Future Groundwater Research Articles

An overview of groundwater response to a changing climate in the Murray-Darling Basin, Australia: potential implications for the basin system and opportunities for management

The Murray-Darling Basin (MDB) is a highly allocated and regulated, mostly semiarid basin in south-eastern Australia, where groundwater is a significant water resource. Future climate predictions for the MDB include an expansion of arid and semiarid climate zones to replace temperate areas. The impacts of climate change are already evident in declining groundwater levels and changes in the connection status between rivers and groundwater, and modelling has predicted a further reduction in future groundwater recharge and ongoing declines in groundwater levels. This is predicted to further reduce river baseflow and negatively impact groundwater-dependent ecosystems (GDEs), and these system responses to a changing climate and extreme events are complex and not always well understood. This report provides an overview of the current state of knowledge of groundwater response to a changing climate for the MDB, and outlines challenges and opportunities for future groundwater research and management. Opportunities for the region include improving data systems and acquisition through automation and novel data sources, and growing capability in integrated, risk-based modelling. Quantification of the groundwater/surface-water connection response to declining groundwater levels, and assessing GDE water requirements and thresholds, would enable identification of vulnerable systems and inform the development of metrics for adaptive management, improving the ability to respond to climate extremes. There is potential to adapt policy to support active management of groundwater where required, including conjunctive use and water banking. Improving knowledge sharing and water literacy, including understanding community values of groundwater and GDEs, would support future decision-making.

VERY LOW FREQUENCY ELECTROMAGNETIC (VLF-EM) SURVEY FOR GROUNDWATER DEVELOPMENT IN BICHI/BAGWAI AREA, NORTH WESTERN NIGERIA

Abstarct
 Detailed Very Low Frequency Electromagnetic (VLF-EM) hydrogeophysical survey was undertaken to identify conductive zones and recommend potential areas for possible groundwater development in the Bichi area of Kano state northwestern Nigeria. Geologically, the area is characterized by porphyritic granite, coarse grained granite and medium to fine grained granite. The VLF-Electromagnetic method was adopted as a fast reconnaissance tool to map possible linear fractures. During the survey, measurements were taken at a station interval of 20 m along each profile line ranging from 0 – 420 m, making a total of six VLF-EM traverses which were mapped in the study area. The filtered components for both real and imaginary parts of the VLF-EM data were plotted against distance for each profile using the Karous–Hjelt filter® computer software to interpret and identify the top of linear fractures. The Very Low frequency (VLF) normal and filtered component anomalies identified ten (10) major geological interfaces suspected to be faults/fractured zones (f1 – f10). These suspected zones were marked as targets for future groundwater development in the area since these anomalous zones are areas of high conductivity and this parameter is one of the physical characteristics of water saturated zones. Therefore, this work has proven that VLF method is robust in tying down good locations for groundwater development in rural areas.
 Keywords: Electromagnetic, Hydrogeophysical, Groundwater Development, Conductive Zones, Fault, Fractures.

Interaction of focused recharge and deep groundwater discharge near a wetland: A study in the Ordos Basin, China

Groundwater mounds and depressions induced by rainfall and evapotranspiration near wetlands/lakes have been widely observed, but their effects on groundwater flow field are poorly known. Here, a sandy hillslope near a wetland in the Ordos Plateau, China, which has a semi-arid climate, is selected for investigation. After identifying temporary groundwater mounds/depressions based on three water level observation wells, a HYDRUS-2D model is setup to obtain the highly transient daily flow field. The variable thickness of unsaturated zone near the wetland, which controls soil water content and unsaturated hydraulic conductivity, is found to be responsible for groundwater mounds resulting from focused recharge and groundwater depressions resulting from nonuniform evapotranspiration. On nonrainy days, evapotranspiration in the lowland is supported by flowpaths from regional groundwater discharge, and in the slope is supported by a flow cell from the upland to the upper part of the slope, which causes water table recession in the upland. On rainy days, focused recharge in the lowland leads to two temporary local flow cells, which break the regional groundwater discharge flowpaths into two temporary flow cells. The two temporary flow cells toward the upland contribute to water table rises in the uplandMoreover, we find focused recharge in rainy days does not change the overall direction of flowpaths controlled by regional groundwater discharge and strong evapotranspiration, but only increase the tortuosity of flowpaths. By coupling daily atmospheric conditions and regional groundwater discharge, this study has implications for groundwater recharge estimation and future groundwater modelling in arid regions.

