Degree Of Karst Development Research Articles

Evaluation of Geo-Environment Carrying Capacity Based on Intuitionistic Fuzzy TOPSIS Method: A Case Study of China

The resource environment is a fundamental prerequisite for the construction of ecological civilization and the realization of sustainable development goals. It is also a core guarantee for human production activities. Conducting an evaluation of regional geo-environmental carrying capacity has significant practical importance for achieving sustainable development in the region. However, the existing evaluation methods for geo-environmental carrying capacity fail to effectively integrate multi-source data, resulting in an incomplete reflection of the level of regional geological carrying capacity. To address this issue, this study introduces the intuitionistic fuzzy multi-attribute decision-making method into the geo-environmental carrying capacity evaluation, according to the unique topographic and geomorphological characteristics of the region. A complete analysis framework is established, which integrates the intuitionistic fuzzy and TOPSIS models to classify the geo-environmental carrying capacity evaluation into five grades: high, relatively high, medium, relatively poor, and poor. Using Meishan, China as an example, the region is divided into 33 geomorphological units based on its geographical features. The results show that: (a) the percentage of natural units with high carrying capacity is 17.27%, that of relatively high natural units is 14.07%, that of medium natural units is 31.70%, that of relatively poor natural units is 27.51%, and that of poor natural units is 9.45%; (b) the geo-environmental carrying capacity exhibits spatial differences and uneven distribution. Furthermore, the average annual rainfall and degree of karst development are the main factors affecting the geo-environmental carrying capacity. These research results and findings can provide technical support for urban planning, regional sustainable development, and ecological environmental protection.

Risk Assessment of Water Inrush from Coal Floor Based on Karst Fractal-Vulnerability Index Method

Hidden karst structures are developed irregularly in the Middle Permian Maokou Formation aquifer from the northern part of the Guizhou coalfield, China. Mining operations associated with the exploitation of coal seams from the lower part of the Upper Permian Longtan Formation are threatened by karst waters from the underlying strata. To improve the accuracy of water inrush risk assessment of the karst aquifer floor in the northern Guizhou coalfield, the karst fractal quantification technique is implemented. In this study, the karst aquifer of the Maokou Formation located under the floor of the No. 15 coal seam from the Honglin Coal Mine is considered as the research object. Based on the karst results predicted by geophysical exploration methods, the fractal theory is used to quantify the degree of karst development, while the risk of water inrush from the floor of the coal seam is evaluated by applying ArcGIS information processing technology combined with the vulnerability index method. The results indicate the following observations: the mean fractal dimension of karst in the study area is 1.53, the karst structures are highly developed, and the overall distribution of karst is characterized by an irregular NW-SE direction; the main controlling factors affecting water inrush from the floor of the No. 15 coal seam are expressed by the water pressure of the aquifer, the abundance of water in the aquifer, the degree of karst development, the thickness of the effective impermeable layer, the mining depth, the coal seam dip angle, and the degree of fault complexity; the areas with the highest risk of floor water inrush are predominantly concentrated in the northwestern and central parts, but there is also a risk of floor water inrush in the first mining area of the No. 15 coal seam. This study takes into consideration complex factors such as the typical karst aquifer and the hydrogeological conditions in the northern part of the Guizhou coalfield, which results in a more realistic interpretation and can provide further guidance for water control activities in the mining area.

Distribution of carbonate rocks and variation analysis of karst water resources in China

Carbonate strata are widely distributed in China, which can be found in more than 30 provinces and cities, covering about 1/3 of the country’s territorial area. Affected by different geological and climatic conditions, carbonate strata in China geographically present different karst landscapes and groundwater resources. Specifically, northern China is dominated by large karst springs, while southern China is characterized by underground rivers. By determining the distribution range of carbonate strata in China, this paper pointed out the locations of large karst springs in the north and underground rivers in the south, analyzed the distribution characteristics of carbonate rocks in the north and south, the degree of karst development as well as their geological and climate genesis, and discussed the differences between karsts in northern and southern China in terms of occurrence forms of karst water and groundwater systems.

