Management Of Groundwater Resources Research Articles

Semi-analytical solutions for land subsidence due to groundwater withdrawal

This paper introduces novel semi-analytical models tailored for estimating land subsidence resulting from groundwater extraction in confined aquifers. These models offer high scalability, allowing them to be applied to various well configurations and pumping schedules. Their development involves the numerical integration of two key analytical solutions: the “nucleus of strain” (NoS) (Mindlin and Chen, 1950), which represents a localised zone within the aquifer where a unit change in pore pressure leads to deformation and subsequent surface displacement, and the classic Theis equation (Theis, 1935) for the pore pressure changes induced by a constant-rate well pumping from a laterally unbounded aquifer. These integrations yield surface displacement components, both horizontal and vertical, expressed as functions of two dimensionless spatial–temporal variables, which encompass aquifer depth, thickness, well placement, pumping schedules, and critical hydro-geomechanical parameters like hydraulic conductivity, porosity, vertical compressibility, and water compressibility. Proposed are two distinct modelling approaches: one employing a lookup table (LT) derived from numerical integration results, and the other providing direct closed-form surface displacement solutions by fitting LT data with “hinge models”, which use piecewise-linear functions linked by sigmoidal curves for computational efficiency. In both cases, surface displacement components are estimated by plugging in the dimensionless variables. Conditions of variable pumping from multiple wells can be addressed by applying superposition of solutions. In essence, these semi-analytical models offer swift computational capabilities for understanding and forecasting land subsidence dynamics. Their scalability makes them adaptable to a wide array of well configurations and scheduling scenarios, rendering them valuable for numerous applications. They are particularly significant for providing preliminary estimates of the impacts of groundwater development, conducting “what-if” tests, and performing sensitivity analyses to identify key factors affecting land subsidence risk. This underscores the importance of these models in sustainable groundwater resource management and in mitigating land subsidence and its associated consequences.

The new region demarcation framework for implementing the joint prevention and control of groundwater pollution: A case study in western of Bohai Bay, China

The joint groundwater pollution prevention and control (GPPC) strategy has been extensively implemented to address the coastal region groundwater pollution challenges in China. However, regional groundwater pollution control and treatment efficiency cannot achieve the expected results due to the lack of regional priority control orders and accurate restoration levels. Thus, this study developed a new region demarcation framework method for delineating GPPC zones, in tandem with a comprehensive pollution index method, the DRASTIC model, source apportionment. To validate the new methodological framework, a case study of groundwater pollution in Qinhuangdao, the western of Bohai Bay, China, was implemented to calculate pollution prevention and control zoning. In total, 340 groundwater samples from shallow aquifers with 9 target pollutants (NO3-, NO2-, NH4+, As, Cd, Cr, Cu, Pb, and Ni) were selected as the dataset for GPPC regionalization. The results showed that GPPC zoning further clarified the direction of groundwater pollution protection and management in Qinhuangdao. Compared to the traditional method, the new GPPC zoning better reflects groundwater mobility characteristics and pollution transport and enrichment patterns in terms of groundwater functional integrity and delineation. This new regional demarcation framework method contributes to providing support for the fine division of groundwater pollution zoning and precise pollution control for groundwater resource management in China.

Toward Sustainable Groundwater Management: A Comprehensive Framework for Resource Protection and Utilization

ABSTRACTThis paper presents a comprehensive framework for the sustainable management of groundwater resources in the Makutupora basin, Dodoma, Tanzania. The framework was developed through a systematic four‐phase methodology. Phase I involved a literature and document review to generate foundational insights. Phase II comprised a review of existing conceptual frameworks to identify best practices. Phase III included primary data collection through interviews, focus groups, and stakeholder surveys to understand current challenges and capacities. Phase IV involved synthesizing the findings to develop the proposed management framework. The framework includes a nested, multi‐scale structure with four hierarchical levels, overarching goals, primary management functions, specific operations, and subordinate tasks. It was informed by sustainability Principles and Intergrated Water Resources Mangagement concepts. The framework facilitates coordinated planning and implementation across relevant organizations through well‐defined roles and regular monitoring/evaluation. Key functions address resource assessment, regulatory compliance, stakeholder participation, financing, and capacity development. Validation by subject matter experts strengthened the framework's grounding in evidence and enhanced its implementation, adaptability, and long‐term sustainability. The final framework is envisioned as a dynamic decision support tool to address the complexities of groundwater utilization, protection, and conservation in an equitable, adaptive manner for current and future generations.

