Search Results (385)

Controlling groundwater levels is essential for the safe construction of complex or high-rise buildings. In México, dewatering regulations lack detailed references, and piezometric data are limited, making precise groundwater control a challenge. This study aimed to develop a numerical groundwater model by translating a conceptual hydrogeological model into a calibrated MODFLOW simulation using the graphical user interface ModelMuse, developed by the United States Geological Survey (USGS). For the project “Torre Tres Ríos”, field measurements recorded a water-table level of 33 m above sea level (masl) in July, rising to 35.74 masl in October due to rainy season recharge and the influence of the Tamazula River, then decreasing to 35.20 masl in November. The model, calibrated with a mean absolute error of 0.15 m and a standard deviation of 0.174 m, effectively represented steady and transient states. A spatiotemporal analysis based on the calibrated numerical model enabled the evaluation of different dewatering scenarios. Initially, deep wells with a pumping rate of 120 L per second (lps) were required for dewatering; however, a wellpoint system was proposed, showing improved performance with a reduced impact on groundwater flow and the surrounding environment during the critical August–November period. This study highlights the importance of numerical modeling in refining dewatering system designs, ensuring adaptability to fluctuating groundwater conditions. By providing a methodology for optimizing dewatering strategies, it contributes to more efficient and sustainable construction practices in regions with complex hydrogeological conditions. Full article

The Santiago–Guadalajara River Basin has an area of 10,016.46 km². The Metropolitan Area of Guadalajara, within the basin, is the second-largest city in the country, with more than 5 million inhabitants. The growth of the urban population, as well as industrial and agricultural activities with insufficient infrastructure for the sanitation of wastewater and its reuse, have caused environmental deterioration of surface waters and gradual depletion of groundwater resources. To assess the level of contamination in surface waters from the presence of heavy metals in the basin, a monthly monitoring campaign was carried out at 25 sampling stations located in the main and tributary streams from July 2021 to April 2022. The following decreasing sequence was found according to the mean concentration values: Fe > Al > Mn > B > Ba > Zn > As > Cu > Cr > Ni > Pb > Cd. The Heavy Metal Pollution Index (HPI) method was applied to assess the level of risk to aquatic life, finding an average global HPI value of 305.522 for the basin, which classifies it as in the critical contamination range. The results also reflect health risks due to the presence of As, Cd, and Ni in some monitored stations. It will be necessary to expand the monitoring network, identify the point and non-point sources of contamination, and implement measures for pollution control to protect aquatic life and human health due to the presence of heavy metals in the river. Full article

Three-dimensional numerical simulation of subsurface flow dynamics in karst conduits at dam sites represents a pivotal component of hydrogeological research, essential for unraveling the intricate behavior of water movement within karstified terrains. This study introduces a novel approach for accounting for the presence of karst conduits and presents a comprehensive three-dimensional flow simulation for the dam site of the Jingxian Pumped Storage Hydropower Plant. This method reduces mesh division, simplifies calculations, and improves model convergence. The findings reveal that the numerical model adeptly captures the declining groundwater levels within the study area, with enhanced precision achieved through the utilization of COMSOL’s Line Mass Source feature. By representing leakage tunnel cylinders as edges, the model significantly improves meshing efficiency, circumventing the computational burden associated with the explicit resolution of intricate geometric details. In the absence of remedial measures, the simulation predicts that groundwater will preferentially drain downstream via two distinct leakage pathways at the dam’s base, presenting a potential threat to the structural integrity and operational stability of the project. To address this risk, the implementation of robust seepage control measures is imperative. Once these measures are established, the dam is expected to function as an effective hydraulic barrier, ensuring the long-term stability and operational efficacy of the hydropower plant. Full article

