Search Results (21)

A hierarchical fuzzy inference system (FIS) integrated with the DRASTIC model is applied in this study to enhance the assessment of shallow groundwater vulnerability in southeast Hungary, a region characterized by extensive agriculture and industrial growth. Traditional groundwater vulnerability models often struggle with parameter imprecision and uncertainty, affecting their reliability. To address these limitations, fuzzy logic was incorporated to refine the classification of vulnerability zones. The hierarchical FIS incorporates the seven DRASTIC parameters: depth to the water table, net recharge, aquifer media, soil media, topography, vadose zone impact, and hydraulic conductivity, assigning flexible ratings through fuzzy membership functions. The model classifies the fuzzy groundwater vulnerability index (FGWVI) into low, moderate, and high categories, revealing that 63.9% of the study area is highly susceptible to contamination, particularly in regions with shallow water tables and sandy soils. Validation was conducted using nitrate (NO₃⁻) concentrations and electrical conductivity (EC) measurements from 46 agricultural wells to assess the correlation between predicted vulnerability zones and actual groundwater quality indicators. The correlation analysis revealed a moderately strong positive relationship between FGWVI and both NO₃⁻ (R² = 0.4785) and EC (R² = 0.528), supporting the model’s ability to identify high-risk contamination zones. This study highlights the effectiveness of the fuzzy-enhanced DRASTIC model in evaluating aquifer vulnerability and provides crucial insights to assist policymakers in identifying pollution sources and developing strategies to mitigate groundwater contamination, thereby alleviating the stress on this critical resource. Full article

This study evaluates the quality and vulnerability of groundwater within the Nakivale Sub-catchment of the transboundary Lake Victoria Basin in Southwestern Uganda. Groundwater quality assessment focuses on its suitability for both drinking and agricultural uses. Hydrochemical analysis of 19 groundwater samples revealed that 90% comply with World Health Organization drinking water standards, although localized contamination was noted, particularly in terms of total iron, nitrate, potassium, magnesium, and sulfates. The drinking groundwater quality index shows that over 90% of the samples fall within the good-to-excellent quality categories. Elevated nitrate levels and chloride–bromide ratios indicate human impacts, likely due to agricultural runoff and wastewater disposal. For irrigation, Sodium Adsorption Ratio analysis revealed medium-to-high salinity hazards in the region, while Sodium Percentage and other parameters indicated low-to-moderate risks of soil degradation. DRASTIC vulnerability assessments identified low contamination risks due to impermeable geological layers, steep terrain, slow groundwater recharge, deep aquifer depth, and clayey soil cover. These findings emphasize the need for conjunctive water resource management, including improved groundwater quality monitoring, public education on sustainable practices, and protective measures for recharge zones and areas highly susceptible to contamination. By addressing these issues, this study aims to preserve groundwater resources for domestic and agricultural use, ensuring long-term sustainability in the region. Full article

Natural springs, recognized as biodiversity hotspots and keystone ecosystems, exert positive ecological influences beyond their immediate extent, particularly in dryland environments. The water feeding these springs, largely governed by natural climatic conditions, is susceptible to anthropogenic impacts. The objective of this study was to determine the factors that cause fluctuations in water availability to springs of the hyper-arid Arava Valley (Israel/Jordan). Using the Standard Precipitation Index, we statistically classified the historical record of yearly rainfall for the past four decades into clusters of dry and wet sub-periods. We assessed changes in vegetation cover around the springs using the Landsat-derived Normalized Difference Vegetation Index (NDVI) for each sub-period. To assess the anthropogenic effects, we examined the correlations between vegetation cover, water extraction from the aquifer, and the status of adjacent agricultural plots that share a hydrological connection with the springs. Our findings revealed fluctuations between wet and dry sub-periods over the last four decades. We observed high responsiveness of vegetation cover around the springs to these fluctuating sub-periods. Of the 25 studied springs, 12 were directly influenced by anthropogenic factors—7 experienced a decline in vegetation, which we attributed to water extraction from the aquifers, while vegetation increase in 5 springs was attributed to water seepage from agricultural areas upstream. In conclusion, addressing vital habitats such as natural springs in arid drylands requires a holistic approach that integrates long-term climatic, ecological, and anthropogenic observations. Full article

