Hydrogeology Journal最新文献

As an important large-scale commercial grain production base in China, the Songnen Plain has a particular need for groundwater resources. Here, the groundwater-storage (GWS) changes estimated by the Gravity Recovery and Climate Experiment (GRACE) and Global Land Data Assimilation System (GLDAS) data are input to the MIKE SHE model to correct the errors of remote sensing data. Through this, the simulation of groundwater levels at the large and medium regional scales (Songnen Plain) from 2005 to 2018 was achieved. The analysis reveals that the groundwater data derived from the estimation of GRACE and GLDAS data have a strong correlation with the measured data, with a correlation coefficient of 0.82 between GRACE and measured groundwater data and a correlation coefficient of –0.76 between GLDAS and measured groundwater data. In addition, estimated groundwater data were added to the MIKE SHE model to simulate Songnen Plain groundwater levels between 2005 and 2018. The simulation results indicate that the correlation between simulated and observed groundwater level data is substantially greater than that between inverted and observed groundwater data. Over the past 15 years, the Songnen Plain’s groundwater levels have exhibited a general upward trend of ~0.028 m/year. The groundwater levels in the northeastern, central, and western portions of the Songnen Plain are falling at a rate of ~0.144 m/year, while the groundwater levels in the southern and northwestern portions of the Songnen Plain and areas near the river are rising at a rate of ~0.513 m/year.

Flooding is a recurring natural phenomenon that can have both life-giving and destructive aspects. In natural environments, floods are often an important element of the seasonal hydrologic cycle that provides water and nutrients to soil, supporting unique, rich and diverse ecosystems. However, flood events can also represent a destructive force that can endanger lives and cause significant damage in urban areas. Karst areas, in particular, are unique because of their special hydraulic characteristics in terms of flood occurrence, the dependence of ecosystems on such events, and attempts to actively store and manage floods. In this article, the hydraulic response of karst aquifers to heavy precipitation events, flood generation, and engineering interventions for flood control are discussed using several examples from karst areas in the Mediterranean region. Flooding mechanisms and regulatory structures in karst poljes are considered using several typical examples from the Dinaric mountain range. In addition, different variants of groundwater abstraction for increasing storage capacity and flood control are presented using examples from France and Montenegro. Managed aquifer recharge in karst areas and adjacent aquifers is demonstrated with examples from Jordan and Algeria. Finally, failed attempts at flood storage in karst reservoirs are presented with examples from Spain and Montenegro. These examples of flood retention in karst areas show the wide range of planning and technical measures and remind us of possible risks and failures in implementation as well as some positive and negative impacts on the environment and especially on ecosystems.

Carbonate rocks in the Mediterranean region form karst landscapes with a variety of morphological and hydrological features, and are of particular interest from a water management perspective as they represent major karst aquifers. The Mediterranean Karst Aquifer Map and Database (MEDKAM) provides a 1:5,000,000 scale map showing the distribution of carbonate and evaporite rocks that can host karst groundwater resources, with additional information on other hydrogeological settings, selected terrestrial and submarine karst springs, caves and karst groundwater-dependent ecosystems. A statistical evaluation shows that carbonate rocks cover ~39.5% of the Mediterranean region within a 250-km focus area from the coastline. North Africa has the largest continuous area of carbonate rocks, while smaller countries in the Middle East and the Dinarides have the largest proportion of carbonate rocks in relation to their total area. Carbonate rocks are also widespread in coastal areas, occurring along ~33.6% (14,000 km) of the total Mediterranean coastline, including large islands such as Crete and Mallorca, and ~25.9% (6,400 km) of the continental coastline. Two additional maps display (1) groundwater recharge, showing a climatic gradient from north to south, and (2) groundwater storage trends, indicating a mean annual karst groundwater loss from 2003 to 2020 of 436 million m³ in the 250-km area. This study quantifies the carbonate rocks in the Mediterranean region and shows their importance for groundwater resources. MEDKAM will serve as a basis for further research and improved international cooperation in karst groundwater management.

