Karst Hazards Research Articles

Exposure of tourism development to salt karst hazards along the Jordanian Dead Sea shore

Abstract. The Dead Sea shore is a unique, young and dynamic salt karst system. Development of the area began in the 1960s, when the main water resources that used to feed the Dead Sea were diverted towards deserts, cities and industries. During the last decade, the water level has fallen by more than 1 m per year, causing a hydrostatic disequilibrium between the underground fresh waters and the base level. Thousands of underground cavities have developed as well as hectometre-sized landslides. Despite these unfavourable environmental conditions, large tourism development projects have flourished along the northern coast of the Jordanian Dead Sea. In this work, which is based on a multi-method approach (analyses of radar and optical satellite data, in situ observations, and public science), we show that a 10 km long strip of coast that encompass several resorts is exposed to subsidence, sinkholes, landslides and flash floods. Geological discontinuities are the weakest points where the system can re-balance and where most of the energy is dissipated through erosional processes. Groundwater is moving rapidly along fractures to reach the dropping base level. The salt that fills the sediments matrix is dissolved along the water flow paths favouring the development of enlarged conduits, cavities and then the proliferation of sinkholes. The front beaches of the hotels, the roads and the bridges are the most affected infrastructure. We point out the importance for the land planners to include in the Dead Sea development schemes the historical records and present knowledge of geological hazards in the area.

Recent advances in karst research: from theory to fieldwork and applications

Abstract Karst landscapes and karst aquifers, which are composed of a variety of soluble rocks such as salt, gypsum, anhydrite, limestone, dolomite and quartzite, are fascinating areas of study. As karst rocks are abundant on the Earth's surface, the fast evolution of karst landscapes and the rapid flow of water through karst aquifers present challenges from a number of different perspectives. This collection of 25 papers deals with different aspects of these challenges, including karst geology, geomorphology and speleogenesis, karst hydrogeology, karst modelling, and karst hazards and management. Together these papers provide a state-of-the-art review of the current challenges and solutions in describing karst from a scientific perspective.

About this title ‐ Advances in Karst Research: Theory, Fieldwork and Applications

Karst landscapes and karst aquifers are composed of a variety of soluble rocks, such as salt, gypsum, anhydrite, limestone, dolomite and quartzite. They are fascinating areas of exploration, study and research. As karst rocks are abundant on the Earth's surface, the fast evolution of karst landscapes and the rapid flow of water through karst aquifers present many challenges from a number of different perspectives. This collection of 25 papers deals with different aspects of these challenges, including karst geology, geomorphology and speleogenesis, karst hydrogeology, karst modelling, and karst hazards and management. Together these papers provide a state-of-the-art review of the current challenges and solutions we face in describing karst from a scientific perspective, while at the same time providing useful data and information for managing karst territories to land planners, developers, and managers of show caves, natural parks and reserves in karst terrains.

Анализ локальной изменчивости физикомеханических свойств покровной толщи как метод оценки карстоопасности (на примере с. Усть-Кишерть)

Analysis of different factors of the natural structure allowed assessing the hazards at the territory of the Ust-Kyshert village characterized by the development of carbonatesulfate karst. In the article, the local karst hazard assessment using integrated physical and mechanical properties showed that the state and stiffness of the overlying mass might be used as the indicators of disintegration of the rocks due to the karst development. A comparative analysis of the resulting cartographic model with the previously proposed model of karst hazard assessment of the studied area is carried out.

New Karst Sinkhole Formation Mechanism Discovered in a Mine Dewatering Area in Hunan, China

