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This paper reports the dynamism of a submarine groundwater discharge (SGD) zone in SW India. Two electrical resistivity tomography (ERT) surveys were conducted in the project area to delineate the seawater-fresh water interface and characterize the subsurface aquifer layers. Beach groundwater dynamics were also studied by continuously monitoring salinity, temperature, and nutrient concentration in the groundwater from three shallow dug wells on the beach. The ERT surveys were planned in such a way as to fall between these dug wells. The flow domain was modeled using a numerical modeling approach, and the rate of fresh SGD flux and its spatial variation along the coastline has been estimated. The study proves that the numerical modeling approach combined with other field measurements and observations, such as ERT and continuous monitoring gives a comprehensive understanding of SGD and associated processes. [ABSTRACT FROM AUTHOR]

This paper describes the existence of high salinity in an inland aquifer system of a limited extent located in the granitic terrain of south India. Salinity levels observed in 55 water samples collected pre- and post-monsoon are discussed. Limited repeat sampling during the two seasons shows no significant change in hydrochemistry, probably due to the prevailing drought conditions during the study period (2017–18). As per the salinity classification based on total dissolved solids (TDS), only one sample indicates freshwater while ~ 40% of the samples are slightly saline, and the remaining have moderate salinity. All the high TDS samples are located over a limited area, and most show the water type as Ca–Mg–Na–Cl–SO4. Hydrochemical data indicate a gradual increase in salinity from west to east. Mainly two distinct processes (1) reverse ion exchange and (2) evaporation are likely to have influenced the groundwater chemistry. Variation in water chemistry between granite and gneiss formations indicates the influence of geology on hydrochemistry. Insignificant changes in hydrochemistry for the limited repeat sampling during pre and post-monsoon periods show a meagre recharge due to failed monsoon. However, depleted stable isotope values with reference to high TDS suggest faster recharge conditions in the granitic region than in the gneissic region. Accumulation of high salinity in the groundwater is restricted to the granitic area. We postulate that the presence of Hornblende Biotite Gneiss along the southern parts of the granitic region may be acting as a boundary for accumulating saline groundwater in a limited area in this region. However, it needs confirmation through further detailed geological and geophysical studies. [ABSTRACT FROM AUTHOR]

River bank filtration (RBF), as one of the sustainable natural treatment techniques, can provide risk-free drinking water supply to rural villages where piped water supply through conventional treatment schemes is very expensive. The main purpose of this paper is to report the results of a RBF production well implemented in a complex hydrogeological setting under the ephemeral Varaha river influenced by the saline coastal aquifer in the Visakhapatnam district of Andhra Pradesh (India) for the supply of drinking water to the nearby rural habitats that have no organized water supply. To understand and identify the hydraulics of the river–aquifer exchanged water, particle tracking analysis to determine the travel times of river water path lines, capture zones, the proportion of bank filtrate and river water, and groundwater into RBF production well consequent to pumping were carried out using modular finite difference groundwater flow model (MODFLOW) in conjunction with a particle-tracking model for MODFLOW (MODPATH). The river–aquifer and well field interaction were studied by developing a two-dimensional two-layer groundwater flow model with a partially penetrating well in an unconfined aquifer. The flow modeling simulation results together with MODPATH particle tracking analyses revealed that the installed RBF production well could yield about 61% river water through bank filtration and the remainder from the groundwater. The flow model was also used to optimize the pumping duration from the RBF production well without compromising the water quality of the bank filtrate water. The optimum pumping duration was estimated to be 5 h a day at the rate of 31.2 m3/h from continuous pumping during the monsoon period. The performance and quality of the bank filtrate from the well demonstrated that the RBF technique could also be a potential and viable approach for the supply of safe drinking water from an ephemeral river-induced bank filtrate influenced by the saline coastal aquifer. River bank filtration (RBF), a process to extract river water and groundwater through RBF wells, is one of the sustainable natural treatment techniques successfully providing risk-free drinking water supply in many urban, periurban, and rural areas in different countries. In India, it is gaining popularity, particularly in rural clusters where piped water supply through conventional treatment schemes has a remote chance of being effective. RBF wells are very effective in removing suspended particles, pathogenic compounds, and microorganisms present in the source water. The quantity of RBF water depends on the user requirements; for a town with a series of RBF wells or a small village using a single RBF well, RBF techniques can be employed. For establishing RBF wells in coastal regions, extra care would be required to fix the pumping rate and its duration to avoid mixing of saline with fresh water. The present study demonstrates the successful implementation of a RBF well on an ephemeral river (Varaha river in Andhra Pradesh State, India) in a saline coastal aquifer. The RBF technique can be employed to any other river reach or waterbody in the region where there is a need for potable water supply with minimum water treatment cost. [ABSTRACT FROM AUTHOR]

This paper conceptualises the factors responsible for water quality change in the aquifer on the basis of a study of flow dynamics, hydro-chemical, and bacteriological processes in a gypsum, lignite, oil, and gas-rich Barmer sedimentary basin in India. The change in colouration, odour, and presence of gases in flowing wells has been analysed. The study revealed that such a change in the quality of the water is mainly occurring in those wells that are located in the transition zone between unconfined and confined parts of the same aquifer. The field and lab analyses have further revealed the presence of pyrites, other iron-rich minerals, hydrogen sulphide (H2S), carbon dioxide (CO2), and methane (CH4) gases in the aquifer. The study suggests that changes in flow dynamics, hydro-chemical equilibrium, and microbiological processes like sulphate reduction, methanogenesis, and reverse methanogenesis are responsible for such changes in groundwater quality. The change in water quality in the unconfined parts of the aquifer is mainly due to in situ pyrite dissolution, bacteria-mediated sulphate reduction, or reverse methanogenesis taking place in the nearby confined parts of the aquifer. The presence of CH4 in non-flowing wells or while drilling new wells appears to be biogenic in nature and has migrated from deeper, confined parts of the same aquifer. The overexploitation of the aquifer has changed the flow dynamics and hydro-chemical equilibrium within the aquifer, and it has prompted the migration of gases from deeper, confined parts of the same aquifer. The water quality change is more prominent in the transitional zone between unconfined and confined parts of the aquifer. [ABSTRACT FROM AUTHOR]

This research examines the implications of rainwater harvesting structure hapa in the Bankura district of West Bengal, India. The paper finds that proper management and harvesting of surface and subsurface runoffs in hapas can facilitate groundwater recharge and increase both net irrigated area and moisture in soil leading to higher cropping intensity and yield in dryland areas. However, dissected plateau and residual hillocks can reduce irrigation efficiency of hapas. Although sprinkler or drip irrigation along with cultivation of drought and lateritic resilient, low moisture crop can help in coping up with geophysical and climatic vulnerability, appropriate crop diversification is also necessary. There is also a need for regular maintenance and desiltation of hapas. The water user groups should play an active role for this, especially for hapas in common land. Further, scientific guidance is necessary for designing appropriate structure of hapas in different geo-physical conditions. [ABSTRACT FROM AUTHOR]

Managed Aquifer Recharge (MAR) has emerged as a multi-facet, sustainable and effective technique to replenish dwindling groundwater resources. Suitable site selection is an important step in the design phase of MAR process. Conventional methods of site suitability studies using GIS and Multi Criteria Decision Analysis (MCDA) does not address the aquifer's response to MAR, while limited modelling-based studies have considered the effect of surface hydraulic factors. In this paper, a fresh approach is presented, that utilises decision model, K-mean clustering technique and numerical model to identify optimal sites for MAR interventions. The methodology was applied in a semi-arid region of Lower Betwa River Basin (LBRB), India. Four different parameter combinations were employed that incorporated the impact of surface and subsurface parameters. Multiple model runs were executed using MODFLOW–NWT to assess the groundwater head response to the infiltrated volume of water. The results indicated that under the least head change category (< 0.7 m), the north and south–east regions of the LBRB were the most appropriate sites. The coalition of geomorphology and drainage density along with aquifer properties such as hydraulic conductivity, specific yield and aquifer thickness were found to be the best suited combination for site selection in LBRB, with maximum spatial coverage (16%) under it. It was observed that the choice of parameter combinations affected the range of groundwater head variations and depended upon the site-specific criteria of accepted head change ranges for determining the best suitable parameter combinations for MAR site selection. [ABSTRACT FROM AUTHOR]