Study on the characteristics of karst development in Beijing

The distribution area of carbonate rocks in Beijing is about 5071.44 km2, accounting for 30.19% of the land area in Beijing. The distribution areas of bare, covered and buried carbonate rocks are 2862.21 km2, 401.86 km2, 1803.37 km2, respectively. The carbonate rocks mainly includes dolomite in Changcheng Group of Jixian System (Jxg), dolomite in Wumishan Group of Jixian System (Jxw), dolomite in Tieling Group of Jixian System (Jxt), Cambrian limestone (Є), Ordovician limestone (O) and carbonate rocks with different ages. The characteristics of karst development in Beijing differ from region to region. In the mountainous areas of dolomite in Changcheng System and Jixian System of Proterozoic, the karst landforms such as hoodoos, series of peaks and gorges are formed by the influence of rock differential solution and shear joints. In the Cambrian and Ordovician limestone distribution areas, middle-low mountains and uvalas are formed; the covered karst is affected by rock composition, regional structure control and environment, and the degree of karst development varies in different regions. According to the ground karst, karst caves distribution and karst spring distribution in Beijing area, the karst development in Beijing is summarized into three types: karst system-based (mainly developed karst cave system), fissure-based (basically undeveloped caves and karst springs, mainly for the development of underground joint fissures in the concealed area) and composite type (the karst spring with relatively large distribution, and a small number of ground karst caves, and the development of underground joint fissures). According to the distribution characteristics of 271 karst water boreholes, 563 geothermal boreholes, 258 ground surface karst caves and 499 karst springs in Beijing, the karst development in Beijing also has typical characteristics of heterogeneity, stratification and staging.

Quantitative Evaluation of Karst Developmental Differences Based on Improved Analytic Hierarchy Process and Multidimensional Extension Matter Element Model

In this study, limestone solubility, rock thickness, burial depth, hydrodynamic cycle, and geological tectonic of mine No. 13 in the Pingdingshan coalfield (China) were selected to evaluate the degree of karst development. The weight of each index factor to the karst development was determined by using the improved analytic hierarchy process. The multidimensional extensional matter model was used to determine the degree of karst development of the four mining areas (named 1st to 4th) of the Pingdingshan mine No. 13. The results show that the degree of karst development differs zonally, with 1st and 2nd mining areas presenting the lowest degree of karst development (grade II-IV, for an average quantification value of 3.0) and 4th mining area having the highest degree (grade IV-V, for an average quantification value of 4.7). In the vertical direction, the development degree of the vertical layer L1-L4 karst in the Carboniferous Taiyuan Formation is grade IV-V, with an average quantitative value of 4.5, whereas the layers L5-L7 in the Taiyuan Formation had a III-V grade, with an average quantitative value of 3.75, and the Cambrian limestone grade was II-IV, for an average quantitative value of 2.75, i.e., the development degree of karst gradually decreases from shallow to deep.

Characteristics, detection, and prevention of karst sinkholes: a case study in Laiwu iron ore mine areas, Shandong Province, China

Karst-related sinkholes are globally recognized geohazards that can be triggered by mining activities. Totally, 136 sinkholes have occurred in the Laiwu iron ore mine area of Shandong Province, China. At the surface, the sinkholes are mostly round or oval shaped. Most are ceiling collapse sinkholes, and they have caused road and building damage, destruction of farmland, connection of surface and ground water, and groundwater contamination. Based on analysis of characteristics on karst sinkhole, geological and hydrogeological conditions, the proposed key factors of the karst collapse in the study area include soil characteristics, degree of karst development in soluble rocks, faults, folds, groundwater dynamic conditions, and human engineering and mining activities. A 300-m-long, 40-m-wide, and 25-m-high cavern was identified with high-density electrical resistivity imaging. Complex solutions were proposed to mitigate karst collapse in the iron ore mining area.

Paleogeomorphic genesis assembly method for paleogeomorphic recovery in the major region of the Tahe Oil Field, Tarim Basin, northwest China

Tahe oil field is the first marine origin oil field in China, with proven reserves of 500 million tons. Given the important role of the paleogeomorphology in controlling the formation and distribution of karst reservoirs, this paper restored the pre-Carboniferous paleokarst landform in the major blocks of the Tahe oil field, via the paleogeomorphic genesis assembly method. First, four types of secondary landform units (karst platform, karst gentle slope, karst steep slope, and karst intermountain basin) were defined. Next, landform identification factors were added to these four types, to further divide the paleokarst landform into ten tertiary landform units. This enabled a more precise identification of the paleogeomorphic landforms. The karst development and the properties of hydrocarbon reservoirs in micro-geomorphic units were assessed. In addition, the relationship between petroleum production and geomorphology was analysed to robustly predict karst reservoirs in the Tahe oil field. The results show that karst develops differently according to the ancient landform units it developed from and that the current karst function is highly dependent on the precursor ancient landform. In addition, the morphology of the ancient landform significantly controls hydrocarbon accumulation, with oil and gas production being highly associated with the degree of karst development in each landscape unit. The research results indicate that the position of the slope in the karst hill and residual peak is favorable for future oil and gas exploration.

