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Groundwater quality assessment is crucial for ensuring safe drinking water, protecting public health, and maintaining sustainable water resources for agricultural and industrial uses. The Awash River basin faces significant groundwater quality challenges due to rapid population growth, high urbanization, large‐scale irrigation, and industrial pollution. The main objective of this study is to evaluate the intrinsic vulnerability of aquifers to pollution in the Awash Basin and identify hotspots requiring urgent intervention using a modified DRASTIC overlay analysis method. In addition to the seven parameters considered in the generic DRASTIC overlay analysis (depth to the water table, recharge, aquifer media, slope, soil media, vadose zone, and hydraulic conductivity), we incorporated land use/land‐cover (LULC) and lineament density (LD) distributions (DRASTIC‐LU‐LD). This modification allowed us to produce more realistic groundwater vulnerability maps for the basin. To identify the most influential parameters in the overlay, sensitivity analysis was conducted using Map Removal Sensitivity Analysis (MRSA) and Single Parameter Sensitivity Analysis (SPSA). Initially, the generic DRASTIC index in the area ranges from 69 to 181, categorizing the area into four vulnerability zones: very low (21%), low (51%), medium (27%), and high (1%). After incorporating LU and LD, the index values ranged from 90 to 240. Based on the percentage of the total area studied, the inclusion of LU decreased the very low and low vulnerability zones from 72% to 44% and the inclusion of LD increased the high‐ and very‐high‐vulnerability zones from 14% to 27%. The areas most vulnerable to groundwater pollution are in the western (upper Awash), middle Awash, and northwestern regions, particularly in city centers where groundwater abstraction is significant. These high‐vulnerability zones coincide with municipal, industrial, and agricultural pollution sources. The vadose zone parameter has the highest impact in both MRSA and SPSA, with a variation index value of 3.08% and a mean effective weight of 27.93%, respectively. By identifying areas vulnerable to groundwater pollution, this study provides a valuable basis for informed decision‐making and the development of effective strategies for protecting groundwater from urban, industrial, and agricultural pollution sources. [ABSTRACT FROM AUTHOR]

The need for adequate data on the spatial and temporal variability of freshwater resources is a significant challenge to the water managers of the world in water resource planning and management. The problems will be acute in the coming years because of the increase in frequency and intensity of hydrologic extremes due to climate change. Therefore, streamflow prediction has become an important area of research because of its importance in flood mitigation, reservoir operation, and water resource management. In this paper, we have tested four Machine Learning models (ML models): Support Vector Machines (SVM), Random Forest (RF), Long Short-Term Memory (LSTM), and Multivariate Adaptive Regression Splines (MARS) for streamflow prediction at daily and monthly time scales in three rivers draining in the different climatic and geological settings. The SVM, RF, LSTM, and MARS models have been trained and tested in the Suvarna, Aghanashini, and Kunderu River Basins in peninsular India. Model intercomparison was made to identify the best suitable model for streamflow prediction. The RF outperforms other models for daily streamflow, and MARS outperforms other models for monthly streamflow prediction in the Suvarna river with Nash-Sutcliffe efficiency (NSE) values of 0.676 and 0.924, respectively. SVM (NSE = 0.741) and RF (NSE = 0.826) are found to be the best models for daily and monthly streamflow prediction in the Aghanashini river. MARS outperformed other models in the case of high, severe, and extreme flow simulation with NSE values of 0.481, 0.374, and 0.455, respectively, in the Aghanashini river. Other hydrological variables (groundwater level data, antecedent soil moisture, potential evapotranspiration data) and a better spatial resolution of rainfall data can be used to develop more accurate machine-learning models for streamflow predictions. [ABSTRACT FROM AUTHOR]

Understanding the slope hydrology and failure processes of rainfall-induced landslides is key to landslide early warning; the heterogeneity of soil (e.g., grain-size distribution in different layers) can markedly affect rainfall infiltration and slope failure patterns. However, the hydrological and failure processes of heterogeneous slopes layered by different soil groups have received little attention. In this study, we use a typical landslide soil composition of rainfall-induced landslide in fault zones as a prototype and via flume experiments to simulate the hydrological evolution, failure processes, and patterns under rainfall conditions on material heterogeneity slopes with a combination of colluvial deposit and fault gouge. Our results showed that rainfall-induced slope settlement and rapid saturation of shallow layers of colluvial deposits led to the occurrence of layer-by-layer shallow flow-slides. The spatial variability of infiltration led to the generation of a relatively dry‒wet interface in deeper layers, causing differential changes in the mechanical properties of the fault gouge; this was conducive to the formation of a steep landslide back wall, perched water table in the shallow layer of the fault gouge, and a rapid increase in porewater pressure, which triggered deep sliding, with a change in the failure pattern to a retrogressive mode. There was a strong linear correlation between the displacement rate before slope instability and the Arias intensity (IA) of the seismic signal; an abrupt change and rapid increase in IA may indicate that the slope entered an accelerating creep stage before failure. The results of this study provide a physical basis for related numerical simulation research and a reference for landslide early warning based on seismic signals. [ABSTRACT FROM AUTHOR]

Sulfur (S) is an essential nutrient vital for ideal plant growth and optimal crop yield. Potatoes in sandy soils of northeast Florida often face challenges due to low organic matter content and a high water table. The S application guidelines must be developed to avoid the under and over-application of S and to optimize integrated nutrient management plans for potatoes in Florida's sandy soils. A comprehensive study evaluated the response of S application in potatoes with S uptake, tuber yield, and quality. For 2 years (2021 and 2022), separate field experiments were conducted at three different locations, while location 1 had a trial replicated (Trial 1 and 2). The study was established in a randomized complete block design with four replications, in which five different rates (0, 45, 90, 135, and 180 kg S ha−1, as gypsum [17% S]) were applied at pre-planting. The results of this study show variations in soil-available S concentrations in response to different application rates and sampling times. The dry above-ground biomass production, S uptake, and potato tuber yield remained largely unaffected by S application. However, specific gravity at location 1 reported the response of the S application in interaction with trials. Location-specific effects, compounded by yearly variations, played a significant role, particularly at location 1. External and internal tuber quality showed inconsistent responses to the S application and interactions with trials and year factor. This study reported the significant influence of irrigation water (containing high amounts of SO42−) on the overall experiment. So, these findings underscore the importance of water nutrient concentration in developing crop nutrient recommendations. In conclusion, this study provides valuable insights into the complex relationship between S application, S uptake, and yield in the unique agricultural context of the sandy soils of Florida. [ABSTRACT FROM AUTHOR]

This study monitored long-term fluctuations in groundwater levels and assessed hydraulic properties within high and low tidal volumes through pumping tests. The pumping and monitoring wells were strategically positioned approximately 180 m away from the coastline of Yongho Bay in Busan. Subsequent derivative analyses of the pumping tests were performed to derive hydraulic properties associated with flow regimes, skin effect, wellbore storage, infinite acting conditions, and boundary conditions. These outcomes contribute to a more comprehensive characterization of the coastal aquifer. The primary objectives of this study encompassed the analysis of well storage during early pumping periods and the determination of boundary conditions during late pumping periods under both high and low tidal volumes. Hydraulic conductivity, well head loss, and well efficiency were found to be significantly influenced by coastal pumping activities within varying tidal volumes. Notably, the late-time drawdown during high tidal volumes revealed insights into the impact of driving forces, such as signal wave shape, influenced by submarine groundwater discharge and submarine seawater recharge. To illustrate the advantages and disadvantages of drawdown derivative analysis, a selected case study was presented. The case study results underscore the considerable influence of tidal volumes on analysis outcomes in coastal pumping scenarios. Notably, the high tidal volume resulted in 11.6% higher hydraulic conductivity, 13.1% higher well head loss, and a 4.97% increase in well efficiency compared to the low tidal volume. This study offers valuable insights into the complex dynamics of coastal aquifers, elucidating the nuanced impacts of tidal variations on changes in hydraulic properties induced by pumping. [ABSTRACT FROM AUTHOR]

