Groundwater Level Dynamics Research Articles

A Semi-Analytical Solution of Two-Dimensional Unsteady Groundwater Flow Outside a Long-Strip Excavation Pit with a Cut-Off Wall

In deep excavation engineering, the implementation of cut-off walls stands as a crucial measure to ensure structural support stability. However, the existing theories for dewatering design often overlook the variations in cut-off wall penetration depths, potentially compromising the efficacy of groundwater control strategies. Addressing this gap, this study conducts a comprehensive investigation into the dynamics of groundwater levels within confined aquifers during the dewatering process of strip excavation pits with cut-off walls. Central to this inquiry is the conceptualization of the entire excavation pit as a singular large-diameter well, with the open part beneath the cut-off wall in the confined aquifer serving as a constant-flux boundary. Employing an advanced analytical modeling approach, the study formulates a robust framework to describe the intricate interplay of unsteady groundwater flow phenomena. Leveraging the techniques of the Laplace and finite cosine transform methods, a semi-analytical solution is derived to elucidate groundwater drawdown patterns over time. The validation of the proposed solution against finite element method results underscores its fidelity and applicability. The parametric analysis reveals a dynamic evolution in drawdown characteristics within the confined aquifer, transitioning from initially cone-shaped distributions to more linear profiles that eventually stabilize with prolonged dewatering. This evolution is governed by the aquifer’s inherent anisotropy and the barrier effect exerted by the depth of cut-off wall penetration. The parametric research also underscores the critical role of lateral boundary distance in influencing groundwater drawdown patterns. The presented solutions can be used to identify optimal penetration depth ratios tailored to specific parameters, thereby offering insights for optimizing dewatering strategies for deep excavation groundwater control. Moreover, a case study was included in this study using the proposed analytical solution, and a comparison was made with field data to validate the practical applicability of the approach.

Characteristics and causes of groundwater level dynamics in the Changji oasis on the northern slopes of the Tianshan Mountains, China

Characteristics and causes of groundwater level dynamics in the Changji oasis on the northern slopes of the Tianshan Mountains, China

Field measurement of entrapped pore‐air pressure and the effect of rising groundwater level in the soil layer

AbstractUnsaturated soil contains pore air, some of which becomes entrapped in the soil layer during the infiltration process. Such entrapped pore air in the soil layer inhibits infiltration, decreases hydraulic conductivity, and causes erroneous estimates of groundwater response. Experimental studies suggest an effect of compressed entrapped pore air on stream discharge. However, few studies have investigated the behaviour of pore air in the field, and no method for measurement of pore‐air behaviour has been established. We measured pore‐air pressure (Pair) with a simple handmade probe, combined with atmospheric pressure (Patm) and groundwater level. The entrapment and compression of pore air were detected based on the pressure difference (ΔP = Pair – Patm). Observations were conducted for approximately 1 year in two small headwater catchments (TC and HA, which have differences in soil depth and groundwater level dynamics) in Ibaraki Prefecture, Japan. Positive responses of ΔP during some rainfall events were confirmed at both TC and HA. Pore‐air entrapment occurred even during weak rainfall events with rainfall intensity of <10 mm/h. During a typhoon event in October 2019, a maximum ΔP of 3.9 kPa was observed at HA. The pore pressure increase recorded by the tensiometer was mostly explained by the increase in ΔP, which was supported by the soil moisture data. Therefore, we concluded that our handmade measurement system could successfully measure Pair and detect pore‐air entrapment in the field. This showed that Pair is not negligible. Total event rainfall was related to the maximum ΔP. It also showed that the rise in the groundwater level plays a significant role in pressurization of the entrapped pore air. We present the first field data demonstrating the effect of groundwater level rise on the pressurization of entrapped Pair.

Unravelling the signatures of submarine groundwater discharge and seawater intrusion along the coastal plains of Odisha, India: a multi-proxy approach.

