Groundwater最新文献

The safe operation of underground reservoirs and environmental protection heavily rely on the water flow through coal pillar dams in coal mines. Meanwhile, research on the flow characteristics in coal pillar dams has been limited due to their low hydraulic conductivity. To address this gap, this study assembled a novel seepage experimental device and conducted a series of carefully designed seepage experiments to examine the characteristics of low-permeability in coal pillar dams. The experiments aim to explore the relationship between water flux and hydraulic gradient, considering varying core lengths and immersion times. Flow parameters were determined by fitting observed flux-gradient curves with predictions from both Darcy and non-Darcian laws. Several significant results were obtained. First, a noticeable non-linear relationship between water flux and hydraulic gradient was observed, particularly evident at low flow velocities. Second, the non-Darcy laws effectively interpreted the experimental data, with threshold pressure gradients ranging 13.60 to 58.64 for different core lengths. Third, the study established that water immersion significantly affects the flow characteristics of coal pillar dams, resulting in an increased hydraulic conductivity and flow velocity. These findings carry significant implications for the design of coal pillar dams within underground coal mine reservoirs, providing insights for constructing more stable structures and ensuring environmental protection.

Groundwater allocation is rapidly becoming a contentious water resource management problem around the world. It is anticipated that the effects of climate change would further aggravate this problem. Conflicts over the distribution of freshwater are expected to increase as stakeholders want to access more groundwater to meet their growing demands. In the United States, water conflicts are settled through a litigation process. Water litigations can be expensive, protracted, and fraught with complex legal and technical difficulties. A landmark groundwater case involving Tennessee (TN) and Mississippi (MS) was recently litigated in the Supreme Court of the United States (SCOTUS). In this case, MS sued TN for stealing their groundwater and SCOTUS unanimously ruled that the water contained in the aquifer that naturally crosses the border between TN and MS is subject to equitable apportionment. This decision has significant ramifications for groundwater management as it established a precedent for resolving future interstate groundwater litigations. Although the Court has previously applied the legal doctrine of equitable apportionment to settle disputes involving surface water use, this is the first instance in which the doctrine has been applied to resolve an interstate groundwater dispute. Therefore, currently, there are little or no guidelines available for equitably distributing groundwater resources between two states. The objective of this article is to examine this historic legal dispute to fully understand the scientific justification for the judicial stances taken by the plaintiff and defendants, and the legal reasoning for the final verdict. We also discuss the challenges this ruling presents for managing interstate groundwater resources.

Mountainous zones are often characterized by complex orography and contacts between different aquifers that usually complicate the use of isotope hydrology techniques. The Apennine chain (Italy) and 10 mountain and mid-mountain areas belonging to it are the objective of this study. An original isotopic data treatment, able to identify the most probable recharge area for several springs/springs' groups/wells, has been developed. The method consists of a two-step approach: (1) the determination of the spring/wells computed isotope recharge elevation; (2) an advanced δ¹⁸O precipitation distribution model over the study area supported by statistical and GIS-based procedures implemented by two processes: first, the clipping of precipitation δ¹⁸O values (depicted from the δ¹⁸O–elevation relationships obtained for each study area) over a most probable recharge area for each analyzed spring or well and, second, the calculation of the overlapping distribution between the spring/well mean δ¹⁸O values ± σ and the precipitation δ¹⁸O content for each outcropping aquifer. A new regional δ¹⁸O gradient covering 150 km latitudinal length of central Italy has been defined. Seven LMWL and δ¹⁸O–elevation relationships able to represent the local precipitation isotopic composition have been obtained. The mean elevation of the springs and wells recharge areas have been assessed by a comparison between the obtained gradient with nine δ¹⁸O gradients available in the literature and those obtained at a local scale. The new isotopic modeling approach can stress whether the mere isotope modeling based on the stable isotope of oxygen agrees with the hydrogeological setting of the study areas.