To date, the important problem of Terzaghi's ground arch model in 1946 has not been solved for loads on circular tunnels. This study comprehensively presented a general analytical solution of Terzaghi's ground arch model for loads on circular tunnels by the limit equilibrium method, considering the complete boundary conditions of the loosening zone, the effects of water pressure, and the stiffness of the lining and ground. The proposed solution indicates the relationship between the load on circular tunnels and that on trapdoors, and there is a negative correlation between the lateral and vertical earth pressures in the ultimate state. Model tests and field measurements were used to verify the proposed solution. The results indicated that the proposed solution agrees well with the experimental results of circular tunnels in dense sand, loose sand, saturated sand, and saturated clay; the solution is significantly less than the design load from Terzaghi's formula in good ground conditions. Moreover, the solution demonstrated an interesting rule: the distribution of total loads (including water pressure) on nonrigid circular tunnels is nearly uniform in saturated granular soil. A particular solution was obtained for circular tunnels in saturated granular soil. In addition, the vertical pressure on a circular tunnel in sand increases and the lateral pressure decreases as the groundwater table increases within the tunnel range; the case where the groundwater table is located at the crown is proved to be a critical condition for shield tunnels in sand. Practical Applications: Previous studies indicate that the load on shield tunnels in good ground conditions would be overestimated by Terzaghi's formula, which was proposed in 1943 and is widely adopted in tunnel design nowadays. In this study, a general analytical solution for loads on circular tunnels was established based on Terzaghi's ground arch model, which was improved by Terzaghi in 1946 for arched tunnels but has not been solved. For various overburden depths, the proposed solution agrees well with the experimental results of circular tunnels in dense sand, loose sand, saturated sand, and saturated clay, but Terzaghi's formula based on trapdoors fails to explain the test results of circular tunnels in sand. The proposed solution is significantly less than the design load from Terzaghi's formula in good ground conditions. The solution is applicable for both shallow and deep circular tunnels, and it will be very helpful for the economical and rational design of shield tunnels normally in good ground conditions, such as sandy soil, crushed rock, and stiff or hard clayed soil. [ABSTRACT FROM AUTHOR]

Mechanisms have been proposed to explain the triggering, development, and persistence of soil liquefaction. The mechanism explaining the horizontal failure plane (triggering) and its depth below the phreatic surface is governed by the flux properties and effective stress at that plane. At the failure plane, the pore water pressure was higher than the effective stress, and the volume change was the highest. The pore water pressure is a function of the soil profile features (particularly the phreatic zone width) and bedrock motion (horizontal acceleration). The volume change at the failure plane is a function of the intrinsic permeability of the soil and bedrock displacement. The failure plane was predicted to occur during the oscillation with the highest amplitude, disregarding further bedrock motion, which was consistent with low seismic energy densities. Two mechanisms were proposed to explain the persistence of soil liquefaction. The first is the existence of low-permeability layers in the depth range in which the failure planes are predicted to occur. The other allows for the persistence and development of soil liquefaction; it is consistent with homogeneous soils and requires water inflow from bedrock water springs. The latter explains many of the features of soil liquefaction observed during earthquakes, namely, surficial effects, "instant" liquefaction, and the occurrence of short- and long-term changes in the level of the phreatic surfaces. This model (hypothesis), the relationship between the flux characteristics and loss of soil shear strength, provides self-consistent constraints on the depth below the phreatic surfaces where the failure planes are observed (expected to occur). It requires further experimental and observational evidence. Similar reasoning can be used to explain other saturated soil phenomena. [ABSTRACT FROM AUTHOR]

In recent years, drought has become a global problem. Undoubtedly, drought monitoring is an important step for combating and reducing the resultant damage. Soil moisture, namely its spatial and temporal variability, is one of the most important environmental variables. Due to the difficulty cost, and timeliness of field measurements, this parameter has not been used widely in drought indexes. The recent development of global databases based on satellite imagery as well as rapid progress in hardware and software for modeling complex processes governing the water balance at the land surface employ these new tools to reduce the limitations in this field. The purpose of this research is to provide a comprehensive drought monitoring approach by integrating remote sensing data and the variable infiltration capacity (VIC) model with the Palmer Index (PDSI) in central Iran. In this study, the components of water and energy balance in the Central Iran region were simulated using the VIC land surface model. The output components of this model, especially soil moisture after evaluation, were used as inputs in the drought index based on Palmer's water balance. The integrated index of the VIC-PDSI in comparison with conventional Palmer indices and the SPI index at the 3, 6, 12, 24, and 48-month intervals was fitted with increments in moisture data and variations in the storage of water extracted from GRACE satellite data. Results showed that the combination of VIC-PDSI had the highest correlation coefficient of 0.87 with groundwater level change compared with other drought indices. [ABSTRACT FROM AUTHOR]

A regional groundwater flow model of the southwestern Crimea within the Alminskii Artesian Basin and the adjacent area of fracture-karst groundwater of Mountain Crimea was developed and calibrated for the current period. Numerical experiments with this model were used to evaluate the changes in groundwater resources under the effect of forecasted climate changes in the 21st century. For this purpose, forecast maps of infiltration recharge were constructed for the study area. The forecast maps of infiltration recharge were constructed from the lowland part of the area with the use of simulation of infiltration water exchange. In the mountain part, the changes in recharge were forecasted taking into account both the infiltration water exchange and the influation, i.e., influation of precipitation into karst forms. The forecast scenario was taken to be the extreme scenario of climate changes SSP5-8.5, implying maximal warming, and an ensemble of Atmosphere-Ocean General Circulation Model of the CMPI 5 family. Three models with the highest contrast of changes in the aridity index were selected from the ensemble forecast, and forecast maps of recharge changes in the 21st century were obtained for them and used in numerical experiments. The total infiltration recharge appreciably differs from its current value—366.4 thousand m3/day: at dry climate, the infiltration recharge is 187.9 thousand, at moderate climate, it is 283.6 thousand, and at humid climate, it is 403.3 thousand m3/day. The results of the forecast modeling of groundwater balance during the 21st century with the use of the maps of infiltration recharge showed a high adaptive role of the storage reserves and the decrease of minimal river runoff at the considered time scale of the order of a hundred years at the current level of groundwater intake. [ABSTRACT FROM AUTHOR]

Pakistan's diverse landscapes and agrarian economy heavily rely on its water resources; however, groundwater scarcity poses a pressing challenge, particularly in the context of agriculture, industry, and households. Groundwater is the predominant water source that faces critical fluctuations influenced by seasonal precipitation changes and agricultural acts. Using Gravity Recovery and Climate Experiment (GRACE) based terrestrial water storage anomalies (TWSA), and water storage components from the Global Land Data Assimilation System (GLDAS), significant variations in groundwater storage are revealed. The analysis uncovers uneven groundwater storage patterns across the country, with distinct trends observed in different provinces. Over the past decade, at the national level, groundwater storage has significantly declined, Punjab showed notable decreases in groundwater storage attributed to overexploitation and rising water consumption; Balochistan, Khyber Pakhtunkhwa, Gilgit Baltistan, and Kashmir have declining trends, and Sindh experienced slightly higher levels of groundwater storage due to flood events. Furthermore, analyses showed that floods have led to substantial increases in storage, impacting all provinces, while droughts have caused significant drops in groundwater storage. These findings underscore the importance of sustainable groundwater management acts and emphasize the importance of provincial strategies and autonomy in developing integrated water resource management approaches, aligning with the country's National Water Policy. [ABSTRACT FROM AUTHOR]

Understanding hydrogeological processes often requires continuous measurements, which in many cases are not cost‐efficient. Time‐lapse geophysical studies are invaluable for investigating dynamic subsurface processes. They offer several advantages over traditional borehole‐based monitoring methods, such as being cost‐efficient and non‐intrusive. However, to be effective as an early warning tool, these studies must provide real‐time information on the processes. This is often not feasible with traditional geophysical methods, which typically do not offer real‐time monitoring. In this study, we present a windowed inversion approach for time‐lapse transient electromagnetic (TEM) monitoring. The advantages of this approach include: (i) immediate and continuous results as each time‐step dataset is acquired; (ii) no limitations on the size of the monitoring period or dataset; and (iii) the use of model information from previous inversion results for robust and continuous outcomes. The results from a synthetic study are followed by two field case studies, demonstrating the advantages of the windowed inversion compared to the inversion of the full dataset. We monitored the water table dynamics of a shallow unconfined aquifer over 8 months and the saltwater intrusion in a confined aquifer over 10 months using a monitoring TEM (mTEM) system while collecting nearly continuous daily measurements. With the windowed approach, the water table dynamics was recovered with an accuracy of 10 cm, and the changes in salinity were tracked with results comparable to those of an EC data logger. [ABSTRACT FROM AUTHOR]