Enteric virus removal by municipal wastewater treatment to achieve requirements for potable reuse

Primary and secondary treatment of municipal wastewater contributes to virus removal upstream of advanced purification to produce water for potable reuse. In this study, virus occurrence by cultivable and molecular methods was measured over a 24-month period in raw wastewater influents and secondary effluents from two municipal wastewater treatment plants that together provide the recycled water source for an advanced water purification facility. Using a rank-paired, covariance-based statistical approach, virus log removal values were determined for four wastewater treatment processes that operate in parallel at the two facilities (two activated sludge processes, trickling filter process, and trickling filter/solids contactor process). The trickling filter process exhibited the lowest observed removal of cultivable enteric virus with a median removal of 1.0 log10 (or 90% removal) and a 5th percentile log removal of 0.73 (or 82%), compared to the greatest removal observed for one of the activated sludge processes (median log removal of 2.4 or 99.6% and 5th percentile of 2.1 or 99.2%). Median log removal observed for male-specific (MS) and somatic (SOM) coliphage was 1.8 (98.6% removal) and 0.5 (70%), respectively, for trickling filter and 2.9 (99.9%) and 2.0 (99%) for activated sludge. Thus, coliphage removal was fairly similar to removal observed for cultivable enteric virus. The cultivable enteric virus 5th percentile removal (0.7) from the trickling filter treatment process was proposed to the state regulator for credit towards state requirements for virus removal related to groundwater augmentation with purified recycled water. Receiving pathogen removal credits for secondary wastewater treatment would allow for an improved margin (safety factor) of credits beyond the minimum required; and in this case may also increase the number of viable future groundwater recharge sites closer to drinking water production wells by reducing the underground travel time otherwise required to obtain sufficient credits.

Prediction of groundwater quality index to assess suitability for drinking purpose using averaged neural network and geospatial analysis

Groundwater quality management is pivotal for ensuring public health and ecological resilience. However, the conventional water quality indices often face challenges related to parameter selection, geographic coverage, and scalability. The integration of machine learning and spatial analysis represents a promising methodological shift, allowing for high accuracy and adaptive management strategies. The Safe Groundwater Project in Unsupplied Areas (2017–2020) employed a comprehensive Groundwater Quality Index (GQI) to evaluate potable groundwater quality across South Korea, utilizing a large dataset comprising 28 water quality parameters and 3552 wells. This study revealed that over 50 % of the evaluated wells (Total 8326 wells) were inappropriate as sources of drinking water, indicating a pressing need for policy revision. The averaged neural network model achieved a high predictive accuracy of approximately 95 % for GQI grades, outperforming other classification models. The introduction of 2D spatial analysis in conjunction with machine learning algorithms notably increased the predictive accuracy for unevenly distributed groundwater samples. Moreover, this combined approach enabled the intuitive visualization of groundwater vulnerability across various regions, which can inform targeted interventions for effective resource allocation and management. This research represents a methodologically robust, interdisciplinary approach that holds significant implications for a framework for future groundwater quality management and vulnerability assessment.

