (geomorphology, hydrology, and ecology) behaviour of river systems. The present work examines the environmental flow, channel metamorphosis, and fluvial functionality of the Damodar River in the context of Damodar Valley Corporation (DVC) dams and development. Structural (dams, barrages, weirs, etc.) and non-structural (urban–industrial and agricultural disposal with effluents, sand mining, etc.) interventions hinder the ecological functionality of the river. This study portrays that the eco-geomorphological behaviour and fluvial functionality of the river have changed due to flow alteration and diversion by dams and barrages and due to rapid urban–industrial and agricultural growth in the basin area. These changes have affected riverine ecological integrity. The ecological functionality level of this study area ranges from 85 to 181, i.e. from poor to good–fair. The ecological functionality level in the sample channel sections (i.e., the immediate upstream and downstream of the Durgapur Barrage) is poor, and the value ranges from 61 to 100 due to the hydrological impact of the barrage and the Durgapur urban–industrial belt. This assessment work will help to restore the fluvial environment for humans as well as riverine biota. HIGHLIGHTS Dams and barrages have altered the hydrological flow regimes, affecting the eco-geomorphological behaviour of alluvial channels.; Dam-induced fluvial metamorphosis is evident in the channel morphological parameters and channel classification.; The fluvial functionality index has been applied to evaluate the ecological functionality level for the restoration of the riverine environment.;

Complex channel planform especially the dynamics of the multi-thread river is empirically examined using the three major dimensions – bar growth, channel length and channel count. To this end, many indices have been proposed to deal with the complex channel response in the context of sediment-energy synergistic scenarios. The existing methods are primarily concerned with the linear or 1D nature of the channel and bar. The present study introduced the areal or 2-D nature of the channel and bar to capture a more realistic picture because, with same length, area of the bar may differ greatly. Therefore, we proposed four indices on channel braiding taking into consideration the area of the channel and bar. We tested our indices to the 28 reaches of the Damodar River, India that showed a significant correlation (∼80%) with the existing standard method. The major highlights of the methods are outlined as follows. • Four novel indices were proposed considering the linear and areal dimensions of the channel and bar. • Proposed indices focus on the unit-free measures with known limits enabling pragmatic comparison with self and other channels. • New methods were tested using field data implying a significant correlation with the existing methods.

Abstract In recent years, groundwater pollution has become increasingly a serious environmental problem throughout the world due to increasing dependency on it for various purposes. The Damodar Fan Delta is one of the agriculture-dominated areas in West Bengal especially for rice cultivation and it has a serious constraint regarding groundwater quantity and quality. The present study aims to evaluate the groundwater quality parameters and spatial variation of groundwater quality index (GWQI) for 2019 using the fuzzy analytic hierarchy process (FAHP) method. The 12 water quality parameters such as pH, TDS, iron (Fe−) and fluoride (F−), major anions (SO4 2−, Cl−, NO3 −, and HCO3 −), and cations (Na+, Ca2+, Mg2+, and K+) for the 29 sample wells of the study area were used for constructing the GWQI. This study used the FAHP method to define the weights of the different parameters for the GWQI. The results reveal that the bicarbonate content of 51% of sample wells exceeds the acceptable limit of drinking water, which is maximum in the study area. Furthermore, higher concentrations of TDS, pH, fluoride, chloride, calcium, magnesium, and sodium are found in few locations while nitrate and sulfate contents of all sample wells fall under the acceptable limits. The result shows that 13.79% of the samples are excellent, 68.97% of the samples are very good, 13.79% of the samples are poor, and 3.45% of the samples are very poor for drinking purposes. Moreover, it is observed that very poor quality water samples are located in the eastern part and the poor water wells are located in the northwestern and eastern part while excellent water quality wells are located in the western and central part of the study area. The understanding of the groundwater quality can help the policymakers for the proper management of water resources in the study area.

The present work investigates the hydrochemical properties of the surface and groundwater of the Mayurakshi River Basin (India) for assessing their irrigation suitability with respect to irrigation hazards. The study involves 72 water samples classified as 48 surface water samples (pre-monsoon: 24; post-monsoon: 24) and 24 groundwater samples (pre-monsoon:12; post-monsoon: 12). Regarding the specific irrigation hazard, percent of sodium and soluble sodium percentage have demonstrated the groundwater vulnerability to sodium while the surface water is observed to be free from this kind of hazard. Similar findings have also been retained for magnesium hazard and the potential salinity hazard. Moreover, regarding the seasonality of the hazards, the post-monsoon season has depicted a higher level of irrigation hazards compared to the pre-monsoon season. The study found that the general evolution of groundwater hydrochemistry and the suitability of water for irrigation are principally governed by carbonate weathering, sand mining, stone crushing, and the development of brick kiln industries. Our methodology can be a good example for similar contexts, especially in developing and tropical countries.