Analysis and prevention of sinkhole collapses during the reconstruction and extension of Guang-Qing freeway, china

The Guang-Qing freeway reconstruction and extension project is located in Guangdong province, China, extending from Guangzhou city to Qingyuan city. The total project length is 57.6 km, 33 km of which is in a karst area where sinkhole collapses are common. Therefore, there were concerns about the safety and security of the roadbed, bridge piles, and other structures associated with the original roadway. The study addresses karst development, covering layer (overburden), and external factors that contribute to catastrophic sinkhole collapse along the project. The study found that the formation of sinkhole collapses is affected significantly by the degree of karst development and soil characteristics, including thickness. Collapses may be triggered directly by external factors that disturb the natural equilibrium. Such factors include heavy rainfall that impacts soil and groundwater conditions, as well as vibration and groundwater flow disruptions that are caused by pile construction and other engineering activities. Prevention measures were adapted to local conditions and optimized based upon safety, reliability and cost-effectiveness.

Spatial analysis for susceptibility of second-time karst sinkholes: A case study of Jili Village in Guangxi, China

After a big karst sinkhole happened in Jili Village of Guangxi, China, the local government was eager to quantitatively analyze and map susceptible areas of the potential second-time karst sinkholes in order to make timely decisions whether the residents living in the first-time sinkhole areas should move. For this reason, karst sinkholes susceptibility geospatial analysis is investigated using multivariate spatial data, logistic regression model (LRM) and Geographical Information System (GIS). Ten major karst sinkholes related factors, including (1) formation lithology, (2) soil structure, (3) profile curvature, (4) groundwater depth, (5) fluctuation of groundwater level, (6) percolation rate of soil, (7) degree of karst development, (8) distance from fault, (9) distance from the traffic route, and (10) overburden thickness were selected, and then each of factors was classified and quantitated with the three or four levels. The LRM was applied to evaluate which factor makes significant contributions to sinkhole. The results demonstrated that formation lithology, soil structure, profile curvature, groundwater depth, ground water level, percolation rate of soil, and degree of karst development, the distance from fault, and overburden thickness are positive, while one factor, the distance from traffic routes is negative, which is deleted from LRM model. The susceptibility of the potential sinkholes in the study area is estimated and mapped using the solved impact factors. The susceptible degrees of the study area are classified into five levels, very high, high, moderate, low, and ignore susceptibility. It has been found that that both very high and high susceptibility areas are along Datou Hill and the foothills of the study area. This finding is verified by field observations. With the investigations conducted in this paper, it can be concluded that the susceptibility maps produced in this paper are reliable and accurate, and useful as a reference for local governments to make decisions regarding whether or not residents living within sinkhole areas should move.

Using GIS to evaluate degree of karstification according to some important factors in carbonate rocks in Iran

This study has been carried out with the aim of mapping karst and evaluation of degree of karstification of carbonate rocks in Iran. Mapping of karstic regions of Iran has been performed by some authors previously, but scale and limited information availability have limited the accuracy of their works. In addition, rock type was considered as the main factor to make a karstification map, and other important factors such as tectonic and climate conditions were ignored. One objective of this paper is a spatial evaluation of karst development in Iran considering the role of the chief factors affecting karst development. In this study, a theoretical karst map was developed on the basis of what is considered to be a proper combination of these factors. The main considered factors are those classified by White (Geomorphology and Hydrology of Karst Terrains, Oxford University Press, Oxford 1988) into three driving forces (i.e., chemical driving force, physical driving force and hydrogeological setting). Precipitation, temperature, relief, rock type, tectonic setting and stratigraphic thickness of soluble carbonate rocks are the main factors classified to describe the mentioned driving forces. In this study, precipitation and temperature are represented by the chemical weathering conditions during the modern and glacial periods prepared on the basis of Peltier’s graphs. The required data were gathered from the updated maps with proper scale and detailed references. Then the data were mapped, classified, weighted and managed in separate layers in GIS environment. The karst index (K i ) is introduced to define the modeled degree of karstification computed by proper combination of six weighted layers, and the final theoretical karst map of Iran is prepared based on the ranked karst index. According to the combination method, values of K i could be in a range 0–400 in which higher values show more degree of karst development. The classified theoretical karst map shows that out of 205,589 km2 of carbonate units (12.62 % of the surface area of Iran) about 78,253 km2 (38.1 % of carbonate rocks) have very low to low degree of development of karstic features. About 98,145 km2 (47.7 % of carbonate rocks) have moderate degree and about 29,192 km2 (14.2 % of carbonate rocks) have high to very high degree of karstification. In other words, 7.81 % of Iran (62 % of the carbonate units) is underlain by carbonate rocks with moderate to high degree of karstification. Densities of caves and karstic springs are hydrogeological features used to check the calculated degree of karstification. For this purpose, complete inventories of caves and karstic springs in Iran were made. Out of 590 caves, 491 caves are located in carbonate rocks. From 1,074 karstic springs (with discharge above 10 l/s), 338 springs have discharges above 50 l/s; 146 caves and 330 springs (with discharges above 10 l/s) occur in rocks in areas of very low to low degree of karstification. About 243 caves and 430 springs fall in the moderate class and 102 caves and 314 springs in areas with high to very high degree of karstification. Cave densities (number of caves per area) are 0.0017, 0.0019, 0.0025, 0.0031 and 0.0046 caves per square kilometer for very low, low, moderate, high and very high classes, respectively. In addition, densities of springs are 0.0041, 0.0043, 0.0044, 0.0103 and 0.0122 springs per square kilometer for very low, low, moderate, high and very high classes, respectively. In other words, densities of caves and springs show a good correlation with the evaluated karstification. Final result is also checked by surface karstic landforms (such as karren and doline) on some examples of well-known karstic regions.