Submarine Groundwater Discharge (SGD) and Seawater Intrusion (SWI) are two contrary hydrological processes that occur across the land-sea continuum and understanding their nature is essential for management and development of coastal groundwater resource. Present study has attempted to demarcate probable zones of SGD and SWI along highly populated Odisha coastal plains which is water stressed due to indiscriminate-exploitation of groundwater leading to salinization and fresh groundwater loss from the alluvial aquifers. A multi-proxy investigation approach including decadal groundwater leveldynamics, LANDSAT derived sea surface temperature (SST) anomalies and in-situ physicochemical analysis (pH, EC, TDS, salinity and temperature) of porewater, groundwater and seawater were used to locate the SGD and SWI sites. A total of 340 samples for four seasons (85 samples i.e., 30 porewater, 30 seawater and 25 groundwater in each season) were collected and their in-situ parameters were measured at every 1-2km gap along ~ 145km coastline of central Odisha (excluding the estuarine region). Considering high groundwater EC values (> 3000 μS/cm), three probable SWI and low porewater salinities (< 32 ppt in pre- and < 25 ppt in post-monsoons), four probable SGD zones were identified. The identified zones were validated with observed high positive hydraulic gradient (> 10m) at SGD and negative hydraulic gradient (< 0m) at SWI sites along with anomalous SST (colder in pre- and warmer in post-monsoon) near probable SGD locations. This study is first of its kind along the Odisha coast and may act as initial basis for subsequent investigations on fresh-saline interaction along the coastal plains where environmental integrity supports the livelihood of coastal communities and the ecosystem.

A STUDY OF THE HYDROGEOLOGICAL REGIME OF THE NATURAL AND TECHNICAL GEOSYSTEM: THE CASE STUDY OF THE DNIESTER GES

The primary objective of the study is to analyse changes in the hydrogeological regime before and after the facility's commissioning, taking into account the impact of human activity on water resources. To solve this problem, it is necessary to regularly measure groundwater levels. This process was carried out by systematically measuring the water level in piezometers for the period from 2010 to 2023 with a frequency of twice a week. To achieve this goal, it was necessary to analyse the geological structure and hydrogeological characteristics of the unconfined aquifers in the soil strata, as well as to investigate the permeability of rocks. Changes in the hydrogeological regime can be caused by both rock compaction due to changes in the stressed deformation state and activation of geodynamic processes, which, in turn, contribute to drainage through faults in the rock mass. The research in the article allows us to more accurately assess changes in the hydrogeological regime of the rock mass, in particular, in the reduction of the water-holding capacity of a certain horizon. The study reveals the possible causes of these changes, such as soil compaction and activation of geodynamic processes, and indicates potential consequences for the hydrogeological environment and water use, when planning and operating other energy facilities in similar conditions. The practical significance of this study is that it helps to understand changes in the hydrogeological environment and their potential impact on water resources. This is important for the development of effective strategies for managing water resources individually and preserving ecosystems in general. Studies indicate that during the period from 2010 to 2023, significant changes occurred in the hydrogeological regime of non-pressure horizons #1 and #2. The analysis of groundwater levels indicates that in certain local areas there is a decrease in the water level, which indicates the degradation of the soil massif. These changes may be related to the effects of drainage, which caused the disruption of structural bonds in soils and their transition to a loose state. In the case when the clay soil, which serves as a waterproofing layer for non-pressure horizon No. 1, loses its waterproofing properties, it can be explained with the help of the Coulomb-Mohr law, which reveals the dependence of the angle of internal cohesion (φ) on the coefficient of internal grafting (С) in soils. In simple language, when structural bonds are destroyed in clayey soils, the filtration coefficient increases [30, p. 240; 15, p. 223; 34, p. 170; 28, p. 2]. The potential cause of the destruction of structural bonds in the soil is described in works [36, p. 3]. Therefore, it can be concluded that the dynamics of groundwater levels indicates the influence of hydrogeological processes on the physical properties of the soil environment, which is important for the further management of water resources and the preservation of ecological sustainability of the region. The practical significance of this study is that it helps to understand changes in the hydrogeological environment and their potential impact on water resources. This is important for developing effective strategies for managing water resources separately and preserving ecosystems as a whole. For example, it is possible to develop models that will predict soil deformations depending on the level of groundwater, which will avoid possible destructive consequences for infrastructure and construction objects. Such data can also be used to improve hydrotechnical structures and determine optimal water resources management strategies in conditions of changing hydrogeological regime. Keywords: Geoecology, constructive geography, geosystems, river-basin systems, river-valley landscape, river natural and technical systems, landscape technical systems, landscape engineering systems, GIS technologies, Dniester PSPP, oolitic limestone, piezometer, aquifer, piezometric surface, soil base, infiltration, Neogene, aquifer.

