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The distribution and characteristics of karst sinkholes is critical for the understanding and evaluation of geohazards. A two-step process, involving computer vision and machine learning methods, has been developed to map and classify depressions as sinkholes. Every depression has been mapped from a LIDAR derived DTM first and later a machine learning random forest binary classifier was then used on the extracted depressions to identify karst sinkholes. The study shows that the two-step method can accurately map karst sinkholes from high resolution DTM even if a visual check must be done on the non-karst sinkhole dataset to improve the classification. [ABSTRACT FROM AUTHOR]

Covered sinkhole, due to its hidden, uncertain, and sudden characteristics, often becomes a key and difficult issue in the prevention and control of karst geological disasters. This paper takes the sinkhole in Yaoshan Huamu Farm, Guilin City as an engineering case, and uses field investigation, indoor and outdoor experiments, and theoretical analysis to systematically analyze the main patterns, influencing factors, and evolution laws of sinkhole. The results show that: (1) High-density resistivity tests show that there are many significant low-resistance anomalies at different locations and depths in the study area, indicating that karst fissures are developed in the study area. This is the basic condition for the occurrence of sinkhole. (2) Drilling results show that the groundwater level in the study area is shallow and groundwater is abundant. Groundwater changes the state and strength of the soil, or dissolves the mineral components of the soil layer and dissolves and transports the soil particle aggregates through subsurface erosion and seepage. Therefore, groundwater destroys the soil structure, resulting in the formation of soil caves or sinkholes. (3) Rainfall monitoring shows that the rainy season from May to July each year provides abundant groundwater for the karst area and changes the physical and mechanical properties of the rock and soil mass; while the small rainfall peak around November may trigger the occurrence of sinkhole through mechanisms such as groundwater level fluctuations and enhanced seepage. (4) The vibrations caused by long-term pumping irrigation, surface water leakage, and planting activities in the study area provide important external dynamic conditions for sinkhole. This study can provide theoretical basis and technical support for the prevention and control of collapse disasters in karst areas. [ABSTRACT FROM AUTHOR]

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]

Abstract In 2021, a sinkhole emerged at the base of the Oana Crater on Azumayama Volcano in northeastern Japan, prompting investigation into its potential link to volcanic activity. Our study examines the phenomenon of sinkhole formation within active volcanic craters. Through meticulous field observations, we provide detailed insights into the sinkhole’s characteristics and explore its underlying causes. By examining the site’s history, we uncover predisposing factors contributing to sinkhole formation. Changes in heat distribution beneath the crater, notably from the northwest to the northeast side, are estimated, affecting the activity of nearby fumaroles. This redistribution of thermal energy triggers significant changes, including the emergence of molten sulfur and heightened fumarole activity. Further analysis reveals the sinkhole’s connection to past hydrothermal activity, notably a similar event in 1966, which served as a conduit for subsurface thermal energy. We assume that weakening of surface geology by hydrothermal fluids and volcanic gases facilitated the sinkhole’s formation in 2021. Notably, while past sinkhole formations at Azumayama Volcano preceded eruptions, the 2021 event occurred independently of mud eruptions but indicates a potential shift in thermal energy pathways within the shallow subsurface. Our findings emphasize the importance of studying local topographical changes within volcanic edifices to elucidate fluids behavior and contribute to understanding eruption mechanisms.

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]

Analytical and numerical solutions for the problem of geosynthetic-reinforced fills over a void have been the subject of investigation for the last four decades. A common feature of this prior work is that all methods have treated the analytical solutions as deterministic. While the treatment of some input parameters must be taken as deterministic, there are other parameters that have uncertainty. Furthermore, the underlying mechanistic models for load and resistance terms in the limit state equations for the reinforced fill over a void problem can be expected to have different accuracy. This paper revisits the problem of geosynthetic-reinforced fills over voids from a probabilistic point of view for reinforcement tensile strain, tensile strength, and geosynthetic stiffness limit states. Particular attention is paid to the method used to select the isochronous stiffness of the reinforcement and the associated uncertainty in the magnitude of that value. The paper demonstrates how the factor of safety from deterministic past practice can be linked quantitatively to the reliability index used in contemporary probabilistic design. Finally, the paper demonstrates the advantage of using product-specific constant-load creep test results to maximise margins of safety for strength and stiffness limit states in both deterministic and probabilistic frameworks. [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]

Introduction. A calculation scheme of karst sinkhole in karst territories using the results of laboratory experimental studies is developed, which makes it possible to determine the shape and size of karst sinkhole depending on the karst cavity dimeter (radius), its depth, the base slope angle and the angle of internal friction of soils composing the slope.Materials and methods. The method of calculation of normal contact stresses in the sloping soil base under the bottom of the cross-beam foundation during the formation of karst sinkholes is given, considering three main cases of karst cavity location in the slope massif with the most unfavourable location of the karst cavity relative to the cross-beam foundation structures.Results. The analytical dependence allowing to determine the theoretical value of the design value of the diameter Lc of the cavity in the sloping base is obtained, as well as to establish the main design dependences for determining the normal contact stresses, which allow to estimate the changes in the VAT parameters of the cross-beam foundation operation after the cavity vault collapse and formation of a complex shape of the collapse funnel.Conclusions. The developed methodology is convenient to use for qualitative assessment of design solutions in the design of cross-beam foundations on a sloping base in karst-prone areas. The obtained variant design values of the main VAT parameters according to the proposed methodology will allow to apply rational design solutions in design.