Fresh and pure water has an important role to play for healthy life. Currently, in many studies higher concentrations of contaminants like calcium, sodium, nitrate, lead, chromium, arsenic, fluoride etc. have been reported that makes the water unfit for its direct consumption. Sources and release mechanism of many such pollutants is still not known. These sources can be anthropogenic or geogenic. This paper deals with one of such contaminants namely fluoride and emphasizes on its release from various minerals viz. Gypsum, fluorite, tourmaline, actinolite, plagioclase, biotite, quartz, kayanite, epidote and orthoclase under different pH environment. It has been noted that maximum fluoride has been released from the fluorite at all pH environment (acidic, normal and alkaline) of water while minimal fluoride was released from kayanite. However, orthoclase, tourmaline and biotite can release fluoride in considerable amount. The attempts were also made to compare the release of fluoride from modern sand (Ganga sediments) with ancient sand (from sandy aquifer) under different pH condition. Outcome of studies shows that maximum fluoride released from the sand at the pH range of 6.1 to 8.2. [ABSTRACT FROM AUTHOR]

An approach has been made in this study to delineate the groundwater potential zones of the Varuna river basin, Uttar Pradesh, India, using the analytical hierarchy process (AHP) and multi-influence factor (MIF) techniques. The present groundwater estimation exhibits an increase in the draft (10%) due to expansion in population, agricultural extent, and industrialization, which ultimately causes water table depletion. This backdrop justifies the need for this particular analysis in the multilayer aquifers of the central alluvial zone. The shallow aquifers are silty and unconfined, whereas the deeper aquifers are coarse, sandy-gravelly, and semi-confined. Basement faults and highs often control the thickness of aquifers in the subsurface. The study considered an integrated approach of AHP and MIF methods with remote sensing and GIS approaches. Various themes (land use/land cover (LULC), soil type, geology, elevation, slope, rainfall, normalized difference vegetation index (NDVI), drainage density, recharge rate, groundwater depth) determined by considering different conditioning factors and eventually employed for computation of groundwater potential index (GWPI) and classified for identifying the groundwater potential zones (GWPZ). Two methods applied to capture the results in a more tangible form as the AHP model works on building a pair-wise comparison matrix to relate conditioning factors to each other. Still, the MIF model considered interrelations among the conditioning factors. The GWPZ of the study area generates with overlay weighted sum method by integrating all thematic layers. The resulting groundwater potential index map is categorized into three groundwater potential zones, namely good, moderate, and poor. Ultimately, by constructing the receiver operating characteristic (ROC) curves for both the groundwater potential models, determine the efficiency of performances and the GWPZ map validated using yield data collected from wells scattered over the study area. The findings of the present paper have important implications for ensuring exploration and sustainability groundwater plans in that particular area. [ABSTRACT FROM AUTHOR]

Groundwater-dependent agricultural intensification has led to unsustainability of groundwater systems in many parts of the world. The unconfined aquifers in the Eastern Indo-Gangetic Plains (EIGP) of India are one of the most extensive aquifer systems in South Asia and are prone to ever intensifying agricultural systems. This paper aims at evaluating the long-term impacts of agricultural intensification on groundwater dynamics in an agriculturally important sub-region of EIGP. The study proposes a multi-model approach, combining the capabilities of vadose zone model (HYDRUS-1D) and aquifer simulation model (MODFLOW) to analyse the recharge and discharge mechanisms in the alluvial Gangetic Plains. The study mathematically reconstructed the vadose zone and aquifer geometry and implemented them into flow models. We demonstrate that the loosely coupled vadose zone and groundwater flow modelling framework is highly suitable for simulating the impact of changed cropping intensity on groundwater dynamics. The recharge estimates from HYDRUS-1D and calibration of regional groundwater flow model offered a robust set of parameter values for the prevalent conditions of EIGP. The results show good correspondence between the observed and simulated water table levels during calibration, with RMSE = 0.56–0.59 m, NSE = 0.76–0.99 and R2 = 0.83–0.91, all within acceptable limits. Projections showed that although the water table in the region would remain fairly stable under lower levels of cropping intensity (135–150%), further increase to 200 and 300% would lead to water table decline at the rate of 0.87 and 1.83 m per year, respectively. These changes could therefore impact future groundwater risk management in EIGP. This reinforces the view that groundwater-dependent intensification may be sustainable in long term only if adaptation strategies and compensatory measures are adopted. [ABSTRACT FROM AUTHOR]

This paper builds on the concept of the "socio‐ecological fix" to emphasise the contradictions inherent in seeking to produce nature through such fixes for insecure petty commodity producers who occupy the class place of both labour and capital. I explore how petty commodity producer households cultivating tobacco in western Tamil Nadu, South India, are reworking labour practices in managing erratic rainfall and groundwater depletion. Agriculture in Tamil Nadu is in decline, and dominated by small and marginal farming households that oscillate between agrarian production and waged work to make ends meet. These unstable petty commodity producer households have historically accumulated in western Tamil Nadu, through labour exploitation and the appropriation of groundwater, in order to transition to petty industry. However the long‐term decline of the region's aquifers highlights the limits of such over‐exploitation. The paper makes two contributions in exploring how petty commodity producer households are remaking space to move beyond agrarian accumulation. First, the paper highlights the biophysical limits of seeking to produce nature through socio‐ecological fixes, therefore acknowledging the mercurial as well as produced aspects of nature as a form of space. Second, in adjusting to such biophysical limits on productive capacity, the paper highlights how petty commodity producer households enact forms of resilience and reworking in decreasing their reliance on waged workers and remaking agrarian landscapes to demand less labour, tending away from accumulation and towards salaried jobs. Overall, the paper looks to explore how petty commodity producers, which constitute a norm in Global South agrarian settings, offer new paths for thinking about forms of class‐entangled geographical space‐making in understanding trajectories of socio‐ecological accumulation. First, the paper highlights the biophysical limits of seeking to produce nature through socio‐ecological fixes, therefore acknowledging the mercurial as well as produced aspects of nature as a form of space. Second, in adjusting to such biophysical limits on productive capacity, the paper highlights how petty commodity producing households enact forms of resilience and reworking as spatial agents, tending away from accumulation and towards salaried jobs. Overall, the paper looks to explore how petty commodity producers, who constitute a norm in Global South agrarian settings, offer new paths for thinking about forms of geographical resistance in understanding trajectories of socio‐ecological accumulation. [ABSTRACT FROM AUTHOR]

Naturally occurring 222Rn and 226Ra concentrations were investigated in groundwater samples collected from different parts of South Bengaluru city using Smart RnDuo monitor developed indigenously by Bhabha Atomic Research Centre (BARC), India. The study area has been divided into two zones on the basis of external gamma radiation dose rates as zone A (100–200 nSv/h) and zone B (above 200 nSv/h). Radon concentration in groundwater for various sites, both supported (contribution from dissolved 226Ra in water) and unsupported (contribution from aquifer rock), was estimated. Assuming that 238U and 226Ra are roughly in secular equilibrium in the aquifer rock, a model has been proposed to predict the uranium (238U) content in the aquifer rocks using onsite measured 222Rn concentration and dissolved 226Ra concentration in the groundwater. Results of a case study carried out at South Bengaluru city, Karnataka, India have been discussed in the paper. [ABSTRACT FROM AUTHOR]

