Karst Aquifer Research Articles

Impact scenarios on groundwater availability of southern Italy by joint application of regional climate models (RCMs) and meteorological time series.

Nowadays the phenomenon of global warming is unequivocal, as confirmed by the latest reports of the IPCC and studies of the climate-change impacts on ecosystems, global economy, and populations. The effect of climate change on groundwater is a very relevant task especially for regions dependent chiefly on groundwater availability, as for the southern Italy. In such a territorial framework, to achieve a detailed hydro-climatological characterization, an Ensemble of 15 RCMs (E15) derived from the EURO-CORDEX project was analyzed considering two IPCC Representative Concentration Pathways (RCP4.5 and RCP8.5). The E15 was calibrated over the period (1950-1996) by a statistical comparison with data observed by the regional meteorological network managed by the former National Hydrological Service (SIMN), Department of Naples. The effects of climate change on air temperature (T), precipitation (P) and, consequently, on actual evapotranspiration (ETR) and effective precipitation Pe (P - ETR) were analyzed until 2100. The latter was considered as a proxy of groundwater recharge of the principal aquifer systems, represented chiefly by the karst aquifers. As a principal result, it was found that the E15 is basically able to reproduce the observed annual precipitation (OBSP) and mean annual air temperature (OBST), being characterized by a very similar frequency distribution. Accordingly, an inferential statistical approach was performed for calibrating E15 precipitation (E15P) and air temperature (E15T) based on the compensation of the difference with OBSP (+ 7%) and OBST (-16%). The E15 projects a reduction in precipitation and an increase in air temperature under both RCPs, with a divergence point between the two scenarios occurring by about 2040. As a principal result, Pe shows declining trends for both RCP scenarios, reaching a decrease of the 11-yrs moving average down to -20%, for RCP4.5, and -50%, for RCP8.5, even if characterized by relevant inter-annual fluctuations.

Assessment of diffusive recharge at regional scale in karst systems, Amazon basin, Ecuador

Karst systems play a crucial role in drinking water supply and biodiversity. Therefore, their comprehensive characterization of their recharge mechanisms is essential for safeguard water resource quality and sustainable management. This study utilizes the open-access thematic cartography of Ecuador to analyze the lithological, geomorphological, and hydrographic boundaries of groundwater karst systems. Then, employing the APLIS method, the diffusive recharge for each system is calculated. As a result, five hydrogeological karst systems and twelve small isolated karst bodies were delineated within the Amazon Region of Ecuador, collectively occupying a total area of 11112 km2. The effective infiltration of precipitation within these systems was found to vary between 11.11% and 77.11%, with a predominant low infiltration range (20%-40%) covering 48% of the karst area. One of the multiple parameters used in water balance calculations is defined by this research, serving as the initial step in creating conceptual models for evaluating karst aquifer systems in Ecuador from a hydrological perspective. The findings not only offer insights into the vulnerability and characteristics of these systems but also establish the foundation for informed decision-making in sustainable groundwater resource management and protection efforts.

Groundwater Model for Karst and Pelitic Aquifer Systems from a Semi-Arid Region Under Climate Change Scenarios: A Case Study in the Vieira River Watershed, Brazil

Water scarcity is a global issue, especially in semi-arid and arid regions where precipitation is irregularly distributed over time and space. Predicting groundwater flow in heterogeneous karst terrains, which are essential water sources, presents a significant challenge. This article integrates geology, hydrology, and water monitoring to develop a pioneering conceptual and numerical model of groundwater flow in the Montes Claros Region (Vieira River Watershed, Brazil). This model was evaluated under various climate change scenarios, considering changes in rainfall, groundwater consumption, and population growth over the current century. The results indicate that a decline in water table levels is inevitable, primarily driven by population growth and high pumping rates rather than rainfall fluctuations. This underscores the urgent need for improved monitoring, model upgrading, and more importantly, targeted water resource management for Montes Claros.