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]

This study investigates the consequences of unsustainable groundwater extraction in the Kabodarahang plain, a region significantly impacted by geohazards, such as land subsidence and sinkhole formation due to excessive groundwater use for agricultural and industrial activities. Over 32 years (1990–2022), a dramatic decrease in groundwater levels by approximately ~41 m has been observed, leading to notable geohazards. Employing radar interferometry techniques with Sentinel-1 satellite radar imagery and the Sentinel Application Platform (SNAP) tool, complemented by field data, this research aims to quantify the rate of subsidence and evaluate the associated risks, particularly in urban and residential zones. Findings from 2017 to 2018 indicate a subsidence rate of 14.5 cm, predominantly in urban areas, thereby elevating the risk of this geohazard. The results underscore the critical need for sustainable groundwater management policies and practices. The study demonstrates the effectiveness of radar interferometry in monitoring subsidence in the Kabodarahang plain and suggests that integrating such techniques with field surveys and satellite data can enhance the detection and management of risks related to unsustainable groundwater usage. This research contributes to the understanding of the impacts of groundwater depletion on geohazards and supports the development of strategies for sustainable groundwater use to mitigate such risks. [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).

Internal erosion is a common reason for dam failure, which is caused by soil subsidence and the formation of sinkholes. This phenomenon typically occurs in internally unstable soils. The dam is located in Neyshabour City and is built on a deep alluvial foundation with gap-graded and concave gradation soils. This study aims to investigate the potential for soil suffusion and the impact of compaction and surcharge on internal erosion. Initially, Data was collected after the dam impounding, index tests were conducted on soil samples. Subsequently, three methods were used to assess the probability of suffusion based on the particle size distribution and experimental criteria. Two methods indicated soil was internally unstable, while one method indicated stability. To study the influence of compaction. Soil samples were tested at different densities under four water head conditions. The results indicated that the soil has the potential for suffusion and is internally unstable. Furthermore, the study found that compaction reduced soil erosion, with the amount of washed fine particles decreasing from 4.5% at 70% relative density to 0.37% at 85% density. Moreover, increasing compaction from 70% to 85% resulted in a deformation decrease from 13.3% to 3.33%.

Spiradiclis yanii Y.Nong & L.Wu (Rubiaceae), a new species from Guangxi, China, is described and illustrated. This new species is most similar to S. tomentosa, but it can be easily distinguished by being densely multicellular villous, leaves narrow elliptic or oblanceolate, apex acute or shortly acuminate, stipules 2–4, linear or linear lanceolate, 4–8 mm, densely villous, corolla tube 3 mm, sparsely pubescent inside, flower homomorphism, lobes 3–5, stamens arising at the base of the tube, stigma 2-lobed, lobes ovoid, slightly swollen, 0.2 mm. The habitat of Spiradiclis yanii is extremely fragile. Therefore, this species deserves close attention and protection. [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]

