Esta pesquisa integrou estudos geológicos, hidrogeológicos, geoquímicos e de isótopos estáveis no município de Sete Lagoas (MG), Brasil, com o objetivo de entender a circulação da água em terreno cárstico e propor alternativas para o seu melhor uso, a fim de se evitar problemas geotécnicos. A área é constituída por calcários neoproterozoicos da Formação Sete Lagoas, onde se desenvolveram condutos cársticos, dando origem ao aquífero homônimo, o qual está coberto por sedimentos cenozoicos inconsolidados e, ocasionalmente, por rochas metasedimentares neoproterozoicas da Formação Serra de Santa Helena. Foi observado que neste aquífero a porosidade primária é muito baixa e a secundária (micro-fraturas) é igualmente reduzida, devido ao preenchimento por calcita. O grande volume de água subterrânea migra através da porosidade terciária caracterizada dominantemente por dois planos de acamamentos carstificados e, em menor grau, por fraturas sub-verticais carstificadas. A recarga, relacionada às chuvas que ocorrem no período de outubro a dezembro, se dá através de sumidouros, entradas de cavernas e onde o calcário está sob os sedimentos cenozoicos. Um detalhado estudo avaliando os efeitos de escala permitiu também o estabelecimento da distribuição das permeabilidades do Aquífero Sete Lagoas. Outros resultados obtidos também estabeleceram que as extrações de águas subterrâneas estão associadas aos eventos geotécnicos cársticos localizados na área urbana do município. A elevada extração das águas subterrâneas faz com que o plano de acamamento carstificado mais raso, em algumas áreas, esteja inteiramente na zona não saturada, provocando os eventos geotécnicos. Um mapa de risco geotécnico identifica, a partir da litologia e do nível de água subterrânea, cinco níveis. Este tipo de mapeamento deveria orientar as extrações e os cuidados na ocupação do terreno urbano em Sete Lagoas, prevenindo ou retardando a ocorrência de novas subsidências ou colapsos. / This research integrated geological, hydrogeological, geochemical, and stable isotope studies conducted in the municipality of Sete Lagoas (MG), Brazil, in order to understand the water circulation in a karst terrain and to propose alternatives for a better water use, aiming to avoid geotechnical problems. The area is constituted by Neoproterozoic limestones from the Sete Lagoas Formation, where karst conduits were developed, giving origin to the homonymous aquifer, which is covered by Cenozoic unconsolidated sediments and, occasionally, by Neoproterozoic metasedimentary rocks from the Serra de Santa Helena Formation. It was observed that in this aquifer the primary porosity is very low and the secondary porosity (micro -fractures) is also reduced, due to the filling by calcite. The great volume of groundwater migrates through the tertiary porosity characterized by two dominant solutionally enlarged bedding planes and, to a lesser extent, by sub-vertical enlarged fractures. The recharge, related to rainfall occurring from October to December, takes place through sinkholes, caves entrances, and where the limestones are under the Cenozoic sediments. A detailed study evaluating the scale effects also allowed the establishment of permeability distributions of the Sete Lagoas Aquifer. Other results obtained also established that the groundwater extractions are associated to karst geotechnical events located in the urbanized area of the municipality. The high groundwater extractions make the shallowest solutionally enlarged bedding plane, in some points, entirely in the unsaturated zone, causing geotechnical events. A geotechnical map identifies five levels of risk, based on the lithology and the groundwater level interaction. This type of mapping should guide the groundwater extractions and caring the urban land occupation in Sete Lagoas, preventing or delaying the occurrence of new subsidences or collapses.

No description available.

Research has long recognized and studied the dynamics of groundwater processes. More recently, groundwater dependent ecosystems (GDEs) are being recognized for their diversity and vulnerability to anthropogenic impact. Groundwater in karst landscapes presents a distinctive situation where flow through the subsurface often moves rapidly on the scale of days and weeks as opposed to years or millennia in other systems. This distinctive situation of karst systems and their vulnerability to human impacts necessitate an integrated and multifaceted approach for the management of these important resources. However, development of such an approach is complicated by the difficulty of obtaining detailed data about the ecosystem, especially in remote areas of developing countries. Additionally, management difficulties related to political boundaries, jurisdictions, and land ownership can result in ineffective and inconsistent policies and practices across a single catchment. In order to address these issues, this dissertation creates a new composite model for groundwater dependent ecosystem (GDE) management in areas of karst development. Within this new composite model, the combination of the Karst Disturbance Index (KDI) and groundwater vulnerability mapping recognizes both human disturbance and how the physical nature of the karst will enhance this impact. These studies bridge the gap between science and management by connecting the final model to management strategies for a sub-catchment of the Rio la Venta watershed, the majority of which is within the Reserva de la Biosfera Selva el Ocote in Chiapas, Mexico. This composite model serves as an adaptable spatial tool for management planning and protection for all components of the karst environment.