Karst aquifers can be particularly vulnerable to human activities and climate change due to their relatively high degree of connection with the surface. This study utilized an ensemble of event-based recharge calculation methods to address the problem of structural uncertainty for the example of the Western Mountain Aquifer (WMA), a Mediterranean karst aquifer located in Israel and the West Bank. Spatially distributed recharge estimates derived from the Soil and Water Assessment Tool (SWAT) and the process-based infiltration model (PIM) were compared to site-specific, empirical regression models. The SWAT and PIM mean annual recharge estimates ranged from 32–34.6% of precipitation, almost equating to the results of empirical regression models (32–36%). Future recharge predictions under the influence of climate change were quantified by parameterizing the SWAT and PIM methods with a downscaled regional climate model of Israel. SWAT predicts a 23% decrease in recharge by 2051–2070 relative to 1981–2001. In contrast, PIM shows a 9% decrease, possibly due to the representation of infiltration through preferential flow pathways and exclusion of surface runoff processes. These divergent projections underline key methodological differences in the representation of hydrological processes. Nevertheless, both methods effectively provided good estimates of groundwater recharge. The recharge rates estimated from the various methods were integrated into MODFLOW to assess their relative impacts on groundwater storage dynamics. The ensemble of MODFLOW projected groundwater storage outputs can provide guidance for sustainable groundwater management in the region.

The Grand Canyon is famous for its awe-inspiring natural wonders, including its caves. Double Bopper and Leandras caves have some of the longest passage lengths in the world and are nestled within the limestone of the Redwall Formation, featuring an intricate maze-like pattern. This study explored previous hypotheses about the formation of these caves. To simulate their development, multiple scenarios were tested utilizing the numerical model CAVE. Model simulation accuracy was evaluated through multivariate statistical analysis. The findings indicated that the intersection of faults surrounding the caves created a highly permeable zone, allowing meteoric and hypogene water to move freely, with or without a single point source of percolation. Given the uncertainty about past hydrogeologic conditions, the caves are estimated to have taken from 4 to 10 million years to develop, consistent with previous studies.

Considering the importance of characterizing groundwater flow for assessing recharge and contaminant transport, this study investigates the potential of two field methods to estimate groundwater fluxes in consolidated aquifers. To accomplish this, both the finite volume point dilution method (FVPDM) test and active distributed temperature sensing (Active-DTS) measurements were conducted in a single piezometer in a chalk aquifer. The FVPDM is a single-well tracer experiment, that provides a measurement of the groundwater flow rate across the tested piezometer. Whereas the Active-DTS method was performed by deploying a fiber-optic (FO) cable outside the piezometer within the gravel filter. The Active-DTS method provided high spatial resolution and local groundwater flux estimates along the heated section. Numerical simulations were used to assess the distortion of the groundwater flow field induced by the presence of the well, demonstrating that the groundwater flux is maximum within the well screen, where the FVPDM test was conducted. In the immediate vicinity of the well, where the heated FO cable was installed, the groundwater flux is lower, and the flow pattern consisted of converging and diverging flow lines. Therefore, the position of the heated FO cable relative to the flow direction is critical and can have a significant impact on the estimation of the groundwater flux. Thus, even if the deployment of the FO cable within the gravel pack minimizes convective effects and opens up interesting perspectives to estimate vertical heterogeneities, this approach may be limited if the position of the FO cable relative to the flow direction is not well known.

The hydrogeological system of the Bajos Submeridionales (BBSS), a large plain in Argentina, remains insufficiently understood. The BBSS is located in the distal part of one of the largest fluvial megafans in the Gran Chaco Plain, South America. The BBSS is sparsely populated and frequently affected by extreme drought and flood events that cause severe problems to communities and economic production. This research aims to improve the current hydrogeologic understanding of the system through the development of the first integrated hydrogeological model for the region. The BBSS hydrogeological system exhibits a relatively simple hydraulic behavior at a regional scale. The definitions of four hydrogeological units (HU) were based on the simplification of the sedimentary column for the area, representing the fundamental characteristics of the dynamics of groundwater flows, their interconnections and the interactions with surface-water bodies and the atmosphere through direct recharge. Due to the lack of available transient data, the hydrogeological conceptual model was numerically tested under a steady-state flow regime. The numerical model was instrumental to test the plausibility of the proposed conceptual model and evaluate the water balance components for the entire aquifer system. The numerical model highlighted the role of stream/aquifer interaction as a primary discharge mechanism and the occurrence of flow exchanges between HUs. A newly installed groundwater monitolring network will support future transient simulations to investigate the temporal evolution of the system and explore management interventions to achieve environmental sustainability criteria.