Drone‐based geophysical surveying is an emerging measuring platform. High time‐cost efficiency and flexibility to survey over inaccessible areas make drones attractive or sometimes the only feasible option to carry geophysical measurements. This study presents a new drone‐towed electromagnetic induction and magnetic gradient sensor system used for near‐surface characterization and areal mapping. The system uses various datasets to enhance processing and interpretation. The system includes; an electromagnetic induction instrument; magnetic sensors; GNSS‐IMU system; photogrammetry; Lidar model data; and geoid model data. Robust data processing and stochastic inversion subsurface characterization for archaeological prospecting with drone‐towed electromagnetic induction and magnetic gradient sensor systems. Robust statistical methods were used to process the data. We conducted the fieldwork at one of the ancient Viking settlements in Denmark. The surveyed area was approximately 100×$\times$200 m. We then implemented and applied a one‐dimensional laterally constrained non‐linear stochastic inversion to image the subsurface electrical conductivity. The inversion results show a consistent conductive layer at 5–8 m depths, likely associated with the groundwater level. This conductive layer is disrupted under a prominent anomaly within a 2–4 m wide area. Our analysis showed that this conductivity disruption could be a flint mine extending 7 m deep. This anomaly also has a strong signature in magnetic gradient data. [ABSTRACT FROM AUTHOR]

ABSTRACT Predicting the tunnel deformation caused by overlying excavation is a crucial catch in current rail transit construction. Most theoretical studies overlook the effect of dewatering on tunnel response. This study utilized Mindlin's stress solution and an improved incremental method to calculate the additional load resulting from excavation. The load increment due to dewatering was determined based on the effective stress principle and a modified Dupuit infiltration curve. Treating the tunnel as a series of segment rings on a Vlazov foundation, the energy variance method and a collaborative deformation model were employed to develop a tunnel deformation prediction model. The proposed model's validity was confirmed by examining two traceable cases. Based on this, further discussion addressed the impact of dewatering depth, tunnel burial depth, tunnel‐pit relative distance, and intersection angle on existing tunnel deformation. Finally, combining the proposed model with multiple regression analysis, a semi‐empirical method was established to determine the tunnel's maximum vertical displacement. The study found that dewatering extends the tunnel force range, and the tunnel subsidence was positively correlated with groundwater level drop depth. The increase in the tunnel burial depth and distance from the excavation center led to a longer soil unloading transfer path, resulting in reduced disturbance to the tunnel. A smaller intersection angle between the excavation's short edge and the tunnel led to less disturbance of the underlying tunnel, which should be avoided in practical engineering. The developed semi‐empirical formulae have sufficient engineering accuracy, guiding the reinforcement of the underlying tunnel. [ABSTRACT FROM AUTHOR]

River-aquifer interactions play a crucial role in water availability, influencing environmental flows and impacting climate dynamics. Where groundwater tables lie below river water levels, stream water can infiltrate into the underlying aquifer, reducing streamflow. However, the prevalence of these "losing" rivers remains poorly understood due to limited national-wide in situ observations. Here we analyze water levels in 17,972 wells across Brazil to show that most of them (55%) lie below nearby stream surfaces, implying that these nearby streams are likely seeping into the subsurface. Our results demonstrate the widespread potential for stream water losses into underlying aquifers in many regions of the country, especially in areas with extensive groundwater pumping. Our direct observations underscore the importance of conjunctively managing groundwater and surface water, and highlight the widespread risk of streamflow losses to aquifers, which could impact global water access and ecosystems that rely on rivers. Most Brazilian rivers are found to have the potential for stream water losses into underlying aquifers, especially in drier climates, thicker aquifers, and regions with extensive groundwater pumping. [ABSTRACT FROM AUTHOR]

This article discusses methods for numerical modeling of geofiltration processes in groundwater, as well as the development and implementation of the proposed methodology for solving hydrogeological problems. The article analyzes the flows of grout waters entering underground aquifers in the form of filtration, and offers optimal solutions for the construction of drainage systems in mountainous areas. The main attention is paid to the development of mathematical models that describe the processes of interaction between groundwater and surface water, taking into account various natural and anthropogenic factors. The article describes methods for predicting changes in the level and state of groundwater, as well as calculating water balance elements. The authors propose mathematical models for describing the movement of groundwater in single-layer media, taking into account the processes of saturation and infiltration. Attention is paid to the use of information technology, mathematical modeling systems and geoinformation technologies to improve the accuracy of hydrogeological research results. The work demonstrates the relevance and prospects of the application of the proposed methods for solving problems of rational use and management of water resources, as well as for the development of new approaches in the field of melioration and water supply. As examples, studies of geofiltration processes in the mountainous regions of the Republic of Uzbekistan are given, where recommendations for the optimal use of groundwater in drinking water supply and irrigation have been developed. [ABSTRACT FROM AUTHOR]

Groundwater is a crucial part of the hydrologic cycle and the largest accessible freshwater source for humans and ecosystems. However, most hydrological models lack explicit representation of surface-groundwater interactions, leading to poor prediction performance in groundwater-dominated catchments. This study presents DECIPHeR-GW v1, a new surface-groundwater hydrological model that couples a Hydrological Response Units (HRU)-based hydrological model and a two-dimensional gridded groundwater model. By using a two-way coupling method, the groundwater model component receives recharge from HRUs, simulates surface-groundwater interactions, and returns groundwater levels and groundwater discharges to HRUs, where river routing is then performed. These interactions are happening at each time step in our new surface-groundwater model. Depending on the storage capacity of the surface water model component and the position of the modelled groundwater level, three scenarios are developed to derive recharge and capture surface-groundwater interactions dynamically. Our new coupled model was calibrated and evaluated against daily flow timeseries from 669 catchments and groundwater level data from 1804 wells across England and Wales. The model provides streamflow simulation with a median KGE of 0.83 across various catchment characteristics, with high performance particularly for the drier chalk catchments in southeast England, where the average KGE increased from 0.49 in the benchmark DECIPHeR model to 0.7. Furthermore, our model reproduces temporal patterns of the groundwater level timeseries, with more than half of the wells achieving a Spearman correlation coefficient of 0.6 or higher when comparing simulations to observations. Overall, this new DECIPHeR-GW model demonstrates remarkable accuracy and computational efficiency in reproducing streamflow and groundwater levels, making it a valuable tool for addressing water resources and management issues over large domains. [ABSTRACT FROM AUTHOR]

Groundwater is crucial for Africa's potable water supply, agriculture, and economic development. However, the continent faces challenges with groundwater scarcity due to factors like population growth, climate change, and over-exploitation. Over the past ten years, machine learning has been increasingly and successfully used in groundwater availability studies across the world. This review paper explores the application of machine learning techniques in groundwater availability studies including groundwater level prediction and groundwater potential mapping studies by focusing on some of the studies conducted in Africa. The methodology involved downloading relevant papers, identifying and categorizing the machine learning algorithms employed, and quantifying their use. Geological and climatic variables were also identified, analyzed, and categorized to measure their usage frequency. The different algorithms and input variables extracted from each paper are graphically represented in this document highlighting the most employed ones. The findings suggest that more research needs to be conducted on the use of machine learning algorithms on this topic in Africa. In the reviewed papers Fuzzy-based algorithms are commonly used. The groundwater level prediction studies primarily focus on input variables related to hydrology/hydrogeology, while for potential mapping, geological aspects are the most investigated variables. In terms of climate, precipitation receives the most attention in the reviewed studies. The study highlights the potential of machine learning in improving water resource management and decision-making in the region. [ABSTRACT FROM AUTHOR]

Groundwater level records in North America are relatively short (<60 years), preventing long‐term analysis of historical changes in groundwater levels associated with drought. In this study, tree ring widths are used to reconstruct groundwater levels in three regions in the North American Cordillera: Central British Columbia (BC), Canada, the Southern Interior Region of BC, and the San Luis Valley in Colorado, USA. Periods with severe drought conditions, identified using regime shift and threshold analyses were: 1890–1900 and 1950–1970 in Colorado, around 1920–1940 in the BC Interior, and 1935–1945 in Central BC. The groundwater level reconstructions are correlated with several climate indices and have similar regime shifts as identified in streamflow and drought records. The groundwater level reconstructions are strongly related to winter snowpack, suggesting that the observed trend of declining snowpack in recent years may lead to declining groundwater availability in these regions. Plain Language Summary: Long‐term records of observed groundwater levels are necessary to understand how groundwater resources may change over time. Unfortunately, many records in North America are considerably short (less than 60 years). This study uses tree ring widths to reconstruct groundwater levels in three mountainous regions of the North American Cordillera. We identify severe past groundwater drought conditions during: 1890–1900 and 1950–1970 in Colorado, around 1920–1940 in the British Columbia (BC) Interior, and 1935–1945 in Central BC, with some of these droughts being more severe than any that occurred in the observed records. We find that periods of groundwater drought in these regions are likely related to reduced winter snowpack, suggesting that future groundwater resources may be at risk, as climate change is already causing declining snowpack in these regions. Key Points: Tree ring records were used to reconstruct groundwater levels for three regions in the North American Cordillera from 1850 to 2002Some historical droughts are more severe than observed droughts, suggesting severe droughts could occur in the futureFuture groundwater levels in these regions will likely be negatively impacted by warming temperatures and declining snowpacks [ABSTRACT FROM AUTHOR]