The long-term overextraction of groundwater in the Beijing–Tianjin–Hebei region has led to the formation of the world’s largest groundwater depression cone and the most extensive land subsidence zone, posing a potential threat to the operational safety of high-speed railways in the region. As a critical transportation hub connecting Beijing and the Xiong’an New Area, the Beijing–Xiong’an Intercity Railway traverses geologically complex areas with significant ground subsidence issues. Monitoring and analyzing the causes of land subsidence along the railway are essential for ensuring its safe operation. Using Sentinel-1A radar imagery, this study applies PS-InSAR technology to extract the spatiotemporal evolution characteristics of ground subsidence along the railway from 2016 to 2022. By employing a buffer zone analysis and profile analysis, the subsidence patterns at different stages (pre-construction, construction, and operation) are revealed, identifying the major subsidence cones along the Yongding River, Yongqing, Daying, and Shengfang regions, and their impacts on the railway. Furthermore, the XGBoost model and SHAP method are used to quantify the primary influencing factors of land subsidence. The results show that changes in confined water levels are the most significant factor, contributing 34.5%, with strong interactions observed between the compressible layer thickness and confined water levels. The subsidence gradient analysis indicates that the overall subsidence gradient along the Beijing–Xiong’an Intercity Railway currently meets safety standards. This study provides scientific evidence for risk prevention and the control of land subsidence along the railway and holds significant implications for ensuring the safety of high-speed rail operations. Full article

This work presents an imaging testing system (software and hardware) that can generate repeatable images through a stabilized port in the soil for processes known to change with time. The system includes (i) a stabilized port in the ground made of standard PVC pipe, with sections lined with a borosilicate glass tube, and (ii) a digital imaging instrument to survey the optically transparent portion of the stabilized port. The instrument uses a probe containing a digital camera and two light sources, one using white lights and one using ultraviolet (UV) lights (365 nm). The main instrument controls the probe using a cable within the stabilized port to take overlapping pictures of the soil under the different light sources. Two examples are provided, one to document the distribution of soil and groundwater contaminants known as non-aqueous phase liquids (NAPL, which include petroleum) at variable water saturation levels and a second one to monitor the growth of a plant over a 2-week interval. In both examples, the system successfully identified critical changes in soil processes and showed a resolution of approximately 15 µm (in the order of the thickness of a human hair), demonstrating the potential for repeated imaging of soil processes known to experience temporal changes. Both examples are illustrative, as additional applications might be possible. The novelty of this system lies in its ability to generate repeated measurements at larger depths than the current shallow systems installed by hand. Full article

Karst aquifers in the Mediterranean region are crucial for water supply and agriculture but are increasingly threatened by climate change and overexploitation. The Jebel Zaghouan aquifer, historically significant for supplying Carthage and Tunis, serves as the focus of this study, which aims to evaluate its availability, quality, and vulnerability to ensure its long-term sustainability. To achieve this, various methods were employed, including APLIS and COP for recharge assessment and vulnerability mapping, SPEI and SGI drought indices, and stable and radioactive isotope analysis. The findings revealed severe groundwater depletion, primarily caused by overexploitation linked to urban expansion. Minimal recharge was observed, even during wet periods. APLIS analysis indicated moderate infiltration rates, consistent with prior reservoir models and the MEDKAM map. Isotopic analysis highlighted recharge from the Atlantic and mixed rainfall, while Tritium and Carbon-14 dating showed a mix of ancient and recent water, emphasizing the aquifer’s complex hydrodynamics. COP mapping classified 80% of the area as moderately vulnerable. Monitoring of nitrate levels indicated fluctuations, with peaks during wet years at Sidi Medien Spring, necessitating control measures to safeguard water quality amid agricultural activities. This study provides valuable insights into the aquifer’s dynamics, guiding sustainable management and preservation efforts. Full article

The phenomenon of seawater intrusion is becoming increasingly problematic, particularly in low-lying coastal regions and areas that rely heavily on aquifers for their freshwater supply. It is, therefore, vital to address the causes and consequences of this phenomenon in order to ensure the security of water resources and the sustainable use of water. The objective of this paper was twofold: firstly, to delineate zones with different salinization levels over time; secondly, to investigate the factors controlling seawater intrusion of the Nile Delta aquifer. Aquifer data were collected in Sharkia governorate, Egypt, over three historical periods of years: 1996, 2007, and 2018. The dataset used to create the linear model of coregionalization consisted of hydrogeological (water level), hydrodynamic (pH, EC, Na, Mg, K, Ca, HCO₃, SO₄), and auxiliary (distances from salt and freshwater sources) variables. Cokriging was applied to produce spatial thematic maps of the studied variables for the three years of the survey. In addition, factorial cokriging was applied to understand the processes beyond the change in the aquifer water quality and map the zones with similar characteristics. Results of mapping the first factor at long range over the three years indicated that there was an increase in seawater intrusion, especially in the northeastern part of the study area. The main cause of aquifer salinization over time was the depletion of the groundwater resource due to overexploitation. Full article