Introduction: Subsidence is the collapse or subsidence of the earth's surface, which occurs for different reasons on a large scale. Usually, this term refers to the downward vertical movement of the earth's surface, which can be accompanied by a small horizontal vector. In many cases, subsidence takes place imperceptibly and gradually, and it is one of the risks whose effects are visible in the long term. One of the most important effects of subsidence is a sinkhole, which can cause many human and financial losses. Usually, areas that face the risk of subsidence will also face the risk of sinkholes in the long term, so it is necessary to control the increasing process of subsidence. The geographical location of Iran has caused many parts of it to be at risk of subsidence. The Qorveh plain in the east of Kurdistan province is one of the plains that has faced the crisis of subsidence due to its hydroclimatic and geomorphological conditions. In terms of geomorphology, Qorveh plain has few limiting obstacles and this problem has provided the basis for the development of human activities including agricultural activities in this plain. Due to the fact that the average rainfall of Qorve plain is about 300 mm and this plain is facing a shortage of surface water resources, therefore a large part of the water resources needed by the agricultural lands of this plain is supplied through underground water sources and this problem causes There has been a sharp drop in the underground water resources of this plain in recent years. Due to the sharp drop in underground water resources and the risk of subsidence, it can be expected that if the current trend continues, the Qorve plain will also face the crisis of sinkholes. Due to the importance of the issue, in this research, using radar images, areas prone to sinkholes have been identified in this plain. Methodology: In this research, Sentinel 1 radar images, Landsat 8 satellite image, information related to piezometric wells in the area and SRTM 30 meters high digital model have been used as the most important research data. The most important tools used in the research are ArcGIS (in order to prepare the desired maps and final outputs), GMT (in order to implement the radar interferometry process), and ENVI (in order to prepare the land use map of the region). And Expert Choice (in order to give weight to the presented solutions). Also, in this research, SBAS time series models (to prepare the final subsidence map of the region), maximum likelihood (to prepare the land use map of the region) and AHP (to weight the proposed solutions) have been used. According to the objectives, this research has been done in 3 stages. In the first step, using Sentinel 1 radar images and the radar interferometry method and SBAS time series, the amount of vertical displacement in the study area has been evaluated. In the second stage, on the basis of the prepared map, library studies, as well as experts' opinions, the areas prone to sinkholes have been identified in Qorve Plain. After identifying the areas prone to sinkholes, the distribution of population points exposed to them has been evaluated. In the third stage, the effective factors in the subsidence of the region have been analyzed and effective solutions have been provided to control it. Results: Examining the state of subsidence occurred in the Qorve plain has shown that this plain has subsided a maximum of 379 mm during a period of 4 years. Therefore, it can be said that the Qorve plain has faced the maximum annual subsidence of about 10 cm. Due to the fact that one of the important effects of subsidence is the creation of sinkholes, in this research, the areas exposed to this hazard have been identified. In order to identify areas prone to sinkholes, areas that have subsidence of more than 200 mm during a period of 4 years (areas that have subsidence of more than 5 cm per year) as areas in They have been identified as prone to sinkholes. It should be noted that the selection of 200 mm was based on the subsidence of the region, the topography of the region, and library studies. According to the results, the areas adjacent to Dezaj city and the areas adjacent to Vinsar, Shekohabad and Ganji villages have a high potential in terms of sinkhole occurrence. Conclusion: The location of Qorve plain has made this plain one of the critical plains in the west of the country. Due to its hydroclimatic situation, Qorveh plain is facing a shortage of surface water resources, and this problem has caused excessive use of underground water resources in this plain. Excessive use of underground water resources in the Qorve plain has caused this plain to face a severe drop in underground water resources, so that the annual average drop of underground water in many parts of this plain has been more than 1 meter. The severe drop in underground water resources has caused the Qorve Plain to face 379 mm of subsidence during the years 2018 to 2022, so the Qorve Plain is facing a subsidence crisis. Due to the fact that one of the important effects of subsidence is the creation of sinkholes, in this research, the areas exposed to this risk (areas with subsidence of more than 5 cm per year) have been identified. Based on the results, the areas adjacent to Dezaj city, the areas adjacent to Vinsar village, the areas adjacent to Shekohabad village and also the areas adjacent to Ganji village have a high potential in terms of sinkhole occurrence. Considering that sinkholes are associated with many human and financial losses, in this research, in order to control the subsidence and prevent the occurrence of sinkholes in Qorve plain, various solutions have been presented, and then, using the AHP model, the most important solutions have been selected. Is. Based on the results, planning based on the environmental capabilities of the Qorve plain with a weight of 0.288 has been selected as the most important solution, followed by the solutions of improving irrigation methods and preventing the cultivation of short-term crops, respectively, with a weight of 0.217 And 0.172 have been selected as the most important solutions. [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]

The recent expansion of the Internet of Things (IoT) owes a lot to the significant contribution of the 6LoWPAN protocol, which has been extensively employed in low-power and lossy networks. To facilitate communication in 6LoWPAN networks, the Internet Engineering Task Force (IETF) has suggested the usage of the Routing Protocol for Low-Power and Lossy Networks (RPL). Despite its usefulness, the open and restricted nature of the RPL protocol renders it susceptible to both internal and external attacks. Since IoT devices connected through the RPL protocol have limited resources like processing power, battery life, memory, and bandwidth, ensuring their security is of the utmost importance. One of the primary obstacles to IoT networks is RPL routing attacks, which disrupt the network's normal routing activities and structure. This study investigates the impact of five RPL routing attacks, namely Blackhole, Sybil, Selective Forwarding (SF), Sinkhole, DIO suppression, and DIS flooding, on the IoT networks' performance. The study evaluated the network's performance for normal and five routing attack scenarios using numerous performance metrics including Link throughput, No. of packets generated (control and data), Sensor data throughput, Packet Delivery Ratio (PDR), and Delay in packet delivery. This work conducted simulations using the Tetcos NetSim v12.1 IoT network simulator tool and is the first to analyze IoT network performance under multiple routing assault scenarios with various performance measures. The analysis showed that the performance metrics of PDR, Sensor data throughput, and No. of data packets transmitted decreased significantly in attack scenarios compared to the normal scenario, with an average decreased percentage of 70%, 70%, and 39.4%, respectively. In contrast, the metrics Link throughput, Delay, and No. of control packets transmitted increased in attack scenarios compared to the normal scenario, with average values supplemented by a factor of 35, 255, and 36, respectively. Additionally, the Destination-Oriented Directed Acyclic Graph (DODAG) real-time formation under different scenarios was provided. [ABSTRACT FROM AUTHOR]