Investigation of Groundwater Potential Zone Using Geophysical and Geospatial Technology in Akuku-Toru Local Government Area, Rivers State, Nigeria

Background of the Study: The study area is located within four communities in Akuku-Toru Local Government Area, which is a coastal region within the Niger Delta. The study area is heavily reliant on groundwater for domestic, industrial, and agricultural purposes. The hydrogeological dynamics of the area are complex, with diverse geological formations and intricate subsurface structures. As a result, an innovative and integrated approach is necessary for effective groundwater management. The study investigated the potential of groundwater resources in the study area and identification of fresh water zones using electrical resistivity, remote sensing, and GIS which employs geophysical surveys, remote sensing techniques, and geospatial analysis to explore the interplay between aquifer characteristics, geological formations, and topographical attributes. The fresh water zones are regions with low saline content.
 Aim: This study aims to assess groundwater potential in some parts of Akuku-Toru Local Government Area by integrating the geophysical data from Vertical Electrical Sounding (VES) surveys with geospatial analysis from GIS and Remote Sensing Technology. The research seeks to provide a comprehensive understanding of groundwater availability and its correlation with geophysical and geospatial parameters.
 Study Design: A thorough methodology was employed to investigate the possibility of freshwater resources in the study area. The approach involved gathering Vertical Electrical Sounding (VES) data from 8 locations, as well as incorporating geospatial data such as elevation, drainage density, geology, apparent resistivity, and slope maps. The collected data underwent rigorous processing, correlation analysis, and reclassification to explore the potential of freshwater resources in the study area.
 Place and Duration of the Study: The research was conducted in four communities (Abonnema, Ekulama, Jacobkiri and Belema) within the Akuku-Toru Local Government Area over a span of 18months. The area's hydrogeological context and topographical features are investigated to determine groundwater potential zones.
 Methods: The research utilized the Vertical Electrical Sounding (VES) method to obtain aquifer resistivity data, reflecting subsurface Lithological variations. Geospatial analysis involved accessing elevation and drainage density patterns. Correlation analysis was also performed to link the geophysical and geospatial data with qualitative interpretations, facilitating the assignment of numerical values representing groundwater potential zones.
 Results: The Correlation analysis revealed insightful patterns. Aquifer resistivity, elevation and slope were identified as influential parameter affecting groundwater potential. The geology of the study area, categorized into dominant formations, exhibited varying degrees of potential for freshwater resources. The Correlation of geophysical and geospatial data provided a comprehensive understanding of groundwater availability across the study region.
 Conclusion: The integration of geophysical and geospatial analysis offers a robust approach to groundwater potential assessment. The research findings contributed to valuable insights into the spatial distribution of potential freshwater resources in the study area. The correlation between aquifer resistivity, elevation, slope, and geology enhanced our understanding of hydrological conditions and provides a foundation for future groundwater studies and management strategies.

Assessing the future groundwater vulnerability of an urban region under variable climatic and land use conditions

Climate change and urbanization threaten groundwater resources due to over-abstraction and contamination. Groundwater vulnerability assessment aids in protecting groundwater resources; DRASTIC is the widely used groundwater vulnerability model (GVM) to assess vulnerability. This study uses an optimized DRASTIC framework to assess the impact of climate and land use change on the future groundwater vulnerability of Chennai Metropolitan Area (CMA). The frequency ratio (FR) and metaheuristic (MH) algorithms are coupled to optimize the rates and weights of GVM to reduce subjectivity. The climatic variables and land use projected for the future period 2030 and 2050 under RCP4.5 and RCP8.5 scenarios. The projected net recharge for the study region varies from 349.95 mm/yr to 458.95 mm/yr, and depth to groundwater level ranges between 4.92 and 6.42 mbgl for scenarios 1 to 4. The RCP4.5 scenario for the far future period (scenario-2) shows an increase in the vulnerability class by 41.64%, and RCP8.5 scenario for the far future period (scenario-4) exhibits a decrease in the vulnerability class by 20.67% of the total area. The integrated groundwater vulnerability analysis found that the CMA groundwater system is in critical condition of high vulnerability for near and far future periods.