This study investigates the complex interaction of biophysical and meteorological factors that drive evapotranspiration (ET) in saline environments. Leveraging a total of 182 cloud-free Landsat 5/8 time-series data from 1988 to 2019, we employed the Surface Energy Balance System (SEBS) model to quantify ET and investigate its relationships with soil salinity, vegetation cover, groundwater depth, and landscape metrics. We validated the predicted ET at two experimental sites using ET observation calculated by a water balance model. The result shows an R² of 0.78 and RMSE of 0.91 mm for the SEBS predicted ET, indicating high accuracy of the ET estimation. We detected abandoned saline farmland patches across Hetao and extracted the normalized difference vegetation index (NDVI), salinization index (SI), and the predicted ET for analysis. The results indicate that ET is negatively correlated with SI with a Pearson correlation coefficient (r) up to −0.7, while ET is positively correlated with NDVI (r = 0.4). In addition, we designed a control-variable experiment in the Yichang subdistrict to investigate the effects of groundwater depth, land aggregation index, soil salinity index, and the area of abandoned saline farmland patches on ET. The results indicate that increased NDVI could significantly enhance ET, while smaller saline farmland patches exhibited greater sensitivity to groundwater recharge, with higher averaged ET than larger patches. Moreover, we analyzed factor importance using Lasso regression and Random Forest (RF) regression. The result shows that the ranking of the importance of the features is consistent for both methods and for all the features, with NDVI being the most important (with an RF importance score of 0.4), followed by groundwater table depth (GWTD), and the influence of the surface area of abandoned saline farmland being the weakest. We found that smaller patches of abandoned saline farmland were more sensitive to changes in groundwater levels induced by nearby irrigation, affecting their averaged ET more dynamically than larger patches. Decreasing patch size over time indicates ongoing changes in land management and ecological conditions. This study, through a multifactor analysis of ET in abandoned saline farmland and its intrinsic factors, provides a reference for evaluating the dry drainage efficiency of abandoned saline farmland in a dry drainage system. Full article

The Cholera-Hospital-based-Intervention-for-7-Days (CHoBI7) mobile health (mHealth) program is a targeted water treatment and hygiene (WASH) program for the household members of diarrhea patients, initiated in the healthcare facility with a single in-person visit and reinforced through weekly voice and text messages for 3 months. A recent randomized controlled trial of the CHoBI7 mHealth program in urban Dhaka, Bangladesh, found that this intervention significantly increased WASH behaviors and reduced diarrhea prevalence. The objective of this present study was to conduct formative research using an implementation science framework to adapt the CHoBI7 mHealth program for scalable implementation in rural Bangladesh, and to promote construction of self-made handwashing stations (CHoBI7 Scale-up program). We conducted a 3-month multi-phase pilot with 275 recipients and 25 semi-structured interviews, 10 intervention planning workshops, and 2 focus group discussions with intervention recipients and program implementers. High appropriateness, acceptability, and adoption of the CHoBI7 Scale-up program was observed, with most recipients constructing self-made handwashing stations (90%) and chlorinating drinking water (63%) and 50% of participants observed handwashing with soap in the final pilot phase. At the recipient level, facilitators included weekly voice and text messages with videos on handwashing station construction, which served as reminders for the promoted water treatment and hand hygiene behaviors. Barriers included perceptions that self-made iron filters commonly used in households also removed microbial contamination from water and therefore chlorine treatment was not needed, and mobile messages not always being shared among household members. At the implementer level, facilitators for program implementation included follow-up phone calls to household members not present at the healthcare facility at the time of intervention delivery, and the promotion of multiple self-made handwashing station designs. Barriers included high patient volume in healthcare facilities, as well as the high iron in groundwater in the area that reduced chlorination effectiveness. These findings provide valuable evidence for adapting the CHoBI7 mHealth program for a rural setting, with a lower-cost, scalable design, and demonstrated the important role of formative research for tailoring WASH programs to new contexts. Full article

