Navegando por Assunto "Karst"
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- An approach to map karst groundwater potentiality in an urban area, Sete Lagoas, Brazil(2020-09-28) Magnabosco, Rafael; Galvão, Paulo; de Carvalho, Ana MacielDue to complex hydrogeological contexts, mapping groundwater potential zones in karst regions is a difficult task. This study was conducted on a karst terrain in Sete Lagoas, Brazil, where rapid urban growth without adequate water resources management resulted in the drilling of unproductive wells and possible aquifer over-exploitation due to the concentration of wells. The objective was to develop a method for mapping groundwater potentiality for karst aquifers, serving as water resources management tool, based on 3D geological modelling, field work and pumping test data, remote sensing, geophysics analysis and production of thematic maps, resulting in the hydrogeological conceptual model. The groundwater potentiality map showed that most potential zones are on the central area, limited by grabens, where limestones are in contact with unconsolidated sediments, on areas with higher density of morphostructural and geophysical lineaments, mainly in east–west and north–east directions, near karst surface features, on thicker karstified zones, with higher recharge rates.
Item An integrated 3D digital model of stratigraphy, petrophysics and karstified fracture network for the Cristal Cave, NE-Brazil(2024-01) Pereira, João Victor F.; Medeiros, Walter E.; Dantas, Renato R.S.; Bezerra, Francisco H.R.; Bruna, Vincenzo La; Xavier Jr., Milton M.; Maia, Rubson P.; Gomes, Daniel D.M.; Silva, Danielle C.C.; Maciel, Ingrid B.Digital Outcrop Models (DOMs) are virtual representations of geological features. Although DOMs are widely used tools in geosciences, their integration with other datasets remains relatively underexplored. We combined a DOM, derived from a photogrammetric survey of a carbonate sequence, with lithostratigraphic, petrophysical (porosity, permeability and uniaxial compressive strength), fracture distribution, and karst dissolution information to compose a single integrated three-dimensional digital model. The study site is one of the entrances of the Cristal Cave (São Francisco Craton, Northeastern Brazil), which has been used as a structural and diagenetic outcrop analog for the Brazilian pre-salt carbonate reservoirs. Data from fracture distributions, measured on the exposed surfaces of the cave, were used to build a Discrete Fracture Network, based on the solution of the stereology inverse problem. Fracture apertures were then modified to generate different scenarios of karstification, thus composing Discrete Fracture and Karst Networks. This integrative approach brought relevant insights into the cave development due to dissolution along fracture clusters. Our methodology offers better geological data handling to build static models to be used in a fluid flow modeling environment, contributing to bridge the gap between geophysics/geology and engineering approaches.Item Análise de suscetibilidade à eventos cárstico-geotécnicos em região centro-urbana do município de Sete Lagoas-MG(2023) Oliveira, Júlia Moura de; Schuch, Camila S.; Galvão, Paulo Henrique FerreiraEm regiões cársticas podem ocorrer diversos problemas atrelados à superexplotação de água subterrânea, sendo um deles os abatimentos de solo, fenômeno que pode estar relacionado à dissolução de rochas carbonáticas. A cidade de Sete Lagoas (MG) teve seu primeiro grande abatimento registrado em 1988 e, a partir daí, houve novas ocorrências ao longo dos anos. Este trabalho fundamenta-se na investigação da evolução da suscetibilidade cárstica-geotécnica em Sete Lagoas, entre as décadas de 1940 a 2020, bem como na análise acerca da ocupação do espaço urbano nesse período. A análise foi realizada por meio da elaboração de mapas de suscetibilidade em intervalos de 20 anos, ponderando fatores de predisposição geológica e hidrogeológica locais. A partir da soma desses fatores, obteve-se o mapa final denominado risco cárstico-geotécnico. Por meio da reclassificação dos valores, definiu-se diferentes níveis de risco na área, em uma escala de 0 (zero) a 10, que vão de baixo a alto risco. Com a elaboração desses mapas, pode-se analisar que a suscetibilidade cárstica-geotécnica vem evoluindo, sendo a região associada ao alto risco cada vez maior na área estudada. Se tratando exclusivamente do alto risco cárstico geotécnico, observou-se que nos últimos 20 anos de análise tem-se que a área associada aproximadamente dobrou de dimensão. Além disso, desde seu aparecimento em 1980, houve um crescimento de aproximadamente 2800% em sua área até o ano de 2020. Outra constatação foi