Seasonal Groundwater Level Dynamics in Unconfined Aquifers across the United States

AbstractGroundwater hydrographs contain a rich set of information on the dynamics of aquifer systems and the processes and properties that influence them. While the importance of seasonal cycles in hydrologic and environmental state variables is widely recognized there has yet to be a comprehensive analysis of the seasonal dynamics of groundwater across the United States. Here we use time series of groundwater level measurements from 997 wells from the National Groundwater Monitoring Network to identify and describe groundwater seasonal cycles in unconfined aquifers across the United States. We use functional data analysis to obtain a functional form fit for each site and apply an unsupervised clustering algorithm to identify a set of five distinct seasonal cycles regimes. Each seasonal cycle regime has a distinctive shape and distinct timing of its annual minimum and maximum water level. There are clear spatial patterns in the occurrence of each seasonal cycle regime, with the relative occurrence of each regime strongly influenced by the geologic setting (aquifer system), climate, and topography. Our findings provide a comprehensive characterization of groundwater seasonal cycles across much of the United States and present both a methodology and results useful for assessing and understanding unconfined groundwater systems.

Spatio-temporal trends in long-term seasonal groundwater level of South-western Punjab using non-parametric statistical tests.

To manage groundwater resources and develop an action plan, it is crucial to understand the long-term behavior of groundwater level (GWL) fluctuations. In this study, Geographic Information System (GIS) and non-parametric statistical tests were applied for detecting long-term (1973 to 2020) spatio-temporal variations and trends in GWL from 137 observation wells evenly distributed across the south-western part of Punjab. This region has experienced significant changes in GWL over the decades. The non-parametric statistical tests included Mann-Kendall (MK), Sens's SlopeEstimator (SSE), and Innovative Trend Analysis (ITA). The study observed significant trends in GWL fluctuations before and after monsoon. The MK and SSE tests showed a statistically increasing trend in observation wells with about 65.7% and 67.2% increase before and after monsoon, respectively. The innovative trend analysis (ITA) also revealed a statistically increasing trend in observation wells with an increase of about 63.5% and 65.7% pre and post-monsoon season, respectively. The results indicate lowering of GWL in the northern districts of southwestern Punjab, while the southern districts experience rising GWLs. This discrepancy can be attributed to diverse agricultural activities and reduced over-exploitation of groundwater in the southern district due to soil salinity and the presence of brackish groundwater. These findings provide valuable insights into the dynamics of GWL in the studied region, highlighting notable trends associated with seasonal variations.

Dynamic change and driving response of shallow groundwater level based on random forest in southwest Songnen Plain

Study regionThe southwest Songnen Plain in China.Study focus:This study investigated the multi-time groundwater dynamic types and the trends of groundwater level. Random forest model was applied to analyse on driving factors of groundwater level.New hydrological insights:This study selected the following data from four periods in 2005, 2010, 2015, and 2020: groundwater depth, precipitation, evaporation, groundwater extraction, dry field area, and paddy field area. Pearson correlation analysis, Kriging interpolation, Mann-Kendall test, and other methods were employed to determine the groundwater dynamic types and changes in level within the four periods. Pearson correlation analysis shows that the dynamic types of groundwater table change greatly in the four periods, and the correlation between groundwater depth and precipitation decreases first and then increases. Kriging interpolation showed that the groundwater depth was lower in the west, and the depth around irrigation areas was higher. The Mann-Kendall test showed that the groundwater depth changed abruptly over time during the irrigation period and rainy season; the average groundwater depth increased by 1.36 m from 2005 to 2010, but only by 0.09 m from 2010 to 2020. The random forest model of groundwater level dynamics and its driving factors was established, and it was found that the size of the paddy field had the greatest influence on groundwater dynamics, affecting 32.15%.

