Hydrogeological Model Research Articles

Numerical Assessments of Flow and Advective Transport Uncertainty for Performance Measures of Radioactive Waste Geological Disposal in Fractured Rocks

Groundwater flow and transport are crucial for performance and safety assessment in the radioactive waste geological disposal. This study presents the groundwater flow and advective transport simulations for assessing the performance of a reference repository placed in fractured rocks. The study involves the concept of radionuclides migrating into the mobile water in fractures surrounding the deposition hole and calculates two specific quantitative indicators in the field of radioactive waste geological disposal. The indicators equivalent flow rate (Qeq) and flow-related transport resistance (F) are used to express the groundwater flow and transport resistance in the host rock. Based on the hydrogeological conceptual model, the study employs DarcyTools to model the groundwater flow and advective transport of a base case. This study then conducts sensitivity analyses by varying the hydraulic conductivity of the key hydrogeological unit and the excavation damage zone. The uncertainty analysis employs multiple discrete fracture network (DFN) realizations to quantify the influences of DFNs on the flow and advective transport. Results show that the hydraulic conductivity of host rock dominates the flow and advective transport in the model domain, and the highest Qeq is 1.91 × 10−4 m3/year, and the lowest F is 7.77 × 105 year/m. Results also indicate that simulations of the hydraulic conductivity variations of hydrogeological units are more critical than those obtained from the variations of DFN realizations (i.e., the uncertainty analysis). The solutions could be useful for site investigations to modify the hydrogeological conceptual model in the study.

Using an Improved SWAT Model to Simulate Karst Sinkholes: A Case Study in Southwest China

Hydrological simulation of the karst area is significant for assessing water resources accurately and exploring the relationship in the hydrologic cycle. However, the existence of sinkholes causes the spatial heterogeneity of aquifers and changes the distribution of surface water as well as groundwater, which makes the traditional hydrogeological model difficult to quantitatively characterize the hydrological processes of the sinkhole. Hence, improving the hydrological model for the karst area is a necessary direction at present. The soil and water assessment tool (SWAT) is one of the most widely used semi-distributed hydrological models right now in the world. In this study, we focused on the upper course of the South Panjiang River and used the pond module of the SWAT model to simulate karst sinkholes, modifying the source code to realize the rapid response to the recharge in karst sinkholes. After the improvement, the surface runoff, especially the peak value of the Xiqiao Hydrological Station at the outlet, has been reduced, while the baseflow of modified subbasins has been increased and the water yield is under a state of water balance. In addition, the model evaluation factor R2 was strengthened from 0.76 to 0.83 and NSE was strengthened from 0.66 to 0.79 of the Xiqiao Hydrological Station during the validation period. The improved model was used to analyze the spatial distribution of hydrological components. Also, it was found there are spatial relations between runoff modulus–slope and baseflow–surface runoff–land use types. The analysis demonstrated that the improved SWAT model could effectively change the hydrological components and simulate the rapid replenishment of karst sinkholes.

Causes of a premature thermal breakthrough of a hydrothermal project in Germany

Sustainable heat extraction is of utmost importance for the economic life of geothermal production systems. Especially in hydrothermal sedimentary basins, a temperature decrease at the production well prompts a financial loss. A premature thermal breakthrough occurred in one of the geothermal projects in the Greater Munich Area, a well-known region for deep, low enthalpy geothermal development in the Upper Jurassic carbonate reservoir (syn. Malm) beneath the North Alpine Foreland Basin. Accordingly, questions are raised regarding the geologic controls on the reservoir´s permeability, the occurring type of heat and mass transport mechanism, and the fitting reservoir model type. 3D seismic data interpretation delineates seismic scale structures potentially influencing the reservoir permeability. Geophysical borehole data characterize sub-seismic scale elements (fractures, karst, and lithofacies), where we correlate them with the inflow zones and the interpreted seismic scale structures. The integration of both scales delineates the reservoir heterogeneity controlled by a lateral change in the carbonate lithofacies overprinted by faults and fractures. A NNW-SSE oriented seismic scale structure matches the orientation of hydraulically active sub-seismic scale fractures, where they are aligned with the maximum horizontal stress orientation. This structure induces additional anisotropic permeability, providing a preferential hydraulic pathway between the wells of the project. This study recommends considering fractured reservoir models to simulate the mass and heat flow in the highly heterogeneous Malm carbonates instead of composite reservoir models of equivalent hydraulic properties. Finally, we present a hydrogeological model describing the reservoir's structural and matrix permeability distribution to act as a basic concept for future thermal-hydraulic numerical modeling. The applied methods in this study are applicable in similar geothermal systems with adequate seismic and geophysical borehole data for future geothermal reservoir characterization, modeling, and management.