The risk of aquifer contamination is determined by the interaction between the pollutant load and the vulnerability of an aquifer. Owing to the decomposition of bodies and degradation of artefacts, cemeteries may have a negative impact on groundwater quality and suitability for use due to the leaching of organic compounds (e.g., biodegradable organics, pharmaceuticals, and formaldehyde), inorganic compounds (e.g., nitrate and heavy metals), pathogenic bacteria, and viruses. Factors such as burial and soil type, rainfall amount, and groundwater depth may increase aquifer vulnerability to pollutants generated in cemeteries. The potential for groundwater contamination was investigated in two cemeteries of the Soure region in Portugal (Samuel–UC9 and Vinha da Rainha–UC10), using the classic DRASTIC model, followed by some adjustments, depending on the particularities of the locations, resulting in a Final Classification considered as Specific DRASTIC. By combining Remote Sensing (RS), Geographic Information System (GIS), and Analytical Hierarchy Process (AHP), groundwater potential zones (GWPZs) were identified, and aquifer vulnerability was assessed, which included the elaboration of thematic maps using GIS operation tools. The maps allowed for the identification of areas with different susceptibilities to contamination: from “Low” to “Very high” for the DRASTIC index and from “Very Low” to “Very high” for the Specific DRASTIC index. Although the difference between the UC9 and UC10 cemeteries is negligible, UC10 is more vulnerable because of its proximity to the community and critically important mineral water resources (such as Bicanho Medical Spa). The Specific model seems better-suited for describing vulnerability to cemeteries. Although there is limited groundwater quality data for the area, the development of vulnerability maps can identify areas that can be sensitive spots for groundwater contamination and establish procedures for pollution prevention. Full article

Karstic aquifers, because of their conduit system, are susceptible to climate change. Ten karst springs in the Zagros region were selected to investigate the impact of climate change under three CMIP6 scenarios: SSP1-1.9, SSP2-4.5, and SSP5-8.5. This study was conducted in three steps: downscaling climate projection, analyzing spring discharge time series, and introducing a new index to assess the impact of climate change on spring flow rate. Applying LARS-WG6, precipitation was downscaled at 14 stations in the study area. Moreover, time series and trend analysis showed that the selected springs have experienced a decrease in their flow rate. Assuming the covariance function between precipitation and spring discharge is constant, new indices (i.e., $I_{Q_d}$, $I_{{dQ}_d}$, and $I_{cc}$) were introduced to highlight the effect of climate change according to the three scenarios. $d{Q}_d$ is the variability of spring discharge from past to future, $I_{{dQ}_d}$ is spring discharge variability over the historical data, and $I_{cc}$ is the effect of precipitation and spring discharge change together. $I_{cc}$ has a range from −0.25 to 0.25 below and above, which is indicative that two extreme conditions including the spring dryness and overflow are in effect, respectively. The main results revealed that the degree of impact at each spring is a function of climate change scenarios and hydrogeological characteristics of the karstic systems. A more noticeable negative trend in spring flow rate is observed for the karst springs characterized by a dominant conduit flow regime and low matrix storage, located in the areas with low cumulative rainfall, and has a stronger relationship with precipitation. Based on the results, decisions on the management of karst water resources should be made considering where the springs bear free surface and pressurized flow conditions. Full article

The basis for the protection and prevention of groundwater pollution lies in the accurate assessment of vulnerability in terms of the exposure of groundwater bodies to contaminants before they are potentially discharged into the environment. The vulnerability assessment consists of calculating the ease with which pollutants can reach the aquifer from the surface through the vadose zone, which effectively reduces the pollutant load when the transit time is long. Index methods are mostly used, as they are based on input data that are readily available, easy to implement and interpret, and which are simple and practical. However, there are also limitations, as some methods are somewhat subjective and provide only a qualitative approximation. This case study aims to develop a methodology that can quantitively estimate the hydrogeological parameters of the aquifer formations of the Valls basin using geophysical methods and the Dar Zarrouk parameters. The specific treatment carried out on data from gravity stations and vertical electric soundings, supported by the available well data, allows for the delineation of the most favourable areas for the exploitation of groundwater resources (higher hydraulic transmissivity) and the areas most susceptible to pollution (with a shorter transit time) on a regional scale. Geophysical methods have proved useful, sustainably providing valuable information without the need to drill new boreholes that could act as preferential pathways for pollutants into the aquifer. Full article