Technical and financial interactions between Iran groundwater institutions: A stakeholder analysis approach

The over-exploitation of groundwater resources (GWR) by the agricultural sector in Lorestan province in the west of Iran has been blamed for the severe depletion of groundwater and irreparable damages to them in this province. This problem partially originates from poor institutional interactions between groundwater institutions especially, their technical and financial interactive links. In this regard, a prerequisite is to study the interactions of the institutions, identify stakeholder institutions, categorize them, and then, study their interactive links. The process of identifying, categorizing, and studying the links of these institutions can be performed by the stakeholder analysis (SA) method. Therefore, based on this method the groundwater institutions related to agricultural sector of Lorestan province were identified, they were categorized according to the interest-power matrix, and their (technical and financial) interactive links were investigated by the social network analysis (SNA) method. Based on the results, 25 institutions were identified as groundwater institutions related to agricultural sector of Lorestan province. According to the interest- power matrix, the institutions located in the two upper categories, i.e, Key Players and Subjects, are the most important groundwater institutions related to agricultural sector of this province. The SNA shows that the institutions have, in general, poor technical and financial interactions and most technical and financial interaction links are the disposal of some limited institutions, which are mostly from the public sector. Policymaking experts have so far identified institutions related to groundwater resources management (GWRM) by relying on their limited information and subjective experience. In this regard, SA method is a comprehensive method to identify relevant institutions, categorize them, and study their interaction links. This study might have significant policy implications for groundwater management concerns in western Iran and the arid and semi-arid regions of the Middle East. The results of this study not only helps policy makers in decisions related to GWRM but also in the analysis and policy-making related to it.

Spatial prioritization of groundwater resources in mountain region of Nepal: a GIS and AHP integrated framework

ABSTRACT Climate change and anthropogenic activities pose major challenges to water resource management in water-scarce mountain regions. Managing and monitoring groundwater effectively is crucial in mitigating these challenges. Understanding groundwater resources and their distribution is necessary for effective management. The present study covers Doramba rural municipality of Nepal. It employed the analytic hierarchy process (AHP) as a multi-criteria decision-making (MCDM) tool integrated with remote sensing (RS) data and geospatial techniques to identify groundwater potential zones (GPZs). The parameters for analysis include drainage density, slope, rainfall, lineament density, land use/land cover (LULC), soil, geology, curvature, roughness, topographic wetness index, and topographic position index. These 11 thematic layers of the study area were prioritized using Satty's AHP method for the delineation of GPZs. The results classified the study area into very high, high, moderate, low, and very low groundwater potential classes, covering 26.71, 27.98, 46.61, 34.71, and 4.89 km2, respectively. The delineated map accuracy was confirmed with a 70.7% prediction rate based on the spatial distribution of 56 springs in the study area. The study's results can be applied to the sustainable management of groundwater resources in the study region and other areas with similar hydrogeological conditions.

Evaluating Empirical, Field, and Laboratory Approaches for Estimating the Hydraulic Conductivity in the Kabul Aquifer