Development of a hybrid Karst Aquifer Vulnerability map by using geospatial and statistical tools. The case study of Ziria aquifer in Northern Peloponnese

Aquifer vulnerability assessment constitutes a crucial tool for the protection and sustainable management of groundwater resources, particularly in complex karst aquifers. This study conducted a detailed comparative analysis of two tailored and widely used vulnerability mapping methodologies, COP and PaPRIKa, to evaluate their performance within a Mediterranean karst groundwater system. The methods were employed for the development of a hybrid vulnerability map after geospatial and statistical analysis. Both COP and PaPRIKa were applied using a combination of geological, hydrological, and geomorphological aquifer characteristics that can potentially influence its vulnerability to contamination. While COP predominantly assigned Low and Very Low vulnerability values across the study area, PaPRIKa identified the Moderate class as dominant, suggesting a finer sensitivity to karst-specific features. To address potential biases in PaPRIKa, a single-parameter sensitivity analysis was performed, leading to adjusted weights and the development of a modified version, PaPRIKa-Mod. A quantitative comparison of all three methods highlighted the varying degrees of consensus and discord, with PaPRIKa and its modification showing the highest consistency, suggesting robust methodological integrity. Conversely, the comparison of COP with either version of PaPRIKa revealed a lesser yet notable concordance, underscoring their capacity to be integrated and their potential to complement each other in vulnerability assessments. Finally, a hybrid vulnerability map was developed from the integration of similar vulnerability classes, attributing the most vulnerable setting prevailing across all methods. The methodological approach that was followed is adaptable and can provide significant insights for vulnerability estimations across different regions and methodological concepts.

Modelling hazards impacting the flow regime in the Hranice Karst due to the proposed Skalička Dam

Abstract. This study examines the hydrogeological hazard associated with the construction of the proposed Skalička Dam in the vicinity of the Hranice Karst. Prompted by the catastrophic regional floods in 1997 and 2010, the design of the dam aims to mitigate floods along the Bečva River downstream of the reservoir. However, concerns have been raised regarding the potential disturbance of the natural groundwater regime in the Hranice Karst and the source of mineral waters for the Teplice spa. This is due in particular to the dam's location in an area with limestone outcrops potentially susceptible to surface-water infiltration. Previous studies have also highlighted the strong correlation between the water level in the Bečva River and the water level in karst formations such as the Hranice Abyss, Zbrašov Aragonite Caves, and other caves in the locality. To address these concerns, a nonlinear reservoir-pipe groundwater flow model was employed to simulate the behaviour of the Hranice Karst aquifer and specifically the effects of the dam reservoir's impoundment. The study concluded that the lateral variant of the dam would have a practically negligible impact on the karst water system, with the rise in water level being only a few centimetres. The through-flow variant was found to have a more significant potential impact on water levels and the outflow of mineral water to the spa, with a piezometric rise of about 1 m and an increase in the karst water discharge to the Bečva River of more than 50 %. Based on these results, recommendations for further investigations concerning the design of the dam and its eventual construction have been formulated to reduce geological uncertainties and to minimize the potential impact of the hydraulic scheme on the hydrogeology of the karstic system.

Evaluation of stormwater runoff pollutant distributions combined with land-use information in a regional karst aquifer in Texas, USA.