Geodiversity, comprising both endogenous and exogenous geological processes, plays a crucial role in shaping the structure and functionality of natural systems, alongside its substantial impact on human well-being. However, the often-overlooked interconnection between geodiversity components limits our comprehension of geosystems. In the Chinchiná River Basin (CRB) in Colombia, located in the northern Andes in South America, we established criteria to differentiate geodiversity classes, calculated indices to understand the distribution of geological elements, and discussed systemic relationships. This comprehensive approach lays the foundation for a holistic comprehension of the territory’s structure and functionality. Our findings revealed the convergence in an area of 1052 km² of 10 rock types, 7 slope ranges, 13 landforms, 5 drainage density features, 610.4 km of faults with 9 kinematic tendencies, 5 soil orders, 5 climate types, a 3328 km surface drainage network with 7 hydrographic orders, 1 underground aquifer, 4 areas with lakes, 2 zones with glaciers, 27 polygenetic and monogenetic volcanoes, and several thermal springs. This discussion explores the implications of various methodologies used to establish the value of the general geodiversity index while also examining the relationships between abiotic elements and their distribution patterns. This forms a fundamental basis for understanding the geosystem services of the basin in terms of regulation, support, and provisioning processes, as well as the culture and knowledge derived from geodiversity. These conceptual elements are indispensable for enhancing the sustainability of a region that is susceptible to the impacts of climate change. Furthermore, they serve as the foundations for the objective’s achievement, as set by the UNESCO Global Geopark project “Volcán del Ruiz”, currently ongoing within the region. Full article

Groundwater vulnerability assessments are vital for protecting valuable resources by revealing susceptibility to contamination. This study developed an enhanced index model to assess the intrinsic vulnerability of a supplied karst aquifer in Qingduo, Henan Province. The model considered the 3-D geological structure and modified indices to account for Northern China’s mild karstification. Emphasizing the absolute infiltration capacity of surface contaminants, the model also integrated the groundwater sources and sinks (SS) index. The vulnerability map revealed that over 60% of the aquifers, including the Qingduo wellfield, exhibited very low to low vulnerability. Conversely, only small areas (<5%) along the Kejing (KJ) fault’s southern wall were classified as highly vulnerable. These findings highlighted the significant role of groundwater flow alongside aquifer conditions. The upward groundwater flow through the Fengmenkou (FMK) faults slowed the downward infiltration of surface contaminants into the lower karst aquifer, effectively reducing vulnerabilities. Lower levels of dissolved lead (Pb) and nitrate (NO₃⁻) in Qingduo groundwater aligned with PI_SSR vulnerability mapping. Sensitivity analysis assessed the results’ sensitivity to index weight assignment. The inclusion of the sources and sinks (SS) index holds implications for semi-quantitatively assessing dynamic groundwater vulnerability by delineating flow patterns. Full article

Groundwater vulnerability assessment helps subsurface water resources management by providing scientific information for decision-makers. Rigorous, quantitative assessment of groundwater vulnerability usually requires process-based approaches such as groundwater flow and transport modeling, which have seldom been used for large aquifer-aquitard systems due to limited data and high model uncertainty. To quantify the vulnerability of regional-scale aquifer-aquitard systems in the East Gulf Coastal Plain of Alabama, a three-dimensional (3D) steady-state groundwater flow model was developed using MODFLOW, after applying detailed hydrogeologic information to characterize seven main aquifers bounded by aquitards. The velocity field calibrated by observed groundwater heads was then applied to calculate groundwater age and residence time for this 3D aquifer-aquitard system via backward/forward particle tracking. Radioactive isotope data (¹⁴C and ³⁶Cl) were used to calibrate the backward particle tracking model. Results showed that shallow groundwater (<300 ft below the groundwater table) in southern Alabama is mainly the Anthropocene age (25–75 years) and hence susceptible to surface contamination, while the deep aquifer-aquitard systems (700 ft or deeper below the groundwater table) contain “fossil” waters and may be safe from modern contamination if there is no artificial recharge/discharge. Variable horizontal and vertical vulnerability maps for southern Alabama aquifer-aquitard systems reflect hydrologic conditions and intermediate-scale aquifer-aquitard architectures in the regional-scale models. These large-scale flow/transport models with coarse resolutions reasonably characterize the broad distribution and vertical fluctuation of groundwater ages, probably due to aquifer-aquitard structures being captured reliably in the geology model. Parameter sensitivity analysis, vadose zone percolation time, wavelet analysis, and a preliminary extension to transient flow were also discussed to support the aquifer vulnerability assessment indexed by groundwater ages for southern Alabama. Full article

