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Using ground penetrating radar in geomorphology
Široký, Jakub ; Křížek, Marek (advisor) ; Engel, Zbyněk (referee)
Ground Penetrating Radar (GPR) is a non-invasive geophysical research method imaging subsurface structures. It expanded widely across geomorphologic investigation during last years because of its speed, low-cost, reliable and large-scale capability. GPR is especially useful in sedimentological studies. The thesis is focused on introducing the basics about the GPR method as it is not well-known in Czech geomorphologic scene. The physical background of the device and the electromagnetic waves is given. A research articles and books recherche helped in creating of a reflection summary amended with Czech terminology and graphic examples. The typical reflection answer of sedimentological features were documented and sorted according to the glacial, periglacial, fluvial, paleolake and slope geomorphologic environments. A sequence of steps for editing and interpreting a radargram was proposed and applied on three model radargrams.
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Application of electrical resistivity tomography technique to detect underground cavities
Kučera, Radek ; Hartvich, Filip (advisor) ; Široký, Jakub (referee)
The electrical resistivity tomography (ERT) method is widely used to detect underground cavities because their air, water or clay infill often has a significant geoelectrical contrast to the surrounding rock. The review part of this study summarizes properties of the method and presents examples of investigation of underground cavities in various geological settings, mainly the crevice-type and karst caves and old mining objects. The case study from the Amatérská cave in the Moravian Karst proved the ability of the technique to detect air and clay filled underground cavities above the depth of 40 m. The resolution of the method is lower at greater depths but some indication of deeply situated Pustožlebská Zazděná and Amatérská caves was captured. Keywords: ERT, underground cavities, caves, Moravian Karst
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GPR data interpretation with use of a combined geoelectrical survey
Široký, Jakub ; Tábořík, Petr (advisor) ; Valenta, Jan (referee)
GPR data interpretation is often difficult due to complex geological environments, reflections ambiguity and time-depth conversion uncertainty. Thanks to the geophysical fields interoperability it is possible to compare results of related survey methods. Radargrams from three model sites were processed and interpreted in an usual way to uniformly amplify all recorded reflections. Results were compared with ERT and EM (DEMP) data within integrated interpretation. GPR data interpretation was extended and new geological and geomorphological interpretations were uncovered. The GPR processing sequence was modified and simplified following outcomes from the integrated interpretation to ease different methods results comparison. Adapting a velocity model to precise time- depth conversion hasn't showed improvements. Key words: ground penetrating radar, electrical resistivity tomography, dipole electromagnetic profiling, integrated interpretation, integrated inversion, GPR processing optimization, sedimentary environment, velocity model
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Using ERT and GPR in polygonal patterned ground analysis
Široký, Jakub ; Křížek, Marek (advisor) ; Hartvich, Filip (referee)
Polygonal cryogenic structures cannot be investigated with conventional methods as they could be harmed during measurement. A real3D GPR and ERT non-destructive surveys were used to examine and prove applicability for topsoil covered ice-wedge pseudomorphs and coarse-grained sorted polygons (patterned ground). A list of processing tools and algorithm suitable for such environments was created and tested. The benefits of 3D measurements are illustrated on horizontal slices and pseudo3D visualisation of 3D Cube. Basic morphometry characteristics of both forms were collected. Abilities of geophysical imaging for advanced shape characterisations are discussed, too. The low-frequency measurements gave better results at both sites. Pseudomorphs, 2 wide and up to 6,5 long, were found penetrating depth bigger than 3,5 . Sorted polygons, 2,5 wide in diameter, were depicted locked by stony ring of width around 1 . Sorting depth extends up to 0,54 depth for sure, perhaps more.
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Using ground penetrating radar in geomorphology
Široký, Jakub ; Křížek, Marek (advisor) ; Engel, Zbyněk (referee)
Ground Penetrating Radar (GPR) is a non-invasive geophysical research method imaging subsurface structures. It expanded widely across geomorphologic investigation during last years because of its speed, low-cost, reliable and large-scale capability. GPR is especially useful in sedimentological studies. The thesis is focused on introducing the basics about the GPR method as it is not well-known in Czech geomorphologic scene. The physical background of the device and the electromagnetic waves is given. A research articles and books recherche helped in creating of a reflection summary amended with Czech terminology and graphic examples. The typical reflection answer of sedimentological features were documented and sorted according to the glacial, periglacial, fluvial, paleolake and slope geomorphologic environments. A sequence of steps for editing and interpreting a radargram was proposed and applied on three model radargrams.
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