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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]

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]

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]

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]

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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]

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]

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]

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]

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]

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]

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]

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]

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]

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 present research investigates the morphology and genetical mechanism of a sinkhole which occurred in 2019 in Murisengo (NW Italy). This landform is representative of several subsidence phenomena that often concern the Monferrato area (NW Italy). In concomitance with the appearance of the sinkhole at the surface, a cone of detrital material was found in the drifts of a nearby underground quarry. A geological survey was performed in the underground quarry in order to understand the interaction between the geological and geostructural features of the rock body and the generation of the sinkhole. Moreover, the underground sinkhole morphology was investigated through electrical resistivity tomography (ERT) surveys performed at the surface. The ERT outputs were combined to obtain a 3D image of the phenomenon and the 3D reconstruction was then compared with the geomorphological and structural setting of the area. Results suggest that a viscoplastic flow of clay‐rich sediments within a conduit in the gypsum bedrock (suffusion process) generated the sinkhole. [ABSTRACT FROM AUTHOR]

Natural hazards are one of the factors that cause financial loss every year, and they occur in most regions of the world, including Iran. One of the hazards that mankind has been dealing with in recent decades, especially in alluvial plains is the phenomenon of land subsidence and sinkhole. Land subsidence and sinkhole due to natural and human causes have been reported in many places. Subsidence or sinkhole will damage human structures that are supported by the earth. Land subsidence is the most important environmental problem in Iran. A major cause of this phenomenon is overexploitation of underground water resources has led to land subsidence, and underground water extraction plays an important role in causing land subsidence. The study area is Abarkooh plain with an area of about 250 square kilometers is a part of the Eqlid-Abarkooh watershed. The lowlands are covered by Quaternary alluvial and some older sediments such as unconsolidated conglomerate, clayey, sandy, and saline areas. Based on geographical location, the study area is located in the geographical range of 53 degrees to 53 degrees and 32 minutes east longitude and 30 degrees and 50 minutes to 31 degrees and 12 minutes north latitude. This area contains medium to fine alluvial fan sediments that end in the salt playa or Abarkooh desert. To determine the high-risk and low-risk areas and routes in the study area, to discover subsurface holes and stratigraphic fractures underground up to a depth of 5 meters and the safe route for contracting works, etc., was used the ground penetrating radar (GPR) method. The results showed that in the areas where there are sinkhole traces in the determined distances around in current research, the attenuation signal of the ground penetrating radar, including the effects of subsurface cavities and stratigraphic fractures was discovered and revealed by GPR. On the side of the mountain slopes and high altitudes in the upstream region, no signal attenuation was observed, and sediments and soil were observed uniformly underground. The ultimate goal of the GPR section is to obtain a cross-section that is most consistent with the geological realities of the region and finally, at the final stage, we can talk about the characteristics, effects, and objectives of the research. The GPR method is an easy and low-cost method that is widely used in the field of natural resources and it is also used in other scientific fields. Regarding the common phenomenon of subsidence and sinkhole, these effects can be found underground, so that humans can prevent the development and expansion of this phenomenon. Also, this method can determine the route and safe area for contracting works, urban development, etc. [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]

Sinkholes are a significant underground hazard that threatens infrastructure and lives and sometimes results in fatalities. The annual cost of sinkhole damages exceeds $300 million, although this estimate is likely underestimated due to the need for national tracking. Sinkholes can also alter natural drainage patterns, leading to increased flood risk. While natural sinkholes occur, those in urban areas are predominantly manmade, caused by soil erosion from defective pipes, typically due to aging. Climate change, storm surges, and urbanization have accelerated subsidence in urban environments, posing greater risks to critical infrastructure and densely populated areas. Extensive research has focused on soil erosion in dams; however, this knowledge does not necessarily apply to erosion through orifices, where gravity and other factors play significant roles. This paper presents a critical literature review on internal soil erosion due to defective pipes (SEDP). The review highlights that hydraulic loading, backfill type, and pipe conditions (defect shape, size, and depth) influence SEDP. Key findings from experiments and numerical studies are summarized, while mechanisms and knowledge gaps are identified. However, it is concluded that the current understanding in this field remains limited, underscoring the urgent need for further experimental and numerical research to expand the knowledge base on SEDP. [ABSTRACT FROM AUTHOR]

Copyright of Science Technology & Engineering is the property of Chinese Society of Technology Economics and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

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. [ABSTRACT FROM AUTHOR]