The evaluation of saturated hydraulic conductivity (Ks) constitutes an invaluable tool for the management and protection of groundwater resources. This study attempted to estimate Ks in the shallow aquifer of Kabul City, Afghanistan, in response to the occurring groundwater crisis caused by overexploitation and a lack of an appropriate monitoring system on pumping wells, based on datasets from well drilling logs, various analytical methods for pumping test analyses, and laboratory-based methodologies. The selection of Ks estimation methods was influenced by data availability and various established equations, including Theis, developed by Cooper–Jacob, Kruger, Zamarin, Zunker, Sauerbrei, and Chapuis, and pre-determined Ks values dedicated to well log segments exhibited the highest correlation coefficients, ranging between 60% and 75%, with the real conditions of the phreatic aquifer system with respect to the drawdown rate map. The results successfully obtained local-specific quantitative Ks value ranges for gravel, sand, silt, clay, and conglomerate. The obtained results fall within the high range of Ks classification, ranging from 30.0 to 139.8 m per day (m/d) on average across various calculation methods. This study proved that the combination of pumping test results, predetermined values derived from empirical and laboratory approaches, geological description, and classified soil materials and analyses constitutes reliable Ks values through cost-effective and accessible results compared with conducting expensive tests in arid and semi-arid areas.

Quantifying groundwater depletion in Arabian Peninsula transboundary aquifer systems: Understanding natural and anthropogenic drivers

Groundwater is the primary source of freshwater for domestic, agricultural, and industrial usage in the Arabian Peninsula countries. It is increasingly becoming a limited resource due to human activities leading to excessive depletion and contamination. Thus, sustainable management of groundwater resources in this region is critical. The groundwater in the Arabian Peninsula countries is primarily found in transboundary systems such as the Wajid, Umm Er Radhuma, and Wasia Aquifers shared between Saudi Arabia, Iraq, Syria, Yemen, and Oman. These systems have no groundwater-sharing agreements, which leads to a lack of data sharing, unsustainable and uncoordinated development, rapid water depletion, water quality deterioration, and land subsidence. This study examines the Wajid, Umm Er Radhuma, and Wasia aquifer systems from April 2002 to May 2021 by analyzing monthly gravity field solutions from GRACE and GRACE-FO satellite data, other remote sensing observations, information from the Global Land Data Assimilation System (GLDAS), as well as field data to determine how regional water resources are changing over time and to identify the factors that influence these resources. The sharp decline in Total Water Storage Anomalies (TWSA) and the Groundwater Storage Anomalies (GWSA) across all three systems is caused by a combination of climatic and human factors. The observed decline in Total Water Storage can be partly attributed to a decrease in regional rainfall, whereas the depletion of Groundwater Storage has a strong correlation with the rise in groundwater extraction for irrigation purposes in the 2010s. The recent rise is groundwater depletion in specific areas of central Saudi Arabia may be attributed to agricultural irrigation and rapid urban development. The results are insightful for monitoring water storage in management plans and decision-making processes to preserve and efficiently use groundwater resources.

Analyses of groundwater level in a data-scarce region based on assessed precipitation products and machine learning

Groundwater, a vital natural resource globally, faces challenges related to data scarcity, particularly in data-limited regions. To address this issue in the region of Bahira in Morocco, we developed an innovative approach for estimating groundwater levels by utilizing precipitation products and employed a random forest (RF) machine learning (ML) model to fill data gaps. Our study involved a comprehensive assessment of ten precipitation products, comprising six Reanalysis Precipitation Products (RPPs) and four Satellite-based Precipitation Products (SPPs). We evaluated their performance across various time scales, including daily, monthly, and seasonal, across different topographical classes. The outcomes highlighted the consistency of ERA5-based datasets, boasting daily correlation to values higher than 0.6, whereas monthly and seasonal correlations exceed 0.8, except during summer. GPM-IMERG, MERRA2, and CPC-UPP also demonstrated commendable accuracy, particularly in plain and mountainous areas. Nonetheless, CFSR, CHIRPS, PERSIANN CDR, and TRMM datasets exhibited limitations, particularly in high mountain areas. To address data gaps, we initially explored correlations between RPPs, SPPs, and groundwater data. However, these correlations failed to meet the accuracy standards required for precise predictions. Notably, the strongest correlations were observed in monitoring stations located in mountainous regions, indicating significant aquifer recharge activities in these areas. In the subsequent phase, the Multiple Imputation by Chained Equations (MICE) machine learning-based imputation method served as a valuable tool for estimating groundwater levels in regions where ground observations were insufficient. Our trend analysis yielded significant insights, with approximately 95% of groundwater points displaying negative trends, with a maximum rate of −0.91 m. In contrast, 69% of precipitation stations exhibited negative trends, with a maximum rate of −0.06 mm. Our approach offers a promising potential to address the challenges associated with the scarcity of groundwater and precipitation data, making it a valuable tool for the assessment, monitoring, and management of groundwater resources.