Fast urbanization can result in significant stormwater runoff pollution due to changes in land use. A 3-year study on the distribution and temporal variations of urban water pollutants in stormwater runoff was conducted, with a specific focus on the influence of land-use patterns in the recharge zone of a regional karst aquifer in Texas (Edwards Aquifer). The presence and concentration of various water pollutants including total suspended solids (TSS), total dissolved solids (TDS), nutrients (nitrite, nitrate, ammonia and phosphate), total carbon (TC) and total organic carbon (TOC), oil and grease (O&G), and eight heavy metals (Fe, Mg, Cu, Pb, Zn, Ni, Cr, Cd) were measured in stormwater samples collected from three bioswales. Results show that average TSS in site S1 (598.87mg/L) and S2 (628.69mg/L), COD in site S1 (103.97mg/L), phosphate in sites S1 (1.44mg/L) and S3 (0.65mg/L), and O&G (ranging from 50.63 to 84.32mg/L) in all three sites surpassed the national average (NSQD). While residential areas were identified as the main sources of nutrients, roads and parking lots were associated with heavy metals. Temporal variations indicated the effect of antecedent dry days on the concentrations of TSS and phosphate. Growing seasons as well as pet feces were associated with elevated nitrate concentrations in residential areas. Organic carbon was found overall higher during warmer months, while heavy metals during cooler months. The study also identified specific land-use practices that can be enhanced to mitigate stormwater pollution, such as the implementation of permeable pavements, rain gardens, and stricter waste disposal regulations. The results of this study offer valuable insights for enhancing stormwater management strategies to better mitigate stormwater pollution in urban regions.

Best Management Practices to Mitigate Contamination of Karstic Aquifers from Emergency Fire-Control Runoff

We propose best management practices to increase karstic aquifer drinking water supplies’ resilience to potential hazardous material impacts where first responders and public safety officials suspect emergency firefighting runoff has entered the subsurface in the aquifer recharge zone. Karstic aquifers are unique because of their direct openings to the land’s surface, which allows contaminants in runoff or other surface waters to rapidly enter the subsurface and impact aquifer water quality. In the United States, 20% of the land surface is karst, and about a third of the groundwater used for drinking comes from karstic aquifers. Proposed best management practices emphasize on-site, real-time evaluation of the transport and fate of HAZMAT that may enter the subsurface and focus on water quality sampling, runoff and groundwater flow modeling, nontoxic dye tracing, and related studies for use in planning before and during an event and after emergency response has ended. We recommend best management practices for evidence-based screening of high-risk sites to facilitate placement of hazardous material sampling devices and emergency responder deployment. The best management practices, tools, curricula, and training described combine with earlier work by the authors to provide a comprehensive menu of actions to (1) help first responders prevent or limit flushing of hazardous material into a karstic aquifer; (2) help emergency management officials understand the consequences of contamination and issue data-driven geographically focused health and safety risk communications; and (3) help provide health and safety officials with relevant science- and data-based information that can help mitigate human and environmental health risks.

Saltwater intrusion simulations in coastal karstic aquifers related to climate change scenarios

Coastal zones are crucial ecosystems supporting significant biodiversity and pertinent socio-economic activities. However, anthropogenic development contributes to socio-environmental complexities, particularly public water supply threats caused by climate change. This research presents a case study on the north-western coast of Yucatan, Mexico, which models potential saltwater intrusion in groundwater for multiple projections of sea level rise and recharge change due to climate change and its implications for the public water supply of the regional population and ecosystem. For this purpose, a previously calibrated and validated numerical model is employed, adapting its boundary conditions, keeping its calibrated hydrogeologic parameters, and considering the 2040 and 2100 climate change projections. Simulation results show that under these projections, significant saltwater intrusion may occur, reducing freshwater thickness due to increased salinity in groundwater and a loss of freshwater sources resulting from brackish-saline wedge intrusion. These scenarios are of particular concern as freshwater in this coastal region is the main source for public water supply and for freshwater input in coastal ecosystems. Moreover, this study underscores the susceptibility of karstic aquifers to salinization, especially in the face of rising sea levels, given their unique hydrogeological characteristics and substantial responsiveness to marine forcings. In spite of the uncertainties in global climate change predictions, this study enhances our understanding of the dynamics of these unique aquifers, and presents future saltwater intrusion projections that offer valuable technical insights to design and implement pertinent and resilient coastal aquifer management strategies.