Sinkholes and land cracks are the phenomena that are common in the semi-arid and arid lands. The destructive effects of sinkholes include destruction of infrastructure such as energy transmission lines and buildings including residential areas which lead to dangers to human life. In the study area, water abstraction from groundwater for irrigation intensified the sinkhole and land crack formation. Soil parameters such as clay percentage, cracks, and sinkholes dominated in different lands. This study focused on the Abarkooh plain with an area of about 200 square kilometers. The region consisted of medium to fine particles of an alluvial fan that had led from the southwest to the northeast which terminated to low land of Abarkooh salty playa. In this research, 129 samples were taken at grid points from the top soils, and four soil samples were collected from the profile of the sample sinkhole for detailed chemical, physical, and mechanical analyses. Clay mineralogy was performed from selected soil samples after primary routine chemical, physical, and mechanical analyses. Multiple linear regression (MLR) as mathematical function was used for predicting sinkhole hazards with soil properties data. The results revealed that soil properties such as water-soluble Na+ and Mg2+ and lime percentage in the soils had important role to soil divergence and liquid soil clays for sinkhole occurrence. Clay mineralogy from clay particles demonstrated that the mixed clay minerals with dominance of chlorite in the area and play the role of montmorillonite could cause soil divergence. The MLR could predict sinkhole hazard with high accuracy, and the ground-penetrating radar (GPR) results confirmed it as complementary method test. It is suggested that land conservation be introduced as the best alternative in the hazard zones of the sinkhole. [ABSTRACT FROM AUTHOR]

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Anthropogenic activity-induced sinkholes pose a serious threat to building safety and human life nowadays. Real-time detection and early warning of sinkhole formation are a key and urgent problem in urban areas. This paper presents an experimental study to evaluate the feasibility of fiber optic strain sensing nerves in sinkhole monitoring. Combining the artificial neural network (ANN) and particle image velocimetry (PIV) techniques, a series of model tests have been performed to explore the relationship between strain measurements and sinkhole development and to establish a conversion model from strain data to ground settlements. It is demonstrated that the failure mechanism of the soil above the sinkhole developed from a triangle failure plane to a vertical failure plane with increasing collapse volume. Meanwhile, the soil-embedded fiber optic strain sensing nerves allowed deformation monitoring of the ground soil in real time. Furthermore, the characteristics of the measured strain profiles indicate the locations of sinkholes and the associated shear bands. Based on the strain data, the ANN model predicts the ground settlement well. Additionally, micro-anchored fiber optic cables have been proven to increase the soil-to-fiber strain transfer efficiency for large deformation monitoring of ground collapse.

LiDAR-based digital terrain models (DTMs) represent an advance in the investigation of small-scale geomorphological features, including dolines of karst terrains. Important issues in doline morphometry are (i) which statistical distributions best model the size distribution of doline morphometric parameters and (ii) how to characterize the volume of dolines based on high-resolution DTMs. For backward compatibility, how previous datasets obtained predominantly from topographic maps relate to doline data derived from LiDAR is also examined. Our study area includes the karst plateaus of Aggtelek Karst and Slovak Karst national parks, whose caves are part of the UNESCO World Heritage. To characterize the study area, the relationships between doline parameters and topography were studied, as well as their geological characteristics. Our analysis revealed that the LiDAR-based doline density is 25% higher than the value calculated from topographic maps. Furthermore, LiDAR-based doline delineations are slightly larger and less rounded than in the case of topographic maps. The plateaus of the study area are characterized by low (5–10 km−2), moderate (10–30 km−2), and medium (30–35 km−2) doline densities. In terms of topography, the slope trend is decisive since the doline density is negligible in areas where the general slope is steeper than 12°. As for the lithology, 75% of the dolines can be linked to Wetterstein Limestone. The statistical distribution of the doline area can be well modeled by the lognormal distribution. To describe the DTM-based volume of dolines, a new parameter (k) is introduced to characterize their 3D shape: it is equal to the product of the area and the depth divided by the volume. This parameter indicates whether the idealized shape of the doline is closer to a cylinder, a bowl (calotte), a cone, or a funnel shape. The results show that most sinkholes in the study area have a transitional shape between a bowl (calotte) and a cone. [ABSTRACT FROM AUTHOR]

Purpose: To investigate factors associated with intrachoroidal cavitation (ICC) and sinkhole formation in eyes with glaucomatous visual-field defects. Methods: This retrospective, cross-sectional study enrolled a total of 2808 eyes of 1482 patients who were diagnosed/treated for glaucoma and underwent swept-source optical coherence tomography (OCT). We first determined the prevalence of ICCs and sinkholes and their locations. Next, we selected one eye from each patient and compared the clinical characteristics of eyes with and without ICCs. Finally, in eyes with ICCs, we compared the clinical characteristics of eyes with and without sinkholes. Blood flow (BF), represented by laser speckle flowgraphy–measured tissue-area mean blur rate (MBR), was measured in the temporal optic nerve head (ONH), temporal peripapillary chorioretinal atrophy (PPA) zone, and in the ICC zone. ICC area and angle were analyzed in OCT en-face images. Mean deviation and total deviation in the central area (TD-central) were measured with Humphrey visual-field testing. Results: A total of 86 eyes (3.1%) had ICCs and 52 eyes (1.9%) had sinkholes. ICC eyes had a lower spherical equivalent and longer axial length (AL) than non-ICC eyes (P < 0.05). Patients with eyes with sinkholes were more elderly and had worse best-corrected visual acuity, worse TD-central, a larger ICC, and lower tissue-area MBR in the temporal ONH, temporal PPA zone, and ICC zone (P < 0.05). Conclusion: In eyes with glaucoma, AL elongation might be linked to ICC formation. Sinkhole formation might be associated with ICC enlargement, impaired ocular BF, and impaired retinal structure and function involving the central area. [ABSTRACT FROM AUTHOR]

