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Karst sinkholes pose a great danger to people and infrastructure in many countries, so effective methods for assessing karst hazard are needed. However, there are currently no modern regulatory documents and methods for assessing the danger of karst sinkholes. The article describes the methods and provides examples of the application of several methods for assessing karst hazard, tested in real conditions in the karst zone of the Bryansk region [ABSTRACT FROM AUTHOR]

Sinkholes in the subgrade disrupt the transportation capacity and usability of roads. The objective of this study is to use infrared thermal images to find sinkholes in the subgrade, and a CNN is applied. Cavities of small and large sizes are artificially simulated to conduct field testing, and cavities are installed in the top, middle and bottom positions. The temperature variations are measured via an infrared camera of 240 × 180 pixels to account for heating and cooling conditions. A convolution neural network (CNN) is applied to classify the measured image according to the sinkhole characteristics, including size, depth and surface materials. The highest accuracy is 90.9% for the locally distributed sinkhole with a surface material of sand. To reflect the characteristics of temperature change, the temperature difference index (TDI) is calculated and the numerical data are converted into an image through the recurrence plot (RP) algorithm. The results of the CNN are raised to 17% through TDI. This study shows that the suggested technique is an alternative method for detecting sinkholes in roads via infrared thermal images. [ABSTRACT FROM AUTHOR]

Alarms about climate change can be found in many daily and weekly news outlets. Many of these alarms raise concerns, rightly, about certain catastrophe to people, the flora and fauna of land, sea, and air, and all of Earth's ecosystems. Some reports in mainstream media include accounts of the vulnerabilities among people in low-lying coastal communities and other precarious environments with increasingly limited access to water, threats from erratic weather events, to hurricanes, drought, wildfires, extreme heat, sink holes, and volcanic eruptions. Climate catastrophe will affect the most vulnerable people hardest and first with loss of life, greater poverty, food and potable water insecurity, infrastructure collapse, and displacement. This essay explores the challenges of climate-related catastrophes and mitigations efforts by the United Nations, Disability Activists, and Catholic Social Teaching initiatives in reference to Persons with Disability by arguing for the need to consider the threats of catastrophe to vulnerable populations first. [ABSTRACT FROM AUTHOR]

Monitoring reclaimed landfills is essential for ensuring their stability and monitoring the regularity of facility settlement. Insufficient recognition of the magnitude and directions of these changes can lead to serious damage to the body of the landfill (landslides, sinkholes) and, consequently, threaten the environment and the life and health of people near landfills. This study focuses on using UAV photogrammetry to monitor geometric changes in reclaimed landfills. This approach highlights the advantages of UAVs in expanding the monitoring and providing precise information critical for decision-making in the reclamation process. This study presents the result of annual photogrammetry measurements at the Słabomierz–Krzyżówka reclaimed landfill, located in the central part of Poland. The Multiscale Model to Model Cloud Comparison (M3C2) algorithm was used to determine deformation at the landfill. The results were simultaneously compared with the landfill's reference (angular–linear) measurements. The mean vertical displacement error determined by the photogrammetric method was ±2.3 cm. The results showed that, with an appropriate measurement methodology, it is possible to decide on changes in geometry reliably. The collected 3D data also gives the possibility to improve the decision-making process related to repairing damage or determining the reclamation direction of the landfill, as well as preparing further development plans. [ABSTRACT FROM AUTHOR]

Carbonate reservoirs in the Central Luconia Province of Malaysia underwent significant karstification during the Miocene. Such features have a detrimental impact on drilling operations, as has been reported for over 40 years in this province. This implies that the karst architecture and geometry may exhibit potentially high-risk behaviours during drilling activities, necessitating a thorough investigation of the features. This study aims to achieve several objectives using Jx field subsurface data, i.e., 3D seismic data and well data, including (1) analysing the interrelationship between karsts and faults, (2) examining the appropriate and effective attributes for analysing the geomorphology of the karst surfaces, and (3) conducting comparative and analog studies to gain a comprehensive understanding of karst formation and characteristics. This research attempted to determine the dimensions and extent of the faults and karsts, which were discovered to be highly connected, and this endeavor is critical for assessing the potential hazardous risk features within the platform. The major fault lineaments that bound the study field were interpreted using the Automatic Fault Extraction (AFE) module application combined with the manual fault-picking technique in the PaleoScan 2022 software. Four main horizon surfaces within the carbonate interval were selected for evaluating karst geomorphology using appropriate seismic attributes, as geomorphology is an important subject that requires serious attention, particularly when determining low-risk regions for drilling programs. Two attributes were extracted from the horizon surfaces: seismic relief and dip attributes, which efficiently distinguish the karst features and define the structural morphology of karsts. Dendritic karst networks, as well as karst collapses or sinkholes, are the most common karst features observed. These features exhibit discontinuity form and synclinal expression (high dip magnitude) when viewed in seismic and using the applied attributes. The comparative and analog study was conducted in Niah Caves, Miri, Sarawak, Malaysia, using karst interpretation employing digital elevation model (DEM) maps and fieldwork. Most of the delineated karst features observed on the DEM map of the Niah Caves are similar to those discovered in the Jx field; however, their dimensions vary between the two carbonate buildups. [ABSTRACT FROM AUTHOR]