Disentangling coastal groundwater level dynamics in a global dataset

Abstract. Groundwater level (GWL) dynamics result from a complex interplay between groundwater systems and the Earth system. This study aims to identify common hydrogeological patterns and to gain a deeper understanding of the underlying similarities and their link to physiographic, climatic, and anthropogenic controls of groundwater in coastal regions. The most striking aspects of GWL dynamics and their controls were identified through a combination of statistical metrics, calculated from about 8000 groundwater hydrographs, pattern recognition using clustering algorithms, classification using random forest, and SHapley Additive exPlanations (SHAPs). Hydrogeological similarity was defined by four clusters representing distinct patterns of GWL dynamics. These clusters can be observed globally across different continents and climate zones but simultaneously vary regionally and locally, suggesting a complicated interplay of controlling factors. The main controls differentiating GWL dynamics were identified, but we also provide evidence for the currently limited ability to explain GWL dynamics on large spatial scales, which we attribute mainly to uncertainties in the explanatory data. Finally, this study provides guidance for systematic and holistic groundwater monitoring and modeling and motivates a consideration of the different aspects of GWL dynamics, for example, when predicting climate-induced GWL changes, and the use of explainable machine learning techniques to deal with GWL complexity – especially when information on potential controls is limited or needs to be verified.

An Overview of Deep Learning Applications in Groundwater Level Modeling: Bridging the Gap between Academic Research and Industry Applications

As a critical component of sustainable water management, groundwater level prediction plays a vital role in mitigating droughts and ensuring adequate water supply. For decades, groundwater level dynamics have been primarily studied through physics‐based models, solving partial differential equations. However, interest has increased over the past few years in using Machine Learning (ML) approaches, like Deep Learning (DL) techniques, to study groundwater fluctuation dynamics more efficiently. DL models utilize complex algorithms to identify patterns that may be difficult to observe with traditional physics‐based models, specifically where the underlying physics is complex or poorly understood or where the available physical model is too simple. The article provides an overview of the literature published since 2001, encompassing 91 works that employed ML models to investigate groundwater‐related issues. Within this body of literature, 47 articles employed ML for groundwater level (GWL) modeling. Later, this article delves specifically into the latest advancements in DL for modeling GWL, including recurrent neural network (RNN), long short‐term memory (LSTM), and gated recurrent unit (GRU), and discusses their technical promising performance and advantages. We found that the most used time scale was monthly, which appeared in 18 articles, followed by the daily time scale, which appeared in 13 articles. The authors of the articles used normalization as a feature scaling method in 18 articles, while standardization was used in 3 articles. Python was the predominant programming language used in 18 studies for developing machine learning models, followed by MATLAB, which was used in 5 articles. Most authors divided their data sets into 60–90% for training and 10–40% for testing. Most studies have focused on pure academic research rather than practical industrial applications. Therefore, this article identifies shortcomings in recent literature on DL for GWL studies and suggests addressing these issues to improve practical application in real‐world settings.

The influence of long-term dynamics of groundwater levels on the winter redistribution of moisture in arable soils of the Ishim steppe