Projected climate change impacts on groundwater recharge in the Urucuia aquifer system, Brazil

AbstractIn this work we analyse the effects of climate change on the recharge and the groundwater flow of the Urucuia Aquifer System in western Bahia State, Brazil (UAS‐BA) in the period 2041–2060. We assessed possible changes and impacts on groundwater recharge with four climate models from the sixth phase of the Coupled Model Intercomparison Project Phase 6 (CMIP6): ACCESS‐ESM1‐5, CanESM5, EC‐Earth3 and MIROC6, under scenarios SSP1‐2.6 and SSP5‐8.5 (Shared Socioeconomic Pathways—SSP). Visual Balan 2.0 aquifer recharge assessment code, and the MODFLOW hydrogeological model were used to analyse the impact of future climate changes on the recharge. The projections of relative change in precipitation, under the SSP1‐2.6 scenario, show a precipitation reduction between 5% and 20%, using ACCESS‐ESM1‐5, CanESM5 and EC‐Earth3 models. Using SSP5‐8.5 scenario, these models behave differently, while the CanESM5 and EC‐Earth3 models indicate an even greater decrease in precipitation, with values up to 35%, the ACCESS‐ESM1‐5 projects an increase in precipitation of up to 25%. Using MIROC6, though, an increase of up to 10% in precipitation in the UAS‐BA is expected, under both scenarios. Regarding temperature, all the models agree with a warming in the future varying from 2 to 3°C. Recharge projections calculated using the Visual Balan 2.0 indicated in general a reduction between 8% and 43%. Using the MODFLOW model, the results show a reduction of recharge to the aquifer varying from 3% to 45% using CanESM5, EC‐Earth3 and MIROC6. The ACCESS‐ESM1‐5 has a 26% reduction (5% increase) under SSP1‐2.6 (SSP5‐8.5). Furthermore, projections indicate a downward trend in the water table in the northern portion of UAS‐BA, reaching a maximum drop of up to 12 m with the CanESM5, under SSP5‐8.5 scenario.

Hydrogeological Survey, Radiometric Analysis and Field Parametric Measurements: A Combined Tool for the Study of Porous Aquifers

The use of isotopic geochemistry for hydrogeological studies is growing internationally. The use of isotopic geochemistry methodologies on hydrogeological survey data, integrated with the use natural tracers, is helpful when defining the hydrogeological model of the aquifer. In particular, the use of radioisotope concentration measurements as natural tracers and the detection of the temperature, redox potential and dissolved oxygen in groundwater in the field provide information on underground water circulation, which is useful for identifying recharge areas and groundwater drainage. Variations in these parameters in the aquifer allow for information about its hydrodynamics to be obtained. The application of this method in a sample area showed how the uranium and radon concentrations, temperature, redox potential and dissolved oxygen vary in the different sectors of the aquifer, depending on water mobility. This information, integrated with the results of a hydrogeological survey of the static levels, distinguished the recharge and drainage areas of the aquifer and the preferential directions in terms of water flow and allowed for information on the mobility of the aquifer in the various sectors to be obtained. The method presented in this paper was tested in a larger hydrogeological study in the southern sector of the shallow aquifer of the S. Eufemia Lamezia plain (Calabria, Italy).

Conceptual principles of watering control under irrigation

The conceptual principles of watering control under irrigation using decision support systems are outlined. Based on the analysis and research of foreign and domestic authors, it has been proven that the effectiveness of watering control depends to a large extent on the methodological approaches used to determine the terms and rates of watering in various decision support systems. It is shown that the most complete potential of varieties and hybrids of various types of crops under irrigation can be realized when establishing and implementing irrigation regimes ensuring the moisture supply of the soil root layer in a narrow range of high humidity (close to field water-holding capacity (FWHC) during the entire growing season.
 It was grounded that the implementation of such irrigation regimes is possible only by applying decision support systems using GIS technologies, which combine hydrogeological models for calculation and forecasting of watering terms and rates, based on the use of soil moisture potential as a criterion of moisture supply availability for plants and Earth remote sensing data (ERSD). Such a combination makes it possible to analyze and apply measurement and forecasting data to the areas not covered by ground observations and provides highly efficient ecologically safe irrigation providing high irrigation water productivity and ecological safety of irrigation.
 The implementation of these principles in the practice of irrigation management ensures the yield of irrigated crops as of 0.85-0.90 of the potential of modern varieties and hybrids, while simultaneously reducing the consumption of irrigation water per unit of yield, as well as minimizing or eliminating losses of irrigation water due to infiltration, development of flooding processes, salinization, and secondary salinization of soils.