The Meitanba Coal Mine in Hunan province, China, has experienced severe karst sinkhole hazards since 1982. Mine dewatering that began in 1955 has produced a groundwater cone of depression encompassing an area of 219.19 km2 as of 2014. Most dewatering-induced sinkholes occurred on three occasions: at the beginning of dewatering, at times when groundwater level dropped beneath the bedrock surface, and at times when water inrushes occurred. Sinkholes would not be typically anticipated in the stabilized groundwater cone of depression. However, over the last decades, many sinkholes including a large one, 80 m in diameter and 30 m in depth, that occurred at a primary school in 2010 have formed in the dewatering zone, even though a series of treatments have been taken to prevent such karst hazards. To determine the dynamic mechanisms of the sinkhole formation in the dewatering zone, the Dachengqiao region was selected as a study site and high-frequency monitoring of groundwater–air pressures was performed in the underlying karst conduit system. The monitoring results showed very intense pressure changes in the dewatering zone with a maximum fluctuation of 54.72 m and a maximum instant fluctuation rate of 70.6 cm H2O/min. The abrupt pressure changes are more likely caused by air blasting and soil collapse and can be a key factor triggering the sinkhole collapses.

Coupling of field investigations and remote sensing data for karst hazards in Egypt: case study around the Sohag City

Karst rocks cover a wide area of Egypt. These rocks include soluble sediments such as carbonate rock formations, evaporites, and sabkha deposits that are characterized by karstification features. Karst features could affect many current and developing projects (urban areas and infrastructure). The areas covered by the rocks susceptible to karstification need detailed studies to examine the presence of karst features and/or sinkholes. The current work provides a detailed evaluation of the karst and/or sinkhole hazards around the city of Sohag, Egypt. This research is rarely done in Egypt, using field investigation and remote sensing application to determine the main karstic rock formations and the distribution of the most problematic sinkhole areas. In this work, different types of the subsidence mechanisms were investigated. Our results indicated that field investigations help in finding different features related to karstification including small-scale versus large-scale features and empty caves versus filled caves. In addition, remote sensing techniques succeeded in predicting and locating the sinkhole areas, and those determinations were verified in the field. Finally, fundamental considerations are discussed to better evaluate and manage the hazard of karst and/or sinkholes.

Integrated approach for sinkhole evaluation and evolution prediction in the Central Ebro Basin (NE Spain)

Evaluation of karst hazards benefits from the integration of different techniques, methodologies and approaches. Each one presents a different signature and is sensitive to certain indicators related to karst hazards. In some cases, detailed analysis permits the evaluation of representativeness either from isolated approaches or by means of integrated analyses. In this study, we present the evaluation of an area with high density of karstic collapses at different evolutionary stages through the integration of surficial, historical, geomorphological and geophysical data in order to finally define the evolutionary model for karst activity development. The obtained dataset permits to identify different steps in sinkhole evolution: (i) cavities and open sinkholes, (ii) filling of these cavities, with materials having different signatures, (iii) the progression from collapses to subsidence sinkholes and (iv) enlargement through collapses in marginal areas of previous sinkholes. The presence of different stages of this evolutionary model permits to determine their own signatures that can be of application in contexts where analysis cannot be so systematic and also to evaluate the definition of the marginal areas of previous sinkholes as the most hazardous sectors.

Оценка карстоопасности территории г. Кунгура на основе общегеологического подхода

Оценка карстоопасности территории г. Кунгура на основе общегеологического подхода

Indirect geophysical characterization of geohazards in mantled karst environments in the Ebro Basin

Karst hazards in the central Ebro Basin are related to subsidence and collapses owing to evaporitic rocks located several tens of metres below the surface. In this type of karst (mantle karst) cavities propagate upwards through a non-soluble rock, in this case Quaternary alluvial deposits. The typical geological series comprises a heterogeneous alluvial unit underlain by a soluble, mainly gypsiferous, substratum and several water tables that usually present high conductivity variations. The highest concentration of karstic evidence is identified along the fluvial flood plain of the Ebro River where clayey deposits dominate at the surface. These boundary conditions produce complex environments for the evaluation of geophysical data related to i) karst activity, ii) the presence of cavities below the water table and within the substratum and iii) the variable sedimentary architecture of fluvial deposits. During the past ten years different geophysical techniques have been used in order to characterize karst hazards in the Central Ebro Basin. These experiences have enabled the evaluation resolution, discrimination characterization and finding of karstic evidence using different approaches. The main success in the application of these geophysical techniques has been the quantification of karst hazards from the record of subsidence processes through changes in density, magnetic susceptibility, apparent conductivity and structure of the alluvial deposits. However, the identification of cavities below the alluvial series still represents a serious handicap wing to nonunivocal interpretations and low resolution or penetration of geophysical techniques.