The aim of the study was to establish the influence of long-term dynamics of the groundwater level on the winter redistribution of moisture in arable soils of the Ishim steppe. Location and time of the study. The Ishim-Irtysh steppe interfluve (Ishim steppe, Russia), 1986–1989 and 2002–2024. Methods. Soil samples were collected during soil-hydrological field observations from the reference pits of arable soils. The soil and subsoil moisture content was determined by thermostat-weighing /in samples collected in the pre-winter period (the second - third decades of October) and at the end of the winter season (the third decade of March). The depth of the groundwater table was measured in the hand-drilled simultaneous with soil sampling for moisture measurement. The layer of cryogenic accumulation and the freezing moisture volume were determined by comparing moisture profiles in mid-October and in the third decade of March. Snow surveying was carried out in the third decade of March. The penetration depth of 0°C temperature was determined using exhaust thermometers. Results. Within the upland areas, during the second half of the 20th century the aquifer rose from various depths to the levels above the critical level. The economic activity was the main reason for the rise. In the early decades of the 21th century, as the groundwater table was above the critical depth, the groundwater level in summer and autumn began to be predetermined by the amounts of precipitation over the previous cold season of the year. The peculiarities of the winter redistribution of moisture in arable soils were found to be largely determined by the depth of groundwater in the autumn season. If in the upland soils the groundwater table was located in autumn at a depth of more than 4 m, which was typical for the 1980s, a layer of cryogenic moisture accumulation was formed below the horizons of intense and complete desuctive drying for spring grain crops, from a depth of 0.8 m. The moisture freezing volume did not exceed 30 mm. Migrated moisture practically did not participate in replenishing the post-vegetation moisture deficit in the upper 1-meter-thick layer of soil. If the groundwater in the second and third decades of October was detected at a depth of less than 4 m, which is typical for upland areas in the 21st century, a layer of cryogenic accumulation can be traced from a depth of 0.4–0.8 m, the volume of freezing moisture can reach 50 mm, and 25 mm in the top 1-meter layer. The frozen moisture in the top meter layer helps reducing the post-vegetation deficit, but promotes conditions for anaerobiosis in the second half-meter soil layer and acts as an “island of cold,” delaying the soil warming in spring to active temperatures. In soils with negative relief forms, the groundwater level during the period of field survey exceeded the critical level. Therefore, specifics of winter moisture profile redistribution in were similar to the established characteristics of this phenomenon in upland soils during the current millennium. Conclusions. The groundwater level in the soil and subsoils of the Ishim steppe uplands showed long-term dynamics under the influence of anthropogenic as well as natural factors over the past twenty years. The autumn depth of the groundwater table determines specifics of winter moisture redistribution in the arable soils of plakors: the higher the level, the greater the amount of moisture freezing is fixed, and the closer the cryogenic accumulation layer is located to the daytime surface.

Spatial and Temporal Patterns of Groundwater Levels: A Case Study of Alluvial Aquifers in the Murray–Darling Basin, Australia

Understanding the temporal patterns in groundwater levels and their spatial distributions is essential for quantifying the natural and anthropogenic impacts on groundwater resources for better management and planning decisions. The two most popular clustering analysis methods in the literature, hierarchical clustering analysis and self-organizing maps, were used in this study to investigate the temporal patterns of groundwater levels from a dataset with 910 observation bores in the largest river system in Australia. Results showed the following: (1) Six dominant cluster patterns were found that could explain the temporal groundwater trends in the Murray–Darling Basin. Interpretation of each of these patterns indicated how groundwater in each cluster behaved before, during, and after the Millennium Drought. (2) The two methods produced similar results, indicating the robustness of the six dominant patterns that were identified. (3) The Millennium Drought, from 1997 to 2009, had a clear impact on groundwater level temporal variability and trends. An example causal attribution analysis based on the clustering results (using a neural network model to represent groundwater level dynamics) is introduced and will be expanded in future work to identify drivers of temporal and spatial changes in groundwater level for each of the dominant patterns, leading to possibilities for better water resource understanding and management.