Numerous variants of the basic deep segmentation model—U-Net—have emerged in recent years, achieving reliable performance across different benchmarks. In this paper, we propose an improved version of U-Net with higher performance and reduced complexity. This improvement was achieved by introducing a sparsely connected depth-wise separable block with multiscale filters, enabling the network to capture features of different scales. The use of depth-wise separable convolution significantly reduces the number of trainable parameters, making the training faster, while reducing the risk of overfitting. We used our developed sinkhole dataset and the available benchmark nuclei dataset to assess the proposed model's performance. Pixel-wise annotation is laborious and requires a great deal of human expertise; therefore, we propose a fully deep convolutional autoencoder network that utilizes the proposed block to automatically annotate the sinkhole dataset. Our segmentation model outperformed the state-of-the-art methods, including U-Net, Attention U-Net, Depth-Separable U-Net, and Inception U-Net, achieving an average improvement of 1.2% and 1.4%, respectively, on the sinkhole and the nuclei datasets, with 94% and 92% accuracy, as well as a reduced training time. It also achieved 83% and 80% intersection-over-union (IoU) on the two datasets, respectively, which is an 11.8% and 9.3% average improvement over the above-mentioned models. [ABSTRACT FROM AUTHOR]

Copyright of Mineral Resources Management / Gospodarka Surowcami Mineralnymi is the property of Mineral & Energy Economy Research Institute of the Polish Academy of Sciences and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Wireless sensor networks (WSNs) are made up of low-energy tiny sensor nodes that can monitor specific environment and transfer data among themselves without the use of a physical media. With the rapid improvements in information technology in recent years, there has been a growing interest among various enterprises in using wireless sensor technologies. Sensor nodes in a WSN with limited energy detect an event, gather data, and send it to the sink node, which is the base node, for further processing and assessment. The design and placement of the sink node can affect a few aspects of WSNs, such as energy consumption and lifetime. Despite their many advantages, WSNs are regarded vulnerable and unprotected. Sinkhole, an adversary attack places serious dangers to the security of such networks within a vast class of varied security assaults that may damage the system's performance. A sinkhole attack is one of the most harmful types of intrusions because it introduces a compromised or created node into the network that tries to entice network traffic by displaying its incorrect and fraudulent routing update. It can also be utilised to send the base station (BS) bogus or fraudulent information. The paper proposes an efficient algorithm for sinkhole attack detection called M-path Sinkhole Attack Detection (MSAD), a solution to the sinkhole problem in WSN. It is suitable for devices with limited resources like sensors. For energy saving in WSNs, the proposed system applies the concept of clustering, and then the proposed simple and light algorithm for intrusion detection algorithm is applied. The proposed method is evaluated against recent algorithms C-LEACH, S-LEACH, ABC and MS-LEACH algorithms and it is found that the proposed method detects the attack with an accuracy rate of 97%, which is higher than other algorithms. [ABSTRACT FROM AUTHOR]

This work presents a sinkhole susceptibility and risk assessment mapping in Guidonia-Bagni di Tivoli plain (Italy), a travertine sinkhole-prone area where sudden occurrences of sinkholes have happened in past and recent times. We collected a point-like sinkhole inventory and we considered a series of different sinkholecontrolling and precursory factors over the study area, related to its geo-litho-hydrological setting and to its terrain deformational scenario, i.e. ground motion rates derived from InSAR COSMOSkyMed imagery. A sinkhole susceptibility map was produced through a machine learning model, namely Maximum Entropy algorithm (MaxEnt). Results highlight that the most determining factors for sinkhole formation are the lithology, the travertine thickness, groundwater and the land use. The sinkhole susceptibility map was then combined with data on vulnerability and elements-at-risk economic exposure in order to provide a sinkhole risk map of the area. The outcomes show that areas at higher risk covers about 2% of the total study area and primarily relies on the zoning of the main urban fabric. In particular, it is worth to highlight that 5% of the whole road-network pavement and 27% of all the residential buildings fall into High and Very High risk classes. Overall, results of this work demonstrate capabilities of machine learning models to assess sinkhole susceptibility for predicting potential sinkhole areas, and provide a sinkhole risk map, along with information on urban environment, as a useful tool for urban planning and geohazard risk management. [ABSTRACT FROM AUTHOR]