Growing human demands are placing significant pressure on groundwater resources, causing declines in many regions. Identifying areas where groundwater levels are declining due to human activities is essential for effective resource management. This study investigates the influence of land use and land cover, crop types, and precipitation patterns on groundwater level trends across the Mississippi River Watershed (MRW), USA. Groundwater storage changes from 2003 to 2015 were estimated using data from the Gravity Recovery and Climate Experiment (GRACE) satellite mission. A spatiotemporal analysis was conducted at four scales: the entire MRW, groundwater regimes based on groundwater level change rates, 31 states within the MRW, and six USGS hydrologic unit code (HUC)-2 watersheds. The results indicate that the Lower Mississippi region experienced the fastest groundwater decline, with a Sen's slope of −0.07 cm/year for the mean equivalent water thickness, which was attributed to intensive groundwater-based soybean farming. By comparing groundwater levels with changes in land use, crop types, and precipitation, trends driven by human activities were identified. This work underscores the ongoing relevance of GRACE data and the GRACE Follow-On mission, launched in 2018, which continues to provide vital data for monitoring groundwater storage. These insights are critical for managing groundwater resources and mitigating human impacts on the environment. [ABSTRACT FROM AUTHOR]

Ground subsidence in urban areas is mainly due to natural or anthropogenic activities, and it seriously threatens the healthy and sustainable development of the city and the security of individuals' lives and assets. Shanghai is a megacity of China, and it has a long history of ground subsidence due to the overexploitation of groundwater and urban expansion. Time Series Synthetic Aperture Radar Interferometry (TS-InSAR) is a highly effective and widely used approach for monitoring urban ground deformation. However, it is difficult to obtain long-term (such as over 10 years) deformation results using single-platform SAR satellite in general. To acquire long-term surface deformation monitoring results, it is necessary to integrate data from multi-platform SAR satellites. Furthermore, the deformations are the result of multiple factors that are superimposed, and relevant studies that quantitatively separate the contributions from different driving factors to subsidence are rare. Moreover, the time series cumulative deformation results of massive measurement points also bring difficulties to the deformation interpretation. In this study, we have proposed a long-term surface deformation monitoring and quantitative interpretation method that integrates multi-platform TS-InSAR, PCA, and K-means clustering. SAR images from three SAR datasets, i.e., 19 L-band ALOS-1 PALSAR, 22 C-band ENVISAT ASAR, and 20 C-band Sentinel-1A, were used to retrieve annual deformation rates and time series deformations in Shanghai from 2007 to 2018. The monitoring results indicate that there is serious uneven settlement in Shanghai, with a spatial pattern of stability in the northwest and settlement in the southeast of the study area. Then, we selected Pudong International Airport as the area of interest and quantitatively analyzed the driving factors of land subsidence in this area by using PCA results, combining groundwater exploitation and groundwater level change, precipitation, temperature, and engineering geological and human activities. Finally, the study area was divided into four sub-regions with similar time series deformation patterns using the K-means clustering. This study helps to understand the spatiotemporal evolution of surface deformation and its driving factors in Shanghai, and provides a scientific basis for the formulation and implementation of precise prevention and control strategies for land subsidence disasters, and it can also provide reference for monitoring in other urban areas. [ABSTRACT FROM AUTHOR]

This study examines the combined effects of decommissioning lignite mining operations and long-term climate trends on groundwater systems and land surface movements in the Konin region of Poland, which is characterised by extensive open-pit lignite extraction. The findings reveal subsidence rates ranging from −26 to 14 mm per year within mining zones, while land uplift of a few millimetres per year occurred in closed mining areas between 2015 and 2022. Groundwater levels in shallow Quaternary and deeper Paleogene–Neogene aquifers have declined significantly, with drops of up to 26 m observed near active mining, particularly between 2009 and 2019. A smaller groundwater decline of around a few metres was observed outside areas influenced by mining. Meteorological data show an average annual temperature of 8.9 °C from 1991 to 2023, with a clear warming trend of 0.0050 °C per year since 2009. Although precipitation patterns show a slight increase from 512 mm to 520 mm, a shift towards drier conditions has emerged since 2009, characterised by more frequent dry spells. These climatic trends, combined with mining activities, highlight the need for adaptive groundwater management strategies. Future research should focus on enhanced monitoring of groundwater recovery and sustainable practices in post-mining landscapes. [ABSTRACT FROM AUTHOR]

Irrigation with saline groundwater has become necessary to overcome freshwater scarcity in the agricultural industry in arid areas. However, the effects of long-term saline groundwater irrigation on soil salinity and bacterial diversity have rarely been examined. In this study, a Lycium ruthenicum field was divided into two parts and subjected to flooding irrigation with saline groundwater (pH 7.81, total salinity 0.95 g L−1) and surface water (pH 7.76, total salinity 0.36 g L−1) for 8 years. After 8 years of irrigation, the soil salinity and salt ion content (i.e., Na+, Mg2+, K+, Ca2+, Cl− and CO32−) in the groundwater irrigation group were significantly greater than those in the surface water irrigation group (p < 0.001), with notable accumulation in the topsoil (0–5 cm) (p < 0.01). The bacterial community structure differed between the surface water and groundwater irrigation groups. Salt-tolerant bacterial groups (e.g., Balneolaceae and Halomonadaceae) and species (e.g., the marine bacterium JK1007, the bacterium YC-LK-LKJ35, and Methylohalomonas lacus) dominated in the groundwater irrigation environment. Additionally, bacterial communities were associated primarily with soil salt ions (RV = 0.66, p < 0.001). The characteristic bacterial taxa in long-term groundwater irrigation soils were salt-tolerant species (e.g., the marine bacterium JK1007, the bacterium YC-LK-LKJ35, and Methylohalomonas lacus). These findings suggest that salinity is the key factor driving differences in bacterial community structure between long-term groundwater and surface water irrigation. The long-term use of surface water and groundwater for irrigation has different impacts on soil environments, with groundwater irrigation having a more pronounced negative effect. Highlights. The long-term effects of this practice on soil salt accumulation and bacterial diversity were examined. This study provides potential applications for sustainable land management in similar ecological contexts. Groundwater irrigation is characterized by saline-tolerant keystone species. Salinity filtering was used to determine the pattern of bacterial community construction. Highlights: The long-term effects of this practice on soil salt accumulation and bacterial diversity were examined. This study provides potential applications for sustainable land management in similar ecological contexts. Groundwater irrigation is characterized by saline-tolerant keystone species. Salinity filtering was used to determine the pattern of bacterial community construction. [ABSTRACT FROM AUTHOR]

This paper presents a statistical analysis of water table depth fluctuations in the Ghahavand plain of Hamedan province, western Iran. The study is based on 49,232 water table depth records collected by the Hamedan regional water authority between October 1988 and March 2016. The data were processed to improve their quality and construct a monthly time series of water table depth. Singular Spectrum Analysis (SSA), a non-parametric technique for time series analysis, was used to analyze the time series. Exponentially Weighted Moving Average (EWMA) was applied to the residuals of the SSA model to monitor management policies and institutions. The EWMA control chart is an effective alternative to the Shewhart control chart when the goal is to detect smaller shifts in the process. One of the key advantages of using EWMA is its robustness to non-normality, making it suitable for real-world applications where data often deviates from the normal distribution. The results indicate that the SSA model fits the data very well. Using EWMA control chart on the residuals of the SSA model revealed three statistically unusual points that need to be examined by water resource management systems. The findings of this study can assist water resource managers in making informed decisions regarding groundwater management policies and practices. [ABSTRACT FROM AUTHOR]