Water security for regions that depend on mountain runoff is threatened by climate change and upstream impacts. To build resilience against water scarcity, groundwater may be an emergency or alternative water source, providing a temporary solution in the event of upstream contamination or during drought. Across western North America, buried-valley aquifers are a viable emergency water source. In Alberta, Canada, buried-valley aquifers supply domestic users; however, little is known about their capacity to supply larger water volumes. Using a regional groundwater model, this study investigated the capacity for buried-valley aquifers to supply water to the City of Edmonton, Alberta (population of 1 million) in an emergency scenario where the principal river water source was unusable. The numerical groundwater model has complex hydrostratigraphy, including glacial deposits, dipping bedrock units, and recently mapped Onoway, Beverly, and Stony buried-valley aquifers. Pumping rates varying from 10 to 375 ML/day were assessed for durations of 3, 30, and 365 days, corresponding to hypothetical response times for a range of emergencies. Although none of the aquifers could supply a sufficient volume of water for no change in service, it is possible that up to 190 ML/day could be sourced from groundwater for a period of 1 year. To achieve high rates of pumping, up to 13 production wells would be required in a buried-valley aquifer. The unique hydrogeological responses to hypothetical pumping scenarios also demonstrate the hydrogeology of buried-valley aquifers from a more holistic viewpoint as part of a regional groundwater flow system.

The Mississippi Embayment aquifer system (MEAS) and the Coastal Lowlands aquifer system (CLAS) are two principal aquifers in the US Gulf Coastal Plain. Despite their importance to the region, a comprehensive characterization of these aquifers has not been achieved yet. In this study, the horizon-assisted lithologic modeling (HALM) method is introduced to integrate horizon structures and well log data for aquifer characterization. By employing horizon restorations, the HALM method proves to be versatile in incorporating various geologic features into lithologic models. The HALM method was applied to characterize both the MEAS and the CLAS in the Louisiana and southwestern Mississippi regions. The resulting large-scale high-resolution hydrostratigraphic model provides a highly accurate representation of aquifer structures in regionally extensive hydrogeologic units, including synclines, angular unconformities, and faulting. Notably, the model highlights the presence of surficial coarse sediments, indicating significant groundwater recharge zones for the Southern Hills aquifer system, the Chicot aquifer, and the Sparta aquifer. Additionally, the Mississippi River alluvial aquifer and the Chicot aquifer are found to be thick and shallow, making them easily accessible for irrigation purposes. Furthermore, the model reveals significant connections between rivers and alluvial aquifers in northern Louisiana, with reduced river–aquifer contact as one approaches the Gulf of Mexico. Comparing the two aquifer systems, the CLAS exhibits relatively thick and extensive aquifers compared to the MEAS. This study not only contributes to advancements in geologic modeling techniques but also enhances the understanding of regional hydrogeology in the US Gulf Coastal Plain.

Investigations focusing on the impacts of mining on groundwater systems typically provide a qualitative analysis of groundwater flow and chemistry, whereas relatively few studies quantitatively analyze groundwater temperature perturbations induced by mining. This study aims to identify the hydrogeological mechanism responsible for changes to groundwater temperature associated with longwall coal mining. Here, the extreme gradient boosting (XGBoost) method was used to construct three models at different phases of mining disturbance to identify the factors governing groundwater temperature dynamics: (1) a pre-disturbance model; (2) an in-disturbance model; and (3) a post-disturbance model. The feature relative importance (FRI) of input variables contributing to groundwater temperature dynamics was quantified for a long-term groundwater monitoring dataset collected from the Ningtiaota Coalfield, Ordos Basin, China. Pre-mining disturbance groundwater temperatures were stable, and the XGBoost model identified the groundwater level of the respective monitoring wells to be the greatest predictor for variation in groundwater temperature. During mining disturbance, proximal monitoring wells exhibited a decline in groundwater temperature, where the FRI of groundwater temperature in an upgradient monitoring well increased by 151–662% relative to the pre-mining disturbance model. The monitoring of aquifer properties and stable isotope composition of groundwaters provided additional evidence to suggest groundwater temperature decreases were associated with increased recharge contributions from surficial Quaternary aquifers. Post-mining disturbance, groundwater temperature and aquifer specific storage demonstrated recovered to pre-mining conditions. This study provides insights into mining-induced groundwater temperature dynamics as a result of changes to hydraulic connection between aquifers.