Co-tracing of groundwater emerging and conventional contaminants in karst area of Southwest China: Distribution, source, and source-specific health risks

Groundwater pollution, especially the co-contamination of emerging contaminants (ECs) and conventional contaminants, is increasingly recognized as a critical global concern. Karst aquifers are found throughout the world, providing critical water sources and sustaining rivers and ecosystems, and are particularly vulnerable to pollution. In this study, the characteristics of the contamination, potential sources, and source-specific health risks related to ECs and trace elements (TEs) in groundwater were investigated in Guiyang (a typical karst city in southwest China). The distribution of TEs followed a descending pattern from urban to suburban to rural areas. Interestingly, the median concentrations (217 ng/L) of Caffeine (CAF) in rural areas surpassed those in urban areas (145 ng/L) and even exceeded these in densely populated areas. Additionally, ECs and TEs in groundwater are significantly influenced by population density and land use types within a 1000-meter buffer zone around the sampling sites. Hierarchical cluster analysis and positive matrix factorization suggested that five principal sources of contamination were identified: domestic wastewater (29.7 %), industrial production (25.2 %), agricultural activities (16.3 %), natural and industrial sources (14.9 %), and pharmaceuticals (13.9 %). Monte Carlo simulations revealed that the non-carcinogenic risks to children in urban areas are significant, with 30.0 % of these risks exceeding the safety threshold. Source-specific health risk assessments indicated that industrial production is the primary source of risk. Furthermore, this study introduces a co-tracing method to trace the sources of groundwater contamination in karst systems. The co-tracing method based on the ECs and TEs allows for a deeper understanding of contaminant transfer and its fate in karst groundwater.

Sinkhole formation induced by descending groundwater in a karst aquifer near a limestone quarry

Sinkhole formation induced by descending groundwater in a karst aquifer near a limestone quarry

Detecting active sinkholes through combination of morphometric-cluster assessment and deformation precursors

Sinkhole hazards pose considerable challenges in the west-central region of Texas. This study integrates multisource datasets and innovative techniques to detect early sinkhole development and identify the processes governing their formation. The techniques employed encompass feature extraction, cluster analysis, and deformation process monitoring. Potential sinkholes were initially mapped using high-resolution elevation data, and a circularity index (CI) threshold value of 0.85 was applied to filter out depressions with noncircular shapes. Subsequently, Persistent Scatterer Interferometry (PSInSAR) followed by the Getis-Ord Gi* statistic methods were used to identify statistically significant subsidence clusters with rates of <−2 mm/yr, indicating active sinkhole formation. The findings reveal the following: (1) surface deformation analysis revealed significant subsidence hotspots, particularly in areas underlain by units containing significant sequences of evaporites, which nominally belong to the Clear Fork Group and the Blaine Formation, compared with those dominated by carbonates; (2) potential sinkholes are undergoing displacement up to a rate of −11.31 mm/yr, and (3) extreme groundwater pumping of karst aquifers and the subsequent decline in groundwater levels are found to be the leading causes of the susceptibility of the region to sinkhole hazards. In such cases, the decline of the water table deprives the overlying bedrock of buoyant support provided by the groundwater in the cavity. The bedrock will undergo sagging subsidence under the influence of gravity and eventually form a sinkhole. Extensive oil and gas activity in the study area, including extreme withdrawal rates and the injection of fluids associated with the activity, are other potential causes of the observed sinkhole susceptibility in several parts of the study area. This study underscores the importance of understanding the geologic, hydrologic, and anthropogenic factors driving sinkhole hazards for effective mitigation strategies to protect public safety, infrastructure, and the environment.