Sea-level rise, in the context of climate change, increases the likelihood of seawater intruding into coastal aquifers. This study assesses the vulnerability of the Pleistocene aquifer in the coastal area of Ba Ria-Vung Tau province, Vietnam. Data for calculation and analysis were collected from 99 boreholes in the study area. Using the vulnerability assessment index (GALDIT) with expanded weights, the vulnerability of the aquifer to the influence of coastlines was evaluated and visualized in a GIS environment. The set of Entropy weights used clearly shows the significance of the component parameters and indicates the characteristics of the risk partitioning of aquifer salinization. The Entropy-GALDIT results divided the Pleistocene aquifer in the coastal area of Ba Ria-Vung Tau province into three levels of vulnerability: high vulnerability zones (3.88% of the area), medium vulnerability zones (55.47%), and low vulnerability zones (40.65%). According to the GALDIT susceptibility zoning map, the western area of Phu My town (along the Thi Vai River), the southwest region of Vung Tau City, and the southeast region of Dat Do District are highly sensitive and not recommended for any purpose. This result provides useful insights into the vulnerability of aquifers in the coastal area of Ba Ria-Vung Tau province, with respect to factors such as the height of the groundwater level above sea level, the distance from the shore to the wells, and the impact of existing seawater intrusion. Accordingly, it is necessary to establish monitoring systems to warn of saltwater intrusion and to develop integrated resource management strategies to ensure the sustainability of groundwater resources in the area. Full article

In the rural and coastal Almyros basin in Magnesia, Greece, the objective of the current study is the assessment of aquifer vulnerability to seawater intrusion using the GALDIT approach. The Almyros aquifer system’s quality and quantity have declined as a result of unsustainable groundwater abstraction for irrigation. The Analytical Hierarchy Process (AHP) of Multicriteria Analysis has been used for the modification of the GALDIT index based on the statistics of experts’s responses to questionnaires on the influence of hydrological, hydrogeological, and other parameters. For all methodologies and time periods, the aquifer’s coastline section had high susceptibility levels, whereas the northeast and southeast had lower values. The most vulnerable area of the aquifer changes over the various time periods of analysis. Full article

Deposition of corpses in the ground is the most common burial practice, which can allow interactions between polluting compounds and the soil, groundwater, and surface water, which may afterwards lead to negative environmental impacts and risks to public health. The risk of cemeteries contaminating groundwater is related to their location, the quantity of clothes, metals and adornments buried, and geographical, geological, hydrogeological, and climatic factors. Using the DRASTIC index and geographical information system (GIS) tools, the potential for groundwater contamination was investigated in eight cemeteries located in the Figueira da Foz region (Portugal), which are the main anthropogenic pollution sources in the area. Aquifer vulnerability was assessed through the development of thirteen site characteristic maps, seven thematic maps, and a DRASTIC index vulnerability map, using GIS operation tools. No studies were found on the development of vulnerability maps with this method and digital tools. Cemeteries UC2, UC4, UC5, UC6, UC7, and UC8 are located within the zones susceptible to recharge, with an average recharge rate of 254 mm/year. Cemeteries UC5, UC7, and UC8 are expected to develop a greater water-holding capacity. The water table depth is more vulnerable at UC6, varying between 9.1 m and 15.2 m. However, results show only a high vulnerability associated with the UC4 cemetery with the contributions T,C > R,S > I > A > D, which should be under an environmental monitoring program. The area surrounding UC4 is characterized by a water table depth ranging between 15.2 m to 22.9 m, mainly fine-grained sands in both the vadose zone and the aquifer media, Gleyic Solonchaks at the topsoil, very unfavorable slope (0–2%), and high hydraulic conductivity (>81.5 m/day). The sensitivity analysis shows that the topography, soil media, and aquifer media weights were the most effective in the vulnerability assessment. However, the highest contributions to index variation were made by hydraulic conductivity, net recharge, and soil media. This type of approach not only makes it possible to assess the vulnerability of groundwater to contamination from cemeteries but also allows the definition of environmental monitoring plans as well as provides the entities responsible for its management and surveillance with a methodology and tools for its continuous monitoring. Full article