This thesis presents a novel resistivity method called Multi-Electrode resistivity technique (MERIT) that is used for high resolution imaging of complex geologic features at depth and near the edges of survey lines. The MERIT electrodes are especially shaped and designed to be self-driven using a robust-direct push technique. Measurements are taken using optimized arrays that are generated using a modified version of the “Compare-R” optimization algorithm. This work focused on both two-dimensional (MERIT2D) and three-dimensional (MERIT3D) applications of the buried array and show the relevance of the additional information gained by the addition of deep electrodes especially in sites with limited survey area. Numerical and laboratory studies are used to test and develop the technique and are later applied to image complex subsurface geologic structures on the field. The configuration of MERIT arrays brings some additional problems in terms the sensitivity of the deep MERIT arrays to a problem of non-uniqueness, mis-information, geometric error and resolution break between the two layers of electrodes. Multiple vertical resolution characteristic curves (RC curves) are analyzed to study the effect of array type, resistivity contrast, target resistivity and implant depth on the above-mentioned problems. Results show that MERIT measurements taken using standard dipole -dipole and wenner arrays along the surface and deep electrodes will strongly suffer from the problem of non-uniqueness or ambiguity while measurements taken using optimized arrays is suitable for MERIT configuration and will not suffer from any problem of ambiguity or non-uniqueness. Based on our result, a procedural guideline is developed to determine optimal MERIT implant depth and resolution cutoff that can be used for successful field implementation and for controlling misinformation during data interpretation. Numerical studies involving simple shapes and complex geometries mostly based on actual geological cross-sections from karst environments were used to compare the effectiveness of MERIT2D in terms its high depth resolution and is compared in detail with traditional 2D and 3D surface resistivity methods of equal foot prints. Similar comparison was made between MERIT3D technique and 3D surface resistivity measurements. Results show that both methods achieve high depth resolution compared to their equivalent traditional resistivity methods. Laboratory experiment conducted using a complex analogue model mimicking actual sinkhole structure is used to test MERIT2D. Also laboratory experiment involving a 3D printed plastic cave model mimicking an actual cave was conducted using MERIT3D approach. Both results show the promise of MERIT approach to image and solve complex geological structures or problems. Finally, the method is applied to collect field data in three case study sites involving complex karst related sinkhole structures and an old landfill site. The result shows the promising capability of the MERIT technique to study challenging geologic conditions with high depth resolution.

Scărişoara Ice Cave has been a catalyst of scientific intrigue and effort for over 150 years. These efforts have revealed and described countless natural phenomena – and in the process have made it one of the most studied caves in the world. Of especial interest is the massive ice block located within its Great Hall and scientific reservations. The ice block, which is the oldest and largest known to exist in a cave, has been the focus of multiple surveying and mapping efforts, typically ones utilizing traditional equipment. In this study, the goals were to reconstruct the ice block/cave floor interface and to estimate the volume of the ice block. Once the models were constructed, we aimed to study the relationships between the cave and ice block morphologies. In order to accomplish this goal, three (3) main datasets were collected, processed, and amalgamated. Ground penetrating radar data was used to discern the floor morphology below the ice block. Over 1,500 photographs were collected in the cave and used with Structure from Motion photogrammetry software to construct a texturized 3D model of the cave and ice surfaces. And a total station survey was performed to scale, georeference, and validate each model. Once georeferenced, the data was imported into an ArcGIS geodatabase for further analysis. The methodology described within this study provides a powerful set of instructions for producing highly valuable scientific data, especially related to caves. Here, we describe in detail the novel tools and software used to validate, inspect, manipulate, and measure morphological information while immersed in a fully 3D experience. With this methodology, it is possible to easily and inexpensively create digital elevation models of underground rooms and galleries, to measure the differences between surfaces, to create 3D models from the combination of surfaces, and to intimately inspect a subject area without actually being there. At the culmination of these efforts, the partial ice block volume was estimated to be 118,000 m3 with an uncertainty of ± 9.5%. The volume computed herein is significantly larger than previously thought and the total volume is likely significantly larger, since certain portions were not modeled during this study. In addition, the morphology of ceiling enlargement was linked to areas of high elevation at the base of the ice block. A counterintuitive depression was recognized at the base of the Entrance Shaft. The thickest areas of the ice were identified for future coring projects. And combining all this a new informational allowed us to propose a new theory on the formation of the ice block and to decipher particular speleogenetic aspects.