In this study, a single-layer SPH approach that takes into account full soil-water interactions is proposed. The approach updates the propagation of pore pressure through combination of volumetric strain and Darcy's law, accounting for the momentum equation, soil constitutive behavior, and the development of pore pressure at each timestep of the simulation. The proposed method is validated by analytical solutions of consolidation problems. To showcase its capability in simulating large-deformation problems with hydro-mechanical interactions, a physical test of a seepage-induced sinkhole was simulated using the proposed SPH method. The good agreements suggest that the proposed method can capture the key features of sinkhole developments and serve as a promising tool to explore the associated failure mechanism. A series of parametric studies are then conducted to reveal the influences of material properties and hydraulic conditions on the failure behavior of sinkholes, including failure patterns, influence zone, and surface settlement. [ABSTRACT FROM AUTHOR]

This study aims to analyze sinkholes by applying QGIS, mapping and comparing the occurrences with existing natural patterns to observe the cause of the occurrence and the solution. Sinkholes are topographic depressions that appear when the underlying bedrock weathers down, commonly found in sedimentary bedrock. They typically form due to drastic changes in groundwater levels. In urban areas, sediments may also be flushed out due to leaks in underground water pipes, increasing sinkhole formation. This study collected data on 41 sinkhole incidents in South Korea. The latitude and longitude of each incident were manually obtained and cross-checked. The locations were also classified by region to indicate whether they were considered rural or urban. The data was put into a spreadsheet and mapped using QGIS, and waterways were imported from OpenStreetMap (OSM) data and refined. The resulting map provides spatial insights into the distribution of sinkhole incidents in relation to waterways and sedimentary rocks. Whereas rural sinkholes tend to occur in areas with sedimentary rock as its bedrock material during summer when precipitation levels are high, sinkholes around urban areas are related to many human disturbances. By identifying patterns of sinkhole occurrences, the aim is to predict the formation of sinkholes to prevent catastrophic losses. [ABSTRACT FROM AUTHOR]

The renaissance botanical garden of 'El Bosque' in Béjar (Salamanca, Spain) presents a pond bounded by a dam in its western part. The latter is formed by two masonry walls interconnected by buttresses. Cubic spaces in between are filled with a variable grain‐size material (silty sand) that allows limited water flow. In recent years, the southern part of the dam has experienced localized and random subsidence that jeopardizes the entrance to part of the garden. To regain access, a proper and reliable diagnosis of the origin, magnitude and relevance of the subsidence must be made. In this regard, we have undertaken a microgravity survey in the dam area to identify places with an anomalous distribution of the filling material in order to foresee further sinking or potential collapsing areas. The precise positioning (2 mm resolution) and accurate terrain correction needed in this kind of high‐resolution gravity surveys (points every 1.5 m) were achieved by creating a detailed digital terrain model (cm resolution) with a remotely piloted aircraft. In addition, we performed three electric resistivity tomography (ERT) profiles at different levels of the garden: (i) on the dam itself; (ii) right on the foot of the dam and parallel to it (5 m below and ∼17 m to the W); and (iii) a bit farther, but also parallel to the dam (8 m below and ∼27 m to the W). The ERT profiles identified high conductivity in water‐saturated areas and determined the paths that rainfall and pond's seepage water follow in the dam and its underground, formed by granites. The geophysical studies were paired with geotechnical analyses of the sunk materials. The study concluded that the thinnest fraction of the dam's filling material (i.e., silts) is being washed away, leaving behind sand with less density and stability, susceptible to collapse. Thus, the observed sinking is related to soil piping, that is to soil internal erosion and compaction issues that force the soil material to re‐adjust geometrically and volumetrically. [ABSTRACT FROM AUTHOR]

Introduction: In cities, the intensity of integrated development, both above and below ground, has been continuously increasing. Unfortunately, associated events such as surface cracking and ground collapse are common, and research into the susceptibility of urban ground collapse (UGC) has consequently, also been increasing. Methods: In this study, we calculated the spatial probability distribution of historical UGC events in Hangzhou, China as a case study. To avoid the influence of the subjectivity of expert opinions on the evaluation results, and to distinguish it from the first version of the UGC sensitivity map in 2021, collinearity and correlation analyses based on geo-detector were conducted, and the 11 most representative factors from 22 candidates were identified. Then, a GIS-based susceptibility assessment system was established and applied to eastern Hangzhou, China. Results: The assessment results were divided into three grades. High-susceptibility areas accounted for 6.08% of the total area and were mainly distributed in the central area on both sides of the Qiantang River. Medium-susceptibility areas accounted for 23.92% of the total area and showed an expanding trend around the central area. Low-susceptibility areas accounted for 12.42% of the total area and were mainly distributed within the bedrock mountainous areas on the west side. Discussion: The assessment model take more urban construction activies into consideration, which can fits better with the trigger factors of UGC itself, and has good applicability for other cities in Zhejiang Province to assess the susceptibility of UGC events. [ABSTRACT FROM AUTHOR]