This paper forms part of the SINEW (sinkhole early warning) project and continues the work conducted by Möller and co-workers in 2022, where 1g experiments demonstrated the feasibility of using distributed fibre-optic sensing (DFOS) for sinkhole early warning. Their experimental campaign highlighted an order of magnitude difference in the strain between the soil and the cable that remains unexplained and weakens confidence in the technology and/or the experimental method. This paper uses three-dimensional finite-element analyses to examine further this discrepancy and the soil–cable interface. The results support the experimental findings and demonstrate that the DFOS signature strain profile is induced by the horizontal movement of the ground, and enhanced when sufficient coupling at the soil–cable interface is achieved. This result holds when modelling is scaled to realistic confining pressure, and its significance is twofold. First, this needs to be accounted for in the DFOS laying technique. Second, particles of cohesionless soils undergo relatively high horizontal displacement away from the centre of the sinkhole, and this means that DFOS cables are able to detect subsidence away from the centre of the sinkhole. The paper illustrates this result and the signature strain profile expected in this case. [ABSTRACT FROM AUTHOR]

The decline in groundwater level is a key factor contributing to cover collapse in karst areas. In this study, the model tests and numerical simulations are conducted to reveal the breeding process and formation mechanism of cover collapse sinkholes caused by the decline of groundwater level in karst area. Firstly, the model tests confirm that the decline of groundwater level generates negative pressure at the lower edge of overlying soil. The negative pressure experiences four distinct phases during the groundwater drawdown process: rapid rise, slow decline, rapid decline, and gradual dissipation. The maximum negative pressure is influenced by the particle size distribution of the overlying soil. Then, the numerical simulations are carried out to investigate the change process of negative pressure caused by the loss of fillers in karst pipe. The simulated results indicate that the rate of groundwater decline and the thickness and initial void ratio of the overlying soil can affect the maximum negative pressure. As groundwater level drops, a negative pressure zone forms underground, causing tensile failure in the surrounding soil and creating an arched soil hole, which weakens the support for the overlying soil. This phenomenon can also lead to the collapse of the overlying soil under its self-weight. Groundwater table decline in karst areas can result in both internal and surface collapses. When the overlying soil is thin, internal and surface collapses occur simultaneously. In contrast, for thick overlying soil, internal collapse happens first, followed by a layer-by-layer collapse, ultimately forming sinkholes. Finally, the breeding process and formation mechanism of the Yujiawan Reservoir sinkholes are discussed. Geological conditions and groundwater level decline significantly affect internal collapse in karst areas, requiring careful consideration from on-site engineers. [ABSTRACT FROM AUTHOR]

The growing economic and societal damage caused by sinkhole activity worldwide requires the development of scientifically sound sinkhole hazard assessment approaches. Currently, there is a striking paucity of quantitative sinkhole hazard studies largely related to the incompleteness of sinkhole inventories and the lack of chronological data. Moreover, the probability of occurrence of sinkholes (i.e., sinkhole hazard) is commonly considered as a steady variable, a concept that may lead to significant hazard over- or under-estimates. The extraordinarily high frequency of sinkhole occurrence of the studied sector of the western shore of the Dead Sea has allowed us to explore for the first time the potential temporal variability of sinkhole hazard parameters. Here, we produced six multi-temporal sinkhole inventories with morphometric data between 2005 and 2021 using remote-sensed imagery. The frequency-size relationships generated for successive time intervals with a total of 667 new sinkholes reveal substantial temporal changes in the sinkhole hazard components (i.e., frequency and size). Moreover, the work illustrates that spatial redundancy (sinkholes nested within or intersecting pre-existing ones) can lead to significant hazard overestimates if not considered, especially in areas with high sinkhole density and clustering. This work discusses the limitations of some widely used methods and concepts for sinkhole hazard assessment and illustrates the advantages of detailed multi-temporal mapping for assessing frequency-size relationships and their temporal trends. [ABSTRACT FROM AUTHOR]

Geotechnical site characterization is very important for construction purposes. This study has been conducted in Diriyah area northwest of Riyadh City, Saudi Arabia, using the Multichannel Analysis of Surface Waves (MASW) method for site characterization through shear wave velocity profiling to 30 m depth. Nineteen MASW lines were carried out in various directions and lengths through the area. The entire process was meticulously parameterized to extract shear wave velocity for subsurface characteristics. MASW results revealed four distinct velocity zones based on National Earthquake Hazard Reduction Program. Fill material was approximately half a meter thick and was classified as very dense soil. The second layer exhibited velocities ranging from 800 to 1,500 m/s, indicating weathered and highly fractured limestone. The third layer showed velocities varying from 1,500 to 1,800 m/s, representing slightly weathered limestone. The fourth layer displayed high velocities ranging from 1,800 to 3,600 m/s, indicating hard and compact limestone rocks. Geotechnical boreholes were drilled down to depths of 10–35 m. These boreholes exposed the geological model that consisted of fill material (silty sand with gravel), followed by highly to moderately weathered limestone with vugs and cracks, and finally, massive limestone rock. Analysis of shear wave velocities identified weak zones, particularly fractured and weathered limestone rocks extending to 12 m in depth. Sinkholes of circular, elongated, and/or conical shapes were observed within this depth range. Moreover, some sinkholes were detected at depths greater than 12 m in specific locations (sites 1, 6, 9, 11, and 17). These sinkholes agreed with the previous study. These results highlight the need for targeted ground improvement methods, such as grouting or underpinning, particularly for construction over weaker zones. Accurate site classification and effective risk management are crucial for addressing these geotechnical and seismic challenges.