Groundwater is one of the valuable resources and due to increase in the population, industrialization and agriculture practices, the groundwater stress has increased to a greater extent. Once the groundwater gets contaminated, remediation is very difficult. The steps to measure the groundwater vulnerability must be taken for sustainable groundwater protection and management planning. In this paper, the DRASTIC model is applied to find out and generate a small-scale map of groundwater vulnerability to assess the contamination in the upper Palar river basin, Tamil Nadu, India. A number of tanneries are located along the banks of the river basin. The quality of groundwater in and around river basin area has been affected very much due to the untreated effluent of the tanneries discharged directly to the river. The DRASTIC model consists of seven hydrogeological parameters including depth to water table, net recharge, aquifer media, soil media, topography, impact of vadose zone and hydraulic conductivity; each factor is assigned by weight and rating which depends upon the influence of the seven hydrological layers of the river basin area. The ArcGIS 10.3 software was used to create the groundwater vulnerability map by overlaying the seven layers, which is intended to show potential areas of groundwater contamination. The results of the study shows that, 50% of the study area falls under very high pollution potential zone, 20% under high pollution potential, 15% under moderate pollution potential, 10% under low pollution potential, and the remaining 5% of the area has no risk. The very high vulnerability class which is covered by the alluvium along the river course is most likely to pollution due to the very lower slope terrains in the direction of the central part, which allows better percolation of contaminants into the groundwater. The low vulnerability class lies in the area covered by the hard rock and clay loam soil in the upper reach of the Palar river which contains mountains and hard rock terrain. [ABSTRACT FROM AUTHOR]

Monitoring groundwater level provides sufficient information on groundwater quantity and quality and is vital in effective management of water resources. This study applies transfer entropy coupled with directed-weighted complex network for the analysis of groundwater levels in the Sina river-basin, Maharashtra, India. All observation wells present in study area have been classified into five clusters using canopy clustering method. The direction and weight of the links of this complex network have been obtained by employing transfer entropy. Seasonal groundwater level data for pre-monsoon (May) and post-monsoon (October) were obtained from centre for groundwater board, Pune, Maharashtra for the period 1990–2009. Data analysis show that both pre-monsoon and post-monsoon groundwater level show significant decreasing trend. The proposed methodology determines the directional relationships between the selected observation wells of different clusters. It recognizes the most influenced well by using node strength and directed clustering coefficients. For each cluster, clustering coefficients and in-strength and out-strength have been calculated. Clustering coefficients for the selected wells of cluster 0 are 1, 1, 1, 0.6844 and 0.6342 which indicates Cluster 0 emerges as the strongest cluster. Similarly, clustering coefficients for cluster 4 are 0.6604, 0.6540, 0.3095, 0.2616 and 0 which means cluster 4 is the weakest among all the clusters formed. Clustering coefficients obtained for all clusters indicate that all wells within a cluster are forming clusters among themselves, however, some are strong whereas others are weak clusters. Therefore, transfer entropy can be effectively applied to groundwater and results obtained from it can be used for forecasting and water resources management. [ABSTRACT FROM AUTHOR]

To develop a specific watershed scenario, the quantity and quality of groundwater resources must be assessed and monitored locally. In the present study, an attempt has been made to identify possible groundwater potential zones, determine the quality of groundwater resources in this region, and evaluate their suitability for drinking and irrigation purposes. This goal has been achieved with the combined use of the weighted index overlay analysis (WIOA), groundwater quality index (GWQI), Remote Sensing (RS), and Geographic Information System (GIS) techniques. The proposed study area, Shanmuganadhi, is marked with superior rainfall, oscillating temperature, and runoff with litho-units encompassing charnockite (CHK) and hornblende biotite gneiss (HBG). Over-abstraction of groundwater and intensive agricultural practices have resulted in declining and degrading water quantity and quality in this area. The resulting integrated thematic map has been classified into five groundwater potential zones, namely poor, low, moderate, high, and very high, covering 3.2, 45.49, 15.3, 27.9, and 8.1% area, respectively. Sixty groundwater samples were collected during the pre-monsoon (PRM) and analyzed for major Physico-chemical parameters. From the water quality index assessment, over 28.0% of the samples fall within the “excellent,” 8.0% “good” and 4.0% “poor” in CHK, followed by 5.71% “excellent,” 48.57% “good,” 37.14% “poor,” 5.71% “very poor” and 2.87% “unsuitable” for drinking purposes in HBG terrain of this region. Irrigation indices also demonstrated that most of the groundwater samples in the CHK and HBG exposed zones exhibited good classes for irrigation purposes, as evidenced by the SAR and %Na+. The outcome, which shows the research area’s groundwater potential zones, is beneficial for improved groundwater resource planning and management. It is concluded that for larger-scale groundwater-quality investigation and assessment, the groundwater quality index-making approach (GWQI) is more practical and dependable. Water planners and decision-makers may find it helpful in effectively controlling and monitoring groundwater quality at the basin or watershed scale. Reducing urban land use and natural runoff from farms can help prevent water contamination in some regions. To ensure the safe use of groundwater, long-term monitoring of these groundwater was suggested. [ABSTRACT FROM AUTHOR]

The study area, upper Gadilam River basin, is located in Vizhupuram district of Tamil Nadu. The number of energized wells in this area has increased manifold due to free supply of electric power until recently by the government of Tamil Nadu, which has resulted in a regional decline in groundwater piezometric heads in this water table aquifer. A hydrogeological study was carried out in the study area. This paper deals with aquifer parameters estimation based on the pumping test data generated in the field. Water level observations in the area indicated that aquifer has undergone less stress condition within the course of time from the yesteryears or early 1995 to June 2004. Transmissivity computed by Theis (1935) method ranges from 301.82 gpd/sq. ft at Ponniyandal to 19,910.14 gpd/sq. ft in Pallavadi towards south central part of the study area. The specific capacity has a range of 0.906 gpm/ft. of dd in Ponniyandal to 121.91 gpm/ft of dd at Kottaiyampalayam in the eastern central part of the study area. Groundwater level in the basin by rainfall recharge and hydrodynamic method is estimated as 69 million cu.m of recharge and 33 million cu. m of groundwater storage. [ABSTRACT FROM AUTHOR]

Groundwater flow modeling has been used extensively worldwide with varying degrees of success. The ability to predict the groundwater flow is critical in planning and implementing groundwater development projects under increasing demand for fresh water resources. This paper presents the simulation of the aquifer system for planning the groundwater development of Varada basin, Karnataka, India using the Galerkin finite-element method. The government of Karnataka State, India is implementing the World Bank assisted project, “Jal Nirmal” for a sustainable development of the region, thereby ensuring a safe supply of drinking water to the northern districts of the state. Varada basin is one of the beneficiaries of the project in Haveri district. Field tests carried out in the study area indicate that the region is predominantly a confined aquifer with transmissivity and storage coefficients ranging from 5.787×10-6 m2/s(0.500 m2/day) to 4.213×10-3 m2/s(3.640×102 m2/day) and 0.011–0.001×10-2, respectively. This study mainly emphasizes the spatial and temporal variability of groundwater potential under different developmental scenarios. The model predictions were reasonably good with correlation coefficients ranging from 0.78 to 0.91 with the root mean square error of about 0.46–0.78 during calibration and validation. The stated accuracies are based on comparisons between measured and calculated heads. The outcome of the study would be a useful input for the conjunctive use of surface water and groundwater planning for the sustainable development of the region. [ABSTRACT FROM AUTHOR]

Well injection replenishes depleting water levels in a well field. Observation well water levels some distance away from the injection well are the indicators of the success of a well injection program. Simulation of the observation well response, located a few tens of meters from the injection well, is likely to be affected by the effects of nonhomogeneous medium, inclined initial water table, and aquifer clogging. Existing algorithms, such as the U.S. Geological Survey groundwater flow software MODFLOW, are capable of handling the first two conditions, whereas time-dependent clogging effects are yet to be introduced in the groundwater flow models. Elsewhere, aquifer clogging is extensively researched in theory of filtration; scope for its application in a well field is a potential research problem. In the present paper, coupling of one such filtration theory to MODFLOW is introduced. Simulation of clogging effects during “Hansol” well recharge in the parts of western India is found to be encouraging. [ABSTRACT FROM AUTHOR]