The endorheic Konya Basin is a vast aggradational plain in Central Anatolia, Türkiye. It occupies a significant portion of Konya Province, covering approximately 50,000 km2. The basin is subjected to intense groundwater withdrawal and extensive agricultural activities with excessive irrigation. These activities have led to human-induced hazards, such as sinkholes and regional land subsidence. Although sinkhole occurrence mainly occurs in the Karapınar area, land subsidence is primarily observed in the central sector of Konya city, with 2 million inhabitants, as well as in various parts of the basin. This study focuses on determining the extent and rate of land subsidence throughout the basin, understanding sinkhole formation, and unraveling their relationship with anthropogenic activities. For this purpose, Interferometric Synthetic Aperture Radar (InSAR) analysis of Sentinel-1 data from 2014 to 2022 was conducted to identify and assess land subsidence. We also used the land cover data and groundwater-level information to better understand the spatial and temporal patterns of land subsidence and sinkhole occurrence. Additionally, the land cover data were used to resolve spatial–temporal variations in the cultivated area and urbanization, which are the main factors governing groundwater exploitation in the region. Our study identified widespread subsidence zones with rates as high as 90 mm/y. Groundwater overexploitation to sustain extensive agricultural operations is the main cause of the high rate of land subsidence. Additionally, it was discovered that the number of sinkholes has substantially increased due to anthropogenic influences, currently amounting to as many as 660. [ABSTRACT FROM AUTHOR]

In the last decades, the scientific community has paid an increasing attention on coastal karst areas, since these are highly urbanized and populated, and attract high number of tourists. This transition zone where anthropogenic, terrestrial, and marine processes simultaneously act, is intrinsically fragile, and its vulnerability to geological hazards is enhanced by the mixing between fresh and salt waters, causing a stronger dissolution on carbonate rocks. In this paper, a case study located along the coastal karst of Apulia, between the provinces of Bari and Brindisi, in one of the most touristic areas of the Region is described. In detail, this manuscript deals with description sinkholes evolution at the coastal zone and seawater intrusion in coastal aquifer. The case study highlights the influence of sinkholes in the modification of coastal geomorphology, potentially leading to natural hazards in terms for communities, urbanized land, and infrastructures. The geological setting presents the Cretaceous limestone bedrock overlain by more recent Cenozoic calcarenites and Quaternary marine terrace deposits. The topography is controlled by structural discontinuities, mainly oriented in SW-NE direction. This area is locally defined “Costa Merlata”, which means “Merlon coast”, as it resembles the merlons of a medieval castle. This is due to a strong control exerted by sinkholes in the genesis of bays and inlets. In fact, in this stretch of the Adriatic coastline, it is possible to observe important freshwater outflows, including the main spa of central Apulia (Torre Canne spa), and several evidence of sinkholes, including recent collapse at a few meters from the coastline. The morphologic evolution is characterized by different phases: individual openings of sinkholes, which evolve to small inlets showing the larger sinkhole inland, accompanied by minor openings toward the sea; the last phase is characterized by well-developed bays, deriving from coalescence of sinkholes, overall entering inland for some tens of meters, by means of progressive failures, also favored by sea-storms. In addition to the sinkhole hazards, the area is affected by inland seawater intrusion. In fact, the hydrogeological setting of the coastal stretch, extending for about 25 km, shows evidence of groundwater salinization, with salinity values ranging from 0,5 g/l to more than 5 g/l. The springs with high discharge rate are in the sand dunes zone (Fiume Grande, Fiume Piccolo, and Fiume Morello) and discharge hundreds of liters of freshwater per second, while several diffuse springs, often with unknown discharge, are submerged. In such complex zone, caves adopted as groundwater monitoring spots, especially near the sea, where fresh water and sea water meet. The latter is also carried out by monitoring of stygofauna, i.e. animal species living exclusively within groundwater. Stygofauna can be considered environmental indicator and natural tracer, since it is highly sensitive to environmental variation; therefore, studying groundwater ecosystems will allow to characterize the groundwater quality and the main freshwater pathways. [ABSTRACT FROM AUTHOR]

Introduction: In cities, the intensity of integrated development, both above and below ground, has been continuously increasing. Unfortunately, associated events such as surface cracking and ground collapse are common, and research into the susceptibility of urban ground collapse (UGC) has consequently, also been increasing.Methods: In this study, we calculated the spatial probability distribution of historical UGC events in Hangzhou, China as a case study. To avoid the influence of the subjectivity of expert opinions on the evaluation results, and to distinguish it from the first version of the UGC sensitivity map in 2021, collinearity and correlation analyses based on geo-detector were conducted, and the 11 most representative factors from 22 candidates were identified. Then, a GIS-based susceptibility assessment system was established and applied to eastern Hangzhou, China.Results: The assessment results were divided into three grades. High-susceptibility areas accounted for 6.08% of the total area and were mainly distributed in the central area on both sides of the Qiantang River. Medium-susceptibility areas accounted for 23.92% of the total area and showed an expanding trend around the central area. Low-susceptibility areas accounted for 12.42% of the total area and were mainly distributed within the bedrock mountainous areas on the west side.Discussion: The assessment model take more urban construction activies into consideration, which can fits better with the trigger factors of UGC itself, and has good applicability for other cities in Zhejiang Province to assess the susceptibility of UGC events.