Indicator assessment of groundwater resource sustainability: Using the framework of socio-ecological systems in Hamedan - Bahar Plain, Iran

Study areaIran. Study focusHamedan-Bahar plain is one of the important plains in the west of Iran, which is facing a shortage of water resources and excessive extraction of groundwater resources. The purpose of this article is to identify and evaluate the status of sustainability governance indicators using the knowledge of local experts, which can be an effective step towards the sustainable management of groundwater resources. In this paper, we apply Ostrom’s Social-Ecological Systems Framework (SESF) as a diagnostic tool with 52 indicators to assess the sustainability of groundwater resources. New hydrological insights for the regionBased on key informant interviews with local experts and stakeholders, we use the TOPSIS technique and the Shannon Entropy methodologies to weigh and rank indicators influencing sustainability. Findings revealed that the indicators within the category Resource Systems (RS) and Resource Units (RU) with values of 0.74, and 0.70, are the most stable contributing factors to local sustainability, respectively. In contrast, the Governance System (GS), Actor (A), and Interaction (I) first-tier variables were evaluated as less stable, along with Outcomes (O). This suggests that social factors and diverse outcomes may need further attention in the region to ensure management and policy development that can better enable sustainable outcomes. This analysis also demonstrates the usefulness of a comprehensive science-based framework for organizing, analyzing, and presenting a wide range of complex information to inform policymakers and planners.

Investigating seawater intrusion and salinization using the integration of hydrochemical and geoelectrical techniques

Seawater intrusion poses a significant environmental threat to water resources, agriculture, and ecosystems. We investigate the extent of seawater intrusion and salinization in the eastern coastal aquifers of Saudi Arabia. Hydrochemical measurements and electrical resistivity tomography (ERT) techniques are used to assess groundwater quality and the subsurface extension of seawater intrusion. Two resistivity profiles, 475 m long each, are analyzed to gain insights into the subsurface geology and seawater intrusion. The inversion of the recorded resistivity data reveal four distinct subsurface layers. The uppermost layer consists of surficial deposits, followed by a sandy seawater intrusion layer, beneath which lies a marl layer, and at the bottom, a dolomitic limestone layer representing the brackish-water aquifer. The ERT results are integrated with hydrochemical and hydrogeologic results from 12 wells to overcome the limitations of the ERT. The findings of this study would facilitate the development of efficient mitigation strategies and sustainable management of the groundwater resources in the study area or similar coastal regions affected by seawater intrusion. Understanding and delineating the boundary between saline and fresh water is crucial for safeguarding water resources for agricultural purposes, preserving ecosystem health, and ensuring the long-term sustainability of water supplies in coastal areas.

Estimation of Groundwater Recharge in a Volcanic Aquifer System Using Soil Moisture Balance and Baseflow Separation Methods: The Case of Gilgel Gibe Catchment, Ethiopia