Deep-karst aquifer spring-flow trends in a water-limited system, Grand Canyon National Park, USA

Better characterization of the water resources of the Grand Canyon National Park (GRCA) and World Heritage Site, USA, will inform management decisions regarding a proposed water supply intake from Bright Angel Creek (BAC) and will inform the associated forecasts on water security related to climate change and the impact on spring-dependent species. Characterization of the water supply for GRCA was improved through multiyear hydrograph analyses at five springs discharging from the Redwall-Muav (R) aquifer: Roaring Springs, Emmett Spring, At Last Spring, Tapeats Spring, and Abyss River Spring. Comparison of snowmelt response timing and mean recession coefficients among the five springs show no significant differences, indicating similar timing of snowmelt-related discharge and flow regimes across 50 km of horizontal and 1,000 m of vertical distance through the aquifer system. The mean water volumes discharged during snowmelt and the mean annual discharge are significantly different between Roaring Springs, Emmett Spring, Tapeats Spring, and Abyss River Spring. Linear regression analyses indicate no annual trends in any of the evaluated aquifer characteristics for any spring, except for more stable baseflow between recessions at Tapeats Spring. Water budgets calculated for Roaring Springs are imbalanced, suggesting missing outflow components, a need to refine the recharge region through dye trace studies, and inaccurate precipitation and evapotranspiration data, requiring model improvement. Continued hydrograph comparisons, trend analyses, and water budgets for additional years and springs will be useful for future groundwater modeling and for forecasting impacts on the R aquifer.

Depth‐based correlation analysis between the density of lineaments in the crystalline basement's weathered zones and groundwater occurrences within the Voltaian basin, Ghana

AbstractGeological structures have been shown by studies to have influence on the occurrence, storage and transportation of groundwater. Understanding the structural network of an area unearths a deep insight into the groundwater dynamics of the area. A geological structural analysis was carried out to reveal the geological structural network of Ghana's Voltaian basin. Using aeromagnetic data, structural density models were generated using the Center for Exploration Targeting grid analysis technique for two depth ranges (that is up to 100 m and 300 m) over the Voltaian basin. The total length of geological structures (lineaments) delineated at depths up to 100 m and 300 m were more than 5000 km and more than 8000 km, respectively. Given this, the study area was observed to be structurally dense at each of the aforementioned depths. The structural density models were discretized into five classes (very low, low, moderate, moderately high and very high regions), each of which was evaluated to determine their spatial association with known locations of groundwater occurrences within the study area using the frequency ratio technique. Frequency ratio results for both structural density models derived at 100 m and 300 m depths show the existence of a strong correlation between high structural density model classes and the known groundwater occurrences. The structural density models were further evaluated using the receiver operating characteristics curve. The area under the receiver operating characteristics curve scores indicates that, although both structural density models showed very good performance (with receiver operating characteristics scores greater than 0.7), the 300‐m depth structural density model performed better than the structural density model generated at a depth of 100 m (with their receiver operating characteristics scores being 0.721 and 0.715, respectively). The obtained results corroborate with literature assertion that groundwater occurrence within the Voltaian basin is mainly associated with structural features. It is expected that the outputs of this study would guide future groundwater exploration programmes within the study area.

Simulation of groundwater flow and seawater intrusion in response to climate change and human activities on the coastal aquifer of Gaza Strip, Palestine

This study has investigated the potential impact of human activities and climate change on the groundwater budget, water levels, and seawater intrusion in the coastal aquifer of the Gaza Strip (State of Palestine) over the next two decades. The impact of a proposed measure to use alternative freshwater provision from desalinated seawater on the future groundwater quantity and quality was also analyzed. Following extensive analysis of available observed data, a three-dimensional groundwater flow model, coupled with variable-density saltwater flow and transport components, was utilized for the investigations. Compared with the benchmark scenario (SC0), the climate change scenario (SC1) suggests that over the next two decades, an average annual aquifer recharge of 6.3 Mm3 can be expected, while the human activities scenario (SC2) indicates that the groundwater levels will decline at a rate of 0.09 m/year with expected urban area expansion. The combined human activities and climate change scenario (SC3) indicate severe groundwater storage depletion and seawater intrusion over the next two decades. The alternative freshwater provision scenario (SC4) indicates a strongly positive response in groundwater recovery (quantity and quality) over the next decades. The findings of this study emphasize strongly that the human activity impact, rather than climate change, is the driving force of groundwater depletion and that groundwater recovery interventions will be crucial in the future and should be implemented urgently.

