Hydrogeology Journal最新文献

Scarce rainfall and strong evaporation add complexities to estimating groundwater recharge in arid and semiarid regions. There are still many gaps in the understanding of how soil water near the ground surface interacts with the atmosphere, which increases the difficulties of determining the contribution of rainfall to groundwater in these regions. This study used a weighing lysimeter to observe the potential recharge over a 1-year period in the Mu Us Desert, northwest China. The observed data were used to explore the infiltration processes and to quantify recharge. The results show: (1) no potential recharge can be observed if the rainfall is less than 12.3 mm/day during the experimental period. The observed annual potential recharge was 29.3 mm, which accounted for 10% of the annual rainfall. (2) The threshold of soil-water content for potential recharge was determined, such that when the average soil moisture along the soil profile (0–100 cm) is larger than 0.12 cm³/cm³, the potential recharge can be observed. (3) The empirical weight function (Poisson distribution) method performed well in the estimation of recharge compared to the observed lysimeter data. In addition, the parameter γ of the Poisson distribution has a linear relationship with the average soil-water content along the soil profile. These findings can help researchers understand recharge, which has significance in groundwater resource management.

Heihe River is the second largest inland river in China, but groundwater is the main source of water in the middle reaches of the Heihe River Basin (HRB). The middle reaches of HRB consists of Zhangye and Jiuquan basins. In view of deficiencies in the groundwater exploration techniques, methods, and accuracy associated with previous studies in the HRB, this study used stratified groundwater exploration (monitoring and sampling) techniques to identify the groundwater flow systems. Three fields were considered—groundwater flow dynamics, temperature, and chemical. The results show that stratified groundwater-level monitoring technology can be used to quickly identify groundwater recharge and discharge areas. The main groundwater recharge area in the HRB’s middle reaches is in the piedmont plain, and most of the rest of this middle basin comprises groundwater runoff areas and discharge areas. Shallow groundwater temperatures (average and variation) reflect the characteristics of groundwater recharge, runoff, and discharge. The shallow groundwater temperature gradually increased from the recharge area to the discharge area, and the temperature annual variation tended to be greatest in the central area. Along the direction of groundwater flow, the δD content of shallow groundwater in the HRB’s middle reaches initially increased and then decreased, and the δD content of groundwater in the vertical direction decreased gradually from shallow to deep. The surface-water/groundwater exchange in the central Zhangye Basin mainly occurred in the shallow areas, within 200 m depth. Thus, stratified groundwater exploration technology is helpful for identifying groundwater flow systems in inland arid basins.

To achieve its ambitious plans to reclaim its deserts through mega projects, Egypt is heavily relying on fossil or little-recharged groundwater. This article revisits the results and methodologies of the studies conducted over the last two decades on groundwater management and uses in the Western Desert. Most previous studies aimed at simulating different groundwater abstraction scenarios by modeling local areas in aquifer systems, but with poor definitions of boundary conditions and limited historical data. Studies were constrained by the unavailability of data, access difficulties, and high collection costs in desert lands. Thus, to propose reliable sustainable groundwater resources development plans and recommendations for future protection strategies, an open-access monitoring network representing regional aquifers is needed. More investigations based on extensive field visits are essential to monitor environmental, economic, and social conditions, identify constraints, and learn lessons for reclaiming desert lands. Moreover, this review highlighted the need to frame a rational strategy for the long-term sustainable exploitation of non-renewable groundwater in the aquifer systems of Egypt and develop an appropriate exit strategy for desert communities in case of serious water resource depletion.

Depth-wise variation in hydraulic structures of volcanic aquifers is rarely investigated when compared to basement and other rocks. A comprehensive dataset is presented here on the hydraulic properties of volcanic aquifers from a large igneous province in Africa. Age- and depth-wise variation in transmissivity (T), yield (Q), hydraulic conductivity (K) and specific capacity (S_c) of volcanic aquifers and water wells were systematically examined for stratigraphic units of various ages (Eocene to Quaternary Period) and well depth (18–882 m). The T ranges from 0.02 to 9,830 m²/day. There is a good correlation between the age of the emplacement of the rocks and their hydraulic properties. The oldest (Eocene) basalts show lower productivity (T, K and Q) when compared to the youngest (Quaternary) basalts. There is no statistically significant depth-wise variation of T, K and Q when one single formation is investigated. The insights gained from the analysis show that increasing the depth of drilling does not necessarily increase aquifer yields and can inform global-scale groundwater modelling efforts. The data challenge the widely held assumption that K and Q decrease with depth. Unlike basement rocks, volcanic rocks show no statistically significant change in hydraulic properties along its depth profile to the depth of 900 m.

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.