Evaluating susceptibility of karst dolines (sinkholes) for collapse in Sango, Tennessee, USA.

Dolines or sinkholes are earth depressions that develop in soluble rocks complexes such as limestone, dolomite, gypsum, anhydrite, and halite; dolines appear in a variety of shapes from nearly circular to complex structures with highly curved perimeters. The occurrence of dolines in the studied karst area is not random; they are the results of geomorphic, hydrologic, and chemical processes that have caused partial subsidence, even the total collapse of the land surface when voids and caves are present in the bedrock and the regolith arch overbridging these voids is unstable. In the study area, the majority of collapses occur in the regolith (bedrock cover) that bridges voids in the bedrock. Because these collapsing dolines may result in property damage and even cause the loss of lives, there is a need to develop methods for evaluating karst hazards. These methods can then be used by planners and practitioners for urban and economic development, especially in regions with a growing population. The purpose of this project is threefold: 1) to develop a karst feature database, 2) to investigate critical indicators associated with doline collapse, and 3) to develop a doline susceptibility model for potential doline collapse based on external morphometric data. The study has revealed the presence of short range spatial dependence in the distribution of the dolines' morphometric parameters such as circularity, the geographic orientation of the main doline axes, and the length-to-width doline ratios; therefore, geostatistics can be used to spatially evaluate the susceptibility of the karst area for doline collapse. The partial susceptibility estimates were combined into a final probability map enabling the identification of areas where, until now, undetected dolines may cause significant hazards.

A model of karst systems of the Usturt plateau (Middle Asia)

The issues relating to the structure and development of desert karst is currently one of the least studied problems. The goal of the research efforts presented in this paper was to create a model of karst systems in the Usturt Plateau and, primarily, of the systems formed by the prevailing numerous surface karst landforms. The model is based on the following main assumptions: the process of emergence of the karst phenomena is probabilistic and occurs independently at non-intersecting sites; the probability of emergence of one depression at a reference site depends only on its area. The increase of the dimensions of a karst landform is a random process that occurs independently of other karst landforms, its speed is governed by random factors, and it is directly proportionate to the existing dimensions of the landform. The model does not assume constancy of climatic characteristics. The testing was conducted at several reference sites of the Usturt Plateau. The research allowed us to reach the following conclusions: the karst depressions of the Usturt Plateau, which are the typical forms of desert karst, are governed by the Poisson distribution of their centres and by the lognormal distribution of their dimensions, similar to the karst depressions in a humid climate. The results may be used in assessments of karst hazard for linear and areal structures, as well as for small-dimensional structures.

Methods for karst hazard forecast and pipeline protection in South Yakutia

The objective of this paper is to consider the ways of monitoring and protecting the pipeline «The Power of Siberian from karst hazards. The method of protection with bored piles has been recommended and the forecasting methods have been overviewed. Thus, ground penetrating radar allows discovering a soil cavity when the overburden layer is not very deep and predicting sinkhole collapse when used in combination with a balance arch model. Monitoring of triggering factors is widely used to forecast karst collapse when the opening is caused by pumping as the data on dynamic groundwater conditions can be obtained in realtime. However, the suggested protection method is expensive and some forecasts might be difficult to make. The authors have suggested the ways to improve the current situation and to reduce the damage caused by karst collapse.

Karst hazard assessment in the design of the main gas pipeline (South Yakutia)

The paper represents the description of the zonal and regional geological factors of geoengineering conditions which characterize the territory in South Yakutia crossed by the designed main gas pipeline. Cryogenic processes and karst are considered to be the most dangerous hazards for gas pipeline maintenance. Karst hazard assessment of the gas pipeline section made in the course of the research has involved a complex of geological methods: geoengineering, geophysical, hydrogeological, and mapping. Sections prone to karst development have been identified. The authors have suggested the measures to protect potentially hazardous sections and to ensure timely informing on sinkhole collapses.