A Hydrogeological Conceptual Model Refines the Behavior of a Mediterranean Coastal Aquifer System: A Key to Sustainable Groundwater Management (Grombalia, NE Tunisia)

The Mediterranean coastal aquifer system of the Grombalia basin (NE Tunisia) offers immense potential as a source of fresh water for agriculture, industry, and drinking water supply. Nonetheless, due to its intricate hydrogeological characteristics and the prevailing issue of groundwater salinity, comprehending its groundwater system behavior becomes crucial for the effective and sustainable management of this aquifer system. Based on the hydrogeological characterization of the Grombalia basin, a novel 3D hydrogeological conceptual model was developed to enhance the understanding of its complex aquifer system. The integration of insights from geological, hydrogeological, hydrodynamic, and hydrochemical components facilitated the construction of the hydrogeological conceptual model. Although the model’s validity faced initial uncertainties due to spatial interpolation of lithological sequences, this study’s thorough and encompassing hydrogeological investigation overcame these limitations. As a result, a more informed comprehension of the aquifer system complexities was achieved. This study reveals that the basin is underlain by an extensive, cohesive Mio–Plio–Quaternary aquifer system. The model demonstrates vertical and lateral hydrogeological continuity between the Quaternary and underlying Mio–Pliocene deposits, enabling groundwater flow and exchange between these layers. Over-abstraction of the Mio–Plio–Quaternary aquifer system has led to a significant drop in piezometric levels and raised the risk of seawater intrusion. These findings emphasize the critical necessity of taking into account the interconnections among hydrogeological units to ensure sustainable groundwater management. The developed conceptual model offers a key tool for understanding the hydrodynamic functioning of the Grombalia aquifer system with a view toward guiding future groundwater management strategies. The application of this approach in the Grombalia basin suggests its potential applicability to other regional aquifers facing comparable challenges.

Bridging the data gap: using remote sensing and open-access data for assessing sustainable groundwater use in Kumasi, Ghana

Abstract Groundwater use has significantly increased in the rapidly urbanising city of Kumasi, Ghana. But there is a lack of understanding of whether the groundwater system can sustain the growing demand in the future amidst climate change and rapid urbanisation. Using remote sensing datasets and a water balance approach, this study estimated the groundwater recharge and assessed how urbanisation has affected its groundwater sustainability. Sustainability is investigated by comparing multi-annual groundwater withdrawals to long-term average annual replenishment. Results show that while groundwater recharge has decreased by 80% from 1986 to 2020, mainly due to substantial (63%) loss of permeable land, groundwater consumption has seen a six-fold increase. Groundwater consumption in 2020 exceeded the long-term average groundwater recharge by 2.2Mm3, suggesting that the current groundwater use trends are unsustainable for future groundwater availability. Under a ‘business-as-usual’ scenario, a four-fold increase in groundwater consumption is predicted by 2050 while climate change and land-cover changes may reduce groundwater recharge by 10% and 55% respectively. Practical measures such as promoting artificial groundwater replenishment approaches, adopting low-impact development and instituting demand management measures must be implemented in the Metropolis. This should be informed by further studies to ascertain the exact condition of the groundwater.