Light non-aqueous phase liquids (LNAPLs), which include various petroleum products, are a significant source of groundwater contamination globally. Once introduced into the subsurface, these contaminants tend to accumulate in the vadose zone, causing chronic soil and water pollution. The vadose zone often contains lens-shaped bodies with diverse properties that can significantly influence the migration and distribution of LNAPLs. Understanding the interaction between LNAPLs and these lens-shaped bodies is crucial for developing effective environmental management and remediation strategies. Prior research has primarily focused on LNAPL behavior in homogeneous media, with less emphasis on the impact of heterogeneous conditions introduced by lens-shaped bodies. To investigate the impact of lens-shaped structures on the migration of LNAPLs and to assess the specific effects of different types of lens-shaped structures on the distribution characteristics of LNAPL migration, this study simulates the LNAPL leakage process using an indoor two-dimensional sandbox. Three distinct test groups were conducted: one with no lens-shaped aquifer, one with a low-permeability lens, and one with a high-permeability lens. This study employs a combination of oil front curve mapping and high-density resistivity imaging techniques to systematically evaluate how the presence of lens-shaped structures affects the migration behavior, distribution patterns, and corresponding resistivity anomalies of LNAPLs. The results indicate that the migration rate and distribution characteristics of LNAPLs are influenced by the presence of a lens in the gas band of the envelope. The maximum vertical migration distances of the LNAPL are as follows: high-permeability lens (45 cm), no lens-shaped aquifer (40 cm), and low-permeability lens (35 cm). Horizontally, the maximum migration distances of the LNAPL to the upper part of the lens body decreases in the order of low-permeability lens, high-permeability lens, and no lens-shaped aquifer. The low-permeability lens impedes the vertical migration of the LNAPL, significantly affecting its migration path. It creates a flow around effect, hindering the downward migration of the LNAPL. In contrast, the high-permeability lens has a weaker retention effect and creates preferential flow paths, promoting the downward migration of the LNAPL. Under conditions with no lens-shaped aquifer and a high-permeability lens, the region of positive resistivity change rate is symmetrical around the axis where the injection point is located. Future research should explore the impact of various LNAPL types, lens geometries, and water table fluctuations on migration patterns. Incorporating numerical simulations could provide deeper insights into the mechanisms controlling LNAPL migration in heterogeneous subsurface environments. [ABSTRACT FROM AUTHOR]

Using the Weigan River oasis as the research area and based on Landsat and measured groundwater depth data, the temperature vegetation drought index (TVDI) was calculated, and the groundwater depth that was measured in the field was used to establish a groundwater level prediction model (R2 = 0.644). Groundwater distribution in the Weigan River oasis was monitored from 2007 to 2020, and the model was verified using data from September 2013 and June 2015. The results indicate the following: (1) From 2000 to 2015, the groundwater depth of the Weigan River oasis was increased in a fluctuating manner and increased from 2.80 m to 5.79 m, and these values fluctuated sharply with a range of change of 106.79%. (2) The correlation coefficient R2 between the measured and predicted water levels in the two periods is 0.67 and 0.61, and the verification effect is good. (3) In the period from 2007 to 2020, the groundwater depth in the irrigated area exhibited a declining trend, where it decreased from the northwest and northeast to the southwest and southeast. (4) In irrigated areas, the GDP, population, and grain yield exerted a greater impact on groundwater depth. However, precipitation and evaporation were not significantly correlated with groundwater depth. [ABSTRACT FROM AUTHOR]

The Silesian Upland in southern Poland is known as a place where subsidence processes induced by mining activities occur in an area of nearly 1500 square kilometres, with many water bodies that formed in subsidence basins. This study concerned the dynamics of changes in the occurrence, boundaries and area of water bodies in subsidence basins (using orthoimagery from 1996 to 2023), as well as the assessment of the factors underlying the morphogenetic and hydrogenetic transformations of these basins. Within the subsidence basins covered by the study, water bodies occupied a total area that changed from 9.22 hectares in 1996 to 48.43 hectares in 2003, with a maximum of 52.30 hectares in 2009. The obtained figures testify to the extremely dynamic changes taking place in subsidence basins, which are unprecedented within such short time intervals in the case of other morphogenetic types of lakes and anthropogenic water bodies (for instance, from 1996 to 2003, the basin of the Brantka water body in Bytom underwent a more than two-fold change in its area, with RA values in the range of 54.4% to 131.9). A reflection of the dynamics of short-term changes in the water bodies in question in the period from 1996 to 2023 is the increase in the water area of the three studied water bodies, which was projected by linear regression to range from 0.09 hectares/year to 0.56 hectares/year. The area change trends, as determined by polynomial regression, suggest a slight decrease in the water table within the last few years, as well as within the next few years, for each of the studied basins. [ABSTRACT FROM AUTHOR]

Landslides on gently inclined loess–bedrock contact surfaces are common geological hazards in the northwestern Loess Plateau region of China and pose a serious threat to the lives and property of local residents as well as sustainable regional development. Taking the Libi landslide in Shanxi Province as a case study (with dimensions of 400 m × 340 m, maximum thickness of 35.0 m, and volume of approximately 3.79 × 104 m3, where the slip zone is located within the highly weathered sandy mudstone layer of the Upper Shihezi Formation of the Permian System), this study employed a combination of physical model experiments and numerical simulations to thoroughly investigate the formation mechanism of gently inclined loess landslides. Via the use of physical model experiments, a landslide model was constructed at a 1:120 geometric similarity ratio in addition to three scenarios: rainfall only, rainfall + rapid groundwater level rise, and rainfall + slow groundwater level rise. The dynamic changes in the water content, pore water pressure, and soil pressure within the slope were systematically monitored. Numerical simulations were conducted via GEO-STUDIO 2012 software to further verify and supplement the physical model experimental results. The research findings revealed that (1) under rainfall conditions alone, the landslide primarily exhibited surface saturation and localized instability, with a maximum displacement of only 0.028 m, which did not lead to overall instability; (2) under the combined effects of rainfall and rapid groundwater level rise, a "sudden translational failure mode" developed, characterized by rapid slope saturation, abrupt stress adjustment, and sudden overall instability; and (3) under conditions of rainfall and a gradual groundwater level rise, a "progressive translational failure mode" emerged, experiencing four stages: initiation, development, acceleration, and activation, ultimately resulting in translational sliding of the entire mass. Through a comparative analysis of physical model experiments, numerical simulation results, and field monitoring data, it was verified that the Libi landslide belongs to the "progressive translational failure mode", providing important theoretical basis for the identification, early warning, and prevention of such types of landslides. [ABSTRACT FROM AUTHOR]

Infiltration-based stormwater best management practices (BMPs) are progressively being utilized to mitigate issues such as increased runoff and poor water quality associated with urbanization. However, they are often difficult to accurately model due to the extensive design variables involved, particularly in high water table regions where groundwater mounding can cause primary infiltration to shift from vertical to horizontal. This study assessed an infiltration-based stormwater management system for a commercial property in Southwest Florida using integrated ArcMap 10.8.2 -ICPR4 software. A unique modeling technique captured the shift from vertical to horizontal infiltration in high water table conditions, employing ICPR4's "percolation ring" and "percolation link". The integration of GIS with the ICPR model enabled detailed modeling, assessment, and visualization of runoff in high water table areas. Three site-specific design storms were employed to analyze the pre- and post-developed conditions of the study area and assess whether existing BMPs met Environmental Resource Permit (ERP) requirements. While the system complies with ERP standards, it was found to be oversized based on storage basin stages and stormwater discharges from the simulated 100-year/24-h storm event. This is because 45–68% of the total volume entering the stormwater management basins infiltrated during the analysis period. The infiltration rate in the models was initially heavily dependent on vertical infiltration. However, horizontal groundwater flow substantially increased with the increasing water stage in the detention ponds after vadose zone saturation. These findings highlight the significance of modeling techniques in accurately capturing the performance of infiltration-based stormwater management systems in high water table conditions. [ABSTRACT FROM AUTHOR]

This study highlights the importance of quantifying groundwater resources for the Monahans and Kermit dune fields in the northern Chihuahua Desert, West Texas, USA, as potential contributors to the regional Pecos Valley Aquifer (PVA). Dunal aquifers in arid environments are often unquantified, may augment regional groundwater resources, and can be compromised by anthropogenic activity. Sedimentary architecture models of these dune fields show perched aquifers with water tables 1–10 m below the surface and southwestern groundwater flow sub-parallel to a Pleistocene/Pliocene acquitard. The deuterium and oxygen isotopic ratios for groundwater from the Kermit and Monahans dune fields show pronounced evaporative isotopic depletion and less isotopic variability than corresponding rainfall, particularly for deuterium values. The radiocarbon and δ13C analyses of dissolved inorganic carbon (DIC) indicate that recharge occurs through enhanced capture of recent precipitation on mostly bare active dunes where infiltration rates are >250 mm/h. In contrast, more evolved 14C values at the western margin (FM = 0.84) and at 30 m below the surface (FM = 0.76) of the dunes, similar to proximal Fm values from the PVA (0.89–0.82), may indicate dissolution of older (>100 ka) DIC from buried playa-lake sediments and less direct atmospheric influence. Mixing models for DIC source partitioning highlighted possible groundwater contamination with hydrocarbon up to 24% in the PVA and in the dunal aquifers. The perched aquifers of the Monahans and Kermit dune fields each contain water volumes >0.1 km3 and may contribute up to 18% of the total annual recharge to the PVA. [ABSTRACT FROM AUTHOR]