South African karst aquifers are mainly associated with the dolomitic lithologies of the Transvaal Supergroup. Despite the socio-economic and environmental importance of these aquifers, no scientifically based methodology to outline areas that need protection from potential harmful activities exists. Thus an intrinsic resource aquifer vulnerability mapping method for karst terrains in South Africa was developed. The methodology is a modification of the COP aquifer vulnerability mapping method, developed by the Hydrogeology Group of the University of Malaga. The method is predominantly based on the capability of the unsaturated zone to filter or attenuate pollutants by different processes but considers two additional factors that either increase or reduce the protection provided by the unsaturated zone. These are surface conditions that control water flowing towards zones of rapid infiltration, and the temporal availability of a transport agent (rainfall). These three factors are combined to obtain a final vulnerability index, which is spatially visualised using five vulnerability classes (ranging from Very Low to Very High). Modifications to the original COP method include, amongst others, the consideration of rock types commonly found in South Africa, a statistical redefinition of high rainfall (wet) years, a revised consideration of rainfall rates to account for dilution processes and the consideration of older, sediment filled swallow holes. The method was applied to produce a vulnerability map for Cradle of Humankind World Heritage Site near Krugersdorp, South Africa. The vulnerability map clearly shows the generally inferior but variable aquifer protection in areas characterised by dolomitic lithologies, while surrounding non-karstic areas offer moderate to high resource protection. The proposed aquifer vulnerability mapping methodology should be used to assess karstic terrains during land use planning and environmental impact assessments. As an easily understandable planning tool the maps can reduce the likelihood of aquifer pollution. / Dissertation (MSc)--University of Pretoria, 2009. / Geology / unrestricted