Hydrogeological and historical aspects of the water supply of Benevento town since Roman times

The research analyses the historical evolution of the water supply systems of the city of Benevento (southern Italy) during centuries. We focused on three main historical periods, namely the Roman, Lombard and Papal times, and the recent-present times. During this long historical time, the water supply amount and quality have changed many times, and this has probably affected the well-being and growth of the city. The best water quality characterized the Roman times, when large karst springs were tapped, feeding the town for centuries. In this period, the town experienced the largest population expansion. On the other hand, the most depressed period was the Papal times, coinciding with the isolation of the city, as it was an enclave of the Pontifical State. During this period, the water supply from external sources was not guaranteed and therefore it primarily derived from the local, low-quality water resources. Only after the unification of Italy, and also after the Second World War, the water supply systems have been improved, and new aqueducts have brought again high-quality waters to Benevento coming from karst aquifers. Nowadays, the drinking water management of Benevento is still a matter of debate. In the near future, the water from a dam-reservoir (Campolattaro dam, Tammaro River) will be exploited to guarantee the water needs of the city, and water-supply systems will undergo further changes . The knowledge about the historical evolution of the water supply of Benevento represents an essential requirement for consciously analyzing the future planning and management of water resources.

Delineation of the Hydrogeological Functioning of a Karst Aquifer System Using a Combination of Environmental Isotopes and Artificial Tracers: The Case of the Sierra Seca Range (Andalucía, Spain)

The Sierra Seca aquifer system is located in the northeast (NE) of the province of Granada, in the Prebetic Domain (Betic Cordillera). It is composed of different aquifer units hosted in the Lower Cretaceous and Upper Cretaceous limestones. The two aquifers are separated by a low permeability marl layer, which effectively acts as a barrier between them. To outline the behavior of the hydrogeological system, 407 samples of precipitation and 67 samples of groundwater were obtained from May 2020 to Oct. 2022 and isotopically (δ18O and δ2H) analyzed. For the estimation of the recharge elevation, a new methodology has been applied to estimate the isotopic content of recharge as a function of precipitation. This allowed the evaluation of the vertical gradient of both precipitation (∇Zδ18OP=−2.9 ‰/km) and aquifer recharge (−4.4 ‰/km≤∇Zδ18OR≤−2.9 ‰/km). Therefore, estimating (1) the recharge zone elevation associated with the aquifer system, which is comprised between 1500 and 1700 m a.s.l., and (2) the transit time of recharge to reach the outflow point of the aquifer system, which varies between 4 and 5 months, is possible. Additionally, three tracer tests were conducted to outline the hydrologic connection between the recharge and discharge zones of the aquifer system. The results show that the Fuente Alta spring drains the limestones of the Lower Cretaceous, while La Natividad spring does the same with the limestones of the Upper Cretaceous. In the case of the Enmedio spring, groundwater discharge is related to infiltration through the streambed of the watercourse fed by the Fuente Alta spring.

Hydraulic impact of pressure transients from water conveyance tunnel on the complex hydrogeological system: A case study HPP Pirot, Serbia

Hydraulic tunnels, integral components of hydropower plant (HPP) systems, traversing diverse rock masses, pose challenges for long-term operation. The study’s main goal was to investigate how hydraulic transients originating from the headrace tunnel transfer through the concrete lining and manifest in surrounding aquifer systems. In this experimental study at the water pressure tunnel of HPP Pirot (Serbia), a novel monitoring approach was employed. The internal piezometers with highly sensitive probes are distributed strategically along the tunnel in different geological environments. This approach involved monitoring of water pressure in the surrounding rock masses and observing the impact of hydraulic transients generated by HPP operation. A comprehensive analysis of monitoring data, incorporating ordinal and partial correlations and considering geological features, provides a profound understanding of groundwater dynamics, pressure transient phenomena, and hydrogeological characterization during HPP operation. The study highlights the complex and spatially diverse hydrogeological environment, emphasizing the varying reactivity of pore pressure during HPP operation, particularly concerning Water Mass Oscillations (WMO). Reactive piezometers near the surge tank demonstrate significant pressure variations, while those located further away display synchronous pressure changes with reduced amplitudes. Schematic hydrogeological models have been created based on the hydraulic impacts of HPPs in different geological environments along the tunnel route. The water pressure response enabled aquifer characterization of (1) a thin-layered, low-fissured aquifer closely related to the reservoir, with low influence on WMO transients; (2) a low-fissured, compartment aquifer or non-aquifer with minimal to no influence on WMO transients; (3) a well-structured karst aquifer system influenced by WMO transients; (4) a fault-controlled zone of deep hypogene karst aquifer discharge highly influenced by WMO transients; and (5) an aquifer with a dominant development of the karst conduit system highly influenced by WMO transients. The study highlights the significance of monitoring water pressure within the rock mass as a fundamental element in analyzing the interaction between water pressure tunnels and the hydrogeological environment. Applying the presented instrumentation and methodology facilitates effective monitoring in research areas where pressure tunnels are constructed.