Boron (B) in soils originates from both natural and human sources, such as agriculture and industry, which contribute boron via fertilizers and irrigation water. Using treated wastewater (TWW) for irrigation is a strategy to address water scarcity in agriculture within arid areas like Tunisia; however, it introduces a risk of B contamination. Thus, the primary objective of this study is to assess the levels of B contamination throughout the entire irrigation system of the TWW “Cebala Borj-Touil” in Northeast Tunisia. To evaluate the lasting impact of TWW irrigation on B and the dynamics of physicochemical parameters across the entire system, soil samples were collected from various depths (0–150 cm) in a control area and gathered both prior to and following irrigation (two campaigns). Water samples utilized for irrigation and water released from drainage were gathered throughout an irrigation cycle. Groundwater sampling took place over two campaigns in April and September of 2018. The findings indicated that B concentrations in irrigation water were below the Tunisian standards (NT 106.03), while in drainage and groundwater, B levels exceeded the standard slightly during some periods. Throughout a three-decade cycle, the patterns of irrigation caused a notable transfer of boron from the topsoil to the groundwater. Therefore, it is essential to regularly supervise the irrigated area system and enhance the drainage system. Full article

Foundation pit dewatering will impact the surrounding underground environment. To mitigate the adverse effects on adjacent underground structures, groundwater recharge is commonly utilized to control groundwater drawdown outside the pit. However, under a barrier effect of underground structures, the recharge effect may be different from that without the barrier effect. Meanwhile, the results of recharging different aquifers may also be different under the barrier effect. Therefore, based on an actual foundation pit project, this paper establishes a three-dimensional finite element model to investigate the impact of recharge on the surrounding environment under the barrier effect. To be specific, the recharge simulations were conducted in aquifers at different depths, and the effects on groundwater, enclosure wall deflection, and ground settlement under each recharge condition were compared and discussed. Furthermore, the optimal recharge scheme under the barrier effect was proposed. The results show the following: (1) When recharge is conducted in an aquifer that is completely cut off by underground structures, both groundwater levels rise and enclosure deflection induced by recharge are dramatic; therefore, caution should be taken when recharging under this condition to avoid an excessive response of recharge on the surrounding environment. (2) When recharge is conducted in an aquifer that is not cut off, most of the recharged water flows far away from the foundation pit, resulting in a low recharge efficiency. (3) When recharge is conducted in an aquifer with a direct hydraulic connection between the inside and outside of the foundation pit, it can significantly raise the groundwater levels of each aquifer, and effectively control the ground settlement without obviously increasing the deflection of the enclosure; engineers could benefit from this recharge scheme to achieve a better recharge effect under the barrier effect. Full article

The proper functioning of peatlands depends on maintaining an adequate groundwater table, which is essential for ecosystem services beyond water retention. Most degraded peatlands have been drained for agriculture or forestry primarily through ditch construction. Rewetting through ditch blocking is the most common initial step in peatland restoration. This study analyzed the hydrological response to ditch blocking in three drained raised bogs in Norway (Aurstadmåsan, Midtfjellmåsan and Kaldvassmyra) using a Before–After–Control–Impact (BACI) design. Following rewetting, all sites demonstrated an average increase in groundwater levels of 6 cm across all piezometers affected by ditch blocking. The spatial influence of ditch blocking extended 12.7–24.8 m from the ditch with an average of 17.2 m. Additionally, rewetting increased the duration of favorable groundwater levels for peatland functioning by 27.7%. These findings highlight the effectiveness of ditch blocking in restoring hydrological conditions, although its impact is spatially limited. Future assessments should also address vegetation recovery and greenhouse gas emission reductions to ensure comprehensive restoration success. Full article