Sindh is in the lower reaches of the Indus River; it is most vulnerable to a variety of upstream water development challenges. The aim of this research was to determine aquifer characteristics in the command area of Tando Allahyar-II distributary within the culmination of underground water potential. The hydraulic properties of the aquifer as well as the susceptibility of the formation to tedious extraction and saltwater upcoming were recognized. Three pumping tests were performed at head, middle, and tail reaches along the selected distributary. The drawdowns were measured at head reach (5.1667 h), at middle reach (6.0 h), and at tail reach (19.667 h) of the selected distributary by performing the pumping tests. Groundwater levels were lower at the tail reach compared to those at the head and middle reaches, likely due to a higher concentration of tubewells in the lower reach. The head and middle reaches showed higher groundwater levels, possibly due to constant head conditions promoting infiltration and recharge. The pumping test versus drawdown analysis revealed that the tubewells should be run with 7-h (on) and 4-h (off) operation. Further, the tubewells at all reaches (head, middle, and tail) should be closed for a minimum of 4 h between operations. This strategy would allow safe groundwater extraction, maintain water quality, and prevent water table depletion in the study area. The hydrodynamic and hydro-salinity behaviors were scrutinized in PWMIN 5.3 (version) by means of the MODFLOW mode. The results were estimated to compare the calibration and validation simulation outcomes using measured data. The model was successfully calibrated, and the root mean square (RMS) value of the head tubewell varied between 0.024 and 0.108, whereas it speckled between 0.0166 and 0.0349 for the middle tubewell and between 0.0659 and 0.0069 for the tail tubewell. The RMS values for hydrodynamic behavior for the head, middle, and tail reaches were less than 10%. These values represent a suitable match between the observed and simulated heads when a water table depletion of 1 to 2 m was observed due to extreme pumping. However, the average relative error values, for all validated procedures, were less than 10%. [ABSTRACT FROM AUTHOR]

This research aims at studying the intrinsic vulnerability of groundwater to diffuse environmental pollutants in the Muravera coastal agricultural area of Sardinia, Italy. The area faces contamination risks arising from agricultural practices, especially the use of fertilizers, pesticides, and various chemicals that can seep into the groundwater. The study examined the interplay among hydrological elements, including soil characteristics, groundwater depth, climate conditions, land use, and aquifer properties. To do that, the outcomes of FLOWS 1D physically-based agrohydrological model were analyzed in parallel with those of the overlay-and-index model SINTACS, in a sort of reciprocal benchmarking. By using FLOWS, water movement and solute transport in the unsaturated zone were simulated by, respectively, solving the Richard Equation (RE) and the Advection-Dispersion equation (ADE). As such, this model allowed to account for the role of soil hydraulic and hydro-dispersive properties variability in determining the travel times of a conservative solute through the soil profile to the groundwater. For FLOWS simulations, a complete dataset was used as input, including soil horizons, soil physical and hydraulic properties of 36 soil profiles, average annual depth to groundwater table at each soil profile (ranging from 1 to 50 meters), and climatic temporal series data on rainfall and evapotranspiration. Detailed analyses of travel times for the movement of 25, 50, 75, and 100% of the solute mass to reach groundwater were conducted, revealing that the depth to groundwater predominantly influences vulnerability. This result was coherent with SINTACS vulnerability map due to the large impact of the depth to groundwater on SINTACS analysis. [ABSTRACT FROM AUTHOR]

AbstractThis study improved the vibratory probe compaction (VPC) technique by combining it with well-point dewatering to address the challenges of treating newly dredged silt ground. Specific methods were presented to determine the operating frequency based on multi-channel analysis of surface waves (MASW) results, as well as the spacing between compaction points derived from vertical vibration velocity measurements. The effects of well-point dewatering were analyzed through field monitoring of groundwater level, pore water pressure, and ground settlement. A comparative evaluation of the reinforcement of the improved and conventional VPC techniques was conducted through in-situ tests. The results indicate that continuous dewatering suppresses the excessive rise of excess pore water pressure during compaction, effectively eliminating equipment tilting and settlement due to sandblasting water, and enhancing construction efficiency by over 40%. The average standard penetration blow count (N63.5) increases from 4.3 to 11.4, the ground bearing capacity reaches 140.8 kPa and the average ground settlement is 42.5 cm. The cone resistance and sleeve resistance also exhibit higher values, and the risk of soil liquefaction is effectively eliminated. The experiments and practices provide some successful experiences for the wider application of this technique in similar newly reclamation grounds. [ABSTRACT FROM AUTHOR]

This publication presents data on geophysical measurements performed in the Rospuda wetlands located in North-Eastern Poland. The measurements were carried out by means of the the Electrical Resistivity Imaging (ERI) method, which so far was to our best knowledge never used in the River Rospuda wetland valley. The ERI data were collected in single survey campaign in November 2022 to account for the wet season. During the campaign two ERI profiles were measured. The aim of the field works was to provide the material for illustration of the arrangement of geological layers creating the wetland. The data repository contains detailed data descriptions for each survey site. The ERI data from the selected survey sites can be used first of all to create the conceptual numerical model of groundwater and surface water interaction in this environmentally valuable area, which is to a certain extent a scientific terra incognita, but also for hydrological investigation of hydraulic conductivity and hydrodynamic field, identify geological structure, and characterize engineering properties of the organic soils. [ABSTRACT FROM AUTHOR]

This study presents the geological and geomorphological characterization of the Pie de la Cuesta landslide, a large (>60 ha) slow-moving (up 4.5 m/month) landslide in Southern Peru. The landslide has been active since 1975 and underwent a significant re-activation in 2016; the mass movement has caused the loss of property and agricultural land and it is currently moving, causing further damage to property and land. We use a combination of historical aerial photographs, satellite images and field work to characterize the landslide's geology and geomorphology. The landslide is affecting the slope of the Vitor Valley, constituted by a coarsening upward sedimentary sequence transitioning from layers of mudstone and gypsum at the base, to sandstone and conglomerate at the top with a significant ignimbrite layer interbedded within conglomerates near the top of the sequence. The landslide is triggered by an irrigation system that provides up to 10 L/s of water infiltrating the landslide mass. This water forms two groundwater levels at lithological transitions between conglomerates and mudstones, defining the main failure planes. The landslide is characterized by three main structural domains defined by extension, translation and compression deformation regimes. The extensional zone, near the top of the slope, is defined by a main horst–graben structure that transitions into the translation zone defined by toppling and disaggregating blocks that eventually become earth flows that characterize the compressional zone at the front of the landslides, defined by thrusting structures covering the agricultural land at the valley floor. The deformation rates range from 8 cm/month at the top of the slope to 4.5 m/month within the earth flows. As of May 2023, 22.7 ha of potential agricultural land has been buried. [ABSTRACT FROM AUTHOR]

Electronics and other anthropogenic sources of noise in urban environments interfere with the early time signals of traditional transient electromagnetic (TEM) surveys due to the mutual inductance effect of transmitter and receiver coils. This poses problems for the detection of shallow geohazards such as karst dissolution features that lead to the subsidence and subsequent damage to infrastructure. The opposing-coils transient electromagnetic method (OCTEM) provides an alternative to traditional TEM surveys that is less sensitive to anthropogenic noise, and which is applied in this study to characterize shallow geohazards in a residential area responsible for subsidence and ground collapse. An investigation in Xiacun Town, China, was supplemented by ground-penetrating radar (GPR), drilling, and groundwater level monitoring to verify the OCTEM results and develop a conceptual model relating site hydrogeological factors to the ground collapse. OCTEM accurately identified shallow Quaternary gravel aquifers across the study area. However, OCTEM failed to identify additional subsidence structures near the collapsed pit demonstrated by the GPR results or the presence of a large, soil-filled cave below the pit determined from drilling. The site was concluded to be at further risk of subsidence and ground collapse associated with groundwater erosion driven by extreme precipitation events and excessive groundwater abstraction. [ABSTRACT FROM AUTHOR]

The dynamics of the water table is an important control on the connection of groundwater to land surface processes. Agricultural intensification has resulted in a significant decline in the groundwater table in the eastern part of the Sanjiang Plain, China. This decline may have caused significant changes in groundwater recharge and circulation, with implications for natural resources and the environment. In this study, hydrogeological (hydraulic head observations, unsaturated zone lithology), hydrochemical (major ions, redox-sensitive parameters, metasilicic acid) and isotopic (δD and δ18O) data was interpreted through spatial analysis, scatter plots and multivariate statistical methods to construct a conceptual model of shallow groundwater circulation in the Sanjiang Plain following decades of agricultural development. The distribution of the hydraulic head clarified the direction of groundwater flow, and the stable isotope compositions confirmed that shallow groundwaters mainly originated from precipitation and river water. Shallow groundwater levels and enriched groundwater isotopic compositions along the Songhua River and in the upper reaches of the Naoli River indicated some influence by evaporation. The relatively high nitrate concentration and coupling of isotope characteristics showed that sandy unsaturated zones enabled groundwater to be easily influenced by land surface processes. In the Jiansanjiang District and Naolihe Basin, the clayey unsaturated zones inhibited the connection between groundwater and the surface. Redox-sensitive components indicated that the groundwater features a reducing environment and weak groundwater update capability. If the current rate of exploitation continues in the Jiansanjiang District, the groundwater levels will continue to decline. [ABSTRACT FROM AUTHOR]