Response to Pumping of Wells in Carbonate and Karst Aquifers and Effect on the Assessment of Sustainable Well Yield: Some Examples from Southern Italy

Carbonate and karst aquifers are of great importance for human water supplies, for supporting aquatic habitats and providing ecosystem services. Optimizing the groundwater withdrawals is therefore essential for obtaining the maximum flow rate for human purposes while minimizing the negative effects on the environment. In particular, when the abstraction of groundwater occurs through wells, the problem of defining the sustainable yield arises. This study analyzes pumping tests conducted in carbonate and karst aquifers in southern Italy to derive indications for defining the sustainable yield of yields. The four examined cases concern the Mesozoic–Cenozoic platform and transition pelagic carbonate rocks characterized by different degree of fracturing and karstification and hosting a carbonate aquifer with variable average groundwater yields. The analysis compared drawdown–time trends and their derivatives for 35 pumping tests with theoretical curves to identify the flow dimension. Parameters useful for examining the well yields were then determined. The results show that the response to the pumping of the investigated aquifers is very variable, both among the different sites and within the same site. Well yields are very different due to aquifer heterogeneity, local hydrostratigraphy and structural setting, and position of the pumping center within the groundwater flow system. To determine the operational pumping rate for a well in this environment, this study emphasizes the importance of analyzing drawdown trends over time to correctly predict the well’s long-term response to pumping. Specifically, when pumping induces a steady-state drawdown response, the focus for defining the sustainable abstraction shifts to the basin or aquifer scale. Conversely, when a transient drawdown response to pumping results, the well’s capacity to capture groundwater becomes the primary factor for well yield and its sustainability.

Tracing pesticide dynamics: High resolution offers new insights to karst groundwater quality

Generally, karst aquifers and springs are highly susceptible to contamination due to the high permeability and, therefore, groundwater flow velocities. The often thin soil cover, accompanied by dolines, can lead to fast infiltration of precipitation water loaded with mobilized contaminants such as pesticides and their transformation products. To date, continuous, temporally highly resolved in-situ monitoring to decipher concentration dynamics for a broad range of pesticides is missing. Therefore, a transportable HPLC-HRMS/MS system (MS2field) was positioned at two karst study sites in the Swiss Jura. Water samples were collected and analyzed for pesticides and their transformation products in-situ every 20 min for 6 weeks in 2021 and 8 weeks in 2022. During the spraying season in 2021, six rain events at site 1 and three at site 2 in 2022 were captured. Concurrently, the water quality parameters electrical conductivity, pH, nitrate, turbidity, and water level, were monitored continuously at high temporal resolution. Further, bacterial cell counts were monitored via online flow cytometry.In 2021, several pesticides and pesticide transformation products were detected in peak concentrations after rain events, of which metamitron showed the highest concentration of up to 1000 ng/L. In one rain event, the Swiss federal and EU drinking water limit of 100 ng/L was exceeded for up to 38 h. Compared with highly frequent MS2field samples collected every 20 min, 42-hours composite samples severely underestimated peak concentrations for all compounds, especially for labile ones. Therefore, it was demonstrated that exceedences of the regulatory limit would have been missed if just composite sampling would have been conducted. Peak concentrations of pesticides coincided with peaks in nitrate concentration and bacterial cell counts following rain events. The correlation analysis showed strong correlations between the three analyzed contaminants (pesticides, nitrate and bacteria), and the proxy parameters electrical conductivity, and pH. The investigation of a second spring revealed similar dynamics indicating that these can be expected in other karst aquifers as well.