Further exploration of the Verkhnechonskoye field of technical groundwater: new research methods and results

The purpose of the research is to refine a geological model of the Verkhnechonsk field of technical groundwater (Eastern Siberia, Russia), reassess groundwater reserves by the industrial category and form a geofiltration model. The article deals with the main approaches used in conducting of field and desk researches. It also introduces the organization experience of large-scale pilot filtration work under time- and personnel-limited conditions at a large operating field. The work is based on the results of long-term regime observations, field experimental and filtration works carried out in 2019- 2020. It uses the information of a geological database on the water and oil intake facility of wells, including a complex of borehole studies, as well as the data on the geological and hydrogeological structure of the field according to archival and published sources. Visual ModFlow Flex software was used to create a geofiltration model. Having conducted and interpreted the works, the justification of a natural hydrogeological model different from the one adopted earlier was performed. Thus, the relationship of two water-bearing complexes – the Verkholensky-Ilginsky complex of the Upper-Middle Cambrian age and the Litvintsevsky complex of the Lower-Middle Cambrian age was proved. The works in the Visual ModFlow Flex resulted in the creation of a geofiltration model, which correlates well with the actual data, allows to identify impenetrable barriers, as well as predicts the geomigration of hydrogen sulfide. It is the first time that the underground water reserves of the field were included in the State balance sheet in full-scale according to the industrial category B. The reassessment was performed for three sites of the field, well loads were adjusted for optimal operation of water intakes. The obtained results of the conducted research imply that the use of geofiltration model is reasonable in the fields of complex geological structure and this model can be used on a permanent basis for monitoring and adjusting of the development mode. The organization experience of works at a large operating oil field can also be useful under the reserve reassessment at analogous fields.

Improved geophysical monitoring of carbon sequestration through parameter linkage to reservoir modeling

Predictive reservoir modeling, even if present in the form of only basic hydrogeological model assumptions, is expected to accompany the majority of carbon capture and sequestration monitoring activities. It thus represents a source of prior information about the migration of injected fluids that can benefit geophysical survey planning and ensuing monitoring. Constraining the imaging of geophysical monitoring data with reservoir modeling is preferable over standalone geophysical imaging because of additional complementary hydrogeological information. However, fully coupled hydrogeophysical data inversion for flow-modeling parameters that control saturation predictions is an involved process. Within the context of three-dimensional electromagnetic (EM) inversion of data from borehole-to-surface layouts, we employ a "poor people's" alternative. The approach constrains geophysical inversion parameters through saturation predictions. The coupling is realized through spatially variable lower and upper parameter bounds that scale with gas saturation magnitudes, the latter provided by reservoir modeling. Enhancement of three-dimensional time-lapse plume EM imaging is demonstrated for simulated sequestration into a depleted gas reservoir.

Characterization of Shallow Groundwater Circulation Based on Chemical Kinetics: A Case Study of Xiong’an New Area, China

Xiong’an New Area, located in the middle of the North China Plain, will have been built as a “city of the future.” Urban planning and construction need to comprehensively consider the constraints of hydrogeological conditions such as aquifer structure and parameters. As the main aquifer in this area, the paleo-channel is heterogeneous and anisotropic, and the two-dimensional hydraulic conductivity in each horizontal direction cannot be obtained from aquifer tests. Therefore, this study adopts a chemical kinetics method to calculate the ionic activity and mineral saturation indices of shallow groundwater, determine the groundwater chemical potential field, and construct a horizontal two-dimensional groundwater chemical kinetics model. This model is used to calculate the hydraulic conductivity, flow rate and retention time of groundwater in areas of different chemical kinetics, as well as evaluate horizontal heterogeneity of the Quaternary paleo-channel aquifer. The results indicate that the groundwater chemical potential field can reflect the characteristics of the groundwater seepage field in each horizontal direction. The paleo-channel is the main channel of groundwater circulation, which shows the statistical difference of its permeability. Alluvial and lacustrine strata affect groundwater circulation due to their different hydrogeological structures and permeability. The groundwater chemical kinetics results of hydraulic conductivity along the paleo-channel are approximately consistent with traditional hydrogeological calculation results derived from aquifer test data. Hydraulic conductivity is higher in the extension direction of the paleo-channel, and lower if the path crosscuts multiple paleo-channels. This feature can be used to build a hydrogeological structure model combined with drilling data. Furthermore, excessive groundwater exploitation will change the actual flow rate and retention time of groundwater, thereby affecting the groundwater circulation conditions. This study of groundwater circulation in Xiong’an New Area by means of chemical kinetics makes up for the deficiency in the study of the unconsolidated sedimentary aquifer anisotropy within the paleo-channel.