de que a explotação de água subterrânea sem um planejamento adequado, durante um longo período, influencia diretamente na evolução desse risco devido à concentração de poços em pequenas áreas. O agrupamento de poços na área urbana do município gera a sobreposição dos cones de rebaixamento, diminuindo ainda mais os níveis de água subterrânea. Esse fato torna o fator hidrogeológico o mais influente no mapa cárstico geotécnico quando comparado ao fator geológico, sendo que o risco ligado à hidrogeologia se altera significativamente no período de tempo analisado. Desde o aparecimento da zona de alto risco cárstico geotécnico, em 1980, essa área está integralmente dentro da mancha urbana relativa as décadas analisadas. Os pontos de abatimentos também estão em sua totalidade dentro das manchas urbanas referentes aos anos de 2000 e 2020. Conclui-se que suscetibilidade cárstica geotécnico está evoluindo no decorrer do tempo. Pode-se perceber também a influência direta da explotação de água subterrânea sem gerenciamento adequado na evolução desse problema, podendo influenciar na ocorrência dos abatimentos na área urbana de Sete Lagoas, principalmente em regiões onde se tem alta concentração de poços.- Assessment of a semi-automatic spatial analysis method to identify and map sinkholes in the Carste Lagoa Santa environmental protection unit, Brazil(2021-01-21) de Castro Tayer, Thiaggo; Horta Rodrigues, Paulo CésarSatellite imaging combined with geoprocessing routines is a promising alternative to establish a viable mapping model of specific landscape features and soil use, with high precision, fast results, and low operational costs. The present study examines the employment of a digital elevation model (DEM) combined with geoprocessing techniques for identifying closed depressions in karst landscapes with the objective of mapping potential sinkholes and uvalas within the limits of the Carste Lagoa Santa Environmental Protection Unit, located in the state of Minas Gerais, Brazil. The proposed method consists of using geoprocessing routines combined with DEMs, topographic analysis, individual points of elevation, and mathematical operations between rasters. To accomplish that, SRTM (Shuttle Radar Topographic Mission) data/images were used to extract contour lines and individual elevation points to identify depressions, delimit their edges, and obtain morphometric data referring to the area, perimeter, and their circularity index. The results were satisfactory, allowing the detection of 1076 depressions within the study area. The results were also analyzed for special morphological cases and circularity patterns and compared with a previous study. Field campaigns allowed the partial validation of the method, which proved to be a viable alternative for preliminary and extensive scale mapping of these important karst recharge features.
Item Assessment of a semi-automatic spatial analysis method to identify and map sinkholes in the Carste Lagoa Santa environmental protection unit, Brazil(2021-01-21) Tayer, Thiaggo de Castro; Rodrigues, Paulo César HortaSatellite imaging combined with geoprocessing routines is a promising alternative to establish a viable mapping model of specific landscape features and soil use, with high precision, fast results, and low operational costs. The present study examines the employment of a digital elevation model (DEM) combined with geoprocessing techniques for identifying closed depressions in karst landscapes with the objective of mapping potential sinkholes and uvalas within the limits of the Carste Lagoa Santa Environmental Protection Unit, located in the state of Minas Gerais, Brazil. The proposed method consists of using geoprocessing routines combined with DEMs, topographic analysis, individual points of elevation, and mathematical operations between rasters. To accomplish that, SRTM (Shuttle Radar Topographic Mission) data/images were used to extract contour lines and individual elevation points to identify depressions, delimit their edges, and obtain morphometric data referring to the area, perimeter, and their circularity index. The results were satisfactory, allowing the detection of 1076 depressions within the study area. The results were also analyzed for special morphological cases and circularity patterns and compared with a previous study. Field campaigns allowed the partial validation of the method, which proved to be a viable alternative for preliminary and extensive scale mapping of these important karst recharge features.Item CARACTERIZAÇÃO GEOMORFOLÓGICA DA REGIÃO CÁRSTICA ARCOS-PAINS E DE SEUS SISTEMAS CÁRSTICOS(2022) Timo, Mariana BarbosaA região do Grupo Bambuí, conhecida como Província Espeleológica do Bambuí (PEB), ocupa