The absence of monogenean parasites in fish is a rare and intriguing occurrence in natural populations, often raising important questions about the environmental and biological factors at play. In this study, we focused on the gill ectoparasites of the Neotropical characid Psalidodon aff. fasciatus, the sole fish species inhabiting an isolated lake, millions of years old, located within a sinkhole in southern Brazil. A sinkhole is a steep, deep depression in the ground that forms a lake disconnected from other bodies of water, creating a unique and highly isolated environment. Over the span of a year, we examined 123 individual fish from this environment and found no ectoparasites on their gills. This striking absence of parasites reveals a complex scenario of evolutionary adaptations, potentially influenced by the isolated nature of the ecosystem. These findings challenge conventional perspectives on species interactions and parasitism, providing new insights into how organisms adapt to specific environmental conditions and prolonged isolation. [ABSTRACT FROM AUTHOR]

This paper presents a broad spectrum of factors that have an impact on the environment once underground mines have been closed, with particular emphasis on hard coal mines. Based on the review of scientific literature and own experience, several types of environmental impacts of closed mines were specified. In the author's opinion, sinkholes pose the most serious hazard to post-mining areas. A high degree of urbanisation of the Upper Silesian Coal Basin and a wide range of mining operations conducted in the past necessitate the post-mining areas development for construction purposes. However, investing in these areas cannot carry risks and pose a threat to public safety. Therefore, a simplified method of determining the probability of sinkhole formation depending on the depth of a shallow void (excavation) in the rock mass was proposed. An algorithm has also been proposed for determining the contribution of individual mining companies to causing sinkhole hazard, which is of great importance in legal proceedings. [ABSTRACT FROM AUTHOR]

Karapınar region (Konya, Türkiye) is one of the important regions of the world in terms of sinkhole formations. The research aimed to map the sinkholes in detail, to determine their spatial distribution and geometrical parameters. For this purpose, the long axes, short axes, depths and the proximity to settlements of the sinkholes were measured and their circumferences and areas were calculated. During the studies, the relationship of the sinkholes with lithology, their cross sections, shapes and the related structures were determined and the sinkholes were divided into five main groups as following: Basement rock sinkholes, Obruk Plateau sinkholes, Seyithacı sinkholes, Siyeklik sinkholes and Basin sinkholes. The d/l ratios of each sinkhole group were separately determined and interpreted. Accordingly, most of the d/l ratios are smaller than 0.2. Namely, the long axes are higher than the depth and it indicates that the shallow and wide sinkholes are common in the region. It has been determined that the fracture systems in the region, as well as the lithology and groundwater factors, are quite effective in the formation and distribution of the sinkholes in the Karapınar region. Considering the distance of the sinkholes to the settlements, Seyithacı sinkholes are the most risky group in the region because they are deep and close to the settlements. [ABSTRACT FROM AUTHOR]

Sinkhole formation caused by leaking pipes in karst soluble rocks is a significant concern, leading to infrastructure damage and safety risks. In this paper, an experiment was conducted to investigate sinkhole formation in dense sand induced by a leaking pipe. Fibre Bragg grating (FBG) sensors were used to record the strain. A balloon was gradually deflated within a bed of wet silica sand to create an underground cavity. Eighteen FBG sensors, with a wavelength range between 1550 nm and 1560 nm, were embedded horizontally and vertically in the physical model at different levels to monitor deformation at various locations. A leaking pipe was installed to induce the collapse of the formed arch above the cavity. The strain measurements suggested the following four phases in the sinkhole formation process: (1) cavity formation, (2) progressive weathering and erosion, (3) catastrophic collapse, and (4) subsequent equilibrium conditions. The results showed differences in the strain signatures and distributions between the horizontal and vertical measurements. During the critical phase of the sinkhole collapse, the horizontal measurements primarily showed tension, while the vertical measurements indicated compression. This investigation demonstrates the effectiveness of FBGs as advanced monitoring tools for sinkhole precursor identification. The study also suggests using FBGs in geotechnical monitoring applications to improve the understanding and mitigation of sinkholes and related geohazards. [ABSTRACT FROM AUTHOR]

We study the interrelations between salt karst and landscape evolution at the Ze'elim and Hever alluvial fans, Dead Sea (DS), Israel, in an attempt to characterize the ongoing surface and subsurface processes and identify future trends. Using light detection and ranging, interferometric synthetic aperture radar, drone photography, time-lapse cameras, and direct measurements of floodwater levels, we document floodwater recharge through riverbed sinkholes, subsurface salt dissolution, groundwater flow, and brine discharge at shoreline sinkholes during the years 2011–2023. At the Ze'elim fan, most of the surface floodwater drains into streambed sinkholes and discharges at shoreline sinkholes, whereas at the Hever fan, only a small fraction of the floodwater drains into sinkholes, while the majority flows downstream to the DS. This difference is attributed to the low-gradient stream profiles in Ze'elim, which enable water accumulation and recharge in sinkholes and their surrounding depressions, in contrast with the higher-gradient Hever profiles, which yield high-energy floods capable of carrying coarse gravel that eventually fill the sinkholes. The rapid drainage of floodwater into sinkholes also involves slope failure due to pore-pressure drop and cohesion loss within hours after each drainage event. Surface subsidence lineaments detected by InSAR indicate the presence of subsurface dissolution channels between recharge and discharge sites in the two fans and in the nearby Lynch straits. Subsidence and streambed sinkholes occur in most other fans and streams that flow to the DS; however, with the exception of Ze'elim, all other streams show only minor or no recharge along their course. This is due to either the high-gradient profiles, the gravelly sediments, the limited floods, or the lack of conditions for sinkhole development in the other streambeds. Thus, understanding the factors that govern the flood-related karst formation is of great importance for predicting landscape evolution in the DS region and elsewhere and for sinkhole hazard assessment. [ABSTRACT FROM AUTHOR]