Understanding the recharge–discharge system of a catchment is key to the efficient use and effective management of groundwater resources. The present study focused on the estimation of groundwater recharge using Soil Moisture Balance (SMB) and Baseflow Separation (BFS) methods in the Gilgel Gibe catchment where water demand for irrigation, domestic, and industrial purposes is dramatically increasing. The demand for groundwater and the existing ambitious plans to respond to this demand will put a strain on the groundwater resource in the catchment unless prompt intervention is undertaken to ensure its sustainability. Ground-based hydrometeorological 36-years data (1985 to 2020) from 17 stations and satellite products from CHIRPS and NASA/POWER were used for the SMB method. Six BFS methods were applied through the Web-based Hydrograph Analysis Tool (WHAT), SepHydro, BFLOW, and Automated Computer Programming (PART) to sub-catchments and the main catchment to estimate the groundwater recharge. The streamflow data (discharge) obtained from the Ministry of Water and Energy were the main input data for the BFS methods. The average annual recharge of groundwater was estimated to be 313 mm using SMB for the years 1985 to 2020 and 314 mm using BFS for the years 1986 to 2003. The results from the SMB method revealed geographical heterogeneity in annual groundwater recharge, varying from 209 to 442 mm. Significant spatial variation is also observed in the estimated annual groundwater recharge using the BFS methods, which varies from 181 to 411 mm for sub-catchments. Hydrogeological conditions of the catchment were observed, and the yielding capacity of existing wells was assessed to evaluate the validity of the results. The recharge values estimated using SMB and BFS methods are comparable and hydrologically reasonable. The findings remarkably provide insightful information for decision-makers to develop effective groundwater management strategies and to prioritize the sub-catchments for immediate intervention to ensure the sustainability of groundwater.

Hydrochemical and Formation Mechanism Studies of Groundwater in Quaternary Aquifer in a Northern Plain of China: An Example of Beijing Plain

Beijing Plain is a very active part of Beijing city regarding the socio-economic and human activities of the region. Over the past four decades, Beijing’s economic development and the continuous drought for nearly 10 years in the 2000s have negatively impacted the groundwater quantity and quality. Therefore, it is necessary to investigate the present situation of groundwater chemistry in this region to develop a comprehensive database and orientation for future research on groundwater quality evaluation. Mathematical statistics, Piper’s trilinear diagram, Gibbs plots, the ion ratio method and PHREEQC software 3.7.3 were used to analyze the groundwater hydrogeochemical characteristics and formation mechanisms of the quaternary aquifers of the Beijing Plain area. Hydrogeochemical results indicated that the groundwater is slightly alkaline, with pH values ranging from 6.76 to 8.65 and an average value of 7.92. The order of major cations in groundwater was Ca2+ > Na+ > Mg2+ > K+ with average values of 66.54 mg/L, 50.58 mg/L, 23.78 mg/L, and 1.81 mg/L, respectively, while the order of major anions was HCO3− > SO42− > Cl− with average values of 284.89 mg/L, 52.1 mg/L and 35.5 mg/L, respectively. The groundwater chemical types are Mg-Ca-Cl-HCO3, Na-Ca-HCO3, Mg-Ca-HCO3 and Mg-Na-HCO3. Research on the main influencing factors and PHREEQC hydrogeochemical inverse simulations results along the four pathways selected confirmed that rock weathering with sulfate, silicate and carbonate rock mineral dissolution and Na+, Mg2+ and Ca2+ ion reaction exchange influenced groundwater hydrogeochemical characteristics of the quaternary aquifers of the Beijing Plain area. Understanding the formation mechanisms of hydrogeochemistry in quaternary plains provides guidance for future studies and, through suggestions and case studies, facilitates decision-making by policy-makers on the sustainable management of groundwater resources.

Assessment of groundwater resources from geophysical and remote sensing data in a basement complex environment using fuzzy-topsis algorithm

This study addresses the pressing global water challenge by focusing on a typical basement complex area experiencing acute water shortage. Indiscriminate well siting without reliable hydrogeological maps has resulted in failed attempts to address water shortages. To overcome these challenges, this research aims to enhance the accuracy and reliability of groundwater potential assessments by incorporating crucial groundwater-related factors.The Fuzzy Technique for Order Preference by Similarity to Ideal Solution (FTOPSIS) method was adopted due to its ability to improve multi-criteria decision-making (MCDM) techniques for effective groundwater resource management. Unlike TOPSIS, FTOPSIS better reflects decision-makers' intentions, especially concerning geological boundaries and natural phenomena. To achieve the objectives of the study, geophysical and remote sensing datasets were utilized. The study employed the electrical resistivity method, utilising the Vertical Electrical Sounding (VES) technique with the Schlumberger array while the remote sensing data used were the Digital Elevation Model (DEM) image and Landsat ETM image which were processed to generate key groundwater conditioning factors. These factors were integrated using the FTOPSIS algorithm. This algorithm facilitated the calculation of the groundwater potential indices by assigning weights based on their level of significance to influencing groundwater potential in order to generate the groundwater potential map (GPM). The GPM was classified into five zones of varying groundwater potential, with very low and low potential occupying 74 % of the total area. Validation with well data yielded an impressive 79 % accuracy, showcasing the model's enhanced precision. Beyond improved accuracy, the study's implications extend to practical applications in groundwater resource management. By providing a clearer understanding of groundwater potentiality, the research can inform more robust decision-making frameworks, promoting sustainable water use not only in the study area but also in similar geological settings of the world.