The quantitative identification of water sources is an important prerequisite for objectively evaluating the degree of aquifer interference and predicting the production potential of coalbed methane (CBM) wells. However, this issue has not been solved yet, and water sources are far from being completely understood. Stable water isotopes are important carriers of water source information, which can be used to identify the water sources for CBM wells. Taking the Zhijin block in the Western Guizhou Province as an example, the produced water samples were collected from CBM wells. The relationships between the stable isotopic compositions of the produced water samples and the production data were quantitatively analyzed. The following main conclusions were obtained. (1) The δD and δ¹⁸O values of the produced water samples were between −73.37‰ and −27.56‰ (average −56.30‰) and between −11.04‰ and −5.93‰ (average −9.23‰), respectively. The water samples have D-drift characteristics, showing the dual properties of atmospheric precipitation genesis and water–rock interaction modification of the produced water. An index d was constructed to enable the quantitative characterization of the degree of D-drift of the produced water. (2) The stable isotopic compositions of produced water showed the control of the water sources on the CBM productivity. The probability of being susceptible to aquifer interference increased with the increasing span of the producing seam combination, reflected in the lowering δD and δ¹⁸O values and the decreasing gas productivity. (3) Three types of water, namely, static water, dynamic water, and mixed water, were identified. The characteristic values of the isotopic compositions of the static and dynamic water were determined. Accordingly, a quantitative identification method for the produced water sources was constructed, based on their stable isotopic compositions. The identification results have a clear correlation with the gas production, and the output of the static water contributes to the efficient CBM production. The method for the quantitative identification of the water sources proposed in this study, can help to improve the CBM development efficiency and optimize the drainage technology. Full article

Today, in developing countries, the low surface water distribution efficiency and the lack of supplying water needs of farmers by surface water resources are compensated by excessive aquifer water withdrawal. This mismanagement has caused a sharp drop in the groundwater level in many countries. On the other hand, climate change and drought have intensified the pressure on water resources. This study aims to evaluate novel strategies for developing surface water distribution systems for stress reduction of the Najafabad aquifer in Isfahan, central plateau of Iran. The performance of several strategies for agricultural water distribution and delivery, such as hydro-mechanical operating system, manual-based operating system, and centralized automatic operating system, was evaluated in this study. In the first step, two indices, i.e., water distribution adequacy and dependability, were obtained using a flow hydraulic simulation model. Then, the water distribution adequacy map and amount of reduction in the water withdrawal of existing wells were determined for each strategy. Finally, using the MODFLOW groundwater simulation model, the changes in groundwater levels due to the normal and drought scenarios (15 and 30%) were extracted during five years for each strategy. The findings for the normal scenario showed that the centralized automatic operating system strategy had the most significant impact on agricultural water management in the surface water distribution system with a 30% increase in agricultural water distribution adequacy index compared to the current situation. This strategy increased the groundwater level by 11.6 m and closed 35% of the groundwater wells. In this scenario, the hydro-mechanical operating system strategy had the weakest performance by increasing the aquifer level by only 1.31 m. In the 15% and 30% drought scenarios, the centralized automatic operating system strategy exerted the best performance among other strategies by increasing the aquifer water level by 10.18 and 9.4 m, respectively, compared to the current situation. Finally, the results showed that the spatial segmentation of the aquifer exerted better efficiency and better monitoring in the more susceptible regions. Full article

Population growth, increasing urbanization and industrialization, mismanagement, and climate change are accountable for the rising depletion and pollution of groundwater worldwide. Consequently, water security, food security, and environmental security are in jeopardy, leading to a severe concern for the sustainable water supply on the Earth. The contamination of groundwater, a complex and hidden resource, is difficult to detect and treat. Therefore, it is essential to evaluate aquifer’s propensity for contamination to protect this precious resource. In this paper, a novel approach integrating the GWQI (Groundwater Quality Index), AVI (Aquifer Vulnerability Index), and geospatial modeling is proposed to explore aquifer susceptibility to contamination, applied to an unconfined aquifer. The Groundwater Quality Index (GWQI) was developed by the conventional method and the Analytic Hierarchy Process (AHP), whereas the Aquifer Vulnerability Index (AVI) was developed using a modified DRASTIC model. It was found that the spherical semi-variogram along with simple Kriging is suitable for interpolating concentrations of groundwater quality parameters. Geospatial modeling indicated that the AHP-based GWQI map is more accurate than the conventional method. The integration of the best GWQI and AVI resulted in an Aquifer Susceptibility Index (ASI) map, which revealed that >80% of the study area falls under ‘severe’ to ‘very severe’ susceptible zones, while about 20% of the area falls under ‘moderate’ or ‘minimum’ susceptible zones. The validation results confirmed that the developed ASI map is reliable. The ASI map can serve as a useful tool for planners and decision makers to devise sustainable aquifer management programs to protect vital groundwater resources from contamination and ensure a safe and reliable water supply under climate change. Full article