Anthropogenically elevated inputs of nitrogen (N), phosphorus (P), and potassium (K) can affect the carbon (C) budget of nutrient‐poor peatlands. Fungi are intimately tied to peatland C budgets due to their roles in organic matter decomposition and symbioses with primary producers; however, the influence of fertilization on peatland fungal composition and diversity remains unclear. Here, we examined the effect of fertilization over 10 years on fungal diversity, composition, and functional guilds along an acrotelm (10–20 cm), mesotelm (30–40 cm), and catotelm (60–70 cm) depth gradient at the Mer Bleue bog, Canada. Simultaneous N and PK additions decreased the relative abundance of ericoid mycorrhizal fungi and increased ectomycorrhizal fungi and lignocellulose‐degrading fungi. Fertilization effects were not more pronounced in the acrotelm relative to the catotelm, nor was there a shift toward nitrophilic taxa after N addition. The direct effect of fertilization significantly decreased the abundance of Sphagnum‐associated fungi, primarily owing to the overarching role of limiting nutrients rather than a decline in Sphagnum cover. Increased nutrient loading may threaten peatland C stocks if lignocellulose‐degrading fungi become abundant and accelerate decomposition of recalcitrant organic matter. Additionally, future changes in plant communities, strong water table fluctuations, and peat subsidence after long‐term nutrient loading may also influence fungal functional guilds and depth‐dependencies of fungal community structure. [ABSTRACT FROM AUTHOR]

This study investigates the isotopic composition of precipitation in Iran and its moisture sources, offering insights crucial for addressing water recharge and management in semi-arid regions. This study analyzes 150 precipitation events collected from 11 stations across Iran over multiple years. The HYSPLIT model was used to trace air mass trajectories contributing to these events. The isotopic composition of precipitation from each moisture source was examined to identify their distinct characteristics. Furthermore, the contribution of each air mass to groundwater and surface water recharge was quantified using the Simmr mixing model in R programming language, combining stable isotope data from precipitation and surface/groundwater samples. Precipitation in northern Iran is associated with low d-excess values, indicating moisture from high-latitude sources, particularly the Caspian Sea, while higher d-excess values in the west and south point to moisture mainly from the Persian Gulf and the Mediterranean Sea. Air mass trajectory analysis via the HYSPLIT model identified the dominant pathways of Continental Tropical (CT), Continental Polar (CP), and Mediterranean (MedT) air masses across Iran. Quantitative analysis using the Simmr mixing model revealed that the CT air mass contributes up to 33.6% to groundwater recharge in southern Iran's karstic regions, while the CP air mass dominates in the north, with up to 46.8% contribution. The MedT air mass, although significant in the west, decreases in influence towards the east. Isotope data from groundwater and surface water sites showed more depleted values than local precipitation, likely due to larger catchment areas. These findings contribute to water management strategies by identifying the variations in moisture sources that influence groundwater and surface water recharge in Iran. Understanding these variations enables the development of targeted strategies for managing water resources in semi-arid regions facing increasing water scarcity. The methodologies applied in this study can be adapted to other regions, providing a valuable framework for sustainable water management in areas where identifying moisture sources is critical. [ABSTRACT FROM AUTHOR]

Soil salinization is a main environmental and ecological problem in irrigated agro-ecosystems especially for the area with shallow groundwater table. Most previous studies mainly focused on the surface and root zone soil salinity, however, the knowledge on spatio-temporal dynamics of soil salinity for both root zone and deep soil as well as driving factors, and the recommended seasonal and annual groundwater depth for salt control was rarely addressed. In this study, 68 cropland sampling experiments and investigations related to soil salinity from the top soil to the depth of 1.80 m, groundwater depth and salinity, and crop types were carried out before and after the crop growing season of 2017-2018 in the Hetao Irrigation District. Soil salinity statistical characteristics showed that the standard deviation of soil salinity in time and space became larger with increasing of temporal mean and spatial mean. The root zone (within depth of 0-0.60 m) soil salinity in the crop growing season were accumulated and desalinated in the fallow season, which was opposite for changes of the deep (within depth of 0.60-1.80 m) soil salinity. The multi-factor variance analysis of variance showed that the driving factors including crop type, groundwater depth at the beginning of crop growing season, averaged groundwater depth in the crop growing season, groundwater salinity and root zone soil salinity at the beginning of crop growing season had significant effects on root zone soil salinity changes in the crop growing season (P<0.05). The influence of groundwater condition and other factors on root zone soil salinity change during crop growing season was closely related to the hydrological year type. At the beginning of crop growing season, the soil salinity in the root zone decreased exponentially with increasing groundwater depth, and the sampling locations with soil salinity below average had a minimum groundwater depth of 1.60 m. Both salt value and salt reduction rate decreased with groundwater depth increased across different soil layers when the average annual groundwater depth was less than 2.50 m. Thus, the sampling locations were selected where the groundwater table depth was less than 2.50 m, and then the median of root zone soil salinity and groundwater depth was obtained by the frequency analysis method. The annual suitable critical control groundwater depth for soil salinity median was 1.77 m. The groundwater depth of sampling locations where soil salinity was significantly higher than the median or mean value were less than 1.77 m. Therefore, in order to control soil salinity, it is recommended that the groundwater depth should be no less than 1.60 m at the beginning of crop growing period, and to maintain an average annual groundwater depth of at least 1.77 m. The research results will provide theoretical support for the design of irrigation scheduling and the rational layout of drainage projects for similar irrigation area in the arid area. [ABSTRACT FROM AUTHOR]

Miami‐Dade County (MDC) has over 112,000 septic systems, some of which are at risk of compromise due to water table rise associated with sea level rise. MDC is surrounded by protected water bodies, including Biscayne Bay, with environmentally sensitive ecosystems and is underlain by highly transmissive karstic limestone. The main objective of the study is to provide first estimates of the locations and magnitudes of septic return flows to discharge endpoints. This is accomplished by leveraging MDC's county‐scale surface‐groundwater model using pathline analysis to estimate the transport and discharge fate of septic system flows under the complex time history of groundwater flow response to pumping, canal management, storms, and other environmental factors. The model covers an area of 4772 km2 in Southeast Florida. Outputs from the model were used to create a 30‐year (2010 to 2040) simulation of the spatial–temporal pathlines from septic input locations to their termination points, allowing us to map flow paths and the spatial distribution of the septic flow discharge endpoints under the simulated conditions. Most septic return flows were discharged to surface water, primarily canals 52,830 m3/d and Biscayne Bay (5696 m3/d), and well fields (14,066 m3/d). Results allow us to identify "hotspots" to guide water quality sampling efforts and to provide recommendations for septic‐to‐sewer conversion areas that should provide most benefit by reducing nutrient loading to water bodies. [ABSTRACT FROM AUTHOR]

Open pit mining frequently requires regional water tables to be lowered to access ore deposits. When mines close, dewatering ceases allowing the water table to recover. In arid and semi‐arid mining regions, the developing pit lakes are predominantly fed by groundwater during this recovery phase and pit lakes develop first into "terminal sinks" for the surrounding groundwater system. With time, the re‐establishment of regional hydraulic gradients can cause pit lakes to develop into throughflow systems, in which pit lake water outflows into adjacent aquifers. In this study, we use numerical groundwater modeling to aid process understanding of how regional hydraulic gradients, aquifer properties, net evaporation rates, and pit geometry determine the hydraulic evolution of groundwater‐fed pit lakes. We find that before the recovery of the regional water table to its new equilibrium, pit lakes frequently transition to throughflow systems. Throughflow from pit lakes to downstream aquifers can develop within two decades following cessation of dewatering even under low hydraulic gradients (e.g., 5 × 10−4) or high net evaporation rates (e.g., 2.5 m/year). Pit lakes remain terminal sinks only under suitable combinations of high evaporation rates, low hydraulic gradients, and low hydraulic conductivities. In addition, we develop an approximate analytical solution for a rapid assessment of the hydraulic status of pit lakes under steady‐state conditions. Understanding whether pit lakes remain terminal sinks or transition into throughflow systems largely determines the long‐term water quality of pit lakes and downstream aquifers. This knowledge is fundamental for mine closure and planning post‐mining land use. [ABSTRACT FROM AUTHOR]