A poorly studied genetic type of sinkhole formation, which is typical for areas where karstified rocks are covered by water-saturated or unsaturated cohesionless soils is considered. The saturated soils can be underlain by an impermeable bed. The occurrence of single (and sometimes numerous) liquefaction-collapse sinkholes on the earth's surface or under the foundation in these geological settings can be caused by the dissolution of soluble rocks, the sudden occurrence of a breach in the impermiable bed, a dynamic or shock loading on water-saturated incoherent cohesionless soils, and the development of vertical upward water flow in cohesionless soils. The latter trigger is often manifested as the recovery of lowered groundwater level due to pumping of karst water. In built-up areas, this can lead to deformation and even destruction of buildings and structures by liquefaction-collapse sinkhole formation. The study of this phenomenon by in-laboratory simulation modeling had shown that these sinkholes are the result of upward-extending piping-collapse failures of soils, in which soil liquefaction plays a significant role. Concepts of the triggers and mechanisms of this process have been proposed. On its basis, the theoretical predictive approaches have been developed. They allow predicting the possibility of liquefaction-collapse sinkhole formation and the size of the sinkhole, taking into consideration the parameters of the engineering structures under threat. [ABSTRACT FROM AUTHOR]

Wireless sensor networks (WSNs) are infrastructure-less in nature and contain a number of autonomous sensor nodes. These sensor nodes are dedicated to monitoring the physical conditions of the environment and are organizing the collected data at a central location. Application areas of WSNs, like heathcare and military surveillance, are sensitive. That's why security of WSNs needs to be very effective. Providing security to WSNs plays a major role as it consists of limited resources. The security system should lie within the boundary of the resource potential and be competent enough to handle attacks. Intrusion detection system (IDS) is one type of defense system that can fulfill the measure of limitation of resources. In this paper, a detection technique is proposed against sinkhole attack using the Euclidean distance of each node from the base station. The main advantage of the proposed technique is that it doesn't require any extra hardware setup and doesn't require extra communication cost. [ABSTRACT FROM AUTHOR]

This manuscript aims to present the framework for the development of a four-stage tool for sustainable groundwater management as one of the highly interactive three-day workshop products. The four stages in the tool are (1) representing the target system, (2) description of the target system using components of DPSIR framework (drivers, pressures, state, impact, responses), (3) development of causal chains/loops, and (4) identifying knowledge gaps and articulating next steps. The tool is an output from the two-day Indo-US bilateral workshop on "Integrated Hydrochemical Modeling for Sustainable Development and Management of Water Supply Aquifers". Four case studies from the invited talks, panel discussions, and breakout sessions were selected to demonstrate the developed four-stage framework to a coastal aquifer (India) and in high plains in Floridian, Piedmont, and Blueridge aquifers (United States of America). The developed tool can be practically used in the development of strategies for the sustainable use of groundwater in various regions around the world (e.g., planning/building/maintaining groundwater recharging structures). Continued work can result in establishing a center for excellence as well as developing a network project. The recommendations from the workshop were: (1) developing vulnerability analysis models for groundwater managers; (2) treatment and new ways of using low-quality groundwater; (3) adopting groundwater recharge; (4) mitigating pollutants getting into the aquifer; and (5) reducing groundwater use. This study provides a framework for future researchers to study the groundwater table related to the effectiveness of water recharging structures, developing a quantitative model from the framework. Finally, recommendations for a future study are more data collection on groundwater quality/recharge as well as enhancing outreach activities for sustainable groundwater management. [ABSTRACT FROM AUTHOR]

Copyright of Nigde Omer Halisdemir University Journal of Engineering Sciences / Niğde Ömer Halisdemir Üniversitesi Mühendislik Bilimleri Dergisi is the property of Nigde Omer Halisdemir Universitesi (NOHU), Muhendislik Fakultesi and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Sinkhole occurrences due to underground water mains operations have piqued people's curiosity. Most research works were in relation to geophysical practices to discover the subsurface cavity. Very few works can be found in relation to the investigation of soil stability due to underground cavity shapes. The actual shape of an underground cavity and its transformation is difficult to predict, though the sinkhole failures are mostly circular in shape on the ground surface. This study explores the three-dimensional collapse stability of three distinct idealized cavity geometries, namely the circular, semi-spherical, and spherical cavities. For an active failure, dimensionless parameters are used to investigate the combined impacts of soil cover, surcharge pressure, soil weight, and internal pressure using advanced finite element limit analysis. Numerical results are compared with the two-dimensional axisymmetric results, and design charts presented to cover a wide range of design parameters for practical applications. [ABSTRACT FROM AUTHOR]