In recent years, the rapid development of the construction economy in Foshan City has led to increasingly apparent geological phenomena of ground subsidence, causing damage to buildings and infrastructures, lowering groundwater level, soil degradation, and environmental pollution. These issues have severely constrained the economic development of Foshan City. This paper utilized SBAS-InSAR technology to monitor ground deformation in Foshan City over the 2017–2022 period and identified 214 potential subsidence hazards. Additionally, integrating extensive surface deformation data from a long time series establishes a risk assessment index system for ground subsidence, primarily driven by construction activities. Further, the mechanism of the ground subsidence was analyzed systematically. Meanwhile, introducing the analytic hierarchy process method (AHP) to assess the risk of Foshan City, the results showed that the proportion of area from high-risk to low-risk zones is 8.55%, 8.64%, 11.79%, 22.38% and 48.64%, respectively. Moreover, this paper proposed corresponding measures to prevent and control ground subsidence. The evaluation results can provide a scientific reference for future geological disaster prevention and management in Foshan City. Full article

The objective of this study was to compare the effects of biochar extract (BE) and mineral potassium fulvic acid (MPFA) on the salt tolerance and growth of Bok Choy (Shanghai Bok Choy) under saline conditions, aiming to utilize saline groundwater resources in the Yellow River Delta region. Based on the mineralization level of saline groundwater in the Yellow River Delta region, all the treatments were cultured in a nutrient solution containing 6 g·L⁻¹ NaCl. Nine treatments were set up: BE (C1: 1 g, C2: 5 g, C3: 10 g, C4: 15 g·L⁻¹), MPFA (H1: 0.2 g, H2: 0.4 g, H3: 0.6 g, H4: 0.8 g·L⁻¹), and a control (CK). The results showed that both the BE and MPFA reduced MDA accumulation, increased SOD and CAT enzyme activities, thereby increasing the number of effective leaves, the maximum leaf length, and the maximum leaf width of Shanghai Bok Choy. However, MPFA was better than the BE at increasing the antioxidant enzyme activities and total chlorophyll content. Correlation analysis revealed that the hydrogen peroxide content and CAT enzyme activity were the most important factors affecting Shanghai Bok Choy yield. Compared to the CK, the BE treatments reduced the hydrogen peroxide content by 1.1–46.4% and increased the CAT enzyme activity by 4.1–68.0%, while the MPFA treatments increased the hydrogen peroxide content and decreased the CAT enzyme activity. Consequently, the fresh weight of Shanghai Bok Choy treated with the BE was 11.01–112.21% higher than the MPFA treatments and 5.17–49.70% higher than the CK. Overall, C3 had significantly lower hydrogen peroxide content than the CK and the highest CAT enzyme activity, which was markedly better than the MPFA treatments. This suggests that C3 may be an effective method for improving the salt tolerance and growth of Shanghai Bok Choy under salt stress. This study provides favorable data to support the solution to the problem of agricultural water use and the realization of sustainable development in the Yellow River Delta. Full article

Groundwater contamination with sub-lethal dissolved contaminants poses significant health risks globally, especially in rural India, where access to safe drinking water remains a critical challenge. This study explores the hydrogeochemical characterization and associated health risks of groundwater from shallow aquifers in the Marginal Ganga Alluvial Plain (MGAP) of northern India. The groundwater chemistry is dominated by Ca-Mg-CO₃ and Ca-Mg-Cl types, where there is dominance of silicate weathering and the ion-exchange processes are responsible for this solute composition in the groundwater. All the ionic species are within the permissible limits of the World Health Organization, except fluoride (F⁻) and nitrate (NO₃⁻). Geochemical analysis using bivariate relationships and saturation plots attributes the occurrence of F⁻ to geogenic sources, primarily the chemical weathering of granite-granodiorite, while NO₃⁻ contaminants are linked to anthropogenic inputs, such as nitrogen-rich fertilizers, in the absence of a large-scale urban environment. Multivariate statistical analyses, including hierarchical cluster analysis and factor analysis, confirm the predominance of geogenic controls, with NO₃⁻-enriched samples derived from anthropogenic factors. The spatial distribution and probability predictions of F⁻ and NO₃⁻ were generated using a non-parametric co-kriging technique approach, aiding in the delineation of contamination hotspots. The integration of the USEPA human health risk assessment methodology with the urbanization index has revealed critical findings, identifying approximately 23% of the study area as being at high risk. This comprehensive approach, which synergizes geospatial analysis and statistical methods, proves to be highly effective in delineating priority zones for health intervention. The results highlight the pressing need for targeted mitigation measures and the implementation of sustainable groundwater management practices at regional, national, and global levels. Full article