The Yamuna flood plains spread across the northern part of Indian subcontinent is home to millions of people. The ever-growing population in these plains make it difficult to sustain the demand of freshwater resources. However, the productive aquifers of flood plains could provide solution for these issues. In this context, it is necessary to understand the aquifer characteristics. Thus, the paper attempts to characterize the aquifer in Palla area of the flood plain using integrated approach. Besides, grain size analysis and site-litholog study, the nature of aquifer material was also ascertained from bulk mineralogy of the sediments using X-Ray Diffraction. The aquifer parameters were estimated with help of long duration pumping test data. Moreover, the effect of pumping on salinity variation and hydrochemical facies evolution was also examined. The sand dominant, unconfined aquifer was estimated to have horizontal hydraulic conductivity in the range of 25 m/day and vertical hydraulic conductivity of 6-7 m /day. While the specific yield of the aquifer was estimated in the range of 0.07-0.08. It is observed that under conducive active flood plain environment, the given sand mineralogy at the site does not allow salinity increase in groundwater even after more than a decade of groundwater pumping. In fact, over years, hydrochemical facies have evolved towards Bicarbonate type. These things put together make the active flood plain aquifer a sustainable groundwater resource. [ABSTRACT FROM AUTHOR]

A hydrogeochemical analysis was conducted to find the suitability of the groundwater for drinking and irrigation purposes in the Kuzhithuraiyar sub-basin, Kanniyakumari district, Tamil Nadu, India. 48 groundwater samples were collected from the different locations of the study area during both the pre- and postmonsoon periods. This study assesses the groundwater quality for drinking and irrigation purposes based on the analytical results, water quality index, Wilcox plot, and irrigation parameters such as electrical conductance, Kelly's ratio, sodium absorption ratio values, magnesium hazards, bicarbonate, and the residual sodium carbonate index. The pH values ranged from 8.5 to 6.5, suggesting generally acceptable conditions. TDS concentrations range from 24 to 1277 mg/L, whereas EC values range from 37.50 to 1996 μS/cm. It is observed from the collected samples that the pre-monsoon water samples TDS' values were exceeded the recommended TDS limits than postmonsoon samples. Water quality indices indicate that 50% of premonsoon samples and 48% of postmonsoon samples are suitable for drinking. In total, 10% of samples are admissible to a doubtful category before and after the monsoon, 6% are good to permissible during the monsoon, and 84% are good to permissible. Kelly's ratio shows that 56% and 48% of samples collected during the post- and premonsoon are suitable for irrigation, respectively, whereas the remaining samples are not. Due to magnesium hazards, 40% and 44% of pre- and postmonsoon samples are not suitable for irrigation. Overall, the postmonsoon samples exceeded the permissible TDS limit (1000 mg/L) by 10% and the premonsoon samples by 6. 13% of samples obtained after the monsoon and 19% collected before the monsoon have a potential salinity greater than three, indicating that these samples are unacceptable. The sustaining water quality and mitigating possible hazards in the Kuzhithuraiyar sub-basin require continuous monitoring and focused measures. [ABSTRACT FROM AUTHOR]

'Water' always has been a key resource for humankind but over the period with increasing population and rapid urbanization, water resource is under immense pressure. Groundwater is the prime source of drinking water and needs proper monitoring in order to have an optimum utilization strategy owing to the current scenario of over-exploitation. Being the part of Deccan trap region, the basin is hot and semi-arid, experiencing moderately dry climate accompanied by episodic drought and erratic showers therefore, the surface water of the basin is ephemeral. In the present study, the probabilistic recharge zones have been delineated by dint of various thematic layers viz. geological setting, geomorphic features, land use, slope gradient, infiltration number, soil physiognomies, curvature and lineament through multi-criteria decision analysis technique in the GIS domain. This has further divided into four categories, viz., very poor, poor, good, and very good zones. Thus, this paper is an attempt to demarcate probabilistic groundwater zones in the Vaniar watershed region using geospatial techniques for better planning and management of groundwater resources. [ABSTRACT FROM AUTHOR]

In the present study, the groundwater spring potential zone (GSPZ) was identified using an integrated approach of remote sensing (RS) and geographic information system (GIS), analytic hierarchy process (AHP), and fuzzy-AHP based on multicriteria decision-making (MCDM). Thus, ten associated factors with groundwater springs have been considered: slope, drainage density, lineament density, geomorphology, lithology, soil texture, land use and land cover, rainfall, groundwater level, and spring discharge. The analysis output was categorized into low, moderate, and high. The result of the AHP model shows the area under the high potential zone (16.61%), the moderate potential zone (60.42%), and the low potential zone (22.61%). The result of the fuzzy-AHP model shows that the area falls under the high potential zone (30.40%), moderate potential zone (41.29%), and low potential zone (22.61%). The validation results showed fuzzy-AHP with the area under the curve 0.806, which is slightly better than 0.779 of AHP. So, the resulting GSPZ map confirms that the thematic layers used in the study have a significant role in groundwater spring occurrence and distribution. It was recommended that any groundwater spring rejuvenation or protection activities must be implemented in medium to very high potential zones. [ABSTRACT FROM AUTHOR]

Groundwater recharge is essential for managing surface and subsoil water resources. Not only for supplying people with daily drinking water, groundwater use for agricultural land and people's livelihood is also continuously increasing. As a result, there has been a decline in groundwater supply in various parts of the world, and it is highly desirable to identify the potential groundwater zones for specific sustainable development. This study aims to use an easy-to-use tool package named Landslide Sustainability Mapping Tool pack (LSM tool Pack) for preparing potential groundwater zone based on R and ArcGIS software integration. This tool uses five modules for processing. Among them, the Feature selection (FS) module brings a novel approach, determining the best subset feature for demarcating the groundwater potential zone. As a result, this best factor subset is used as an input of this tool pack. Additionally, PE modules evaluate the performance of proposed models in statistical performance metrics. In addition, the receiver operating characteristic (ROC) curve was obtained with the integration of Performance Evaluation (PE) modules and ARC maps, which helps visual interpretation in evaluating models. This study uses the LSM tool Pack in the Rupnarayan river basin to map the potential groundwater zone based on fourteen controlling factors selected through the FS module, which will further help the local government to make a substitute policy. [ABSTRACT FROM AUTHOR]

Climate change impact on a groundwater-dependent small urban town has been investigated in the semiarid hard rock aquifer in southern India. A distributed groundwater model was used to simulate the groundwater levels in the study region for the projected future rainfall (2012-32) obtained from a general circulation model (GCM) to estimate the impacts of climate change and management practices on groundwater system. Management practices were based on the human-induced changes on the urban infrastructure such as reduced recharge from the lakes, reduced recharge from water and wastewater utility due to an operational and functioning underground drainage system, and additional water extracted by the water utility for domestic purposes. An assessment of impacts on the groundwater levels was carried out by calibrating a groundwater model using comprehensive data gathered during the period 2008-11 and then simulating the future groundwater level changes using rainfall from six GCMs [Institute of Numerical Mathematics Coupled Model, version 3.0 (INM-CM.3.0); L'Institut Pierre-Simon Laplace Coupled Model, version 4 (IPSL-CM4); Model for Interdisciplinary Research on Climate, version 3.2 (MIROC3.2); ECHAM and the global Hamburg Ocean Primitive Equation (ECHO-G); Hadley Centre Coupled Model, version 3 (HadCM3); and Hadley Centre Global Environment Model, version 1 (HadGEM1)] that were found to show good correlation to the historical rainfall in the study area. The model results for the present condition indicate that the annual average discharge (sum of pumping and natural groundwater outflow) was marginally or moderately higher at various locations than the recharge and further the recharge is aided from the recharge from the lakes. Model simulations showed that groundwater levels were vulnerable to the GCM rainfall and a scenario of moderate reduction in recharge from lakes. Hence, it is important to sustain the induced recharge from lakes by ensuring that sufficient runoff water flows to these lakes. [ABSTRACT FROM AUTHOR]