Rapid Urbanization Has Changed the Driving Factors of Groundwater Chemical Evolution in the Large Groundwater Depression Funnel Area of Northern China

With the rapid development of urbanization, the chemical evolution of groundwater has been significantly affected by human activities. However, the driving mechanisms of groundwater chemical evolution at different stages of urbanization are still unclear, which severely affects the implementation of groundwater protection. This study investigated the driving mechanisms of groundwater chemical evolution based on the long-term series (from 1985 to 2015) of hydrochemical data from 19 groundwater monitoring sites in rapidly urbanizing areas (Shijiazhuang, Hebei Province, China). The results show that the concentrations of various chemical components in groundwater gradually increase with the acceleration of the urbanization process, especially NO3−, which has increased from 13.7 mg/L in the primary stage of urbanization (PSU) to 65.1 mg/Lin the advanced stage of urbanization (ASU), exceeding the World Health Organization (WHO) drinking water standard (50 mg/L), indicating that the groundwater chemistry has been significantly affected by human activities. The main hydrochemical types have changed from the HCO3•SO4-Ca•Mg-type water in the primary stage of urbanization (PSU) to the SO4•HCO3-Ca•Mg-type water in the advanced stage of urbanization (ASU). It is worth noting that there are obvious differences in driving factors of groundwater chemical evolution at different urbanization stages. In the primary stage of urbanization (PSU), the driving factors were carbonate and rock salt dissolution, cation exchange, and industrial activities. However, in the intermediate stage and advanced stage, the driving factors were changed to carbonate and gypsum dissolution, groundwater over-exploitation, agricultural fertilization, and domestic sewage. Based on the above conclusions, it is suggested that future groundwater management should control the amount of agricultural fertilizers, apply scientific fertilization, and prohibit the discharge of various types of non-compliant sewage, while strengthening the supervision of groundwater extraction to reduce the impact of urbanization development on the groundwater chemical evolution process.

Geospatial Assessment of Managed Aquifer Recharge Potential Sites in Punjab, Pakistan

Groundwater is a precious natural resource that is vital to various aspects of life. Punjab is experiencing groundwater stress due to urbanization and population growth, leading to overuse and reduced aquifer recharge. Sustainable groundwater supplies can only be created through better management and artificial recharge techniques. This study uses multi-influencing factor, literature-based, and combined techniques to identify and characterize groundwater-managed aquifer recharge potential sites (GWMARPSs) in Punjab. There are limitations to the previous work in this field, and these factors have not been used to estimate GWRPSs in the study area. The study uses GIS and RS techniques to overlay twelve geo-informative layers, with rainfall being the most significant factor. High-quality data and observations from the field are incorporated into the model. The study classifies the GWMARPSs into five categories, with Punjab having 0.34%, 13.29%, 60.68%, 25.26%, and 0.43% of the least, poorly, moderately, well-, and highly suitable sites. Punjab’s southern regions are least suitable for recharge, while some areas in eastern and northern Punjab are well-suited for recharge. Alluvial plains, valleys, low-lying areas, and areas with volcanic landforms are classified as least to poorly suitable zones. Model predictions are validated using piezometric level data and ROC and exhibit good performance (AUC, 0.74). This study could serve as a baseline for future groundwater research.

Nitrate Legacy in a Tropical and Complex Fractured Volcanic Aquifer System

AbstractNitrate legacy is affecting groundwater sources across the tropics. This study describes isotopic and ionic spatial trends across a tropical, fractured, volcanic multi‐aquifer system in central Costa Rica in relation to land use change over four decades. Springs and wells (from 800 to 2,400 m asl) were sampled for NO3− and Cl− concentrations, δ18Owater, δ15NNO3, and δ18ONO3. A Bayesian isotope mixing model was used to estimate potential source contributions to the nitrate legacy in groundwater. Land use change was evaluated using satellite imagery from 1979 to 2019. The lower nitrate concentrations (<1 mg/L NO3−N) were reported in headwater springs near protected forested areas, while greater concentrations (up to ∼63 mg/L) were reported in wells (mid‐ and low‐elevation sites in the unconfined unit) and low‐elevation springs. High‐elevation springs were characterized by low Cl− and moderate NO3−/Cl− ratios, indicating the potential influence of soil nitrogen (SN) inputs. Wells and low‐elevation springs exhibited greater NO3−/Cl− ratios and Cl− concentrations above 100 μmol/L. Bayesian calculations suggest a mixture of sewage (domestic septic tanks), SN (forested recharge areas), and chemical fertilizers (coffee plantations), as a direct result of abrupt land use change in the last 40 years. Our results confirm the incipient trend in increasing groundwater nitrogen and highlight the urgent need for a multi‐municipal plan to transition from domestic septic tanks to regional sewage treatment and sustainable agricultural practices to prevent future groundwater quality degradation effectively.