uma área de aproximadamente 150.000 km2e abrange as porções centro oeste, norte e noroeste de Minas Gerais; leste do Distrito Federal; nordeste de Goiás; sudeste do Tocantins; e oeste da Bahia.Devido à grande área ocupada pela Província Espeleológica do Bambuí, esta pode ser dividida em distritos.O objetivo desteartigo é a caracterização da Região Cárstica de Arcos-Pains, e de seus sistemas cársticos correlatos, a partir da utilização de dados geológicos, geomorfológicos, espeleológicos e hidrográficos. O carste regional é bem evoluído, com extensos maciços calcários marcados por diferentes tipos de lapiás (karren). Além disso, apresenta drenagem predominantemente subterrânea com a presença de sumidouros, ressurgências, cânions, dolinas e feições residuais, comuns na paisagem cárstica. Estruturas geológicasmarcantes, como dobras e falhas, também se fazem presentes.Por outro lado, as atividades humanas podem impor profundas modificações na paisagemdesta importante região cárstica, especialmente por causa damineração, visto que ali encontram-se instaladas diversas empresas de extração de calcário, além de indústrias cimenteiras e deprodução de cal. Tal uso do solo, aliado à precária gestão do Patrimônio Espeleológico, vem ocasionado impactos ambientais significativos no carste regional. Dessa forma, ter como base os estudos do carste faz-se extremamente necessário, pois a sensibilidade dos aquíferos cársticos à poluição é muito alta.Item Environmental and legal aspects of karst areas. Lamoreaux, P.E.(Environmental Geology, 1997) Lamoreaux, P. E.; Powell, W. J.; LeGrand, H.E.implicações regulatórias Karst para configurações cárstica subsidência de proteção ambiental- Epigean and hypogean drivers of Neotropical subterranean communities(2020-10-29) Rabelo, Lucas Mendes; Souza-Silva, Marconi; Ferreira, Rodrigo LopesIn addition to cave size and other subterranean habitat characteristics, cave entrances are important structurers of neotropical cave communities. However, little is known about the epigean ecosystems factors that might dictate the influence of entrances and the relationship among surface and cave communities, as entrance re-gions are ecotonal zones between the epigean and hypogean ecosystems. We aimed to assess the influence of epigean and hypogean factors as potential drivers of inver-tebrate species richness in Neotropical caves as well as the influence of the regional pool of invertebrate diversity on cave invertebrate diversity.
Item ESTUDOS DE VALES SECOS EM ÁREAS CÁRSTICAS: REVISÃO E POSSIBILIDADES(2022-06) Nogueira, Adivane Morais; Uagoda, Rogério; Caldeira, DandaraO carste apresenta regiões de conexões entre os sistemas fluviais e cársticos o fluviocarste, dispondo de feições típicas, como os vales secos. Tais feições vêm sendo estudadas de diversas formas para contribuir no entendimento da dinâmica geomorfológica do carste. Este estudo visa fazer uma revisão sobre vales secos em sistemas cársticos, tendo em vista observar o potencial científico destas áreas para diversas aplicabilidades. A revisão utilizou como principal forma de busca a plataforma Web Of Science (todas as bases), abrangendo o período entre 1945-2020, que abordavam sobre tais feições, com o uso das seguintes palavras-chave: karstic valley, dry valleys, blind valley, relict valley, ancient valley, fossil valley, solution valley, paleovalley e paleokarst valley, resultando em vinte e sete trabalhos, com diversas propostas de análise, evidenciando os fatores envolvidos na dinâmica fluviocárstica. O levantamento permite observar que são poucos estudos considerando a extensão de ocorrência de rochas carbonáticas no mundo, havendo concentração das pesquisas no continente europeu. No Brasil, apesar de dispor de regiões carbonáticas e das várias áreas mapeadas com ocorrência de cavernas, principalmente no bioma Cerrado, não há pesquisas sobre o tema, mesmo que viabilizem a identificação dos fatores que influenciam evoluções dos sistemas fluviocársticos.Item Global distribution of carbonate rocks and karst water resources(2021-04-21) Goldscheider, Nico; Chen, Zhao; S. Auler, Augusto; Bakalowicz, Michel; Broda, Stefan; Drew, David; Hartmann, Jens; Jiang, Guanghui; Moosdorf, Nils; Stevanovic, Zoran; Veni, GeorgeKarst regions offer a variety of natural resources such as freshwater and biodiversity, and many cultural resources. The World Karst Aquifer Map (WOKAM) is the first detailed and complete global geodatabase concerning the distribution of karstifiable rocks (carbonates and evaporites) representing potential karst aquifers. This study presents a statistical evaluation of WOKAM, focusing entirely on karst in carbonate rocks and addressing four main aspects: (1) global occurrence and geographic