The main aim of this paper is to demonstrate the capabilities of Remote Sensing (RS) and Geographic Information System (GIS) techniques for the demarcation of suitable sites for artificial recharge of groundwater aquifers, in the Loni watershed, located in Unnao and Raebareli districts, Uttar Pradesh, India. In this study, the SCS-CN model, groundwater depth data and morphological parameters (bifurcation ratio, elongation ratio, drainage density, ruggedness number, relief ratio, and circulatory ratio) have been used to delineate the recharge sites for undertaking water conservation measures. Augmentation of water resource is proposed in the watershed by constructing runoff storage structures, like check dam, percolation tank and nala bund. The site suitability for these water harvesting structures is determined by considering spatially varying parameters, like runoff potential, slope, groundwater fluctuation data and morphometric information of the watershed. GIS has been used as an effective tool to store, analyse and integrate spatial and attribute information pertaining to runoff, slope, drainage, groundwater fluctuation and morphometric characteristics for such studies. [ABSTRACT FROM AUTHOR]

High arsenic in natural groundwater in most of the tubewells of the Purbasthali- Block II area of Burdwan district (W.B, India) has recently been focused as a serious environmental concern. This paper is intending to illustrate the statistical modeling of the arsenic contaminated groundwater to identify the interrelation of that arsenic contain with other participating groundwater parameters so that the arsenic contamination level can easily be predicted by analyzing only such parameters. Multivariate data analysis was done with the collected groundwater samples from the 132 tubewells of this contaminated region shows that three variable parameters are significantly related with the arsenic. Based on these relationships, a multiple linear regression model has been developed that estimated the arsenic contamination by measuring such three predictor parameters of the groundwater variables in the contaminated aquifer. This model could also be a suggestive tool while designing the arsenic removal scheme for any affected groundwater. [ABSTRACT FROM AUTHOR]

Oil contamination causes serious geoenvironmental concern and adversely affects the soil environment due to the release of toxic by-products. Hence, the aim of the study was to investigate the influence of oil contamination on soil physical and chemical properties and phytoremediation as a treatment option based on field studies conducted for analyzing significant parameters. The sites selected were near National Institute of Technology, Surathkal, Karnataka (site-1), and another is close to the oil refinery (Kuthethur, Karnataka, India, as site-2). Phytoremediation of oil-contaminated samples was carried out by Chromolaena odorata. The evaluation of soil physical and chemical properties includes field and laboratory tests. A pumping test was conducted to estimate aquifer parameters in the field. The hydraulic conductivity for field soil sample (unsaturated condition) is carried out by a filter paper test. Laboratory tests to evaluate physical and chemical parameters include total petroleum hydrocarbons of contaminated (crude oil varying from 0 to 10% at an interval of 2%) and uncontaminated samples and plant parameters. Characterization of contaminated and uncontaminated soil sample was performed by Fourier transform infrared (FTIR) spectroscopy. The results obtained reveal that physical properties of soil (moisture content, liquid and plastic limit) got affected due to oil contamination. Relative hydraulic conductivity was established as 0.46 (uncontaminated) and 0.57 (contaminated) for soil samples and led to the conclusion that hydraulic conductivity was drop down by 10% due to oil contamination. Total petroleum hydrocarbon analysis reveals that the uptake/presence of hydrocarbons by showing increased concentration in contaminated soils (5% and 10%) by the plant species. This is further confirmed by FTIR results. The TPH concentrations in the contaminated soils were reduced up to 50–60% and also showed better plant growth after 7 weeks of transplantation. Hence, considered plant species possess high potential for degrading oil contaminated in the soil. [ABSTRACT FROM AUTHOR]

In this paper, a bivariate-copula-based methodology is presented to assess the risk associated with hydroclimatic variability on groundwater levels in an unconfined aquifer at the Manjara basin in India. Rank correlation analysis is used to identify the association between the El Niño-Southern Oscillation (ENSO) index, precipitation, and groundwater levels. It is found that the dependencies among the hydroclimatic variable pairs are statistically significant and the dependence structure can be modeled by using bivariate Archimedean copulas. The groundwater level or depth-to-groundwater table (DGWT) in the study region is found to be responsive toward interannual precipitation variations that are influenced by the ENSO phenomenon. For probabilistic representation of hydroclimate variables, various probability distributions are evaluated and it is found that the precipitation and DGWT are best fitted using lognormal and Weibull distributions, respectively, whereas the ENSO index is best fitted using nonparametric-based normal kernel density function. For modeling joint dependence structure of hydroclimatic variable pairs (precipitation-DGWT, ENSO index-precipitation, and ENSO index-DGWT), appropriate Archimedean copulas (viz, Ali-Mikhail-Haq, Clayton, Gumbel-Hougaard, and Frank families) are evaluated. On performing standard statistical tests, it is found that the Frank copula is best representing the joint dependence structure for all three variable pairs. Then the Frank copula-based joint distributions are used to derive conditional distributions and to perform risk analysis of groundwater levels. The study suggest that the copula-based methodology can be used effectively for modeling dependence structure of hydroclimatic variables and for risk assessment of groundwater levels under changes in hydroclimatic conditions. [ABSTRACT FROM AUTHOR]

Many human communities living in coastal areas in Africa and Asia rely on thin freshwater lenses for their domestic supply. Population growth together with change in rainfall patterns and sea level will probably impact these vulnerable groundwater resources. Spatial knowledge of the aquifer properties and creation of a groundwater model are required for achieving a sustainable management of the resource. This paper presents a ready-to-use methodology for estimating the key aquifer properties and the freshwater resource based on the joint use of two non-invasive geophysical tools together with common hydrological measurements. We applied the proposed methodology in an unconfined aquifer of a coastal sandy barrier in South-Western India.We jointly used magnetic resonance and transient electromagnetic soundings and we monitored rainfall, groundwater level and groundwater electrical conductivity. The combined interpretation of geophysical and hydrological results allowed estimating the aquifer properties and mapping the freshwater lens. Depending on the location and season, we estimate the freshwater reserve to range between 400 and 700 Lm-2 of surface area (±50 %). We also estimate the recharge using time lapse geophysical measurements with hydrological monitoring. After a rainy event close to 100% of the rain is reaching the water table, but the net recharge at the end of the monsoon is less than 10% of the rain. Thus, we conclude that a change in rainfall patterns will probably not impact the groundwater resource since most of the rain water recharging the aquifer is flowing towards the sea and the river. However, a change in sea level will impact both the groundwater reserve and net recharge. [ABSTRACT FROM AUTHOR]

Copyright of Hydrogeology Journal is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Dewatering in deep opencast mines generally focuses on extraction of seepage water from the phreatic zones above the ore/mineral deposits and storm water that collects in mine pits. But at the Neyveli lignite deposit in the Cuddalore District, there was a danger of the mine floor bursting due to the hydrostatic head pressures in the underlying thick confined aquifers, a problem not previously encountered anywhere in India. Hydrogeological studies established the feasibility of mining the lignite by maintaining a constant cone of depression (pressure relief) in the surrounding aquifers below the mine by continuous pumping through a pre-planned network of wells. This depressurizing process had to be designed to tackle multi-layered confined aquifers and water table conditions. This paper traces the multi-faceted evolution in developments to control ground water at the Neyveli Mines. [ABSTRACT FROM AUTHOR]

In Neyveli, Tamilnadu, India, a deep-seated multi-layered confined aquifer is being continuously pumped to permit safe mining of lignite. This paper highlights the various ground water recharge studies undertaken to quantify the potential of recharging the Neyveli hydrogeological basin to maintain the regional ground water balance. GIS studies were used to analyze artificial recharge in the Neyveli basin, commencing from the deep water table zone (recharge area) in the western upland part, the confined aquifer zone closer to the active mining area, and the confined zone further away in the east, down-dip and closer to the coast. [ABSTRACT FROM AUTHOR]

This paper deals with the drinking water quality of the Ganga-Kali sub-basin which occupies 1300 km2 over parts of Aligarh and Etah districts. Water samples were collected from shallow and deep aquifers and were analyzed for major ions and trace elements. The analytical data were interpreted according to published guidelines. Chemical analysis shows that the groundwater in the basin is alkali bicarbonate type. Trace element studies of water from the shallow aquifer show that the concentration of toxic metals Fe, Mn, Cd, Pb, and Cr+6 are above permissible limits which may present a health hazard. The water from the deep aquifer is comparatively free from contamination. The aquifers are subject to contamination due to sewage effluents and excessive use of fertilizers and pesticides in agriculture. [ABSTRACT FROM AUTHOR]