Hydrogeological assessment and aquifer potential of a coastal area, South Nigeria: insights from VES surveys and spatial analysis

ABSTRACT This study provides a comprehensive analysis of aquifer properties using vertical electrical sounding (VES) surveys conducted in Eket, Nigeria, to address the challenges of groundwater management in coastal areas. The VES method was employed for hydrogeo-electrical analysis and to investigate the hydrogeological dynamics of the region. The results reveal varying subsurface layers with distinct resistivity values. Spatial distribution analysis indicates densely settled areas exhibit lower resistivities, while sparsely settled regions show higher resistivities. The spatial location labeled EK2 features the largest aquifer, measuring 246.70 m, predominantly located in the central research area. Aquifer depths range from 87.10 to 250.20 m, with variations in thickness highlighting geographical heterogeneity and its impact on groundwater transport. These spatial differences in groundwater characteristics are crucial for understanding groundwater movement, storage, and extraction potential. The study underscores significant variability in porosity, reflecting differences in the aquifers’ water storage capacity and susceptibility to contamination. These findings have important implications for groundwater flow rates and extraction feasibility. The research provides essential data for hydrogeological investigations and groundwater resource management, emphasizing the intricate relationship among geological formations, aquifer properties, human activities, and the potential risks of contamination in variable porosity zones.

Exploring groundwater patterns in Souss-Massa Mountainous Basin, Morocco: A fusion of fractal analysis and machine learning techniques on gravity data

Groundwater potential in Morocco’s Souss-Massa mountainous basin (SMMB) is being identified using geospatial tools and geological data. We deployed four mathematical models, namely Data-Driven Multi-index Overlay (DMIO), Geometric Average (GA), Support Vector Machine (SVM), and Logistic Regression (LR), to establish data-driven patterns among the nine influencing factors, primarily drainage density, permeability, slope, distance to rivers, elevation, lineament density, distance to lineaments, intersection node density, and rainfall. Based on the Concentration-Area (C-A) fractal approach, the findings of the four models were developed and classified into five levels of potentiality ranging from very low to very high. The regions designated as having high and very high potentialities for the DMIO, GA, SVM, and LR models, respectively, account for 22.44 %, 9.80 %, 19.36 %, and 26.77 % of the overall basin. We validated the models by calculating each model's area under the ROC curve (AUC). The estimated AUC values are more than 70 %, suggesting the model performs well. The four models' performance was compared, revealing that the SVM model outperforms the others. Gravimetric data shows that possible groundwater zones closely coincide with gravimetric lineaments. The findings of this study can provide valuable insights to decision-makers, allowing them to improve decision-making processes and develop holistic groundwater resource management in the Souss-Massa mountainous basin (SMMB).