Numerical modeling of NE Brazil coastal aquifer: Fault controlled conduits for seawater intrusion

Saline intrusion is a problem that mostly affects coastal aquifers around the world, either owing to anthropic and/or natural factors. The Barreiras Aquifer, which is located on Brazil's northeastern coast and of an unconfined hydraulic nature, is subject to this due to a water demand increase. This aquifer is located in an area structurally controlled by neotectonic activity. Increased complexity occurs in the form of variations in saturated thickness, hydraulic conductivity and exploited flow rates. This study aimed to construct a numerical model of dependent density flow for the Barreiras Aquifer using the SEAWAT software (USGS) and simulate saline intrusion over 20 years of pumping wells that currently exploit approximately 750 m³/h. The results can contribute to local hydrogeological management and assist managers. Simulation results with variation of recharge between dry and rainy periods and reduction of well exploitation flow rates were also obtained. The two main local faults, Boa Cica and Tabatinga, striking NW-SE and NE-SW, respectively, were simulated in a calibrated transient hydrogeological model as zones of high hydraulic conductivity (conduits) as well as in the inverse form (barriers) and offered a better fit considering the faults as zones of relatively higher hydraulic conductivities and preferred pathways for saltwater intrusion progression. A two-dimensional resistivity cross-section was used to constrain the electrical property of the NW striking fault, whether in the form of a resistive anomaly or conductive anomaly. The interpretation of the 2D geoelectric model is consistent with the conductive geoelectric anomaly associated to the Boa Cica Fault, where its transtensional nature favors wider saline contamination.

Data and insights to advance characterization of groundwater resources in the Plaine des Gonaïves, Haiti

The Plaine des Gonaïves houses a regionally significant yet data-scarce coastal aquifer in one of the driest regions of Haiti. It is the primary source of water for the region, including Haiti’s third largest city, Gonaïves. Pressure on groundwater resources will be compounded as municipal water services modernize and energy infrastructure enables the resurgence of commercial agriculture. In anticipation of increased stress and greater impacts, this study was undertaken (including data discovery, reconnaissance, and analysis) to gain insights and to advance understanding of the groundwater resources. The alluvial aquifer covers >115 km2, exceeds 100 m thickness, and supports pumping yields as high as 532 m3/h. The heterogeneous multilayer aquifer exhibits hydraulic conductivities that range by an order of magnitude, influencing groundwater flow, residence times, and chemistry. Significant recharge occurs in the central and upgradient portions of the plain; river infiltration appears to be a more significant recharge source than direct infiltration. In the downgradient portion of the plain, confined aquifer pressure increases and discharge areas include the Quinte River, springs, wetlands, ditches and canals. Underlying the alluvium, discontinuous groundwater in bedrock with structural influence may mix with the alluvial aquifer, affecting isotopic composition and water chemistry. Increased abstraction, climate change, and intensification of agriculture and urban development could have consequential impacts on water quantity, water quality and ecosystems. The results, insights, and supporting datasets are a baseline to guide planning and to advance a hydrogeological conceptual model that supports sustainable and informed groundwater management.