Several methodologies allow for the detection and mapping of existing sinkholes in order to asses and manage the associated hazards and risks. These phenomena, linked to the presence of soluble rocks, are well known globally as they can cause severe damage to man‐made structures. In this paper, we propose an integrated method applied to a test‐site area in NE Italy where, on May 11 2017, a failure shaped like a sinkhole, suddenly occurred along a main regional road, which then had to be closed to traffic in part as a result of a landslide developing on the slope just upstream from the surface depression which had already formed. The slope was reprofiled, a paved barrier was placed at the toe of the slope, and the road itself was finally repaired and restored. In the test site, a detailed morphological and geological survey was performed, as well as several integrated multi‐scale geophysical investigations, both in correspondence to the sinkhole location and in surrounding areas where other depressions were found. Results confirm the absence of large cavities down to the maximum investigated depth and highlighted a complex geological situation with abrupt lateral variations, a straight correlation between different geomorphological and geological elements, and the role of water paths. Geophysical investigations were found to be a useful tool to monitor the future evolution of the identified phenomena and to prevent further collapses and disasters along roads. [ABSTRACT FROM AUTHOR]

Abstract Key message Dolines may provide important safe havens for many plant species and play a key role in maintaining biodiversity. The combined effects of forest age and topographic position influence the biodiversity patterns of these unique habitats. Forest managers, conservationists, and researchers need to work together in order to maintain the species richness and composition of these habitats under environmental changes. Context Dolines are the most prominent geomorphological features in many karst landscapes that may provide important microhabitats for many species. Aims We aim to contribute to a better understanding of how forest age and topographic position influence the plant species richness and composition of vascular plants within doline habitats. Methods We studied the effects of forest age (four age classes: from 5- to 10-year-old stands to more than 90-year-old stands), topographic position (south-facing slope, bottom, and north-facing slope), and their interaction on the distribution of vascular plants and mean Ellenberg indicator values in dolines using detrended correspondence analysis and mixed-effects models. Diagnostic species for the forest age classes and topographic positions were also determined. Results Different groups of vascular plant species usually showed significant preferences for certain topographic positions and/or forest age classes in dolines. In general, the number of species in all studied groups of plants increased after a few years of canopy removal. The number of plant species in almost all groups was lowest in dolines covered with 40–45-year-old forests. The moist and nutrient-rich doline bottoms covered with 90–120-year-old forests harboured many climate change vulnerable plant species. Conclusions Forest age and topographic position considerably influence the species richness and composition of vascular plants in dolines; therefore, forest managers and conservationists need to consider their potential impacts when evaluating the effects of climate warming on karst landscapes.

The problem of road-related sinkhole stability has long been one of the main safety concerns to pavement engineers. Collapse and blowout failures are two typical types of pipeline-related sinkhole failures. Although much research on sinkhole stability analyses can be found in the literature, most of them assume a simple circular or rectangular shape of a cavity. In this study, the problem of sinkhole stability in an ellipsoidal cavity is investigated under both blowout and collapse conditions using advanced finite element limit analysis with adaptive meshing in an axisymmetric condition. A dimensionless pressure ratio is defined to represent sinkhole stability that is a function of many design parameters such as depth ratio, elliptical shape ratio, and soil strength ratio. Selected results are compared with published solutions, and comprehensive solutions of the parametric study are presented in the form of charts for use by design engineers. The present study contributes to the understanding of sinkhole stability under an ellipsoidal cavity, and it should be of interest to the road engineering community.

Subsurface salt layer dissolution along the western shores of the Dead Sea is considered to be the primary cause for extensive large sinkhole formation in the past 40 years. Many of these sinkholes are arranged in clusters and are filled with water from nearby springs. The Mineral Beach resort was built in an area with a thermal spring with water emerging at around 40 °C at the Shalem sinkhole cluster. Unfortunately, the same spring was responsible for the destruction of the resort as it supplied water undersaturated with respect to halite, which promoted dissolution and sinkhole formation. The sinkholes in the Shalem cluster drain out in sudden catastrophic events and then slowly fill again. The drainage mechanisms of this phenomenon are studied in the Shalem-2 sinkhole cluster using leveling data collectors and ground-based LiDAR surveys over a period of 5 years, including thirty-five drainage events. Drainage volume and fluxes calculated using water level and topographic data obtained by LiDAR scans suggest that the formation of additional sinkholes beneath the pond's bottom triggers drainage events. The subsequent flux shows that the evolution of the newly formed sinkholes either improves the hydraulic connection or temporarily seals the connection between the surface pond and deeper caverns/aquifers. The drainage event ends when either the hydraulic connection is sealed or when the level of water in the pond drops to the level of the newly formed sinkhole. The large volumes of drained water and drainage fluxes imply the existence of a well-developed active underground draining system. [ABSTRACT FROM AUTHOR]