Principalement associés à des milieux carbonatés, les aquifères karstiques présentent des écoulements souterrains rapides via des réseaux de fractures ou de conduits. Ces écoulements rapides sont à l’origine de la vulnérabilité de ces milieux dans le cas de la propagation de contaminants. Dans le cadre de la maîtrise environnementale, l’enjeu de ce travail de thèse est d’améliorer la compréhension du fonctionnement hydrodynamique d’un aquifère karstique étudié par le CEA. L’objectif est d’évaluer les contributions respectives de chacune des deux porosités aux écoulements souterrains. Trois approches ont été menées afin d’atteindre cet objectif : (1) le traitement des données hydrodynamiques et physico-chimiques par analyses corrélatoires, (2) la modélisation « double milieu » des variations du niveau de nappe, et enfin (3) l’interprétation de traçages artificiels pour la modélisation double milieu du transport. Cette thèse a permis de mettre en évidence la présence de deux milieux au sein de l’aquifère karstique étudié, avec : une porosité primaire (porosité de matrice) supportant les écoulements lents et la capacité de stockage du milieu souterrain, et une porosité secondaire (porosité de fissures/fractures ou de matrice fissurée) responsable des écoulements rapides et de la fonction transmissive de l’aquifère. Ce caractère « double milieu » est interprété comme la présence d’une fissuration (ou fracturation) spatialement étendue à l’échelle de la surface du site d’étude (17 km²). Ce résultat démontre qu’une approche « double milieu » est adaptée à la modélisation des écoulements souterrains et du transport (avec un milieu matriciel et un milieu fissuré/fracturé). Cette approche « double milieu » a ainsi permis de reproduire les chroniques piézométriques marquées par des récessions à double pente, ainsi que les courbes de traçages marquées par un retard de la restitution du traceur, et ce grâce à la contribution du milieu matriciel. De plus, les paramètres ajustés de ce modèle double milieu témoignent d’une densité de fissuration/fracturation spatialement variable au sein du milieu souterrain. Enfin, ces travaux apportent une quantification des flux d’eau échangés entre le milieu matriciel et le milieu fissuré/fracturé, 38 % de l’infiltration est stockée dans la matrice à l’échelle d’un évènement pluvieux. Cette approche « double milieu » montre également la contribution significative du processus de diffusion aux transferts de soluté vers le milieu matriciel lors de la propagation du traceur au sein du milieu fissuré/fracturé. La diffusion de soluté depuis le milieu matriciel, permet ensuite de reproduire la restitution tardive du traceur. / Karst aquifers are characterized by complex flow mechanisms induced by multiple porosities (matrix, fracture, conduit) which are responsible of the karst aquifer vulnerability to pollutant infiltrations. In the context of the environmental management, this thesis aims at enhancing the hydrodynamic functioning understanding of a karst aquifer. More specifically, the objective is the assessment of the multiple porosities contributions to the groundwater flow. Three approaches have been led during this work: (1) signal processing of the hydrodynamic and physical-chemical data by correlation analysis, (2) double medium modelling for reproducing the groundwater level (GWL) variations, and (3) double medium transport modelling for interpreting tracer test data. The double medium behaviour of the studied karst aquifer has been highlighted in this thesis with: a primary porosity (matrix porosity) supporting slow flows and representing the storage function and a secondary porosity (porosity of a fissured or a fractured matrix) responsible of the rapid flows and the transmissive function of the aquifer. This double medium behaviour has been interpreted as a spatially extended fracturation at the scale of the studied site (17 km²). This result makes a double medium approach relevant for simulating groundwater flows and solute transport (considering a matrix and a fractured medium). This double medium approach has succeeded in reproducing groundwater level variations marked by double-slope recessions and tracer breakthrough curves marked by a strong tailing, thanks to the matrix medium contribution. Moreover, the adjusted parameters of the double medium model indicate spatial variations of the underground media fissure/fracture density. Finally, this work brings a quantification of the exchanged flow between the two media during a recharge event (38 % of the infiltration is stored in the matrix medium), and shows the significant contribution of diffusion process to solute transfers in the matrix medium during the tracer propagation in the fractured medium. Then, the solute diffusion from the matrix allows reproducing the tracer tailing observed during tracer tests.