Groundwater Level Dynamic Impacted by Land-Cover Change in the Desert Regions of Tarim Basin, Central Asia

Groundwater is essential to residents, ecology, agriculture, and industry. The depletion of groundwater impacted by climatic variability and intense human activities could threaten water, food, and socioeconomic security in arid regions. A thorough understanding of groundwater level dynamics and its response to land-cover change is necessary for groundwater management and ecosystem improvement, which are poorly understood in arid desert regions due to a scarcity of field monitoring data. In our study, spatiotemporal characteristics of groundwater level impacted by land-cover change and its relationship with vegetation were examined using 3-years in-situ monitoring data of 30 wells in the desert regions of Tarim Basin during 2019–2021. The results showed that the depth to groundwater level (DGL) exhibited obvious spatial and seasonal variations, and the fluctuation of DGL differed significantly among the wells. The cultivated land area increased by 1174.6, 638.0, and 732.2 km2 during 2000–2020 in the plains of Yarkand, Weigan-Kuqa, and Dina Rivers, respectively, mainly transferring from bare land and grassland. Annual average Normalized Difference Vegetation Index (NDVI) values increased with time during the period in the plains. DGL generally exhibited a weakly increasing trend from 2019 to 2021, mainly due to human activities. Land-cover change significantly affected the groundwater level dynamic. Generally, the groundwater system was in negative equilibrium near the oasis due to agricultural irrigation, was basically in dynamic equilibrium in the desert region, and was in positive equilibrium near the Tarim River Mainstream due to irrigation return water and streamflow. NDVI of natural desert vegetation was negatively correlated with DGL in the desert regions (R2 = 0.78, p &lt; 0.05). Large-scale land reclamation and groundwater overexploitation associated with water-saving irrigation agriculture development have caused groundwater level decline in arid oasis-desert regions. Hence, controlling groundwater extraction intensity, strengthening groundwater monitoring, and promoting water-saving technology would be viable methods to sustainably manage groundwater and maintain the ecological environment in arid areas.

Gleysols genesis and fluvial dynamics in a quaternary floodplain of the meandering river, Minas Gerais, Brazil

Soils are good indicators of the stability of environmental systems. In meandering river floodplains, they assess river channel morphology, incision process, groundwater level dynamics, and avulsion processes. The morphological properties and physicochemical attributes give gleysols unique characteristics about formation conditions and evolution degrees related to fluvial dynamics, thus allowing elaborate models of floodplain evolution in meandering rivers. This manuscript aimed to analyze the relationship between gleysols evolution and fluvial dynamics, in the quaternary floodplain of a meandering river, in the Mogi Guaçu River basin in the State of Minas Gerais. We described three profiles, in concave and convex margins of the river, identifying facies and considering the morphological characteristics of the gley horizons. Physicochemical analyses, determination of major and minor elements, and oxides were carried out on the samples of horizons and deposits of the profiles. For the characterization of the river channel, morphometric parameters were measured. Concentrations of silica, titanium dioxide, alumina, ferric and manganese oxides, plus the molar relations of provenance (P), leaching (L), parent material (M1 and M2), oxidation (O), hydrolysis (H), and the alteration geochemical index (CIA-K) were determined to compare the profiles pedological evolution. The three analyzed profiles were classified as typic Dystrophic Tb Haplic Gleysol (P1 and P2) and typic Alic Tb Haplic Gleysol (P3) so that the relation silt/clay demonstrated profile 3 to be the most evolved (weathered). Concentrations and behavior of oxides, associated with molar relations and conditions of the surfaces S II and S III of the flat floodplains morphological, demonstrated that the meandering process, with avulsion linked to erosion and deposition, affects gleysols evolution, suggesting genesis with compound or polygenetic profiles. Under a cyclical interpretation, the evolution of gleysol profiles, with truncation and horizon overlaying, reflects processes of avulsion, incision, and floods, as well as are proxies for interpreting the quaternary evolution of the Mogi Guaçu River meandering process.