Dynamic Steady State in Coastal Aquifers Is Driven by Multi‐Scale Cyclical Processes, Controlled by Aquifer Storativity

AbstractCoastal aquifers supply freshwater to nearly half the global population, yet they are threatened by salinization. Salinities are typically estimated assuming steady‐state, neglecting the effect of cyclical forcings on average salinity distributions. Here, numerical modeling is used to test this assumption. Multi‐scale fluctuations in sea level (SL) are simulated, from tides to glacial cycles. Results show that high‐frequency fluctuations alter average salinities compared with the steady‐state distribution produced by average SL. Low‐frequency forcing generates discrepancies between present‐day salinities estimated with and without considering the cyclical forcing due to overshoot effects. This implies that salinities in coastal aquifers may be erroneously estimated when assuming steady‐state conditions, since present distributions are likely part of a dynamic steady state that includes forcing on multiple timescales. Further, typically neglected aquifer storage characteristics can strongly control average salinity distributions. This has important implications for managing vulnerable coastal groundwater resources and for calibration of hydrogeological models.

Three-Dimensional Hierarchical Hydrogeological Static Modeling for Groundwater Resource Assessment: A Case Study in the Eastern Henan Plain, China

Groundwater is closely related to hydrogeological structure and hydro-lithology, which mainly refers to the spatial distributions and properties of the environment where groundwater occurs. To analyze the constraints of hydrogeological structure and hydro-lithology on regional groundwater resources in the Eastern Henan Plain, China, we reconstructed the three-dimensional (3D) hierarchical models at two scales, hydrogeological structural models and hydro-lithological models, using hydrogeological cross-sections. First, the hydrogeological structural models of four aquifer groups, corresponding to four formations of the Quaternary in the study area, were reconstructed. Second, the hierarchical hydro-lithological model was built using SIS and IK estimation under the constraint of each aquifer group model space, respectively. Compared to global model, the variograms of hierarchical model captured more spatial characteristics of lithology in each aquifer group. The IK hierarchical model presents more continuities, clear boundaries, and realistic geometric shapes of the three lithologies, excluding the banding characteristics of the IK global model. The hierarchical SIS models reproduced the lithology distribution of each aquifer group and captured small changes in the lithology, with the smallest absolute percentage errors (APEs). Third, coupling the SIS hierarchical models and the groundwater levels, the groundwater resource in the study area was estimated to have a total volume of 1.2339 × 104 m3. The shallow groundwater in the study area is mainly concentrated in Hebi City and the Puyang basin of the Yellow River, and deep groundwater is mainly concentrated in the northern Anyang City and Hebi City. Finally, the possible quantities of shallow and deep groundwater recharges were estimated for future groundwater management decision in the study area. The hierarchical hydrogeological model, groundwater resource assessment, and possible groundwater recharge estimation can also provide a basis for groundwater vulnerability, groundwater extraction, and land subsidence assessment.

Pragmatic Validation of Numerical Models Used for the Assessment of Radioactive Waste Repositories: A Perspective

The safety case for a radioactive waste repository relies heavily on results obtained by numerical models that assess the long-term performance of the engineered and natural barrier systems. Given that important engineering and public policy decisions are based on these models, it is essential that we critically evaluate their abilities and limitations, and thus justify the level of confidence we have in the inferences drawn from the modeling. In this article, we discuss some of the issues surrounding the modeler’s attempts to test, corroborate, confirm, and verify numerical models—a process sometimes referred to as model validation. This wide-ranging topic is approached by first examining its deep roots in the philosophy of science and hypothesis testing. However, the application of these principles to radioactive waste isolation calls for a more pragmatic approach, which has the narrower goal of corroborating site-specific models and their usefulness for a specific purpose. We focus on the practical aspects of validating hydrogeological models that are used to understand the evolution of the repository system. We will make the case that the responsible use of numerical models requires a sufficient understanding of the quality and robustness of the simulation results, with direct implications for how these results need to be interpreted, and how they can (or cannot) be used in support of important policy decisions.

Middle Jurassic–Lower Cretaceous stratigraphy of the northern Great Australian Superbasin: insights from maximum depositional age constraints from the U–Pb detrital zircon record