Copyright of Grundwasser is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Underground water main leakage is one of the main causes of instability of soils and sinkholes. In the event of a water main burst, the pressure is upward and hence the soil layer should be analyzed for blowout stability. Conversely, leakage from low-pressure utilities such as sewer pipes would erode the surrounding soil media and leave it unstable with an internal opening created. In such a situation, the possible failure scenario would be in collapse stability. This study set out to quantify the collapse stability performance of three idealized cavity shapes above the damaged pipe. Advanced numerical limit analysis was used to obtain upper and lower bound solutions of the problem. The study provides useful engineering information in the form of design charts and tables for a wide range of design parameters, which can greatly assist in decision making by practical engineers. [ABSTRACT FROM AUTHOR]

Extraordinary amounts of greenhouse gases can be stored within the monimolimnion of meromictic lakes, that is, in the water body which is excluded from mixing events. Lake Burgsee (Thuringia, Germany) is a shallow (depth <5 m) lake with a approximately 24 m deep sinkhole, which is fed by underground brine sources and has formed such a monimolimnion. We investigated the carbon dioxide and methane dynamics in this meromictic lake, from production potentials in the sediment via concentrations in the monimolimnion and mixolimnion to emissions to the atmosphere. In the monimolimnion, we found one of the highest methane concentrations (up to >5 mmol L−1) ever reported for a natural freshwater lake, while carbon dioxide concentrations in the water and methane production rates in the sediments were rather ordinary and within the range of holomictic eutrophic lakes. At the thermocline, gas concentrations accumulated to approximately 100 μmol L−1 CH4 and 80–230 μmol L−1 CO2. Estimated fluxes to the atmosphere reached considerable 3.5 mmol CH4 m−2 d−1 and 1.5 mmol CO2 m−2 d−1 above the sinkhole and 0.8 mmol CH4 m−2 d−1 and 0.4 mmol CO2 m−2 d−1 above the near‐by shallow lake center in 2018. Our results demonstrate that lakes in natural brine areas may provide significant storages and releases of greenhouse gases and require further investigation. Plain Language Summary: In meromictic lakes, the deepest water layer, the monimolimnion, is stagnant and not included in seasonal water circulation. Organic matter continuously sinks down into the oxygen‐free monimolimnion, where it is decomposed into the final gaseous products carbon dioxide (CO2) and methane (CH4). Lake Burgsee is a meromictic shallow (depth <5 m), brine‐fed lake with a approximately 24 m deep sinkhole. At the bottom of the narrow sinkhole, salinities are as high as in brackish water and cause a chemical stratification of the water body—a monimolimnion—in approximately 18 m depth. CH4 concentrations above the sediment reach >5 mmol L−1, which is more than one order of magnitude higher than at the water surface and among the highest CH4 concentrations found in freshwater lakes worldwide. Further, emissions of CH4 and CO2 from the water to the atmosphere were considerable in 2018, and about four times higher above the sinkhole than above the shallow lake center. These results demonstrate, that lakes in natural brine areas may store and release significant amounts of greenhouse gases and require further investigation. Key Points: In the urban meromictic Lake Burgsee, methane production potentials in the sediment are similar to eutrophic holomictic lakesAt its deepest site, it contains one of the highest methane concentrations (>5 mmol L−1 CH4) ever reported for a natural freshwater lakeLake Burgsee emits up to >3 mmol m−2 d−1 CH4 to the atmosphere above the sinkhole and <1 mmol m−2 d−1 CH4 at a near‐by shallow site [ABSTRACT FROM AUTHOR]

The soil leakage characteristics of depressions in karst areas should be explored by investigating their soil Ca and Mg contents. As a starting point, in a karst landform typical of Guizhou Huajiang dry valley karst watersheds, we selected surface depression and performed a field investigation, soil profile excavation, and soil sample collection. The soil samples were pretreated and taken to the laboratory for soil physical and chemical analysis. The data were processed, and the Ca and Mg contents of the soils were analyzed to determine the spatial variation characteristics of soil leakage in the depression. We found that in the depression watershed, the Ca and Mg contents in the 0–30 cm soil profile generally increased with increasing soil depth, and the Ca and Mg contents in the 30–150 cm soil profile exhibited more variability with increasing soil depth. The Ca and Mg in the soil surface profiles from the top of the slope, middle of the slope, base of the slope, bottom of the depression, and sinkhole showed obvious characteristics of a sedimentary soil leakage migration path. In combination with analyses of the soil K and N contents, the soil Ca and Mg contents can be used as an index of the likelihood of soil and water leakage in karst depressions. [ABSTRACT FROM AUTHOR]