En esta investigación hemos estudiado, por primera vez, microclimas kársticos como sistemas dinámicos no lineales. En particular, hemos analizado y modelizado los microclimas de las cuevas españolas de Altamira y El Rull y sus conexiones con el clima exterior. Con este objetivo, hemos utilizado la técnica de modelización global, la cual pretende extraer modelos directamente de datos observacionales. Esta técnica está bien adaptada al estudio de sistemas complejos reales y se apoya en los teoremas de embedding. El embedding permite, en principio, reconstruir sistemas usando las variables disponibles y algunas de sus derivadas; por tanto, abre la posibilidad de modelizar microclimas kársticos incluso si algunas variables de estado no están disponibles o no pueden medirse en la práctica. También ha demostrado ser aplicable a series temporales muy cortas, lo cual constituye también una ventaja en comparación con otros tipos de modelización. Los microclimas de cuevas están dirigidos por el clima exterior. La variedad de climas externos y de configuraciones de las cavidades lleva a una variedad de microclimas kársticos. No obstante, uno de los controles más relevantes es normalmente la diferencia de temperatura entre el interior y el exterior. En general, los microclimas kársticos son muy estables en relación a variables como la temperatura o la humedad (comparadas con las exteriores). Por el contrario, los niveles de CO2 y 222Rn en el aire muestran notables oscilaciones estacionales a lo largo del año, por lo que estos gases son adecuados para caracterizar las dinámicas de las atmósferas de cuevas. Los microclimas de cuevas se suelen entender como la superposición de componentes deterministas y estocásticas. La hipótesis de una componente determinista frecuentemente se considera ineludible porque es una hipótesis habitual en la física clásica y porque las aproximaciones que permiten detectar determinismo a partir de datos observacionales son escasas. El haber encontrado modelos en forma de conjuntos de ecuaciones diferenciales evidencia fuertemente que los microclimas kársticos son, de hecho, deterministas y pueden ser razonablemente aproximados mediante sistemas deterministas de baja dimensión. Además, proponemos que su complejidad en realidad proviene de su sensibilidad a condiciones iniciales y perturbaciones (lo que se conoce indistintamente como comportamiento determinista-caótico o comportamiento caótico). Aunque algunos de nuestros modelos sólo capturan la parte periódica de la dinámica, un ligero afinado de un coeficiente fue suficiente para encontrar modelos que convergen a atractores caóticos y que son más coherentes son el comportamiento no trivial de los retratos de fase observacionales. Esto indica que los microclimas de Altamira y El Rull son caóticos o cercanos al caos. Además, todos lo modelos muestran largos transients, lo que indica que pequeñas perturbaciones pueden lanzar el sistema a un estado de caos transitorio. En todos los casos, la fuente de caos es el clima exterior (un sistema caótico de alta dimensión bien establecido), mientras que el karst reduce la dimensionalidad debido a su efecto aislante, lo cual lleva dinámicas de menor dimensión, capturadas por los modelos. Hasta ahora la evolución temporal de las concentraciones de CO2 y 222Rn en cuevas y su relación con el clima externo se ha abordado predominantemente mediante aproximaciones estadísticas, las cuales no pueden garantizar la existencia de relaciones causales. Se han propuesto algunos modelos matemáticos para el estudio de microclimas, pero son locales (aplicables sólo a fragmentos de las series temporales), estáticos o se centran en algún aspecto particular (por ejemplo, el descenso de CO2 inmediatamente después de una visita turística). Por primera vez, hemos encontrado sistemas de ecuaciones diferenciales representan de forma global estos microclimas kársticos (aunque las oscilaciones diarias y de alta frecuencia no se han considerado en este estudio). Es más, aunque restringidos a ambientes kársticos, estos son los primeros modelos dinámicos climáticos extraídos directamente de datos observacionales, ya que todos los anteriores se basan en consideraciones teóricas. Para Altamira, encontramos modelos basados en variables internas. Para ambas cuevas encontramos modelos que relacionan las variables internas y los forzamientos externos (la humedad del suelo para Altamira, el número de visitantes diarios para el Rull y la temperatura exterior para ambas). Otra innovación introducida en esta investigación es el uso de series temporales observacionales como forzamientos externos (temperatura exterior, humedad del suelo y número de visitantes). Por primera vez en el estudio de un fenómeno real, se han presentado modelos globales formulados de forma no-autónoma. Esto ha permitido reducir la complejidad del proceso de búsqueda y validación de modelos, así como la posterior reinyección de esta complejidad original en los modelos. Es más, ha permitido el estudio de la respuesta de los microclimas kársticos a diferentes escenarios climáticos hipotéticos. En conclusión, el hallazgo de estos modelos es un notable paso adelante en el estudio de las cuevas de Altamira y El Rull, así como una exploración metodológica que ha abierto caminos fructíferos para el futuro de la investigación de microclimas kársticos.

The Diploma Thesis deals with the water pollution entering the Protected Landscape Area Moravian Karst via surface streams. In order to quantify the extent of the pollution surface streams entering the Moravian Karst were selected. A survey of a region of interest was done. Actual volume flow rate, measurements of physicochemical parameters, water samplings, laboratory analyses of samples were done monthly from April to November 2019. Conductivity, pH, temperature, oxidation-reduction potential, concentration of dissolved oxygen, and oxygen saturation were measured in situ. Afterwards, COD, BOD, phosphate, total phosphorus, ammonia, nitrites, nitrates and Kjeldahl nitrogen were determined in the laboratory. Organic nitrogen and total nitrogen were also calculated. The results were evaluated with a respect of Government Decree No. 401/2015 Coll. Material flows were calculated for selected parameters and used as other criterion that evaluate the water pollution of monitoring surface streams. Areas out of the PLA needing an enhanced protection of watercourses were proposed based on quantified pollution. Cooperation with two primary schools in the Moravian Karst supported the research. Pupils and their teachers were trained, and they measured phosphate in surface streams from April to November 2019. The website related to phosphorus in surface water were created and results of phosphate measurement were uploaded there.

The aim of this master thesis was to create a geographic information systém (GIS) for the needs of cycling. The proposed route connects Vyškov and Blansko and allows you to get to know beauties of the Moravian Karst and the Drahanská vrchovina. The whole thesis was created in software ArcGIS for Desktop 10.4.1 from the company Esri. In addition to the actual processing of data from measurement and GIS creation, I have tried various database queries and analytical task over the data. The final GIS was published on the web and is accessible to the public. It allows you to display the characteristics of the route and points of interest without having to turn off individual layers.