The goal of a wireless sensor network (WSN) is to connect numerous nodes via a multi-hop self-organizing network. A variety of sensor nodes are arranged and positioned in relation to other nodes to provide safe data exchange. Sensor nodes watch as a sink node processes the data. The network includes a variety of assaults, including floods, wormhole, black hole, sinkhole, and so on. One of the most challenging tasks in WSN is secure routing because of the existence of attacks. The technology of attack detection is employed to identify attacks and enhances the security of data transmission. It provides a way to ignore network threats, enabling secure communication. Most recent efforts have been focused on implementing secure data communication in wireless sensor networks. However, the more accurate detection attack was not achieved. Numerous intrusion attackers are available to compromise network data packet communication. To provide better data distribution amongst soldiers in a combat environment, this wireless network invader node needs to be identified. Hence, in a WSN context, data transmission with a military scenario entails armed men engaged in combat, such as fighter aircraft, tankers, and shot ships. Finding intrusion attackers is a difficult task, especially in the highly dynamic military wireless sensor network. Therefore, different techniques are developed in WSN for achieving attack detection accuracy with minimal delay and maximum data delivery rate. [ABSTRACT FROM AUTHOR]

This study explores the intricate relationship between land subsidence and urban development in the Quetta and Mastung districts, focusing on the challenges and opportunities for mitigating subsidence impacts on future development. Quetta, the capital of Baluchistan province in Pakistan, covers 3,447 km² and has a population of 1.001 million, having experienced significant growth over the past five decades. Mastung district, adjacent to Quetta, spans 3,308 km² with a population of 35,129 according to the 2017 Census. Over the past thirty years, both districts have undergone rapid urbanization across various sectors, including industry, trade, transportation, and real estate. This urban expansion, however, has led to environmental challenges, notably land subsidence, which threatens urban development plans and regional progress. Land subsidence in Quetta and Mastung is driven by several factors: excessive groundwater extraction, the collapse of the traditional Karez system, structural weight on compressible soils, and the natural consolidation of alluvial soils. "InSAR" (Interferometric Synthetic Aperture Radar) imagery highlights the extent of this subsidence, showing a maximum Line of Sight (LOS) rate of 15 cm/year in Quetta and approximately 4–5 cm/year in Mastung. These findings emphasize the urgent need to address land subsidence to ensure sustainable urban development in both districts. [ABSTRACT FROM AUTHOR]

Mobile ad hoc networks (MANETs) offer a decentralized communication solution ideal for infrastructure-less environments like disaster relief zones. However, their inherent lack of central control and dynamic topology make them vulnerable to attacks. This paper examines the impact of various attacks on mobile nodes within two network types: randomly and uniformly distributed stationary networks. Four types of attacks are investigated: delay, dropping, sinkhole (alone), and a combined black hole attack (dropping + sinkhole). The effects of these attacks are compared using the packet delivery ratio, throughput, and end-to-end delay. The evaluation results show that all single attacks negatively impacted network performance, with the random network experiencing the most significant degradation. Interestingly, the combined black hole attack, while more disruptive than any single attack, affected the uniformly distributed network more severely than the random network. [ABSTRACT FROM AUTHOR]

Terrace erosion has become increasingly pronounced due to the rising incidence of heavy rainfalls resulting from global climate change; however, the processes and mechanisms governing erosion of loess terraces during such events remain poorly understood. A field investigation was performed following a heavy rainfall event in the Tangjiahe Basin to examine the soil erosion characteristics of loess terraces subjected to heavy rainfall events. The results show that various types of erosion occurred on the terraced fields, including rill, gully, and scour hole in water erosion, and sink hole, collapse, and shallow landslide in gravity erosion. Rill erosion and shallow landslide erosion exhibited the highest frequency of occurrence on the new and old terraces, respectively. The erosion moduli of the gully, scour hole, and sink hole on the new terraces were 171.0%, 119.5%, and 308.7% greater than those on the old terraces, respectively. In contrast, lower moduli of collapse and landslide were observed on the new terraces in comparison to the old terraces, reflecting reductions of 34.2% and 23.4%, respectively. Furthermore, the modulus of water erosion (32,102 t/km2) was 4.5 times that of gravity erosion on the new terraces. Conversely, on the old terrace, the modulus of gravity erosion (8804.1 t/km2) exceeded that of water erosion by 14.5%. Gully erosion and collapse dominated the erosion processes, contributing 67.8% and 9.4% to soil erosion on the new terraces and 38.7% and 34.0%, respectively, on the old terraces. In the study area, the new terraces experienced significantly greater erosion (39,252 t/km2) compared to the old terraces (16,491 t/km2). Plastic film mulching, loose and bare ridges and walls, inclined terrace platforms, and high terrace walls, as well as the developing flow paths, might be the key factors promoting the severe erosion of the terraces during heavy rainfall. Improvements in terrace design, construction technologies, temporary protective measures, agricultural techniques, and management strategies could enhance the prevention of soil erosion on terraces during heavy rainfall events. [ABSTRACT FROM AUTHOR]

An innovative approach that combines isogeometric analysis (IGA), limit analysis, machine learning, and the multivariate adaptive regression splines (MARS) model is presented in this paper to investigate sinkhole stability of circular cavity. The upper bound limit analysis method using IGA and second-order cone programming (SOCP) is employed to analyze circular cavity stability. Based on Bézier extraction, the non-uniform rational B-spline (NURBS) is used to generate a set of NURBS surfaces that define the boundary of the soil domain. The proposed approach is validated through comparative analysis with previous studies, demonstrating its effectiveness in accurately predicting soil stability. A large dataset consisting of 5000 randomly generated runs is used to train the machine learning algorithm that is integrated with the MARS model. The results show high accuracy, with a small mean squared error of 10–3, in predicting the undrained stability of circular cavities. The integration of IGA, limit analysis, machine learning, and the MARS model contributes significantly to advancing computational techniques for assessing soil stability. The proposed approach offers a comprehensive and precise tool for engineers and researchers, providing an accurate design formula for evaluating the undrained stability of circular cavities. [ABSTRACT FROM AUTHOR]