In this study, groundwater irrigation potential zones are identified by measuring an integrated irrigation water quality index using a GIS platform in the Vishwamitri River Basin (VRB) region, Gujarat, India. Classification of different irrigation potential zones is about the collective paraphernalia of thematic maps, namely, electrical conductivity (EC), sodium adsorption ratio (SAR), Na+, Cl−, and HCO3−, which principally regulate the groundwater quality for irrigation. The EC, SAR, and chloride values are > 3000 µS/cm, > 9 meq/L, and > 10 meq/L, respectively, indicating 98.78%, 41.78%, and 84.88% of the total area, respectively, belong to groundwater both hazardous and unsuitable for irrigation. Similarly, 39.55% of the total area is unsuitable for irrigation due to its high Na+ concentration. The permeability, porosity, and infiltration risk usually appear when excessive sodium ions reduce the rate of flow of irrigation water which moves in the lower soil zones. Similarly, high bicarbonate and chloride concentrations have been denoted to hamper the development of several crops causing symptoms analogous to lime-induced chlorosis due to toxic effects of the salt. The final irrigation potential map is marked by four levels, such as "most suitable," "moderately suitable," "moderately unsuitable," and "unsuitable for irrigation." Approximately, 56.69% of the total VRB region are covered with unsuitable for irrigation purposes. In such areas, irrigation must be avoided in usual conditions, and the halophytes, namely, Khati palak (Atriplex stocksii), Lamb's quarters (Chenopodium album), and Rudravanti (Cressa cretica) should be recommended with high soil permeability and proper drainage facilities. The soil must be highly permeable for groundwaters with high salinity and sodicity. Based on this study, policymakers and environmental managers can estimate the resource implications for drinking and irrigation. [ABSTRACT FROM AUTHOR]

Evaluation of aquifer potential is essential, as the potable water demand has increased globally over the last few decades. The present study delineated different zones of groundwater potential and groundwater quality of the Kallada River basin (KRB) in southern India, using geo-environmental and hydrogeochemical parameters, respectively. Geo-environmental variables considered include relative relief, land use/land cover, drainage density, slope angle, geomorphology, and geology, while hydrogeochemical parameters include pH, electrical conductivity (EC), Cl−, Fe3+, and Al3+ concentrations. Analytical hierarchy process (AHP) was used for categorizing groundwater potential and quality zones. Nearly 50% of KRB is categorized as very high and high groundwater potential zones, occupying the western and midland regions. The central and west-central parts of KRB are characterized by excellent groundwater quality zones, while the eastern and western parts are characterized by good and poor groundwater quality zones, respectively. By integrating the groundwater potential and groundwater quality, sustainable groundwater management is observed to be necessary at about 54% of the basin, where site-specific groundwater management structures such as percolation ponds, injection wells, and roof water harvesting have been proposed using a rule-based approach. This integrated groundwater potential-groundwater quality approach helps policymakers to implement the most suitable management strategies with maximum performance. [ABSTRACT FROM AUTHOR]

Groundwater quality monitoring and geochemical characterization in the phreatic aquifer are critical for ensuring universal and equitable access to clean, reliable, and inexpensive drinking water for all. This research was intended to investigate the hydrogeochemical attributes and mechanisms regulating the chemistry of groundwater as well as to assess spatial variation in groundwater quality in Satna district, India. To accomplish this, the groundwater data comprising 13 physio-chemical parameters from thirty-eight phreatic aquifer locations were analysed for May 2020 by combining entropy-weighted water quality index (EWQI), multivariate statistics, geochemical modelling, and geographical information system. The findings revealed that the groundwater is fresh and slightly alkaline. Hardness was a significant concern as 57.89% of samples were beyond the permissible limit of the World Health Organisation. The dominance of ions were in the order of Ca2+ > Na+ > Mg2+ > K+ and HCO3− > SO42− > Cl− > NO3− > F−. Higher concentration of these ions is mainly concentrated in the northeast and eastern regions. Pearson correlation analysis and principal component analysis (PCA) demonstrated that both natural and human factors regulate groundwater chemistry in the region. The analysis of Q-mode agglomerative hierarchical clustering highlighted three significant water clusters. Ca–HCO3 was the most prevalent hydro-chemical facies in all three clusters. Geochemical modelling through various conventional plots indicated that groundwater chemistry in the research region is influenced by the dissolution of calcite/dolomite, reverse ion exchange, and by silicate and halite weathering. EWQI data of the study area disclosed that 73.69% of the samples were appropriate for drinking. Due to high salinity, Magnesium (Mg2+), Nitrate (NO3−), and Bicarbonate (HCO3−) concentrations, the north-central and north-eastern regions are particularly susceptible. The findings of the study may be accomplished by policymakers and groundwater managers to achieve sustainable groundwater development at the regional scale. [ABSTRACT FROM AUTHOR]

Groundwater is a crucial natural resource for providing reliable and long-lasting water supplies across the globe. The integrated approach used in the current study involved the use of multiple techniques to assess groundwater potential zones (GWPZs) and identify suitable areas for artificial recharge sites. The methods used in the study were a combination of geographic information system (GIS), analytic hierarchy process (AHP), and fuzzy analytic hierarchy process (Fuzzy-AHP) to accomplish this goal. The study considered multiple thematic maps, such as drainage density, elevation, geomorphology, slope, curvature, topographic wetness index (TWI), geology, distance from the river, land use and land cover (LULC), and rainfall, to determine the GWPZs. AHP and Fuzzy-AHP were used to weight thematic maps based on their relative importance in controlling groundwater availability and recharge, and then a weighted overly analysis in a GIS environment was utilized to derive the final GWPZs map. After completing the weighting of thematic maps, both AHP and Fuzzy-AHP models categorized GWPZs into low, moderate, and high categories in the study area. In this study area, GWPZs were classified as poor, moderate, and high using both the AHP and Fuzzy-AHP models. According to the AHP model, 5.41% of the area's GWPZs were categorized as poor, 70.68% as moderate, and 23.91% as high. The Fuzzy-AHP model, on the other hand, categorized 4.92% as poor, 69.75% as moderate, and 25.33% as high. To validate these results, the receiver operating characteristic curve (ROC) and area under the curve (AUC) were used to explore the prediction accuracy, resulting in an accuracy rate of 70.1% for AHP and 71% for Fuzzy-AHP. These findings suggest that the Fuzzy-AHP model is effective in accurately identifying GWPZs in this area. Additionally, using remote sensing (RS) and GIS, the current study created a map by overlaying the lineament and drainage maps to determine suitable locations for artificial recharge. One-hundred-forty suitable locations for artificial recharge sites were identified based on Fuzzy-AHP. The study's reliable findings assist decision-makers and water users in the research area to use groundwater resources sustainably. This information aids in sustainable planning and management of groundwater resources, ensuring their availability and sustainability for future generations. [ABSTRACT FROM AUTHOR]