In the space environment, cosmic rays and high-energy particles may cause a single-event upset (SEU) during program execution, and further cause silent data corruption (SDC) errors in program outputs. After extensive research on SEU and SDC errors, it has been found that SDC errors in the routing program in satellite networks may lead to the emergence of Sinkhole (SH) and Grayhole (GH) nodes in the network, which may cause damage to satellite networks. To find and solve the problems in time, a digital-twin-based detection and protection framework for SDC-induced SH and GH nodes in satellite networks is proposed. First, the satellite network fault model under SEU and the generation mechanism of SH and GH nodes induced by SDC errors are described. Then, the data structure based on digital twins required by the proposed detection and protection framework is designed, and the detection methods of SH and GH nodes induced by SDC errors are proposed. SKT and LLFI simulation tools are used to build a simulated Iridium satellite network and carry out fault injection experiments. Experiment results show that the accuracy of the proposed detection method is 98–100%, and the additional time cost of routing convergence caused by the proposed framework is 3.1–28.2%. Compared with existing SH and GH detection methods, the proposed methods can timely and accurately detect faults during the routing update stage. [ABSTRACT FROM AUTHOR]

The phenomenon of underground subsidence due to the conditions and characteristics of landforms in Central Iran, on the one hand, and human activities, on the other hand, has become one of the acute and severe issues in land management in Iran. Due to the existence of a multivariate function and the dependence of some parameters on each other, it was necessary to use intelligent functions in modeling subsidence events. The study area is Abarkooh plain, with an area of about 200 square kilometers as part of the Eqlid-Abarkooh watershed. For predicting sinkhole hazards in the study area by artificial intelligence model (ANNs, DT and SVM), the input data were physiography of the study area, and 130 soil samples taken from soil surface for chemical, physical, and mechanical analyses. GPR surveys were performed to detect breaks in stratigraphy and sinkholes in the subsurface to depth until 5 m. The results showed that the models predicted well the sinkhole hazard, and that some soil parameters, including Mg2+ in the soil and lime, COLE and EC have the most impact on creating sinkholes in the study area. The GPR results showed some geological horizons inremptions and subsurface holes in subsoils. The artificial intelligence models confirmed predicting high-risk areas which adapted to heterogeneous layers underground. The artificial intelligence model with more severe factors affecting subsidence and sinkhole in the natural–human disaster could be one of the best methods to forecast disasters. [ABSTRACT FROM AUTHOR]

The local population in an agricultural field in Puebla State's sub-urban has been affected by the prolonged drought periods and exceptional precipitation events of 2021, modifying the urban, agricultural, and industrial activities in the region. The main objective is to identify the geohydrology, climatology, geophysical, and geomechanics proxies to understand the new phenomenon that led to the formation of the sinkhole in the non-karstic zone. The results revealed that the sand and silt particles of the volcanic sediments have been removed from the agricultural subsoil probably due to the intense exploitation of groundwater. Moreover, the exploitation strata indicated the existence of organic silt at 15 and 25 m, with high compressibility, less mass volume, and high water saturation conditions. Henceforth, these strata were considered as anomalies with low resistivity that are related to strong fluctuations in the water table that favored the collapse. Results of the void calculation formulation and the correlation with the removal of sediments of erosive susceptibility in the subsoil strata adjacent to the sinkhole demonstrate that the removal of sediments causes the collapse due to removal of finer sediments. The data integration allows us to determine that the sinkhole has been formed because of a combination of factors such as subsoil erosive conditions, extraordinary hydrometeorological events, hydraulic gradient flows, and the intense exploitation of groundwater in the region. Detecting the causes of sinkholes can predict the susceptibility of the territories, elaborate strategies to avoid risk, anticipate response–mitigation actions, and sustain the water safety plans for sustainable public policies. [ABSTRACT FROM AUTHOR]

The current work explores the suitability and advantages of utilizing ground penetrating radar (GPR), and electrical resistivity imaging (ERI) in the hazard assessment process of Sannur cave associated with water inrush, structural instability, and engineering uncertainty in the site. The huge cave was discovered during mining of alabaster stone in the Egyptian Eastern Desert and considered a karst feature hosted in Eocene limestone with a several types of speleothems. The area is well-known for its high degree of karstification due to a long period of water erosion and the development of fractures network. Detailed geological and geophysical studies, including geological mapping of the area, 3D laser scan, fracture trend analysis, 2D GPR, and 2D ERI has been carried out to study the suitability of the site for safe touristic activities. GPR data delineated numerous probable cavities and fractures (fissures) within limestone formation due to karstification processes below the road heading down to the cave conformable to those analysed fractures exposed at the surface. The integration of GPR and ERI data in the yard outside the cave opening shows good correlation in the determination of lithostratigraphic sequence and dimensions of two electrically conductive clay lenses in addition to inferred fractures striking NW-SE conformable with outcrop studies of fractures in the vicinity of the cave. Recommendations were proposed to be taken into consideration for preparing the site and the results encourage the integrated application of such geophysical techniques for the reconnaissance and further detailed characterization of the karst features within the area. [ABSTRACT FROM AUTHOR]