Sinkholes are a major geohazard caused by underground mining, significantly deteriorate the ecological environment. To understand deeply the formation mechanism of widespread sinkholes in mining areas, the unsaturated Material Point Method (MPM) was employed to study the mechanical and hydraulic characteristics during the sinkhole formation process in a southwestern mining area. This study explored the impacts of different mining modes and rainfall intensities on sinkhole characteristics and validated the results with 3D laser scanning data. Results show that prolonged and concentrated rainfall and subsurface mining activities are the main factors contributed to the formation of sinkholes. The initial rainfall infiltration behavior significantly elevates groundwater levels, leading to saturation of the surface moraine soil layer. Subsequent mining activities result in double funnel-shaped fracture zones. The differences in the expansion rates of various fracture zones lead to widespread subsidence on the surface first, followed by the evolution into sinkholes in the central area. The multi-channel mining mode is identified as the main factor causing the enlarging of sinkholes, while variations in rainfall intensity affect the distribution and morphologies of these sinkholes. [ABSTRACT FROM AUTHOR]

Machine learning can offer an efficient method to identify and map caves, sinkholes, and other cave-like features (i.e. sinkholes, rockshelters, voids) using remotely sensed imagery. While there exists a body of work applying machine learning for sinkhole identification, little work exists for caves. In the densely forested and rugged Maya Lowlands, developing such a methodology can help archaeologists to identify previously unknown caves that may contain important archaeological materials. Here, we introduce a proof-of-concept project that uses random forest and lidar-derived landscape morphometrics to map caves and other cave-like features in northwest Belize. Several undocumented caves and cave-like features were identified in our study area based on model results. Next steps towards making a more robust version of this model include the addition of more training data and integration of a larger number of morphologic parameters. Based on the results described here as well as those in cited works focused on caves, we proposed machine learning as a first step in cave and cave-like feature identification, followed then by fieldwork and ground-truthing. [ABSTRACT FROM AUTHOR]

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In this work, electrical resistivity tomography was carried out together with physical hydrogeology techniques to evaluate the karst aquifer in the northwest region of the Yucatán Peninsula in a study area near the western edge of the Ring of Cenotes of the Chicxulub Crater. In addition, based on a systematic compilation of open-access data of water levels reported for the peninsular aquifer, maps of groundwater isolines and groundwater flows were generated using IDW interpolation, Empirical Bayesian Kriging, and the Flow Net method. From these results, a shallow aquifer is observed, with the presence of heterogeneities such as possible dissolution conduits and/or flooded caverns, approximately 20 m below ground level, formed by the dissolution processes of limestone rocks. On a regional scale, the geomorphological influence of the Ring of Cenotes on groundwater flows was observed. In general, the flow directions observed from these maps coincide with those conceptualized for this region of the peninsular aquifer. Nevertheless, some differences were observed depending on the interpolation method used. Our results contribute to hydrogeological studies carried out in the periphery of this ring, where the vulnerability of the aquifer to anthropogenic contamination has been highlighted due to the intrinsic features of the karst environment. [ABSTRACT FROM AUTHOR]

This study investigates the processes leading to karst development in the southeastern part of Riyadh city extending up to Al Kharj. Numerous solution features such as sinkholes, collapsed dolines, and solution caverns are common in the area. The role of water in the development of the karst features was investigated using an integrated geological and hydrochemical approach. Geological investigations included the petrographic analysis of rock samples collected from zones of intense karstification with special emphasis on mineral dissolution. The study showed that the Sulaiy Formation is commonly fractured, brecciated, foliated, and contains numerous cavities, vugs, and openings. These features have formed by mineral dissolution by circulating groundwater, which has removed anhydrite beds from the underlying Arab–Hith sequence. Karstification likely started from the tectonically weak zones when there was more groundwater recharge. Studies show that during the early to mid-Holocene period, the climate in the Arabian Peninsula was humid, promoting groundwater recharge and subsequent mineral dissolution, though the process of karstification must have started much earlier. Hydrochemical findings reveal that mineral dissolution (halite and calcium sulfate) is the main process affecting groundwater chemistry. The Piper plot revealed two main hydrochemical facies: the (Ca2+ + Mg2+)–(Cl+ SO42−) Type (Type A) and the (Na+ + K+)–(SO42− + Cl) Type (Type B). Most of the samples belong to Type B, typical of groundwater facies affected by dissolution of halite and anhydrite mineral. The absence of the (Ca2+ + Mg2+)–(CO32− + HCO3−) type of groundwater facies indicates a lack of recent groundwater recharge and the removal of carbonate minerals from the system through precipitation, as evidenced by the saturation indices. Plots of the major ionic pairs (cations vs. anions) in groundwater indicate strong halite and gypsum/anhydrite dissolution. Of the three carbonate minerals, calcite has the highest average saturation index followed by aragonite and dolomite. This suggests significant past rock–water interaction leading to carbonate dissolution. Presently, any additional calcium or carbonate ions introduced into the water lead to calcite precipitation. The study indicates that the process of karst development may not be active today. Currently, groundwater chemistry is mainly influenced by rock–water interaction leading to gypsum/anhydrite dissolution, which has resulted in a high concentration of Na+, Ca2+, Cl− and SO42− ions in groundwater. The dissolution of gypsum and halite from the Hith Formation weakens the structural integrity of the overlying Sulaiy Formation, creating large underground cavities. These cavities increase the risk of roof collapse, leading to cover-collapse sinkholes as the roof becomes too thin to support the weight above. [ABSTRACT FROM AUTHOR]