Assessing karst hazards in urbanized areas. Case study and methodological considerations in the mantle karst from Zaragoza city (NE Spain)

Mantle karst environments can be analyzed by means of historical, geophysical and geomechanical approaches with the objectives of avoiding urban development in hazardous areas or to establish guidelines for foundation design. Nevertheless, geophysical and geomorphological techniques can show complexities in interpretation in urban domains. In order to analyze their limits and resolutions, historical approaches, geophysical surveys and field inspection are here combined with the analysis of building and construction problems in urbanized sectors. The particular case study presented is a sinkhole affecting three different domains: an agricultural area, an uncultivated plot and an urbanized zone where surficial karst evidences affecting streets, roads and buildings are observed. The results obtained permit to analyze the noises from urban environments for both magnetic and electromagnetic (multifrequency) techniques, and the limitations of ground penetrating radar (GPR) survey in agricultural areas with clayey soils and subhorizontal conductive layers. The comparison and evaluation of different approaches and geophysical techniques in the three domains permit to define an efficient routine in order to characterize surficial evidences, structural changes in underground materials, and changes in their geophysical characteristics.

Actual extension of sinkholes: Considerations about geophysical, geomorphological, and field inspection techniques in urban planning projects in the Ebro basin (NE Spain)

Aerial photographs, historical cartographies, and field inspection are useful tools in urban planning design on mantled karst because they permit a wide time interval to be analyzed. In the case of Zaragoza city, several works have confirmed the interest of these approaches in configuring the urban planning code and therefore represent a promising technique. Nevertheless, some caveats should be taken into account when using this kind of information. A detailed analysis is presented comparing (in a case study from the surroundings of Zaragoza) geomorphological, historical analysis, and field inspection with geophysical data. Field inspection in a noncultivated area permits the constraint of the presence of karst indicators below the geomorphological resolution of aerial photographs and shows results consistent with geophysical surveys. The studied case shows an inner zone coinciding with the sinkhole mapped from aerial photographs that correlates with changes in the position of the substratum and changes in thickness of alluvial sediments. The integrated analysis permits us to define an external subsidence ring around the geomorphological sinkhole whose surface is twice the size of the inner zone. This outer ring is indicated by geometrical changes in GPR profiles, increases of thickness of the conductive shallower unit toward the collapse, and small collapses on marginal cracks. These results support the higher extension of karst hazards linked to sinkholes with respect to their geomorphological expression and the needed detailed analysis to constrain the real sinkhole size or the use of security radii surrounding this surficial evidence when geomorphological data is used for the hazard analyses or the urban planning at karstic zones.

Karst Environments: Problems, Management, Human Impacts, and Sustainability: An Introduction to the Special Issue

Karst systems are extremely complex, and due to a number of geological and hydrological characteristics, they can be included among the most fragile and vulnerable environments in the world. Complexity of karst is expressed bythe enormous variations existing in different karst regions (White, 1988). The difficulties inherent in such variability were appropriately described by Beck (1999), who wrote, ‘‘Learning to understand the systematics of karst terrain and how to deal with it safely requires serious effort—often a lifetime of study.’’ This means, in other words, that man must make a strong effort to learn to live ‘‘in harmony with’’ karst, rather than to live ‘‘on’’ karst. Many problems we face when interacting with karst environments are best solved through changes in human systems rather than through alterations of karst environments. This is because subtle changes in fragile karst systems change them significantly. Because karst covers 10 to 20% of the earth’s surface and provides 40 to 50% of the world’s drinking water (Ford and Williams, 2007), it requires a specific approach to mitigate negative human impacts and allow sustainable development. In this sense, protection of karst groundwater is essential in many countries. Karst hydrologic systems are highly vulnerable to pollution, water withdrawals, and changes in land use (Bakalowicz, 2005; Calo` & Parise, 2009). In addition, the dissolution of limestone creates voids in the subsurface that can lead to collapses that directly affect the built environment by inducing severe damage, property loss, and disruptions to daily life. Management of karst environments is a very delicate matter, and how to manage pollution, karst hazards, and human impacts on karst landscapes is a question worthy of discussion (White, 1990; Parise and Pascali, 2003).