distribution of karst; (2) karst in various topographic settings and coastal areas; (3) karst in different climatic zones; and (4) populations living on karst. According to the analysis, 15.2% of the global ice-free continental surface is characterized by the presence of karstifiable carbonate rock. The largest percentage is in Europe (21.8%); the largest absolute area occurs in Asia (8.35 million km2). Globally, 31.1% of all surface exposures of carbonate rocks occur in plains, 28.1% in hills and 40.8% in mountains, and 151,400 km or 15.7% of marine coastlines are characterized by carbonate rocks. About 34.2% of all carbonate rocks occur in arid climates, followed by 28.2% in cold and 15.9% in temperate climates, whereas only 13.1 and 8.6% occur in tropical and polar climates, respectively. Globally, 1.18 billion people (16.5% of the global population) live on karst. The highest absolute number occurs in Asia (661.7 million), whereas the highest percentages are in Europe (25.3%) and North America (23.5%). These results demonstrate the global importance of karst and serve as a basis for further research and international water management strategies.Item Habitat and Population Data of Troglobitic Armored Cave Catfish, Ancistrus Cryptophthalmus Reis, 1987, from Central Brazil (Siluriformes: Loricariidae)(Environmental Biology of Fishes, 2001) Trajano, EleonoraItem IDENTIFICAÇÃO E CARACTERIZAÇÃO DE FEIÇÕES EXOCÁRSTICAS NOENTORNO DO RIO AZUIS, AURORA DO TOCANTINS –TO(2023-08) Alves, Luiz Ricardo Ferreira; Morais, Fernando deO presente estudo teve como objetivo identificar e analisar as feições de relevo que integram a área cárstica no entorno do rio Azuis, situada no município de Aurora do Tocantins, região sudeste do estado do Tocantins. A fim de atender tal proposição, foi elaborada uma carta geomorfológica em escala de detalhe (1:25.000) com base na adaptação de procedimentos metodológicos das escolas francesa e holandesa de cartografia geomorfológica. De modo geral, foram verificadas feições exocársticas, como maciços calcários, surgências, sumidouros, dolinas, uvalas e poljés. Processos geomorfológicos responsáveis pela configuração do relevo foram identificados, confirmando o grande potencial para estudos dos sistemas cársticos, bem como dos atrativos naturais.- Inside or out? Cave size and landscape effects on cave-roosting bat assemblages in Brazilian Caatinga caves(2020-04-08) Carlos Vargas-Mena, Juan; Cordero-Schmidt, Eugenia; Rodriguez-Herrera, Bernal; A. Medellín, Rodrigo; de Medeiros Bento, Diego; M. Venticinque, Eduardo; Jorge OrtegaCave bats have an intimate association with their roosts. Size, structural heterogeneity, and microclimatic conditions are traits of caves known to affect the structure of these assemblages. The effects of the natural and anthropogenic landscape factors around caves on the structure of these assemblages are poorly known, especially in areas with large cave clusters. We assessed the effects of cave size and surrounding landscape attributes on the richness and species composition of cave-roosting bats in 13 caves distributed in two landscapes with large cave clusters in Caatinga dry forests, Brazil. In a 1-km buffer around caves, we obtained 13 internal cave and external landscape variables. Candidate univariate models using generalized linear models were constructed and the Akaike information criterion was used for model selection. The cave size model explained richness and variance in the species composition; larger caves tended to have greater richness and assemblage composition varied depending on the cave size, hence affecting the occurrence of certain species, some of conservation concern (Natalus macrourus, Furipterus horrens). The cave connectivity model affected only the richness; caves located in denser cave clusters had higher richness likely attributed to movement of bats among caves by a more diverse array of species. Both environmental and anthropic variables affected species composition, but differently depending of the landscape context of cave location (protected versus nonprotected area). The extent these landscape variables affected the species composition was due to species-specific responses, and observed in the mean colony sizes of the species shared between the cave systems. All the landscape variables that we tested affected the structuring process of cave-roosting bats assemblages, and evidences that variables found in disturbed karstic landscapes also affect the structure of the assemblage (e.g., large colonies of vampire bats). However, the ubiquitous effect of cave size on both richness and species composition reinforces the critical importance of the roost in the life of these flying mammals.