Sinkholes can cause significant damage to infrastructures, agriculture, and endanger lives in active karst regions like the Dead Sea's eastern shore at Ghor Al-Haditha. The common sinkhole mapping methods often require costly high-resolution data and manual, time-consuming expert analysis. This study introduces an efficient deep learning model designed to improve sinkhole mapping using accessible satellite imagery, which could enhance management practices related to sinkholes and other geohazards in evaporite karst regions. The developed AI system is centered around the U-Net architecture. The model was initially trained on a high-resolution drone dataset (0.1 m GSD, phase I), covering 250 sinkhole instances. Subsequently, it was additionally fine-tuned on a larger dataset from a Pleiades Neo satellite image (0.3 m GSD, phase II) with 1038 instances. The training process involved an automated image-processing workflow and strategic layer freezing and unfreezing to adapt the model to different input scales and resolutions. We show the usefulness of initial layer features learned on drone data, for the coarser, more readily-available satellite inputs. The validation revealed high detection accuracy for sinkholes, with phase I achieving a recall of 96.79% and an F1 score of 97.08%, and phase II reaching a recall of 92.06% and an F1 score of 91.23%. These results confirm the model's accuracy and its capability to maintain high performance across varying resolutions. Our findings highlight the potential of using RGB visual bands for sinkhole detection across different karst environments. This approach provides a scalable, cost-effective solution for continuous mapping, monitoring, and risk mitigation related to sinkhole hazards. The developed system is not limited only to sinkholes however, and can be naturally extended to other geohazards as well. Moreover, since it currently uses U-Net as a backbone, the system can be extended to incorporate super-resolution techniques, leveraging U-Net based latent diffusion models to address the smaller-scale, ambiguous geo-structures that are often found in geoscientific data. [ABSTRACT FROM AUTHOR]

Discontinuous deformations, such as sinkholes, pose significant challenges in post-mining areas due to their unpredictable nature and potential hazard to surface development and the safety of local communities. Therefore, monitoring the post-mining regions should be treated as a continuing task. This study addresses the ongoing problem of sinkhole formation in the former “Przyjaźń Narodów – Szyb Babina” (Babina) lignite mine located in the glaciotectonic region of Muskau Arch in western Poland. The research uses airborne and terrestrial laser scanning methods to identify and monitor discontinuous deformations, focusing on a newly discovered sinkhole. The methodology involves differential analysis of Digital Elevation Models (DEMs) and their derivatives obtained from airborne laser scanning (ALS) and periodic terrestrial laser scanning (TLS) measurements. The results of ALS DEM analysis allowed the successful identification of 75 confirmed sinkholes, the largest measuring 12.8 m in diameter and 4.8 m deep. Whereas, differential DEM analysis indicated new sinkholes that developed between 2011 and 2020 in the area of shallow underground mining. Two-year TLS monitoring of the new sinkhole showed no progression in its dimensions. However, localised erosion processes associated with water transport were detected. The study shows that sinkhole formation processes are active 5 decades after the end of mining and highlights the importance of continuous monitoring of post-mining areas with advanced laser scanning methodss. [ABSTRACT FROM AUTHOR]

In wireless sensor networks (WSNs), sensor nodes are randomly distributed to transmit sensed data packets to the base station periodically. These sensor nodes, because of constrained battery power and storage space, cannot utilize conventional security measures. The widely held challenging issues for the network layer of WSNs are the packet-dropping attacks, mainly sinkhole and wormhole attacks, which focus on the routing pattern of the protocol. This thesis presents an improved version of the second level of the guard to the system, intrusion detection systems (IDSs), to limit the hostile impact of these attacks in a Low Energy Adaptive Clustering Hierarchy (LEACH) environment. The proposed system named multipath intrusion detection system (MIDS) integrates an IDs with ad hoc on-demand Multipath Distance Vector (AOMDV) protocol. The IDS agent uses the number of packets transmitted and received to calculate intrusion ratio (IR), which helps to mitigate sinkhole attacks and from AOMDV protocol round trip time (RTT) is computed by taking the difference between route request and route reply time to mitigate wormhole attack. MATLAB simulation results show that this cooperative model is an effective technique due to the higher packet delivery ratio (PDR), throughput, and detection accuracy. The proposed MIDS algorithm is proven to be more efficient when compared with an existing LEACH-based IDS system and MS-LEACH in terms of overall energy consumption, lifetime, and throughput of the network. [ABSTRACT FROM AUTHOR]

The Italian national territory is characterised by the widespread presence of cavities dating back to different periods, especially in urban areas. The lack of knowledge of the position of the entrances, planimetric developments and state of preservation contributes to accentuating the unknowns related to sinkhole risk, which are directly related to potential cavity collapses with the opening of surface chasms. To deepen knowledge with a view to risk mitigation, a method has been developed to employ surveys obtained from Unmanned Aerial Vehicles (UAVs) to locate entrances even in hard-to-access urban areas. These surveys, properly supported with GNSS stations, were then integrated with cavity surveys obtained from low-cost lidar mounted on iPhones. Comparisons were made with traditional surveying techniques to better understand the reliability of the surveys made with low-cost lidar. The 3D models obtained, combined with geomechanical surveys of the rock masses hosting the cavities, allowed the application of simplified and empirical methods for an initial stability assessment. This method was tested on a portion of the municipality of Grotte di Castro (Province of Viterbo—Italy). [ABSTRACT FROM AUTHOR]