An electrical resistivity imaging-based strategy to enable site-scale planning over covered palaeokarst features in the Tournaisis area (Belgium)

Since the beginning of the 20th century, more than 150 sinkhole occurrences, mainly dropout (or cover-collapse) sinkholes, have been reported in the Tournaisis area (south-eastern Belgium). Land-use planning in such a context has to take into account hazards linked with sinkhole subsidence and collapse. Management maps, drawn at a regional scale, point out zones where karstic risks have to be taken into account when dealing with infrastructure or building projects. However, karst hazard is highly variable in three dimensions at the local scale. Therefore, for such purposes, an accurate methodology is needed to detect and delineate covered karst features, especially when located in urbanized areas.As geophysical investigations are sensitive to contrasts in physical properties of soils, these methods can be useful to detect such targets. The specific karstic context encountered in the Tournaisis area strongly guides the choice of investigation techniques. Electrical resistivity imaging (ERI) methods were tested on a well-known site where dropout sinkholes occurred formerly. This site was also studied using static cone penetration tests (CPT) and boreholes. A 3D inverted resistivity model was computed based on the 2D ERI models obtained after inversion. Resistivity profiles were extracted at each CPT location and compared to geotechnical results to determine an empirical and site-specific resistivity law that allows discrimination between weathered zones and sound limestone. Performance tests were conducted to evaluate the potential of the proposed methodology for two typical engineering problems based on two current hypotheses. Borehole data were used as ground truth. Similar performance tests were also computed using the CPT depth to bedrock model. The results of these performance tests are compared and discussed. Finally, an ERI-based investigation strategy is proposed to assess karst hazard in palaeokarstic context, such as encountered in the Tournaisis area, at the scale needed for building and infrastructure purposes.

ГЕОДИНАМІКА

The optimum complex of geophysical research methods (gravimetry, PIEMPZ, VEZ, ZS) to iden­tify unstable areas associated with the development of natural and anthropogenic karst is present. An interpretation of the results, based on a complex calculation using an integrated option - features a comprehensive index (PCF), which is consistent with the criterion for karst hazard. The 3D models of the distribution of probability criterion for karst hazard individual sections of the mine fields.

The Effectiveness Experiment Study on The Hidden Karst Detection Method of City Tunnel Engineering

Lateral variations of the karst of deep buried tunnel engineering is big. The heterogeneity of it is strong. The tunnel is combined with Changsha Rail Transit Line 2 at one section of the first phase construction. Under the urban environmental conditions, it is considered to use auxiliary seismic wave imaging method assistanting with Rayleigh surface wave method. It is the detection and prediction method of comprehensive geological analysis of karst hazard, which identified the underground targets of deep buried tunnel effectively. To avoid a single technique multiple solutions, it can reflect the complexity of karst formations geological features objectively. Therefore, it can reduce the risk of drilling and take appropriate treatment measures to provide adequate and reliable basis.

Characterization of karst hazards from the perspective of the doline triangle using GPR — Examples from Central Ebro Basin (Spain)

Ground Penetrating Radar (GPR) is a widespread technique to locate and characterise karst hazards (cavities and paleocollapses). In this paper, we show that the internal structure of sediments obtained from GPR surveys can also be used as an indicator of active karst processes. A classification of karst hazard problems by means of GPR in the GPR-doline triangle is proposed, with three end-members: cavities, evidences of subsidence and paleocollapses. These end members show particular signatures in the GPR-profiles. The field examples shown in this paper indicate that GPR survey is a geophysical technique that offers a very high resolution and provides structural and sedimentological information of the subsoil. The use of grid maps, elaborated from GPR data, is an efficient way to determine anomalous sectors (lateral changes of electromagnetic properties, different reflectivity and qualitative penetration depth variations or velocity wave propagation changes). Their relationships with the structural features obtained from GPR-profiles (on-lap geometries, zones with depressed reflectors, folded reflectors or laterally abrupt structural limits) can be used as indicators of karstic processes.