Metamodelling of Naturalised Groundwater Levels at a Regional Level in New Zealand

Groundwater is under pressure from increasing demands for agriculture, industry, domestic uses and support of ecosystems. Understanding the natural state of a groundwater system helps policy makers manage groundwater sustainably. Here we developed a metamodelling approach based on stepwise linear regression that emulates the functionality of physically-based models in the three primary aquifers of the Greater Wellington region of New Zealand. The inputs for the metamodels included local weather data, and nearby river flow data. The metamodels were calibrated and validated against the available simulations of naturalised groundwater level time series from physically-based models for 47 selected wells. For 36 of these wells, the metamodels had Nash-Sutcliffe Efficiency and coefficient of determination over 0.5, showing that they could adequately mimic naturalised groundwater level dynamics as simulated by the physically-based groundwater models. The remaining 11 wells had unsatisfactory performance and were typically located far away from rivers or along the coast. The results also showed that modelled groundwater levels in the aquifer’s recharge zone were more sensitive to short-term (less than 2 weeks lag) than long-term river flow (above 4 weeks to 1 year lag), whereas the converse pattern was observed for the aquifer’s discharge zone. Although some special considerations are needed, this metamodelling framework can be generally applied to other aquifers to support groundwater resource management at a lower cost than updating physically-based models.

Groundwater level dynamics in a subtropical fan delta region and its future prediction using machine learning tools: Sustainable groundwater restoration

Study regionThe Damodar Fan Delta, West Bengal, India. Study focusThe depletion of groundwater resources worldwide is escalating due to its profuse demand for drinking, irrigation, domestic, and industrial uses. Overexploitation of groundwater in a subtropical fan delta region with rapid population growth like the Damodar Fan Delta in India is of great concern for sustainable mapping, monitoring, and managing water resources. During 2000–2020, the Damodar Fan Delta portrayed an increase in semi-critical community development blocks, implying a decline in groundwater level. To this end, the present study intends to show the groundwater level dynamics including its future prediction, using machine learning algorithms based on the seasonal groundwater level data from 2013‐14 to 2020‐21 for 30 wells. New hydrological insights for the regionPost-monsoon kharif and rabi depicted a higher fall rate in the groundwater level compared to the pre-monsoon and monsoon periods. Future predictions using the best-fit model indicated an increasing trend in the depth of groundwater levels in the future (2025–26). The extreme gradient boost regressor appeared to be the best model, while the decision tree regressor was the worst performer. The major controlling factors of groundwater level dynamics were decreasing rainfall and increasing groundwater abstraction due to population growth and increased demand for irrigation, domestic, and industrial water.

Investigating groundwater and surface water interactions using remote sensing, hydrochemistry, and stable isotopes in the Barotse Floodplain, Zambia

ABSTRACT Groundwater and surface water are inseparably linked, thus the understanding of their interactions is indispensable toward developing effective conjunctive water resource management strategies, particularly for ecosystems, such as wetlands, which provide numerous ecosystem services. This study aimed to identify potential areas of Groundwater-surface water (GW-SW) interactions and mechanisms that facilitate them using remote sensing, hydrochemistry, and stable isotopes. The results of remote sensing analysis using Normalised Difference Vegetation Index (NDVI) show that the vegetation is sensitive to the dynamics of groundwater level, with shallower levels (<10 m) in the lower reaches compared to deeper levels (>10 m) in the upper catchment. The study postulates that the near surface groundwater level, maybe due to the near proximity river system (Zambezi River) losing water to recharge the aquifer system, compared to upstream which may be discharging to floodplains (gaining system). Using Hierarchical Cluster Analysis (HCA) of the hydrochemical data, surface, and groundwater showed three similarity clusters of hydrochemistry consisting of Ca-Mg-HCO3, Na-HCO3, and Na-Cl. These zones are further investigated and likely represent geological variability, aquifer confinement, and the degree of GW–SW interactions. The outcomes of this research provide critical input for integrated protection and conservation of ecosystem services in floodplain and aquifer systems.