Measuring Nitrate Leaching in the Vadose Zone of Loess Soils—Comparison of Batch Extraction and Centrifugation

The nitrate concentration in the subsoil moisture of the vadose zone is an important indicator for future groundwater quality, which is classically determined via centrifugation. Batch extraction is an inexpensive and easy alternative method, but whether these methods measure the same soil water, nitrogen species, and nitrate concentrations is unclear, in particular for loess soils. Two experiments were carried out to assess the differences in nitrate and other anion concentrations between centrifugated soil moisture (centrifugated at different speeds and times) and batch extractions (using double-distilled water and 0.01 M CaCl2). Batch extraction resulted in lower nitrate (−20%) and chloride (−15%) concentrations than centrifugation, mainly due to anion exclusion, where soil microporosity controls the contribution of diffusion, denitrification, and leaching processes. Vice versa, batch extraction overestimated the concentration of nutrients that occur as precipitates in or sorb the soil matrix, such as sulphate (+50%) and ammonium (+96%). Batch extractions can only be used as a proxy to determine actual nitrate concentrations of soil water. However, they are useful to monitor changes in nitrate leaching over time in response to (policy) measures taken. They can also be used as “early warning indicator” and to improve the reliability of spatial explicit monitoring networks.

A Python Application for Visualizing an Imbricate Thrust System: Palomeque Duplex (SE, Spain)

This paper introduces a Python application for visualizing an imbricate thrust system. The application uses the traditional geologic information to create an HTML geological map with real topography and a set of geological cross-sections with the essential structural and stratigraphic elements. On the basis of the high geological knowledge gained during the last three decades, the Palomeque sheets affecting the Cenozoic Malaguide succession in the Internal Betic Zone (SE Spain) were selected to show the application. In this area, a Malaguide Cretaceous to Lower Miocene succession is deformed as an imbricate thrust system, with two thrusts forming a duplex, affected later by a set of faults with a main strike-slip kinematic. The modeled elements match well with the design of the stratigraphic intervals and the structures reported in recent scientific publications. This proves the good performance of this Python application for visualizing the structural and stratigraphic architecture. This kind of application could be a crucial stage for future groundwater, mining, and civil engineering management.

Soft computing assessment of current and future groundwater resources under CMIP6 scenarios in northwestern Iran

Excessive use of water resources in combination with climate change threaten to significantly reduce groundwater in arid and semiarid regions. We studied the effects of climate change on the groundwater level for the important Dehgolan Aquifer in northwestern Iran. The water level in this aquifer has dropped by about 35 m during the last 30 years. Soft computing techniques were used together with climate projections in three methodological steps to estimate the groundwater level drop by 2045. Firstly, MODFLOW was used to simulate groundwater flow and movement. Secondly, simulation results, support vector regression (SVR), and least-squares SVR (LSSVR) machine learning models were used to predict groundwater levels for the future 20-year period (2026–2045). The whale optimization algorithm (WOA) was used to improve the prediction results by optimizing the SVR parameters. Thirdly, three climate models of CMIP6 (ACCESS-CM2, BCC-CSM2-MR, and CMCC-ESM2) were used to predict the changes in precipitation for the future period (2026–2045) using SSP 2.6 and SSP 8.5 scenarios. The results showed that the MODFLOW-LSSVR model predicted the groundwater level more accurately than MODFLOW-SVR and MODFLOW-SVR-WOA. The calculation scenario containing previous month groundwater level, monthly aquifer withdrawal, and monthly precipitation had the highest performance in predicting groundwater level with root mean square error (RMSE), mean absolute percentage error (MAPE), and Nash Sutcliffe efficiency (NSE) equal to 0.305 m, 0.014 m, and 0.998, respectively. The results indicate that precipitation may decrease in the future period for the SSP 8.5 scenario (about 6% compared to the reference period 1987–2005). This decrease, along with the continuation of the current aquifer withdrawal, will cause a drop of about 36 m (during 28 years) of the groundwater level (1.3 m per year). The results reveal that the drop could be reduced to 12 m by adopting a 25% reduction in the current aquifer withdrawal. The findings show the necessity of providing a suitable management approach to prevent future aquifer exhaustion due to the continuation of the current withdrawal situation in the region.