Noble gases, oxygen-hydrogen isotope ratios, and ion compositions were measured at three sampling points (KUM, OTN, and ASO) from December 2013 to July 2021. The ³He/⁴He values at the three sampling points remained stable in the range of 3–4 Ra throughout the observation period, suggesting that the supply of deep-seated gases to the aquifer was stable. The ⁴He/²⁰Ne values of KUM and OTN indicate that the supply of surface-source fluids to the aquifer decreased relative to that of deep-seated fluids at KUM and OTN. In contrast, in the ASO site, both the surface- and deep-seated fluids supplied to the aquifer were stable. The δD–δ¹⁸O relationship indicated the supply of deep-seated water to the KUM and OTN aquifers but not to the ASO aquifer. Nevertheless, the δD–δ¹⁸O relationship remained stable throughout the observation period, suggesting that the supply of deep-seated water to the three stations was stable. The Li/Cl and 1/Cl relationships for the three sampling points were plotted within a narrow range throughout the observation period, suggesting that the groundwater recharge was stable. Neither spikes nor step changes owing to the 2016 Kumamoto earthquake were observed in any of the data. These results indicate that the KUM and OTN aquifers are constantly supplied with deep fluids from the fluid-rich zone beneath the Kumamoto region, and that only deep-seated gas was supplied to the ASO aquifer. We also confirmed that these supply conditions were unaffected by the 2016 Kumamoto earthquake or the subsequent aftershock activity.

It is suggested that in addition to seismicity deep fluid injection may cause surface uplift and subsidence in oil and gas-producing regions. This study uses the Raton Basin as an example to investigate the hydromechanical processes of surface uplift and subsidence during wastewater injection. The Raton Basin, in southern central Colorado and northern central New Mexico, has experienced wastewater injection related to coalbed methane and gas production starting in 1994. In this study, we estimate the extent and magnitude of total vertical deformation in the Raton Basin from 1994 to 2020 and incremental deformation between the years 2017 to 2020. Results indicate a modeled uplift as much as 15 cm occurring between 1994 and 2020. Between 2017 and 2020, up to 3 cm of uplift occurred, largely near the northwestern injection wells. Most modeled uplift between 1994 and 2020 occurred near the southern wells, where the greatest cumulative volume of wastewater was injected. However, modeled subsidence occurred around the southern and eastern wells between 2017 and 2020, after the rate of injection decreased. Modeling indicates that while the magnitude of modeled uplift corresponds to cumulative injection volume and maximum rate in the long-term, short-term incremental deformation (uplift or subsidence) is controlled by changes in the rate of injection. The number of yearly earthquake events follows periods of rapid modeled uplifting throughout the Basin, suggesting that measurable surface deformation may be caused by the same injection-induced pore pressure perturbations that initiate seismicity.

Random walk particle tracking (RWPT) is a discrete particle method that offers several advantages for simulating solute transport in heterogeneous geological systems. The formulation is a discrete solution to the advection-dispersion equation, yielding results that are not influenced by grid-related numerical dispersion. Numerical dispersion impacts the magnitude of concentrations and gradients obtained from classical grid-based solvers in advection-dominated problems with relatively large grid Péclet numbers. Accurate predictions of concentrations are crucial for reactive transport studies, and RWPT has been recognized for its potential benefits for this kind of application. This highlights the need for a solute transport program based on RWPT that can be seamlessly integrated with industry-standard groundwater flow models. This article presents a solute transport code that implements the RWPT method by extension of the particle tracking model MODPATH, which provides the base infrastructure for interacting with several variants of MODFLOW groundwater flow models. The implementation is achieved by developing a method for determining the exact cell-exit position of a particle undergoing simultaneous advection and dispersion, allowing for the sequential transfer of particles between flow model cells. The program is compatible with rectangular unstructured grids and integrates a module for the smoothed reconstruction of concentrations. In addition, the program incorporates parallel processing of particles using the OpenMP library, enabling faster simulations of solute transport in heterogeneous systems. Numerical test cases involving different applications in hydrogeology benchmark the RWPT model with well-known transport codes.

Laboratory experiments and numerical simulations were performed to explore the influence of intersection geometry on fluid flow and solute transport in fractures. Fractures were engraved and sealed into an acrylic plate and two orthogonal intersections with different geometry were constructed. The effects of curvature and relative shear displacement at intersections on preferential flow and solute transport were investigated. By solving the Navier–Stokes (NS) equation, the fluid mixing and solute distribution were predicted. The results showed that the geometric characteristics at the intersection have a significant effect on the preferential flow and solute distribution. The results agreed well with the experimental results, in terms of flow direction, preferential flow rate, and heterogeneous solute distribution. With an increase in curvature, the flow difference between the two outlets increases gradually. Increasing curvature can reduce the preferential flow and weaken the inhomogeneity of solute distribution. An increase of relative shear displacement decreases the pressure gradient and flow rate at the entrance of the two branch fractures, and thereby increases preferential flow and inhomogeneity of solute distribution. The results provide a basis and reference for further exploring the relationship between the geometric characteristics of fracture intersections and flow behaviors.