Hydrogeology Journal最新文献

An analysis of expert perspectives on groundwater governance arrangements in South Africa is presented, particularly those arrangements that are pertinent to the complex and socially and ecologically significant implications of exploiting unconventional oil and gas (UOG). The paper presents a detailed assessment of literature on groundwater governance research, the findings of which are applied as a framework for a series of expert interviews, comprising hydrogeologists, lawyers, engineers, and governance specialists. This methodological approach was adopted as a means to enable an analysis of opinions on the current situation of groundwater governance in South Africa and how fit-for-purpose this is for managing the exploitation of UOG. The analysis was also informed by observation of participants at several relevant decision-making and stakeholder events. Whilst the findings indicated a generally positive evaluation of the initial steps taken to assess UOG impacts and engage relevant communities, recurrent criticisms also are featured across the interviews. Key implications arising from the research include: (1) the need for continued stakeholder engagement, and government follow-through on the outcomes of these processes, (2) the necessity for detailed groundwater-specific regulations to be drafted at the earliest opportunity, to ensure that the energy policy vacuum does not have a negative knock-on effect for effective groundwater management, and (3) the prevalence of significant governance gaps, particularly regarding regulatory and institutional capacity, and the need for continued development of a functional network of institutions to effectively manage UOG exploitation alongside groundwater resources.

In the Middle East and North Africa (MENA) area, groundwater overdraft has negative impacts and ramifications for not only the groundwater resources themselves but also for other environmental factors and for socio-economic continuity. Jordan is already facing negative consequences, without enough time for reversing the deteriorating situation. Exploitation of nonrenewable groundwater resources worldwide has been driven by increasing supply to household, industrial and agricultural sectors without adequately taking into account social, economic, ecological, geological, environmental and ethical considerations. This study analyses the development of the nonrenewable groundwater resources in Jordan and its consequences, to serve as a case study for what is happening in the MENA area. The consequences of such overexploitation in Jordan can be summarized as follows: declining groundwater levels; mobilization of salt-water bodies; ceasing or decreasing spring discharge; declining biodiversity with many ecological, environmental and socio-economic consequences leading to increasing unemployment and poverty; and land instability in the form of land subsidence and enhanced risk of earthquakes. The study concludes that the impacts and ramifications of overexploiting nonrenewable groundwater resources are generally irreversible, and the measures needed to stop the deteriorating state of groundwater resources are unavailable or unlikely to be implemented within the coming two decades. The question that remains is whether and when human actions can change from those of conquerors, invaders, and raiders to those of friends and lovers of the Earth.

Underground dams are a technology for artificially increasing existing groundwater resources. They modify the natural groundwater flow in aquifers and, typically, cause hydraulic heads to rise upstream and fall downstream of the dam. However, such modifications must be defined to forecast their environmental, economic and/or social impacts. A steady-state semianalytical solution is proposed for evaluating the two-dimensional distribution of hydraulic head caused by an underground dam fully penetrating a homogeneous and inclined aquifer. The dam is impermeable, of rectangular shape, and its length concerns a limited part of the aquifer width. The developed solution is based on the method of fundamental solutions. Analysis of the semianalytical solution included sensitivity tests and a satisfactory comparison with numerical modelling. Dimensionless graphs relating the dam geometry to maximum hydraulic-head variations upstream and downstream of the dam are given. The proposed solution was applied at two field sites, giving satisfactory results. A semianalytical solution is also developed for an artificial recharge area and/or a pumping well near the underground dam. Interestingly, in the case of highly permeable aquifers, the increase in hydraulic head created by the dam may be much higher than that created by managed aquifer recharge (MAR), despite high injected flux. These semianalytical solutions will be useful applications for assessing the long-term spatial distribution of hydraulic head induced by underground dams, or for testing the combination of dams with pumping wells or MAR technology. They are intended to guide the design of such structures, especially to quickly test various configurations.

Groundwater is an important water source in Arizona, accounting for about 41% of water use in this mostly arid-to-semiarid state in the southwestern United States, and the availability of groundwater resources in the state is a concern. To provide accessible information from depth-to-groundwater data, a series of web-based interactive maps were developed, called the Arizona Groundwater Explorer (AGEx). Scripts were written to harmonize and synthesize groundwater datasets from the two largest publicly available sources, subset these data to address different groundwater availability questions, and display the results in online, interactive maps. The combined dataset contained 1,820,122 depth-to-groundwater measurements from 1891 through 2022 from 41,918 wells in Arizona. Data views are provided for 20 topics, including recent (2020 or later) depth to groundwater (4,569 wells), historical (pre-1950) depth to groundwater (4,287 wells), wells with long-term (≥50 years) records (1,183 wells), wells with recent groundwater level decline (277 wells), wells with recent groundwater level rise (120 wells), and linear trends in groundwater levels over ten 10-year periods (number of wells ranging from 341 in 1978–1987 to 1,208 in 2003–2012), among others. With ongoing drought in the region resulting in declining surface-water supplies in Arizona, groundwater may play an even larger role in satisfying water needs in the state. The AGEx series of maps provides a nonspecialist audience with an improved understanding of historical, current, and changes in groundwater levels in Arizona.