Soil water‐groundwater interactions are important in determining the moisture profile in a soil column. However, the Noah Land Surface Model (Noah LSM), the land surface component of several general circulation models, does not consider groundwater effects. The present study investigates the impact of integrating a groundwater model into the Noah LSM. By performing experiments forced by observations at the surface, insights into the characteristics of soil moisture evolution with and without the aquifer are investigated. In the absence of surface precipitation, soil moisture is shown to exhibit an exponential decay rate without the aquifer (termed as Noah‐Cntl). This is because evapotranspiration dominates other processes governing the soil moisture evolution. Based on scale analysis, we derived an analytical equation that could well represent the aforementioned exponential variation in soil moisture. Presence of the aquifer (termed as Noah‐GW) makes the capillary processes important as well. The result is a slower decay of soil moisture as compared to Noah‐Cntl without surface precipitation. Soil moisture evolution in both the models is a function of vegetation and soil types. As a result, the aforementioned decay timescale displays significant heterogeneity over the Indian region, with Central India exhibiting relatively faster decay rates. We also performed 24‐year long experiments with observed interannually varying forcing that indicates an enhancement in the annual mean soil moisture at all levels due to groundwater effects. This enhancement is particularly prominent during the post‐monsoon season, reaffirming the results of the drain‐out experiments mentioned above. Plain Language Summary: Land surface processes are integral parts of weather and climate. Hence, an accurate representation of these processes is crucial from prediction and understanding points of view. However, state‐of‐the‐art land surface models do not incorporate some essential components that make these models erroneous. This study integrates a groundwater model into an existing land surface model and characterizes its impact on the evolution of soil moisture. We discuss factors affecting soil moisture decay rate over the Indian subcontinent without surface forcing. We show that the post‐monsoon and annual mean soil moisture increases in the presence of a groundwater model. However, spatial heterogeneity of groundwater effects is dependent on parameters like soil type and surface rain rate. Key Points: A prognostic model for groundwater is developed and integrated inside the Noah Land Surface ModelAnalytical solutions for the rate of change of soil moisture in the absence of surface water forcing are derived to explain model resultsPresence of an aquifer increases the soil moisture retention capability in the Noah Land surface model [ABSTRACT FROM AUTHOR]

Krishna delta along the east coast of India presents a complex hydrogeological and hydrogeochemical situation with Holocene marine transgression events marked by paleo strand lines and subsequent evolutionary trends of the delta marked by numerous paleochannels/lobes. These paleochannels/lobes act as huge repositories for groundwater in the near surface aquifer systems with depth levels varying between 10 and 80 m bgl (below ground level) with high recharge potentials and are underlained by brackish water aquifers deposited during the marine transgressional events. These near surface aquifer systems have been subjected to over abstraction of groundwater to meet the irrigation and drinking water demands through multiple shallow well field systems resulting in vertical migration of brackish water and mixing with near surface freshwater aquifers. These processes are dominant in the regions with high abstractions and relatively low or insignificant mixing in the low abstraction and high recharge regions. Sixteen trace metals Beryllium (Be), Cobalt (Co), Strontium (Sr), Boron (B), Nickel (Ni), Molybdenum (Mo), Lead (Pb), Vanadium (V), Copper (Cu), Chromium (Cr), Zircon (Zn), Manganese (Mn), Arsenic (As), Iron (Fe), Selenium (Se) and Barium (Ba) were analyzed from the groundwater of the near surface aquifer systems at 29 sites covering the entire delta complex. Almost all the trace metals incorporated lie within safe and acceptable limits prescribed by WHO/BIS excepting Sr, B, Mo, Pb, V, Mn, As, and Fe located at few isolated sites due to localized pollution impacts prevailing in the low-lying delta regions. The spatial distributional trends, intensity levels and their impacts on natural/ anthropogenic processes are analyzed and presented. Pollution indices related to Contamination Factor (CF) and Pollution Load Index (PLI) are estimated and applied to arrive at different levels of contamination against each element. A number of graphical cross plots are also drawn between TDS and different trace metal levels to assess the trends of each element in relation to fresh and brackish water zones and their impacts on salinization and anthropogenic processes. Multivariate statistical analysis (correlation matrix and factor analysis) are also used to assess the natural/ anthropogenic impacts. The overall analysis indicates dominant brackish water mixing processes and low to moderate impacts due to several automobile units, agro-based fertilizer units, aqua forms, electro chemicals and coal-based industries in addition to municipal wastes and sewerage disposal sites existing in the delta region. [ABSTRACT FROM AUTHOR]

A computationally simple kernel method is proposed for obtaining drawdowns due to unsteady pumping of large diameter wells. The kernels can be worked out even on a hand-held calculator. The new method can also be used to obtain residual drawdowns. The new method yields results as good as those obtained using earlier methods. [ABSTRACT FROM AUTHOR]

The present study was intended for assessing the contamination level of various heavy metals in surface soil and groundwater around the automobile workshops situated at different locations in the Kollam District of Kerala state, India. The procured soil and groundwater samples were analyzed for cadmium, zinc, iron, lead, nickel, chromium, copper, manganese, and arsenic using atomic absorption spectrophotometer by following standard procedures. The contamination level of these metals was assessed using the pollution indices like enrichment factor (EF), geo-accumulation index (Igeo), contamination factor (CF), and pollution load index (PLI). The results revealed that the concentrations of all analyzed metals in the surface soils of the automobile workshops were higher than the control. On the contrary, the concentration of no heavy metal in the groundwater was either equal to or higher than the limit prescribed by WHO. However, the concentration levels of Fe, Pb, Cu, and Zn were either equal to or higher than the control values. Based on the Igeo, CF, and EF, it was found that the contamination intensity of the heavy metals in soil decreased in the following order: Fe > Pb > Cd > As > Cr > Zn > Cu > Ni > Mn. From the results of PLI, it was interpreted that the sampling sites S2, S4, and S5 were highly polluted. Non-contamination of underground water from the age-old workshops is the uniqueness of the present study against the other studies, which were completed in alluvial formations with inverse results. In the studied region, the groundwater is stored in the hard rock formations and its hydraulics remains different from alluvial aquifers. [ABSTRACT FROM AUTHOR]

Around the globe, seawater intrusion in the coastal aquifer is a significant problem. Excessive groundwater extraction because of population growth, industrialization, tourism, and other anthropogenic activities and geogenic processes initiates and accelerates this problem. The contaminated groundwater impacts the health, economic activities, and social and cultural development of coastal regions. This work aims to explore the current status and a holistic comprehending review of geophysical studies applied to delineate the seawater intrusion in the high-quality coastal aquifers in India, as well as its origin and causes, mitigation strategies, and recent advancements in geophysical techniques to access the qualitative and quantitative properties of the complex aquifer system. In the future, it is recommended to do a detailed subsurface imaging of the entire coastal belt of India to decipher the lateral and vertical variation of the lithological conditions and seawater intrusion in space and time with improved/advanced geophysical techniques, which can lead toward sustainable development. [ABSTRACT FROM AUTHOR]

In semi‐arid regions as in India, where agriculture relies on groundwater abstraction, increase of water resources availability through managed aquifer recharge (MAR) or rainwater harvesting (RWH) is often perceived as a major solution. Studies on these structures' efficiency exists but despite the interest, limited information is available on the temporal variation of their replenishment. In a monsoon driven climate, the inter‐annual variations are crucial to assess the potential of water storage and multi‐year management especially for these structures. Here, we aim at developing a methodology to reconstruct water storage of RWH tanks to further improve our understanding on long term efficiency and multi‐years drought management. To tackle this issue, long‐term monitoring of a RWH tank located in Telangana in Southern India is achieved by a combination of field monitoring over 2 years (tanks surface and water levels) and a daily water balance compared to LANDSAT measurements of the tank area. The procedure allows reconstructing the tank filling dynamic over a 14‐years period at a daily time step and show the extreme variability of the tank filling level. During this period, the yearly maximum tank volume ranges from 8650 to ~200 000 m3. On the 14‐years period, the tank reach its maximum capacity only once and, for 1/3 of the time, yearly maximum replenishment is below 15% of its capacity. The surface water availability remains limited in time since the tank dries‐up annually, except for 2 years. However, water percolation to the aquifer is slightly enhanced for some years. During this monitoring period, very few extreme raining events (6) contribute for more than 50% of the collected volume. This observation highlights (1) the dependency of the structure to extreme storm events, (2) the limited capacity for a multi‐year's management and (3) the farmers vulnerability to successive droughts. [ABSTRACT FROM AUTHOR]