Integrating in-situ data and spatial decision support systems (SDSS) to identify groundwater potential sites in the Esan plateau, Nigeria

Establishing suitable groundwater resource areas is a challenging endeavour across the globe. However, novel spatial technologies have emerged as valuable tools for the effective strategy, management, and assessment of groundwater resources, especially in data-scarce emerging economies. The current study used spatial decision support systems (SDSS) for evaluating and defining groundwater potential sites (GPSs) in Nigeria's Edo central region to promote sustainable governance of groundwater. By merging multiple groundwater contributing theme layers, a leading-edge information-based multiparametric analytical hierarchy process (AHP) was applied to define the groundwater prospective areas. By systematically assigning weights to every subject-specific layer and feature, the subject matter layers of geology, geomorphology, drainage density, slope, soil properties, landuse/landcover, rainfall distribution, hydraulic conductivity, transmissivity, curvature, proximity to surface water bodies, and elevation were generated and used for groundwater potential map generation. Each thematic layer's weights were allocated and adjusted depending on their qualities and relevance to groundwater recharge. The multicollinearity (MC) analysis was used to evaluate the model's predictive capacity. Finally, groundwater potential sites were created by integrating the theme-specific maps with the weighted total overlay computation tool. The study area contained three separate groundwater potential sites: low, moderate, and high. According to the regional geographic distribution, the largest portion of the area (65%) fell within the moderately significant groundwater potential geographical area. The high and low GPSs, which both have a low curvature and a valley plain characteristic, account for 25% and 10%, respectively, of the entire area. The outcomes were contrasted with the yield of groundwater from boreholes gathered in the study region. The validation analysis found an acceptable 88.89% similarity. This highlights the potential for the groundwater map's significant prediction. Therefore, the applied approach is a viable choice for the advancement of groundwater in the central Edo region and with comparable geology all over the globe.

Quantitative Assessment and Validation of Groundwater Pollution Risk in Southwest Karst Area

AbstractGroundwater pollution risk assessment is a useful tool for groundwater pollution prevention and control. However, it is difficult to accurately quantify groundwater flow and contaminant fluxes in karst areas and different types of karst areas have different hydrogeological characteristics. Therefore, the assessment of groundwater pollution risk in karst areas must use different assessment indicator systems. This study developed a new methodology that modified the vulnerability assessment model PLEIK, determined pollutant fluxes considering hydrogeological conditions, and revised parameter weights using the random forest method. The resulting PLEIKD-RF model was used to assess the risk of groundwater contamination in the southwestern karst region and its validity was verified. The results showed that the groundwater pollution risk in the region was low, with 65.64% of the low and relatively low risk areas located in the middle and high mountainous regions. 11.81% of the high and relatively high risk areas were sporadically located in the western and central regions, which were mainly controlled by the distribution of the pollution sources and the karst development. The accuracy of the results of groundwater pollution risk assessment in the study area was 71.87% as verified by the horizontal difference method. The results of the sensitivity analysis indicated that accurate, detailed, and representative data on the protective layer, surface water-groundwater interactions, and pollution source loads would improve the accuracy of groundwater pollution risk zoning. This assessment method provided a reference for similar assessments and the results provide a basis for the protection and management of groundwater resources in the region.

Exploring the InSAR signature associated with river-sourced recharge in California’s San Joaquin Valley

Recharge is a critical component for understanding aquifer systems and the sustainable management of groundwater resources, yet this process is challenging to measure at policy-relevant spatiotemporal scales. Building upon previous research, we tested the hypothesis that InSAR can be used to observe river-sourced recharge if the underlying recharge pathways are associated with sufficient clay content. Our analysis leveraged the decomposition of InSAR time series with interpretations of 3D resistivity models derived from airborne electromagnetic (AEM) surveys. We focused our analysis on two study sites where high density AEM data were available and river-sourced recharge is determined to have occurred during wet years: (1) near Fresno, California and (2) near Visalia, California. Sediment type and hydrogeological structure from AEM supported our hypothesis with the InSAR signature attributed to river-sourced recharge occurring only in the study site with semi-confined to confined conditions and relatively high fraction of interbedded clay within recharge pathways. The timing to peak amplitude, the key feature we wanted to isolate in the InSAR data, near Visalia was interpreted as a pressure pulse front associated with river-sourced recharge propagating into the San Joaquin Valley. This study further validated the potential of InSAR, coupled with AEM data, to map and monitor river-sourced recharge in aquifer systems. As InSAR data become more accessible, this approach holds promise for broader applications in groundwater science and management worldwide.