Understanding and quantifying the flow process at fracture intersections is critical for the accurate modeling of field-scale discrete fracture networks (DFNs) but remains challenging. Particularly, the geometric features of the inflection points inside the intersection are usually ignored, limiting insight into the flow behavior at the intersection. To fill this knowledge gap, the effect of the inflection curvature at intersections was investigated based on direct numerical simulations by solving Navier-Stokes equations. The inflection points at the intersection were classified as α and β, corresponding to the radii of curvature R_α and R_β, respectively. The effect of R_α, R_β on flow redistribution and head loss was systematically analyzed and the sensitivity to flow nonlinearity was determined by the Morris method. The results demonstrated that the inflection curvature of the intersection has a significant effect on head loss but a negligible effect on flow redistribution. With the increase of curvature radius, the flow nonlinearity caused by inflection β enhances and that caused by α diminishes. Nonlinear flow is more sensitive to variations in R_β than R_α. The effect of intersection geometry diminishes with the decrease of hydraulic gradient or the increase of distance from the intersection. Further, the critical distance of the intersection’s interference range was assessed by considering different indicators. The results can provide a reference for parameter selection and calculation simplification in DFN modeling.

Groundwater is present at shallow depth under many coastal low-lying cities. Despite the importance of protecting coastal urbanised areas from flooding and climate-change-induced sea-level rise, the effects of shallow groundwater fluctuations are rarely investigated. The aim of this study was to determine characteristics of shallow groundwater, including spatial and temporal trends in depths to groundwater and their relationship to natural and anthropogenic stressors. The study uses depth to groundwater measurements from a uniquely extensive and densely spaced monitoring network in Ōtautahi/Christchurch, New Zealand. Data-driven analysis approaches were applied, including spatial interpolation, autocorrelation, clustering, cross-correlation and trend analysis. These approaches are not commonly applied for groundwater assessments despite the potential for them to provide insights and information for city-wide systems. The comprehensive approach revealed discernible clusters and trends within the dataset. Responses to stresses such as rainfall events and stream flow were successfully classified using clustering analysis. The time series analysis indicated that in areas of shallow groundwater, low variation in levels occurred and this was also found using clustering. However, attributing some clusters to specific hydrogeological attributes or stressors posed challenges. The primary feature in hydrograph classification proved to be the proximity to tidal rivers and their correlation with tidal signals. These results highlight the value of using large datasets to characterise spatial and temporal variability of shallow groundwater in urban coastal settings and to assist with monitoring infrastructure planning in the face of future climate-change hazards.

The Cambodia-Mekong River Delta Aquifer, a vital transboundary aquifer in the Lower Mekong Region of Southeast Asia, faces escalating challenges due to excessive groundwater extraction for agriculture and domestic purposes. In response, this study utilizes the Gravity Recovery and Climate Experiment (GRACE) satellite estimates, combined with land-surface-model and remote-sensing datasets to estimate groundwater storage anomalies (GWSA) across the aquifer where traditional monitoring is limited. The study further evaluates the consistency of GRACE-derived data in comparison to both localized in situ measurements and a global-scale hydrological model. Additionally, the spatio-temporal trends in groundwater depletion over a 14-year span (2003–2016) were mapped. The results reveal a good agreement between GRACE-derived GWSA, PC-Raster Global Water Balance (PCR-GLOBWB) model outputs, and observed in situ measurements, thereby underscoring the pivotal role of satellite observations in comprehensively assessing groundwater resources within the aquifer. The findings expose a concerning downward trend, with groundwater storage declining at a rate of ~0.68 cm/year, resulting in a total volume loss of 18.28 km³ over the 14-year span. Notably, the depletion rate is higher in the coastal regions of the Mekong Delta and certain areas within the Tonle Sap Basin. Discrepancies between GRACE and observed GWSA are attributed to multiple factors, including the absence of local signals, intricate hydrogeological dynamics, limitations in specific yield and storage estimations, and the uneven distribution of monitoring wells in the region. This research emphasizes the potential of GRACE estimates to supplement in situ observations on a regional scale, establishing a critical foundation for transboundary groundwater management strategies.