Resilience, stress and sustainability of alluvial aquifers in the Murray-Darling Basin, Australia: Opportunities for groundwater management

Study regionMain alluvial aquifers of the Murray-Darling Basin (MDB), Australia Study focusAround 75% of total metered groundwater use within Australia’s Murray-Darling Basin (MDB), arguably the nation’s most important food and fibre production region, is extracted from eight main alluvial aquifer systems. To date, regional-scale analyses of groundwater resilience, stress and sustainability for the region have not been completed. This study provides a systemic overview of the main alluvial systems anchored in these concepts. To achieve this, we combined three lines of evidence encompassing: a) long-term trend analysis of groundwater levels; (b) calculation of groundwater footprint indices considering volume and quality; and (c) an explicit comparison of groundwater management areas in terms of groundwater usage, sustainable use, storage volumes, presence and diversity of groundwater-dependent ecosystems (GDEs), and buffering capacity to absorb changes in recharge rates. New hydrological insights for the regionThe novelty of our work rests upon an integrated assessment of these three lines of evidence incorporating twelve different metrics to prioritise future groundwater management efforts. Results indicate that eleven out of twenty-two groundwater management areas show resilience, stress and/or sustainability issues, and a further two with emergent issues. Efforts to improve our understanding and management of these key groundwater resources would be most effective if focussed on these areas.

Groundwater recharge estimation under changing climate and land use scenarios in a data-scarce Bahi (Manyoni) catchment in Internal Drainage Basin (IDB), Tanzania using Soil and Water Assessment Tool (SWAT)

Spatio-temporal studies of groundwater recharge establish a groundwork for comprehending the effects of climate and land use change on groundwater resources, particularly in areas where groundwater is a primary source of water such as the Internal Drainage Basin (IDB), Tanzania. Therefore, quantification of groundwater recharge for years the 2050s and 2080s was executed using the SWAT in Bahi (Manyoni) Catchment (BMC) in IDB. Shared Socioeconomic Pathways (SSPs) climate scenarios particularly SSP245 as medium emission and SSP585 as high emission scenario were used. Monthly calibration and validation of the SWAT model were performed by using streamflow data from a gauged sub-catchment within BMC. Obtained Nash-Sutcliffe Efficiency (NSE) for the calibration period from 1971 to 1982 was 0.79 and for the validation period from 1983 to 1990 was 0.69. Later, performed another validation using actual evapotranspiration in an ungauged BMC achieved NSE of 0.59. The findings from calibrated model depicted, under the impact of climate change alone, it was estimated that there will be a slight increase in overall annual average groundwater recharge of 3.05 mm/y under SSP245 and to 5.12 mm/y under SSP585 in year 2050s whereas under collective impact of climate and LULC change an increase of 2.31 mm/y under SSP245 and of 3.98 mm/y under SSP585 in year 2080s from a baseline of 4.5 mm/y in 1980s. This indicates the impact of LULC alone to be trivial. In the steep slope areas, the catchment with 15% reduced rainfall will experience lower recharge of up to 24% whereas gentle slope areas with a 25% increase in rainfall will experience a recharge of up to 123% compared to the baseline period. Established groundwater recharge zones give imperative information to IDB managers in relation to water management plans to optimize future groundwater recharge.