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Channels eroded by groundwater flow in Strelec quarry: erosion processes and factors influencing channel evolution
Soukup, Jan ; Bruthans, Jiří (advisor) ; Grmela, Arnošt (referee)
Large depression cone in water table was formed due to mining in surroundings of Střeleč quarry. The concentrated inflow from conduits to quarry is up to 70 l/s. Large conduit systems are created by flowing water into the quarry. The biggest conduit system was at least 300 m long and 17 m high with maximum calculated volume of 22 thousands m3 . Evolution of these conduits usually takes several months to few years. Fast conduit evolution allows to study erosion processes in detail in situ. In the thesis I am describing conduits, character of flow and erosion processes. Measured flow velocities in conduits are up to 0,4 m/s with hydraulic gradient 1 to 5%. Flow velocities and hydraulic gradients are typical for piping erosion. Piping initially forms small protoconduits. The bigger conduits are formed as water is progressively drained from larger area. Conduits are following fracture surfaces, which are also limiting the conduit propagation to the sides. Above water table the conduits are enlarged mainly by mass wasting of undercut sandstone slabs. For distinguishing less and more erodible parts of sandstone, we adapted and partially developed a method for measuring erodability (REI) and drilling resistance (DR). Both are used to compare different types of sandstone surfaces. In lowermost part of the...
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Limits for the use of thermal waters on the example of the conceptual model of the Benesov-Usti aquifer system of the Bohemian Cretaceous basin
Datel, Josef ; Krásný, Jiří (advisor) ; Grmela, Arnošt (referee) ; Némethy, Peter (referee)
Limits for the use of thermal waters on the example of the conceptual model of the Benesov-Usti aquifer system of the Bohemian Cretaceous basin PhD thesis Résumé Josef V. DATEL, MSc. The very work was carried out in the Bohemian Cretaceous Basin, which forms the largest basin structure of Upper Cretaceous age in the territory of the Czech Republic and takes up a major part of northern and eastern Bohemia. A crucial impulse for the research was new exploratory work in approximately the last 10 years, whose intention was to intensify thermal water sources exploration. Several new boreholes and wells were drilled and these have brought to light information about the hydrogeological structure exploited. The groundwater system of the Benesov and Usti nad Labem area, taking up around 2000 square kilometers, is more or less a closed hydrogeological unit with a relatively easily definable boundary. Its groundwater occurs mainly in Cretaceous aquifers. In some parts it is necessary, though, to take into account the ground water in underlying and surrounding geological structures as part of the hydrological balance. The largest thermal water accumulation known so far in the Czech Republic with temperatures often exceeding 30 degrees centigrade and in some spots approaching 40 degrees centigrade can be found in the...
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Using environmental tracers and other methods to estimate mean residence time and water flow in karst areas, Czech Republic
Bruthans, Jiří ; Krásný, Jiří (advisor) ; Bosák, Pavel (referee) ; Buzek, František (referee) ; Grmela, Arnošt (referee)
5. CONCLUSTON -Springs in 9 se|ected areas Were studied. Areas difÍer in geo|ogy (|itho|ogy, tectonics, intensity of metamorphism), recharge intensity (móuntainous coniřa lowland areas) and intensity of karst development differing by climatic conditions, geology -Concentrated recharge is only minor importance in most of areas compared to diffuse recharge -Most of the springs (90%) show predominant infiltration during last two decades with minor content (0-30%) of water infi|trated in sixties and sevénties of the twentieth century (based on tritium content). Analysis of lBO variations in spring water indicate that contribution of short residence time component (MRT in weekš to months) is about 5-20o/o of the spring yield -These numbers are similar or somewhat lower to results of MRT studies in other karst areas in the world (mostly vast carbonate bodies), which show mean residence time of water in karst aquifers to be from several years to hundreds of years -Volume of water in catchments of particular springs based on mean yield of spring and mean residence time is in orders of units to tens of millions m3 -|n studied karst areas SFo and CFCs can give re|iab|e resu|ts. |f no data from trítium are available the residence time must be considered as a minimum age. -Mean residence time of water percolating...
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Channels eroded by groundwater flow in Strelec quarry: erosion processes and factors influencing channel evolution
Soukup, Jan ; Bruthans, Jiří (advisor) ; Grmela, Arnošt (referee)
Large depression cone in water table was formed due to mining in surroundings of Střeleč quarry. The concentrated inflow from conduits to quarry is up to 70 l/s. Large conduit systems are created by flowing water into the quarry. The biggest conduit system was at least 300 m long and 17 m high with maximum calculated volume of 22 thousands m3 . Evolution of these conduits usually takes several months to few years. Fast conduit evolution allows to study erosion processes in detail in situ. In the thesis I am describing conduits, character of flow and erosion processes. Measured flow velocities in conduits are up to 0,4 m/s with hydraulic gradient 1 to 5%. Flow velocities and hydraulic gradients are typical for piping erosion. Piping initially forms small protoconduits. The bigger conduits are formed as water is progressively drained from larger area. Conduits are following fracture surfaces, which are also limiting the conduit propagation to the sides. Above water table the conduits are enlarged mainly by mass wasting of undercut sandstone slabs. For distinguishing less and more erodible parts of sandstone, we adapted and partially developed a method for measuring erodability (REI) and drilling resistance (DR). Both are used to compare different types of sandstone surfaces. In lowermost part of the...
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Limits for the use of thermal waters on the example of the conceptual model of the Benesov-Usti aquifer system of the Bohemian Cretaceous basin
Datel, Josef ; Krásný, Jiří (advisor) ; Grmela, Arnošt (referee) ; Némethy, Peter (referee)
Limits for the use of thermal waters on the example of the conceptual model of the Benesov-Usti aquifer system of the Bohemian Cretaceous basin PhD thesis Résumé Josef V. DATEL, MSc. The very work was carried out in the Bohemian Cretaceous Basin, which forms the largest basin structure of Upper Cretaceous age in the territory of the Czech Republic and takes up a major part of northern and eastern Bohemia. A crucial impulse for the research was new exploratory work in approximately the last 10 years, whose intention was to intensify thermal water sources exploration. Several new boreholes and wells were drilled and these have brought to light information about the hydrogeological structure exploited. The groundwater system of the Benesov and Usti nad Labem area, taking up around 2000 square kilometers, is more or less a closed hydrogeological unit with a relatively easily definable boundary. Its groundwater occurs mainly in Cretaceous aquifers. In some parts it is necessary, though, to take into account the ground water in underlying and surrounding geological structures as part of the hydrological balance. The largest thermal water accumulation known so far in the Czech Republic with temperatures often exceeding 30 degrees centigrade and in some spots approaching 40 degrees centigrade can be found in the...
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