Enhancing groundwater potential zone mapping with a hybrid analytical method: The case of semiarid basin

Groundwater resource management is a critical component of sustainable water use, necessitating accurate and nuanced mapping of groundwater potential zones. This study analyzed the groundwater potential of Algeria's 43,750 km2 Chelif Basin (more than 17% of the area of Northern Algeria) using a combination of both subjective and objective mapping techniques. The adopted approaches encompass the benchmark analytical Fuzzy Analytic Hierarchy Process (Fuzzy-AHP) and the DEcision MAking Trial and Evaluation Laboratory (DEMATEL) methodologies to quantify interdependencies of criteria related to groundwater potential. The analysis focused on ten criteria related to groundwater potential, including core moisture availability and key hydrological factors like distance to river, topographic wetness index, and hydrological soils. Fuzzy-AHP achieved slightly higher groundwater prospecting accuracy (AUC = 0.730) than classic AHP (0.716), with benchmarking against 15 related studies indicating robust performance. Instead of the most commonly used criteria in groundwater literature such as lineament, stream order, recharge rate, and drainage density, this study employed alternative factors to challenge and validate the efficacy of the proposed methodology. The decision to omit certain criteria facilitated a more focused and manageable analysis, yet still delivered a robust evaluation of groundwater potential in the studied area. Moreover, this approach underscores the adaptability of the proposed methodology to accommodate varying sets of criteria, tailored according to the availability of data and specific research objectives. Additionally, the DEMATEL evaluation reveals new insights into subtle prioritization divergences, specifically between domain specialist opinions and analytical assessments of the criteria. The integration of fuzzy logic and causal relationship mapping through DEMATEL provides a comprehensive and robust foundation for groundwater potential modeling.

Deciphering hydrogeochemical evolution in the multilayered Ilhas-São Sebastião aquifer system, Brazil: Implications for groundwater resources management

This study examines the hydrogeochemical processes shaping groundwater quality in the Ilhas-São Sebastião aquifer system, situated at the interface of the Central and Southern Recôncavo basins in the densely populated area near the Brazilian metropolis Salvador. Analysis of 71 groundwater samples reveals distinctive hydrogeochemical compositions in aquifers. In the São Sebastião aquifer, alkalis (Na+ + K+) and strong acids (Cl− and SO42−) prevail. Furthermore, a moderate correlation of Na+–Cl-marks an evolution from Mg–Ca–HCO3 to Mg–Ca–Cl and Na–Cl facies. In contrast, the Ilhas aquifer displays a Na+>Ca2+>Mg2+>K+ relationship for cations and HCO3− > Cl− > SO42− > CO32− for anions and a recharge-discharge trajectory from the Mg–Ca–HCO3 to the Ca–Na–HCO3 facies. Additionally, it presents greater mineralization and dispersion of physicochemical parameters, especially around sub-basin depocenters. Its hydrogeochemical signature is characterized by robust correlations between TDS and EC, and between these parameters and SO42−, HCO3−, Ca2+, and Mg2+, complemented by moderate correlations of EC with Na+ and Cl−. Bivariate Gibbs diagrams and ionic ratios indicate silicate weathering and ion exchange as the primary geochemical processes controlling solute concentrations in both aquifers. However, in the Ilhas aquifer, a subordinate contribution from reverse ion exchange is indicated by weak (TDS–Na+, TDS–K+, Na+–Ca2+, K+–Ca2+) and positive TDS–Ca2+ and TDS–Mg2+ correlations. Conversely, negative chloroalkaline indices and the moderate Na+–Cl- correlation indicate that reverse ion exchange processes are mostly absent in the São Sebastião aquifer. Instead, both chloroalkaline imbalance reactions and silicate weathering contribute equally to the observed geochemical patterns. Groundwater geochemical signatures indicate recharge on flexural margins, active water-rock interaction in large depocenters, and mixing of hydrogeochemical facies between aquifer units. These insights contribute to a comprehensive understanding of groundwater evolution, crucial for effective water resource management in the region.