Karstic sinkholes are peculiar structures hosting specific biological communities. Birds are still little studied in this regard. This note reports, for the first time, original data relating to the density of breeding species occurring within a sinkhole in central Italy obtained with a fine-grained and time-expensive sampling technique (mapping method). The results were compared with data sampled with the point counts method carried out in the same phenological period. We recorded 22 breeding species, all typical of meso-thermophilous forests and ecotonal habitats of hilly central Italy. Among them, two species (Turdus merula and Troglodytes troglodytes), typical of shady, undergrowth habitats, were recorded in the deepest part of the sinkhole (−70 m from the top). No significant differences emerged between the relative frequencies of the species obtained with the two methods, except for Luscinia megarhynchos (overestimated with the mapping method) and Aegithalos caudatus (underestimated). At the community level, the comparison of the two methods revealed similar values in univariate diversity metrics, Whittaker plots did not show a significant difference (ANCOVA test), and ordinary least squares regression between the frequencies showed a highly significant correlation. Therefore, in these peculiar habitats, data obtained from the two methods are comparable: since the point counts method needs lower sampling effort, it appeared to be more effective when compared to the mapping method to study these peculiar habitats. [ABSTRACT FROM AUTHOR]

Rotary sinking electrochemical (RSEC) milling is a version of electrochemical milling that can be adopted to machine some aerospace parts. When the cutting depth is kept constant during the RESC milling, the material removal rate (MRR) is directly proportional to the feeding speed, and the feeding speed is dependent on the current density of the workpiece surface, which is affected by the layout of the side outlet hole. To increase MRR, a new principle based on simulations of electric and flow fields is proposed to optimize the number and diameter of side outlet holes. Through the electric field simulation, the positions of key points with the lowest average current density at side and corner regions are confirmed. On this basis, the average dissolution rate in a rotation cycle is calculated to determine the optimal number of outlet holes. Subsequently, via the dynamic flow field simulation, the average value and standard deviation of electrolyte speed in the machining gap are obtained to further optimize the tool geometry with various diameters and numbers of outlet holes. Finally, the maximum feeding speed and MRR are measured experimentally at different applied voltages, and the results verify the effectiveness of the new optimal principle. [ABSTRACT FROM AUTHOR]

To investigate the multiscale interaction characteristics of Landfall Typhoon Lekima (2019), this study analyzed the characteristics of the different scale vortex structure and interactions among different scales based on vorticity equation diagnosis. The analysis is based on the simulation results of the WRF model which has been thoroughly verified. The main results are as follows: the original vorticity dominated by the meso-a scale vorticity increases with height and then decreases, with maximum vorticity distributed at 900 hPa. The meso-β scale vorticity varies significantly with altitude, while the meso-γ scale vorticity field exhibits obvious positive vorticity below 850 hPa. The meso-a scale vorticity tendency primarily maintains negative, contributing significantly to the overall reduction in the original vorticity field over time. The increase in mid-to-upper-level (above 550 hPa) original vorticity is mainly related to the variations in the meso-β and meso-α scale vorticity fields. The original vorticity dominated by the meso-a scale vorticity increases with height and then decreases, and the whole layer vorticity decreases over time. The meso-β scale vorticity varies significantly with altitude and time, while the meso-α scale vorticity field consistently exhibits significant positive vorticity below 850 hPa. The vorticity equation diagnosis revealed that the primary source terms of the vorticity tendencies are the twisting and stretching terms, and the main sink terms being horizontal and vertical vorticity transport terms below 900 hPa. The source terms and sink terms exchange above 850 hPa. Scale separation results show that the primary contributions of all impact factors originate from the meso-a and meso-γ scale fields (accounting for over 80% of the total), with the contribution of the meso-a scale being less than that of the meso-γ scale and a notable contribution over 35.5% of the interactions between different scales. [ABSTRACT FROM AUTHOR]

On February 11, 2022, the Brengi streambed caved in, and a sizable sinkhole (33.57 N and 75.33 E) was developed. The Brengi stream is a major tributary of the Upper Jhelum River in Kashmir Himalaya. The sinkhole swallowed the entire stream flow and caused mass mortality of fish and other aquatic creatures, besides disrupting completely the local water supplies. The present study analyzed the ancillary data reports, geological and topographic maps, satellite and Google Earth images, and climatic data in conjunction with the field, geophysical and chemical tracer studies to understand the causes of sinkhole formation, the outlet of captured flow and its associated hazards. The study indicated the sinkhole as a "Collapse Sinkhole" formed due to the collapse of the limestone (Triassic) roof cap of an existing deep-seated underground cavern through a prolonged dissolution and physical erosion by the weakly acidic stream and groundwater circulation under suitable climatic conditions. In this area, the limestone bedrock covered under a thick pile of overburden alluvial material comprises large structural discontinuities (bedding planes, fractures, joints and shear zones) and karst features. Before the collapse, a large water pool consisting ~ 80 m3 of the water column was estimated to be at the sinkhole site. Proton Precession Magnetometer survey around the sinkhole indicated that the underlying caverns are about ~ 100 m long downstream. A stream flow of ~ 15.03 m3/s was estimated to be swallowed by the sinkhole continuously for a couple of weeks till its closure. As a consequence, an estimated area of ~ 77.15 km2 comprising 58% agricultural/horticultural land, 25% vegetation cover and 10% built-up area was at high risk of catastrophe downstream of the sinkhole. From the tracer study, the outlet of the sinking water was found located at 16 km downstream at Achabal springs with an average flow velocity of ~ 1.3 km/h from the sinkhole site to the outlet. The sinkhole is a part and characteristic feature of karst topography of the area. Therefore, a detailed study on sinkhole susceptibility and hazard assessment is required. Although the sinkhole formation is an event of local significance in terms of the scale of the disaster, it may be of extreme importance in planning a given investment and management of local groundwater resources and karst springs. [ABSTRACT FROM AUTHOR]