The water table fluctuation (WTF) method is popular for groundwater recharge (GR) estimation, but its accuracy is challenged when applied in areas with thick vadose zones because of the signal lag and attenuation with depth and uncertainties from barometric pressure effect and lateral flow. Improvement of the WTF method used the linear regression method and Darcy's law, and has been assessed to give satisfactory results. In particular, the improved method presented lower GR (20–34%) relative to the conventional method. GR decreased from the centre to the edge of the tableland. The regional average GR was 63–81 mm year−1, equivalent to 11–14% of annual average rainfall. Lag times between recharge and rainfall ranged from 1 to 9 months. Rainfall and vegetation dominated the spatiotemporal variability of GR. Our study provides reference and technical support for GR estimation with the WTF method in regions with a thick vadose zone. [ABSTRACT FROM AUTHOR]

The presence of uranium in groundwater has become a growing concern due to its potential health implications. This abstract focuses on the assessment of uranium concentrations in groundwater samples collected from the Kangra district. The study employed rigorous sampling and analysis techniques to evaluate the extent of uranium contamination and its distribution in the groundwater resources of the region. A comprehensive survey was conducted across various locations within the Kangra district, involving the collection of groundwater samples from different depths and geological formations. The collected samples were subjected to meticulous laboratory analysis, employing advanced spectroscopic method of LED fluorimeter to quantify uranium concentrations. The findings reveal varying levels of uranium in the groundwater samples, with concentrations ranging from minimal to elevated levels. The distribution of uranium was observed to be influenced by geological factors, hydrological characteristics, and anthropogenic activities. This research contributes to the understanding of little uranium contamination in the Kangra district's groundwater, serving as a valuable resource for policymakers, researchers, and stakeholders striving to ensure the safety and sustainability of the region's water resources. [ABSTRACT FROM AUTHOR]

The general population's health is directly related to the quality of the water used for drinking. As a result, research will be done on the radiation levels in the groundwater in the Charkhi Dadri area in the Indian state of Haryana. Using the LED Fluorimetry Technique, the concentration of uranium in drinking water samples taken from sources including hand pumps and tube wells of varying depths from the district will be determined. 40 water samples are gathered from various districts sites. With average value of 41.30 μg/L, variations in uranium level were noted within the range of 2–99 μg/L. The average value of uranium concentration is within the safe limit of 60 μg/L as recommended by Atomic Energy Regulatory Board, India but greater than 30 μg/L, the safe limit recommended by World Health Organization (WHO 2011). The value of cancer mortality is varying from 0.03 × 10–6 to 1.4 × 10–6 with mean value of 0.38 × 10–6 and that of cancer morbidity varying from 0.06 × 10–6 to 2.75 × 10–6 with mean value of 0.75 × 10–6. LADD value varying from 0.15 to 7.29 µg kg−1 d−1 with mean value of 1.90 µg kg−1 d−1 and HQ varying from 0.12 to 6.07 with mean value of 1.50. 60% of the samples showed HQ values greater than unity, this shows noteworthy danger of chemical poisonousness of uranium. [ABSTRACT FROM AUTHOR]

The reactivation mechanism of multi-slide landslides entails high complexity, and the shear mechanical properties of high groundwater-level landslides are crucial for analyzing the formation mechanism of reactivated landslides. Taking the K39 landslide of Wenma Expressway in Yunnan Province as the research object, we identified the geological and hydrogeological conditions of the landslide, the physical and mechanical properties of the slip zone soil, and the landslide deformation law using geological mapping, geotechnical engineering, indoor testing, and in situ monitoring. The results show the landslide exhibited alternating acceleration and deceleration movements under seasonal heavy rainfall and high groundwater levels. The shear strength of the soil in the deep sliding zone was greater than that of the soil in the shallow sliding zone. The deep and shallow sliding zone soils showed a decrease in shear strength with increased water content. Moreover, the residual strength of the deep sliding zone soil displayed a negative rate with an increased shear rate. In contrast, the residual strength of the shallow sliding zone soil exhibited a positive rate. Furthermore, under different shear rates, the residual internal friction angle and cohesion of the deep sliding zone soil decreased with increased water content, whereas only the residual internal friction angle of the shallow sliding zone soil followed this pattern. Finally, we performed a sensitivity analysis using the GA-BP neural network for the ring shear test parameters of the deep and shallow sliding zone soils, which included consolidation pressure, water content, and shear rate. Our analysis revealed that the residual strength of deep sliding zone soils is most affected by water content, whereas the residual strength of shallow sliding zone soils is most affected by consolidation pressure. Furthermore, it was found that the effect of water content on residual strength is much greater than the effect of shear rate on residual strength for both deep and shallow sliding zone soils. The study results contribute to a unified understanding of how shear rate affects residual strength mechanisms, support research on shear mechanical properties for multiple landslide revivals, and inform engineering practices and policies in landslide-prone areas. [ABSTRACT FROM AUTHOR]

The potential for static liquefaction of tailings is a major focus in the design and operation of tailings storage facilities. This research models the behaviour of unsaturated tailings, with a variety of degrees of saturation, addressing the propensity for static liquefaction during monotonic loading. Unsaturated triaxial tests, including constant suction conditions and constant water–air mass conditions, were performed. A bounding surface plasticity model was used to simulate the results. The constant mass condition is relevant to undrained closed-system loading, which may prevail during fast deformation after the tailings becomes unstable, when the air and water in the pore space remain locked inside the tailings. Boyle's law and hydraulic hysteresis were accounted for to model the changes of pore air and water pressures, and suction, with the change in tailings volume. Good agreement was achieved between test results and model simulations. Additional simulations to mimic rising water tables under constant total stress states in the field, situations that may trigger instabilities, are also shown. Results are added to charts which relate peak and post-liquefaction strengths, as well as collapse lines, to measures of initial state, for unsaturated conditions, which may be of use in practice. [ABSTRACT FROM AUTHOR]

Organic compounds pose significant environmental concerns, including groundwater contamination. Clays are commonly used as liners to prevent contaminant permeation into the groundwater tables, necessitating an understanding of clay's behavior in the presence of organic compounds. The presence of organic contaminants results in changes in the dielectric constant of pore fluid, which influences the interparticle energies and double layer thickness in the soil-pore fluid system. This study aims to elucidate the mechanisms of these changes by examining the response of smectite and kaolinite to variations in the dielectric constant. Experimental tests, including Atterberg limits, unconfined compression strength, water adsorption, sedimentation, pH, and XRD, were performed on clay samples at different concentrations of water-isopropyl alcohol mixtures. Results indicate that smectite exhibits higher Atterberg limits and water adsorption capacity compared to kaolinite. Smectite also shows more pronounced changes in response to decreasing dielectric constant. Conversely, changes in kaolinite's behavior were attributed to variations in pore fluid viscosity and dipole moment. These findings emphasize the importance of considering viscosity and dipole moment alongside dielectric constant in predicting kaolinite behavior. Overall, this study enhances the understanding of how variations in pore fluid dielectric constant affect the geotechnical and geo-environmental behavior of smectite and kaolinite. [ABSTRACT FROM AUTHOR]

Herbicides (HBCs) are extensively used in modern agriculture. However, their potential negative impacts on environmental media have emerged as a significant environmental concern. In this study, we employed positive matrix factorization (PMF) to identify the potential sources of HBCs. Furthermore, we utilized a multi-matrix ecological risk model to assess the risks associated with HBCs in both surface water and groundwater in the black soil region of Northeast China. The findings revealed that the levels of ∑ 15 HBCs in surface water and groundwater ranged from 585.84 to 6466.96 ng/L and 4.80 to 11,774.64 ng/L, respectively. The PMF results indicated that surface runoff and erosion accounted for 50% of the total HBCs in water, serving as the primary sources. All tested HBCs exhibited acute risk values within acceptable levels. The risk index for the ∑ 15 HBCs was categorized as "moderate risk" in 31% of the surface waters and 13% of the groundwaters. However, 4% of the groundwater sampling sites reached the "high risk" level. The chronic risk quotient of ∑ 15 HBCs in surface water and groundwater was 92% and 62% at the "high risk" level, respectively. Interestingly, non-carcinogenic HBCs contributed more significantly to the ecotoxicology of the aquatic system than carcinogenic HBCs. This study provides comprehensive information on the legacy of HBCs in water bodies and emphasizes the potential risks posed by HBCs to aquatic systems. The results obtained from this study could help relevant management authorities in developing and implementing effective regulations to mitigate the ecological and environmental risks associated with HBCs. [Display omitted] [ABSTRACT FROM AUTHOR]