- A new cave-dwelling species of Spelaeobochica (Pseudoscorpiones: Bochicidae) from Brazil(The Journal of Arachnology, 2012) Ferreira, Rodrigo Lopes; Ratton, Pedro; Mahnert, VolkerKarst , morfologia, neotropical, troglóbios
Item Persisting while changing over time: modelling the historical biogeographic of cave crickets (Orthoptera, Grylloidea) in Neotropics(2023) Castro-Souza, Rodrigo Antônio; Sobral-Souza, Thadeu; Rabelo, Lucas Mendes; Zefa, Edison; Ferreira, Rodrigo LopesUsing species distribution modelling (SDMs) techniques, we predicted the biogeographic history of crickets commonly found in Neotropical caves as a way to detect potential long-term environmental refuges in South America. Our models were built based on a thorough investigation of existing database regarding the genus Endecous Saussure, 1878 (Ensifera: Phalangopsidae) occurrences. The predictions of their distribution were obtained for two paleoclimate scenarios (LGM — 21 ka and Mid-Holocene — 6 ka), the current climate scenario (0 ka) and one future global warming climate scenario (RCP8.5, 2080–2100). Our findings suggest that in the past, the potential distribution of the crickets was wider, with potential forest corridors connecting different karst areas with caves within their occupancy area. The future prediction indicates a drastic reduction in their spatial distribution with an increased potential for isolation in subterranean ecosystems. Atlantic humid forest patches and caves represent the main environmental refuges for these crickets. Considering the ongoing impacts on surface environments and future climate change, the conservation of caves and karst landscapes has become one of the main strategies for the maintenance of these crickets and all the correlated subterranean communities.Item Priority caves for biodiversity conservation in a key karst area of Brazil: comparing the applicability of cave conservation indices(2018-05-09) Rabelo, Lucas Mendes; Souza‑Silva, Marconi; Ferreira, Rodrigo LopesLandscapes in tropical regions have been greatly altered by human activities, as a product of growing demands for mineral and agricultural production, as well as those related to the generation of energy (e.g., hydroelectric, wind). In this scenario, caves have suffered several impacts, sometimes irreversible, as they are generally associated with rocks of high economic value and are closely related to epigean systems. Several indices have been proposed to guide conservation policies for the world’s speleological heritage, although few of them consider cave biodiversity as a criterion. To address this knowledge gap, we tested the applicability of four newly proposed indices to assist researchers and policy-makers select priority areas for global cave biodiversity conservation. To compare indices, we used data from 48 caves of the largest carbonate region of South America (Bambui geological group), all found within the Cerrado, a global biodiversity hotspot. Each of the four indices considered cave biodiversity as a criterion, although only three adequately evaluated this attribute. Based on results of Simões index and CCPi, which were the most appropriate in relation to indicate priority caves for biodiversity conserva-tion in regions where the fauna and its distribution are not fully known, 15 of the 48 caves were identified as conservation priorities.Item Quaternary depositional facies in cave entrances and their relation to landscape evolution: The example of Cuvieri Cave, eastern Brazil(Catena, 2017) Martim, Paulo M. Haddad; Hubbe, Alex; Giannini, Paulo C.F; Auler, Augusto S; Piló, Luís B; Hubbe, Mark; Mayer, Elver; Wang, Xianfeng; Cheng, Hai; Edwards, R. Lawrence; Neves, Walter AUm estudo na Caverna de Cuvieri permitiu novos conhecimentos sobre a dinâmica e evolução de tipos de facies sedimentares e sua relação com a paisagem próxima.Item Speleothem in Sandstone: Maranhão as a Geo-Speleological Scenario(2024-06-26) Castro, Cláudio Eduardo de; Silva, Flávia MartinsThe municipality of Carolina, located in the southern region of Maranhão, features a terrain composed of hills and plateaus formed from sandstone lithology originating from the Balsas Group formations. This region houses geological features such as caves and speleothems, which pertain to endokarst, primarily formed through erosive processes. Due to its significant speleological potential, the region has been studied by the Conservation Units Research Group (GEUC) of the Maranhão State University (UEMA) since 2013.