The Spatio-Temporal Dynamic Patterns of Shallow Groundwater Level and Salinity: The Yellow River Delta, China

Shallow groundwater in coastal aquifers is a highly dynamic and complex system with a high risk of seawater intrusion. Analyzing the spatio-temporal dynamic patterns of groundwater can help to manage the groundwater resource and prevent it from degradation. Based on the groundwater level (GWL) and electrical conductivity (EC) monitoring data of 18 observation wells in the Yellow River Delta (YRD) from 2004 to 2010, this research analyses the groundwater dynamics using a robust seasonal trend decomposition technique (STL) and spatial interpolation method to detect the groundwater spatio-temporal dynamic patterns of groundwater level and salinity. Combined with hydro-climatic data, the Pearson correlation method and the Mann-Kendall (MK) trend analysis were used to further reveal the impacts that induce their trends and seasonal variations. Our analyses show that the risk of seawater intrusion into local shallow aquifers in this region is high, with the mean groundwater level over 42% of the region lower than the local sea level, and the mean groundwater EC over 96% of the region met the standards for seawater intrusion. In addition, the trends of groundwater level generally declined by 0.01~0.45 m/a and salinity increased by 1.153~25.608 μs/cm.a, which are consistent with the trend of precipitation decline. The seasonal dynamics of groundwater level and salinity are highly correlated with the seasonal components of rainfall and evaporation. It can be concluded that the extent of seawater intrusion will increase in the future with sea level rise. The approaches used in this study proved to be effective and can certainly serve as an example for the analysis of the spatio-temporal dynamics of groundwater in other coastal regions.

ОЦІНКА РОЗВИТКУ ДЕФОРМАЦІЙ ЗЕМНОЇ ПОВЕРХНІ НА ШАХТНОМУ ПОЛІ СТЕБНИЦЬКОГО КАЛІЙНОГО РОДОВИЩА ЗА ДАНИМИ ГІДРОГЕОЛОГІЧНОГО МОНІТОРИНГУ

The paper presents the data generalization of the observations of hydrogeological monitoring of mining sites on the dynamics of groundwater level. The processing of hydro-regime studies conducted in 2009-2021 in the area of the mine bypass of the № 2 pit was carried out. Hydrogeological sections reflecting changes in water levels over time were prepared. The most important factor in the lowering of the ground surface is salt karst development. The evaluation of the intensity of karst collapse processes was based on the interpretation of the results of the dynamics of the subsurface water level. The site network consists of more than 30 observation wells drilled into suprasaline and Quaternary aquifers. The main causes of deformation of the salt rock massif and the earth's surface have been identified. These are a decrease in the geomechanical strength of the rock due to its hydration and subsequent subsidence under the geostatic load of the overlying rock, and subsidence of the clay layer covering the salt rock due to the karst process. Based on the observed data, hydrogeologically oriented spatial zoning of the mining concession was performed. As a result of the development of a complex depression in the area of influence of the karst drainage, a drop in the water level in the gypsum-clay horizons was observed over the entire area in 2009-2019. The depression funnel runs in a northwesterly direction, indicating the development of a karst channel in the salts. Significant inflow of suprasaline water in the southwestern and central parts of the mine field combined with intense karstification of the salt massif and gypsum-clay cap deposits within the depression funnel resulted in significant deformation of the earth's surface, formation of karst funnels, and technogenic and ecological threats to critical infrastructure objects. To prevent a man-made ecological catastrophe, it is urgent to develop a scientific rationale for the maximum permissible changes in the environmental parameters of the man-made geological system of the № 2 mine of the Stebnytsky potash deposit during the post-mining phase.

The dynamics of the Akhangaran basin's groundwater level in relation to physical-geographical and anthropogenic factors

This article describes the physical and geographical factors of groundwater formation in the Akhangaran river basin and around the Almalyk mining and metallurgical combine (AGMK), changes in groundwater levels at water intakes, precipitation, and evaporation in the study area. Comprehensive research methods, include the analysis of scientific and technical information on the geographical, hydrogeological, geomechanical and mineralogical compositions of the Almalyk industrial region, underground and surface waters, as well as the study of all valuable components by chemical, and X-ray structural methods, and atomic emission spectroscopy. Integration and point methods are used for measuring current velocity. Basic, detailed, abbreviated and graphical methods for measuring water flow are perfomed by electric metrs. Experimental filtration studies are carried out and systems of observation wells are organized. Additionally water temperature is measured with thermocouples and water density, salt concentration, and water pH are measured using ionomers.