Karst aquifer discharge response to rainfall interpreted as anomalous transport

Karst aquifer discharge response to rainfall interpreted as anomalous transport

A methodology providing new insights into the flow patterns of karst aquifers: an example from SW Türkiye

A methodology providing new insights into the flow patterns of karst aquifers: an example from SW Türkiye

Influence of submarine groundwater discharge on the nutrient dynamics of a fringing-reef lagoon

Study regionThis study investigates nutrient distribution and flux dynamics in a coral reef lagoon in Quintana Roo, Mexico, located on a permeable limestone coast of the Mesoamerican Barrier Reef System. Study FocusEmphasis is placed on submarine groundwater discharge (SGD) as a crucial contributor to nutrient pathways, including ammonium (NH4+), nitrate and nitrite (NOx-), hydrogen silicate (HSiO3-), hydrogen phosphate (HPO42-), and urea. Inputs vary with SGD magnitudes and sources and by proximity to active spring discharges. Groundwater multi-tracer analysis and multiple linear regression identify 226Ra as explaining NH4+ variability due to long-term groundwater processes, while 223Ra predicts NOx-, HSiO3-, and urea due to short-term inputs. No significant relationship was found between HPO42- and any radium isotope, indicating complex behavior in coastal karst aquifers. New hydrological insights for the regionThe findings highlight complex nutrient dynamics in coastal karst settings, with SGD-derived fluxes primarily consisting of dissolved inorganic nitrogen (DIN) and HSiO3-. Although lower in concentration, HPO42- and urea fluxes are significant compared to other karst environments. Radium isotopes distinguish between short-term and long-term, as well as new and recycled nutrient inputs. Groundwater inputs transport fresh nutrients to healthier reefs, whereas processed, recycled inputs were detected near degraded reefs. These insights are essential for understanding global nutrient cycles and coral health, particularly in the context of global change and anthropogenic disturbances affecting coral reef ecosystems.

Study of the development patterns of water-conducting fracture zones under karst aquifers and the mechanism of water inrush

The hydrogeological conditions of the Qianbei coalfield are complex, and karst water in the roof rock frequently disrupts mining operations, leading to frequent water inrush incidents. Taking the representative Longfeng Coal Mine as a case study, research was conducted on the development pattern of the water-conducting fracture zone and the water inrush mechanisms beneath karst aquifers. On the basis of key stratum theory and calculations of the stratum stretching rate, the karst aquifer in the Changxing Formation was identified as the primary key stratum. It was deduced that the water-conducting fracture zone would develop into the karst aquifer, indicating a risk of roof water inrush at the working face. Numerical simulations were used to study the stress field, displacement field, and plastic zone distribution patterns in the overlying roof strata. Combined with similar simulation tests and digital speckle experiments, the spatiotemporal evolution characteristics of the water-conducting fracture zone were investigated. During the coal mining process, the water-conducting fracture zone will exhibit a "step-type" development characteristic, with the fracture morphology evolving from vertical to horizontal. Near the goaf boundary, the strain gradually decreases, and the instability of the primary key stratum significantly impacts the mining space below, leading to the closure of interlayer voids or the redistribution of water-conducting fissure patterns. Field measurements of the water-conducting fracture zone reveal that postmining roof fractures can be classified into tensile-shear, throughgoing, and discrete types, with decreasing water-conducting capacity in that order, the measured development height of the water-conducting fracture zone (51 m) aligns closely with the theoretical height (51.37 m) and the numerical simulation height (49.17 m). Finally, from the perspective of key stratum instability, the disaster mechanisms of dynamic water inrush and hydrostatic pressure water inrush beneath the karst aquifers in the northern Guizhou coalfield were revealed. The findings provide valuable insights for water prevention and control efforts in the Qianbei coalfield mining area.