GRACE (Gravity Recovery and Climate Experiment) and its follow-on mission have provided since 2002 monthly anomalies of total water storage (TWS), which are very relevant to assess the evolution of groundwater storage (GWS) at global and regional scales. However, the use of GRACE data for groundwater irrigation management is limited by their coarse (≃300 km) resolution. The last decade has thus seen numerous attempts to downscale GRACE data at higher – typically several tens of kilometres – resolution and to compare the downscaled GWS data with in situ measurements. Such comparison has been classically made in time, offering an estimate of the static performance of downscaling (classic validation). The point is that the performance of GWS downscaling methods may vary in time due to changes in the dominant hydrological processes through the seasons. To fill the gap, this study investigates the dynamic performance of GWS downscaling by developing a new metric for estimating the downscaling gain (new validation) against non-downscaled GWS. The new validation approach is tested over a 113 000 km 2 fractured granitic aquifer in southern India. GRACE TWS data are downscaled at 0.5 ∘ (≃50 km) resolution with a data-driven method based on random forest. The downscaling performance is evaluated by comparing the downscaled versus in situ GWS data over a total of 38 pixels at 0.5 ∘ resolution. The spatial mean of the temporal Pearson correlation coefficient (R) and the root mean square error (RMSE) are 0.79 and 7.9 cm respectively (classic validation). Confronting the downscaled results with the non-downscaling case indicates that the downscaling method allows a general improvement in terms of temporal agreement with in situ measurements (R=0.76 and RMSE = 8.2 cm for the non-downscaling case). However, the downscaling gain (new validation) is not static. The mean downscaling gain in R is about +30 % or larger from August to March, including both the wet and dry (irrigated) agricultural seasons, and falls to about +10 % from April to July during a transition period including the driest months (April–May) and the beginning of monsoon (June–July). The new validation approach hence offers for the first time a standardized and comprehensive framework to interpret spatially and temporally the quality and uncertainty of the downscaled GRACE-derived GWS products, supporting future efforts in GRACE downscaling methods in various hydrological contexts. [ABSTRACT FROM AUTHOR]

Copyright of Hydrogeology Journal is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The present investigation attempts to assess the harmful heavy metals and uranium exposure in shallow aquifers of the highest populated district Nagaon in the central Brahmaputra floodplain of Assam, India. Spatial distribution using the inverse distanced weighted interpolation method in Arc GIS, various pollution indices and health risk assessment indices pooled with statistical studies were employed to appraise the pollution scenario and potential health risk. The contamination degree index for the three locations was 14.09, 21.43 and 25.95, signifying a considerable degree of contamination. The excess cancer risk due to the radioactivity of uranium in adults and children of Nagaon district is negligible compared to the prescribed limit of 1.67×10−4 set by the Atomic Energy Regulatory Board. The average concentration of the analyzed heavy metal follows the order Mn > Fe > Zn > Cu > Ni > U > Pb > Cr > Cd. The notch box plot study reveals that the risk associated with the ingestion of water contaminated with heavy metals is higher than the dermal absorption. The HQIngestion of manganese in children shows a higher range (0.003–6.85) than in adults (0.002–4.12), with a median value of 0.14 compared to 0.08 in adults. Both adults and children are vulnerable to non-carcinogenic risks, and the risk is higher in children than in adults. [ABSTRACT FROM AUTHOR]

The micro-watershed development programme in India promotes the recharging of groundwater tables to facilitate irrigation in otherwise rainfall-dependent agricultural communities. This study investigates the potential of agricultural extension agencies in encouraging the sustainable use of the common-pool resource of groundwater through local governance. Findings suggest that extension agencies strongly influence farmers' crop choices (a representation of irrigation use), in accordance with the proposition that knowledge dissemination on groundwater use and its impact encourages collective action (U7-SES framework). Finally, farmers with higher irrigation demand are the conduit between the extension agency and community, highlighting their potential for programme management. [ABSTRACT FROM AUTHOR]

A climatic water balance study, along with an analysis for stable isotopes (oxygen-18 and hydrogen-2), and hydrogeochemical signatures were together used to understand the groundwater recharge environment and hydrogeochemical processes in the semi-arid region of Gooty Mandal, District of Anantapur, India. The study revealed that the annual potential evapotranspiration was thrice the annual rainfall, indicating the influence of evaporation both during rainfall and after infiltration resulting in the enrichment of salts in the soil and the stable isotopes in shallow groundwater. Stable isotopic signatures suggest that the source of groundwater recharge is contributed by several components and not just direct precipitation. The argument is further supported by the relation between oxygen-18 and chloride. The most dominated water type in the dry season was found to be sodium-chloride followed by calcium-sodium-bicarbonate, while in the wet season calcium-sodium-bicarbonate was followed by sodium-chloride. Calcium-magnesium-chloride and sodium-chloride showed high temporal variability in stable isotopic concentrations, particularly in wells with shallow groundwater, suggesting that the rainwater might have undergone evaporation before recharge and/or recirculation due to agricultural activities. Hydrogeochemical signatures show that 61% of the samples sodium concentration decreased with the increase in chloride ions, revealing that the cation exchange reaction absorbs sodium in exchange for magnesium and calcium. Almost all samples from the calcium-sodium-bicarbonate, sodium-bicarbonate and magnesium-bicarbonate water types and a few samples of sodium-chloride and calcium-magnesium-chloride water types had a low chloride concentration (< 10 mmol/l), implying that the silicate weathering is also a major source through which these ions get into the groundwater. [ABSTRACT FROM AUTHOR]

The present study investigates the groundwater quality for domestic and irrigation purposes in a coastal aquifer in the West Godavari delta region based on geochemical evaluation, integrated multivariate statistical analysis and entropy water quality index (EWQI). The study area is underlain by the Quaternary sediments with unconsolidated to semi consolidated sand, silt and clay formation. In the study, the significant hydrochemical facies of groundwater observed were Na-Mg-Cl-HCO3−, Na-Cl-HCO3− and Mg-Na-Cl-HCO3−. The results revealed that the area occupies high salinity groundwater controlled mainly by evaporation and also by rock weathering-solubilization to some extent. The concentrations of major cations and anions decreased in the order: Na+ > K+ > Mg2+ > Ca2+ = Cl− > HCO3− > SO42− > NO3−. The chemical constituents of the samples TA (85%), TDS (100%), TH (83%), Mg2+ (91%), Cl−(81%) and SO42 (12%) exceeded the limits, making them unfit for drinking. Based on EWQI (53.3–143.4), nearly 70% of groundwater samples were of poor to very poor quality for drinking, which required treatment, and the remaining 30% of samples were unsuitable for domestic purposes. Some samples of the irrigation suitability parameters (Na%, SAR, RSC, PI, CAI, KR and CCR) exhibit moderate to good categories, which can be used for irrigation with proper management. The multivariate statistical analysis was performed to understand the relationships among the chemical constituents present in groundwater. TDS is highly correlated with EC, TH, Ca2+, Mg2+, Na+, K+, HCO3− and Cl−. Principal component analysis (PCA) applied to the datasets showed that the first three PCs accounted for 65% of total variance cumulatively 94.5% for a total of 7 PCs. The PCA results indicate that the variation of groundwater quality is possibly attributed to various anthropogenic and geogenic factors, rock–water interactions and ion exchange processes in groundwater. The uncontrolled drawl of subsurface waters and aqua forming at an advanced rate when compared with recharge has led to this coastal aquifer being in a critical stage. [ABSTRACT FROM AUTHOR]

Assessment of groundwater chemistry of a region is important to determine its usability. The objective of this study is to understand the hydrochemistry and groundwater quality especially with respect to fluoride in the Perambalur District, Tamil Nadu, India where groundwater is used without treatment for drinking and agricultural purposes. Groundwater samples were collected from 44 locations once every three months between September 2015 and July 2018. Mixed Ca–Mg–Cl, Ca–HCO3, Na–Cl and mixed Ca–Na–HCO3 types were the predominant hydrochemical facies. Fissile hornblende biotite gneissic rocks had more fluoride concentration than the charnockite rocks in the study area. These weathered rocks leach high concentration of fluoride to groundwater. Ion exchange processes played a major role in fluoride dynamics in groundwater. Fluoride concentration was comparatively high in the wells where the groundwater level fluctuation is at deeper levels. Groundwater in most of the wells were suitable for drinking purpose based on the ions analysed, but few wells were unsuitable for drinking and irrigation purposes. Based on health risk assessment, children are likely to be more affected than infants and adults through intake of high fluoride groundwater from the study area. [ABSTRACT FROM AUTHOR]