The Great Australian Superbasin, incorporating the Great Artesian Basin, is host to one of the largest artesian groundwater systems on Earth. However, despite the crucial nature of this resource to Australian agriculture, industry and rural communities, key aquifer units remain poorly studied, apart from the exposed eastern/southeastern portions of the superbasin. In this study, maximum depositional age (MDA) estimations for stratigraphic units, derived from detrital zircon U–Pb geochronology, were undertaken across the Carpentaria and northern Eromanga basins, representing the northern Queensland sector of the Great Australian Superbasin. The objective was to better constrain the ages of key aquifer and aquitard units, thereby facilitating improved stratigraphic correlations and future hydrogeological modelling. Age dating of detrital zircon significantly enhances the confidence, accuracy and precision of age assignments based solely on palynology, especially in continental facies. Furthermore, the provision of MDA estimates permits confident correlation of endemic Australian spore-pollen zonations (used to date continental strata), and dinocyst zonations (used to date marine strata) to the international time-scale. Results indicate that calculated MDAs are commonly either equivalent to, or appreciably younger than, stratigraphic age estimates based on palynostratigraphy. Therefore, several of the most economically strategic aquifer units in the superbasin have been revised upwards in geological time. Similar geochronological campaigns are required in the central, western and southern superbasin to facilitate both high-resolution correlation of key aquifer units across the superbasin and the detailed tracking of the Jurassic to Early Cretaceous paleogeographic evolution of eastern Australia. Key points U–Pb detrital zircon maximum depositional age (MDA) constraints generated are applied to the Jurassic–Cretaceous stratigraphy of the northern Great Australian Superbasin. MDA estimates facilitate robust correlation of endemic Australian palynostratigraphic zones to the international time-scale, reducing chronostratigraphic uncertainty. Several of the key aquifer units across the northern superbasin (e.g. Hooray Sandstone) yield MDA estimates younger than age assignments based on palynostratigraphy and have been revised upwards in geological time. Several units yield divergent MDA estimates, suggesting either unit diachroneity or miscorrelation, indicating that the chronostratigraphic framework of the northern superbasin (and the superbasin at large) warrants further examination.

How do turbidite systems behave from the hydrogeological point of view? New insights and open questions coming from an interdisciplinary work in southern Italy.

Turbidite successions can behave either as aquitards or aquifers depending on their lithological and hydraulic features. In particular, post-depositional processes can increase rock permeability due to fracture development in the competent layers. Thus, at a local scale, turbidite systems warrant further detailed investigations, aimed at reconstructing reliable hydrogeological models. The objective of this work was to investigate from the hydrogeological perspective a turbiditic aquifer located in southern Italy, where several perennial and seasonal springs were detected. Considering the complex hydrodynamics of these systems at the catchment scale, to reach an optimal characterization, a multidisciplinary approach was adopted. The conceptual framework employed microbial communities as groundwater tracers, together with the physicochemical features and isotopic signature of springs and streams from water samples. Meanwhile, geophysical investigations coupled with the geological survey provided the contextualization of the hydrogeological data into the detailed geological reconstruction of the study area. This modus operandi allowed us to typify several differences among the samples, allowing identification of sources and paths of surface water and groundwater, along with diffuse groundwater outflow along streams. As a final result, a hydrogeological conceptual model was reconstructed, underlining how at a very local scale the lithologic, hydraulic, and geomorphological heterogeneity of the studied relief can lead to an improved hydrogeological conceptual model compared to that of other turbidite systems. These results open new questions about the hydrogeological behavior of turbiditic aquifers, which could be pivotal in future research. In fact, these systems could support relevant ecosystems and anthropic activities, especially where climate change will force the research of new (and probably less hydrogeologically efficient) water sources.

Evolution and modeling of mine water inflow and hazard characteristics in southern coalfields of China: A case of Meitanba mine

In this paper, the hydrogeological characteristics in the southern coalfields of China are first briefly outlined. Then, taking the Meitanba mine as an example, the evolution and modeling of mine water inflow are studied. Finally, the hazard characteristics related to mine water and mud inrush are analyzed. The results show that the main mine water sources in the Meitanba mine area are groundwater, surface water and precipitation. The evolution of mine water inflow with time indicates that the water inflow is closely related to the development of karst structures, the amount of water from rainfall infiltration, and the scope of groundwater depression cone. The mine water inflow increases with time due to the increase in mining depth and the expansion of groundwater depression cone. Using the big well method and following the potential superposition principle, a hydrogeological model considering multi-well interactions has been developed to predict the mine water inflow. Based on the monitored data in the Meitanba mine area over a period of nearly 60 years, it is found that with increasing mining depth, the number of water and mud inrush points tended to decrease. However, the average water and mud flow rate per point tended to increase.