The North American obligate cave fauna: regional patterns

The obligate cave faunas of nine regions of the United States –Florida Lime Sinks, Appalachians, Interior Low Plateaus, Ozarks, Driftless Area,Edwards Aquifer/Balcones Escarpment, Guadalupe Mountains, Black Hills, andMother Lode – are described and compared. The number of aquatic(stygobitic) species ranged from zero (Black Hills) to 82 (Appalachians), andthe number of terrestrial (troglobitic) species ranged from zero (Florida LimeSinks) to 256 (Interior Low Plateau). Even at the level of genus, overlapbetween regions is low. Several predictor variables (karst area, number ofcaves, number of long caves, number of deep caves, distance from the Pleistoceneice margin, distance from the late Cretaceous Sea, and vegetation type – asurrogate for productivity) were assessed using rank order statistics,especially rank order multiple regression with a backward elimination procedure.For both stygobites and troglobites, only number of caves was a significantpredictor. The absence of a karst area effect suggested that the degree of karstdevelopment is better described by the number of caves rather than area ofkarst. There was no evidence that distance to Pleistocene glacial boundaries wasimportant, but there was some support for the importance of distance from late Cretaceous sea margins, a potential source of aquatic subterranean colonists. Finally,there was no indication that surface productivity had an effect on speciesrichness. Analysis was complicated by correlations among predictor variables.

Geologic Reservoir Analysis, Mississippian Madison Formation, Elk Basin Field, Wyoming-Montana

The Elk Basin field is in the north end of the Big Horn basin, on the Wyoming-Montana state line. The structure is a NW-SE-trending asymmetric anticline approximately 8 mi long, 4 mi wide, and has about 5,000 ft of structural closure. Oil production from the Mississippian Madison Group was discovered in 1946. Cumulative production is now more than 75 million bbl of oil from 5,100 acres; productive closure is about 1,400 ft. A recent core study of the Madison reservoir shows it can be divided into several separate, distinct geologic and production units. The Madison carbonate sequence has been greatly altered and distorted by groundwater erosion, by the formation of karst topography and subsequent solution brecciation in Late Mississippian-Early Pennsylvanian time, and by selected remineralization in certain areas of the field. The overall effect of karst activity was the collapse of sections of the upper Madison, up to 300 ft thick, into brecciated rubble zones. As a result of such collapse, entire blocks of the upper Madison have no effective communication with each other. There are areas of remineralization which, because of redeposition of dissolved carbonates, silica, and anhydrite into pore space and fractures by the downward-percolating groundwater, have local, relatively impermeable zones. These zones form local stratigraphic traps. Zones of insoluble residue of clay and rock fragments form an effective barrier between the A and B producing zones, and explain the different reservoir characteristics of each zone. Groundwater action removed the more soluble limestone but left the less soluble dolomite, and formed the good secondary porosity now found in the Elk Basin Madison. The secondary porosity zones can be correlated and subdivided into readily recognizable and distinct units. The fact that such subdivision is possible demonstrates a certain degree of continuity of solution action. The understanding of this continuity is necessary to the evolution of efficient drilling and flooding programs. Electric-log and core evaluations of the Madison in other Big Horn basin fields indicate reservoirs similar to the Elk Basin Madison reservoir. However, most of the other Madison fields do not show the same degree of karst development. From the above-mentioned variations, a multiple working hypothesis can be developed for reservoir engineering analysis. The overall hypothesis provides a good vertical and areal model of the Elk Basin Madison reservoir. Practical application of the hypothesis has resulted in a rather dramatic production response. The exploration implications are that geologists need to understand the characteristics of known reservoirs before they can conduct effective exploration for new reservoirs.

Les conditions geologiques de la chute de Sassenage pres de Grenoble

Abstract Geologic investigations showed that in spite of the degree of karst development, construction of an underground tunnel for a hydroelectric installation was possible in the vicinity of the Sassenage falls near Grenoble (France), in the area of the Sassenage fold-fault. Only two small cavities were encountered over a distance of some 3.5 kilometers. The results of the geologic studies that prepared the way for construction of the installation (which began operation in 1958) are summarized.