Hydrological data‐driven models require the time series of several hydrological events with different time resolutions. The interpretation of any time series event is generally difficult without some sort of filtering or converting it to a single index value. The simultaneous analysis of two or more hydrological events over a definite time span may be more informative about the region of interest. For this purpose, a new index, referred to as the successive coincidence deficit index (SCDI), was introduced to identify sinkhole‐prone regions using the persistent water deficit concept. In this study, monthly integrated multi‐satellite retrievals for GPM based precipitation (P) and gravity recovery and climate experiment‐based groundwater storage (GWS) datasets over Konya Closed Basin (KCB) in Türkiye were used to analyse the sinkhole occurrence. The main finding of this study is that SCDI distribution with high index values, concentrated on the southwestern part of KCB, is in line with the sinkholes occurred mainly after 2010. The proposed SCDI could also serve as a kind of drought index, which enables practitioners to quantify the relationship between drought and sinkhole occurrence. Moreover, the event coincidence analysis was utilized to detect deficiency in GWS over the KCB, which was associated with a rate of 0.8 for P deficiency, and this rate reaches up to 0.9 in the sinkhole region analysed in this study. As a conclusion, the proposed methodology can detect sinkhole‐prone regions to construct risk maps for stakeholders, policymakers, and end users. [ABSTRACT FROM AUTHOR]

Water-filled sinkholes known locally as cenotes, found on the Yucatán Peninsula, have remarkable biodiversity. The primary objective of this study was to explore the biotechnological potential of Gram-positive cultivable bacteria obtained from sediment samples collected at the coastal cenote Pol-Ac in Yucatán, Mexico. Specifically, the investigation aimed to assess production of hydrolytic enzymes and antimicrobial compounds. 16 S rRNA gene sequencing led to the identification of 49 Gram-positive bacterial isolates belonging to the phyla Bacillota (n = 29) and Actinomycetota (n = 20) divided into the common genera Bacillus and Streptomyces, as well as the genera Virgibacillus, Halobacillus, Metabacillus, Solibacillus, Neobacillus, Rossellomorea, Nocardiopsis and Corynebacterium. With growth at 55ºC, 21 of the 49 strains were classified as moderately thermotolerant. All strains were classified as halotolerant and 24 were dependent on marine water for growth. Screening for six extracellular hydrolytic enzymes revealed gelatinase, amylase, lipase, cellulase, protease and chitinase activities in 93.9%, 67.3%, 63.3%, 59.2%, 59.2% and 38.8%, of isolated strains, respectively. The genes for polyketide synthases type I, were detected in 24 of the strains. Of 18 strains that achieved > 25% inhibition of growth in the bacterial pathogen Staphylococcus aureus ATCC 6538, 4 also inhibited growth in Escherichia coli ATCC 35,218. Isolates Streptomyces sp. NCA_378 and Bacillus sp. NCA_374 demonstrated 50–75% growth inhibition against at least one of the two pathogens tested, along with significant enzymatic activity across all six extracellular enzymes. This is the first comprehensive report on the biotechnological potential of Gram-positive bacteria isolated from sediments in the cenotes of the Yucatán Peninsula. [ABSTRACT FROM AUTHOR]

In karst regions, the occurrence of sinkholes is a common cause of roadway failures, leading to significant embankment deformation and instability. The advantages of geosynthetic reinforcement have been proven in practice in numerous countermeasures to lessen the impact of localized sinkholes, and associated design methodologies have been developed. However, some existing design methods assume there is no deformation in geosynthetics embedded in soils, and the effect of matric suction in soils is not considered either. This study suggested an analytical approach that took into account the strain in the geosynthetic reinforcements as well as the impact of matric suction. The developed design method was used to conduct parameter studies under various matric suction conditions. The method was validated against the experimental results, and the feasibility of the developed method was also compared with the existing design methods. The findings demonstrate that, in comparison to the method created here, existing design methodologies produce more conservative results. The strain and the deflection of the geosynthetic calculated using the suggested method are lower than those provided by the current design methodologies. [ABSTRACT FROM AUTHOR]

Abstract A huge number of sinkhole events has been recorded in different Italian urban areas, with an occurrence frequency largely increasing in the last decades, sometimes even causing loss of human lives. The main reason for such catastrophic events is the presence of man-made underground cavities, excavated within soft rocks, several decades ago and then abandoned, at shallow depths. Here, the possibility of interaction with overlying buildings and infrastructures and the corresponding sinkhole hazard is relatively high. In such contexts, the low mechanical properties of the soft rock formations where the cavities have been excavated, like those formed of calcarenites, which outcrop in large areas of Southern Italy, and their high susceptibility to weathering processes, represent one of the most important predisposing factors for instability. Therefore, assessing the stability of underground cavities is crucial for land management and planning purposes. The mechanically-based stability charts developed by Perrotti et al. (Int J Geomech 18(7):04018071, 2018) have proved to be a valid tool for preliminary stability assessment and, although allow to identify an eventual proneness of the cave to instability, they do not provide quantitative assessment about the safety margin itself. In that regard, this study intends to present the most recent outcomes obtained in the development of the methodology and is aimed at promoting an enhanced way for their application, so that the charts can become an operative tool for preliminary sinkhole hazard assessment in similar regions in the world.

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Anthropogenic activity significantly transforms components of the natural environment. The area of the Dąbrowa Basin has been heavily altered by long-term industrial activities, primarily mining. As a result, numerous excavations and sinkholes have been created, many of which have been largely reclaimed as water bodies. Despite substantial anthropogenic pressure, such water bodies can serve as habitats for valuable fauna and flora species. The article presents the results of chemical analyses of waters in selected anthropogenic reservoirs within the Dąbrowa Basin and assesses whether stonewort communities (Charales) still occur in these areas. The conducted research shows a high ability of stonewort to adapt to the changing parameters of reservoir waters. [ABSTRACT FROM AUTHOR]