Application of remote sensing and GIS to assess groundwater potential in the transboundary watershed of the Chott-El-Gharbi (Algerian–Moroccan border)

Remote sensing (RS) and Geographic Information Systems (GIS) have become widely used in various fields around the world in recent years. In this paper; we attempt to delineate the groundwater potential zone in the transboundary watershed of Chott-El-Gharbi using the integration of RS, GIS methods. Eight influencing thematic layers viz. geology, rainfall, water table level, lineaments density, slope, drainage density, elevation, and land use/land cover were used. Afterward, Analytical Hierarchy Process technique, which offers good functionality for mapping the groundwater potentiality was used, where ranks and weights, assigned to each factor are computed statistically, based on their relative importance in terms of groundwater potential. Then, groundwater potential zones are classified into five categories namely excellent, high, medium, low, and very low zone, which represent 964.48 km2 (7.33%), 1467.30 km2 (11.15%), 7969.51 km2 (60.57%), 2639.52 km2 (20.06%), and 116.19 km2 (0.88%) of the study area, respectively. The very low potential region is found in the southern region of the study area, which is covered by mountains. Moreover, excellent groundwater potential zones are located at the central part of the region of Chott, which has quaternary formations where the infiltration is high. On the other hand, moderate and poor groundwater potential zones cover by the bare lands in the study area. Finally, the results were carefully validated with the yields data of various boreholes in the study area, which reveals an accuracy achievement of 72.41%. The finding of this research constitutes a valuable contribution towards the water resources management, and it forms a significant decision support tool for equitable and sustainable utilization of groundwater resources in the transboundary watershed of Chott-El-Gharbi. The study's findings will also serve as a benchmark for future research and studies, such as hydrogeological modeling.

From sediments to soils: changes in pore water metal bioavailability

The use of sediments as soils is an area of interest for Beneficial Use of dredged sediments. In this study the impact of the transition from sediments to soils is researched by looking at the seasonal and long year (10 year) change in pore water metal chemistry of sediments which are considered clean (class A) according to the Dutch soil directive. This study is based on a combination of geohydrological, geochemical and ecotoxicological risk models and validated against measured pore water concentrations for metals over an dry/wet period. The pore water metal concentrations are compared against standards and expressed as at Risk Characterization Ratio’s (RCR) values. The RCR values are high (> 1) during the first 3 years after the application of sediments as soil, especially at the end of the summer. The multi substances Potentially Affected Fraction (ms-PAF) shows a similar trend as the RCR values, although it takes 5 years before the combined calculated potential ecotoxicity is below the legal 40% threshold level. Translated to land use, it is advised to restrict land use for farming on soils where these clean (class A) sediments are applied for a five-year transition period.Article HighlightsBeneficial Use of sediments should take into account the different conditions when used as soils.Use of sediments as soils lead to a predicable seasonal and multiple year trend in metal concentrations in pore water.The predicted results in metal pore water concentrations are translated into an advice for temporal land use.

Groundwater Potentiality Assessment of Ain Sefra Region in Upper Wadi Namous Basin, Algeria Using Integrated Geospatial Approaches

Water demand has been increasing considerably around the world, mostly since the start of the COVID-19 pandemic. It has caused many problems for water supply, especially in arid areas. Consequently, there is a need to assimilate lessons learned to ensure water security. In arid climates, evaluating the groundwater potential is critical, particularly because the only source of drinking water and irrigation for the community is groundwater. The objective of this report is to locate and identify probable groundwater basins in the upper Wadi Namous basin’s Ain Sefra area. GIS and RS were used to evaluate the parameters of morphometry and to demarcate groundwater potential zones by using eight different influencing factors, viz., geology, rainfall, height, slope, land cover, land use, and lineaments density are all factors to consider. The analytical hierarchical process (AHP) was used to give weightages to the factors, and definitions within each attribute were sorted in order of priority for groundwater potentiality. The major findings of the research were the creation of groundwater-potential zones in the watershed. The hydrogeological zone of the basin was assessed as follows: very poor (0.56%), poor (26.41%), moderate (44.72%), good (25.22%), and very good (3.1%). The groundwater recharge potential zones are concentrated in low cretaceous locations, according to analytical data. The groundwater potential regions were checked to field inventory data from 45 water locations to corroborate the findings. The qualitative findings and the groundwater inventory data agreed 77.78%, according to the cross-validation study. The produced groundwater potential map might substantially assist in the development of long-term management plans by enabling water planners and decision-makers to identify zones appropriate for the placement of productive wells and reducing investment losses caused by well drilling failures. The results of the study will also serve as a benchmark for further research and studies, such as hydrogeological modeling.