This study aims to investigate the trend of water-level changes in lakes (Lake Tuz and Lake Beyşehir) and sinkholes (Timraş and Kızören) in the Konya Closed Basin located in Turkey. Water-level changes in these lakes and sinkholes were investigated along with changes in meteorological parameters (precipitation, temperature, and evaporation) and groundwater trends that indicate the climate in the region. Several statistical tests can be used to determine the significance of hydrological trends over time. These tests are divided into two categories: parametric and nonparametric. In this study, the nonparametric Innovate Sen trend test, the Modified Mann–Kendall trend test, and the parametric Linear trend test were used. According to the trend analysis, the water levels of Kızören and Timraş sinkholes decreased over time, while the water levels of lakes Tuz and Beyşehir increased. These results are supported by the trends in the meteorological data and groundwater level data of the stations determined with the Thiessen polygons and sub-basin boundaries. [ABSTRACT FROM AUTHOR]

Inverse modeling is one of the useful solutions to create a logical model with relationships between observed and measured values. In geophysical and subsurface investigations such as cavities or mineral explorations, solving inverse problems using problem physics in a partial differential equation (PDE) system is very important. In this research, COMSOL multiphysics' optimization interface, combined with a PDE or physics interface, was used to solve inverse-modeling problems. Also, a framework is presented to solve undetermined inverse problems using COMSOL multiphysics' optimization. COMSOL multiphysics does not include a gravity calculation module. However, since Poisson's equation governs gravity and electrostatics, a gravity model can be created in the electrostatics module by changing the electrical permittivity value. We present a general adjoint state formulation that may be used in this framework and allows for faster calculation of sensitivity matrices in a variety of commonly encountered underdetermined problems. First of all, 2D inversion of gravity data has been run and validated in COMSOL multiphysics software using one synthetic model and synthetic data in a forward modeling process. Afterward, using real gravity data surveyed along a cross-section of the sinkholes in the NW of Abarkuh, the lateral structure and subsurface cavities were estimated. The inverted gravitational acceleration values, then cross-correlated with observed gravity data and available surface pieces of evidence such as sinkholes and circular structures. The results indicated that our COMSOL-based routines for the solution of PDE-based inverse problems using adjoint states, while high in computational speed, can be used in modeling a wide range of physical systems governed by the partial differential equation laws and also can accurately discriminate between low-density contrast regions and background. [ABSTRACT FROM AUTHOR]

This paper presents new plastic solutions of a spherical cavity in undrained anisotropic clay under axisymmetric conditions by utilizing the upper bound (UB) and lower bound (LB) finite element limit analysis (FELA). The anisotropic undrained shear (AUS) failure criterion for anisotropic clays is employed to determine the sinkhole collapse by considering the influence of anisotropy. The stability number for the sinkhole collapse is defined as a function of the cover-depth ratio of a sinkhole, the dimensionless overburden factor and the anisotropic strength ratio. The effects of these parameters on the values of the stability number and the active collapse mechanisms of spherical cavities are thoroughly explored. The stability equation for predicting undrained stability of a spherical cavity is presented with an effective approximation solution to the problem based on nonlinear regression analyses of the average bound solutions generated from FELA. The proposed equation can be used as a quick and efficient tool for determining the undrained stability of this problem in practice, where the anisotropy effect of clay is also taken into account. [ABSTRACT FROM AUTHOR]

Road-related sinkholes are of great concerns nowadays, appearing frequently in media stories. In the undrained stability analysis, a dimensionless stability number that is known as Broms and Bennermark's original stability number expresses the combined effect of surface surcharge pressure, self-weight of the soil, and the supporting pressure. This "critical" undrained stability number, Nc, is used in this paper to formulate three-dimensional (3D) upper-bound and lower-bound solutions in active (collapse) and passive (blowout) scenarios of sinkhole stability using the classic trapdoor problem. Design charts, tables, and equations were developed to cover a wide range of practical design parameters. Together with modern geophysics techniques for the detection of underground cavity as well as the findings of the associated failure patterns in this paper, the study should, therefore, be of value to practitioners in their daily decision making. [ABSTRACT FROM AUTHOR]