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Starting from autumn 2016, the Czech Geological Survey has been focused on assessing the impact of planned extension of the Turów coal mine, an extensive open-cast mine located in the eastern part of the Zittau Basin (Lower Silesia, Poland). In particular, we aimed on possible effects on groundwater regime in the adjacent Czech part of the Zittau Basin, the Hrádek sub-basin, and in the borderland Frýdlant area. The Hrádek sub-basin is filled by Tertiary deposits with coal covered in the eastern part by up to 80 m thick Quaternary, predominantly glaciofluvial deposits. In the Frýdlant area, the Tertiary deposits form outliers further NE of the Zittau Basin and are largely covered by the Quaternary glaciofluvial deposits, up to 20-60 m thick. The glaciofluvial deposits (porous, quartzose sands and sandy gravels, locally well-sorted) form an important aquifer in the study area. It was assumed that the extension of the Turów coal mine could affect not only the Tertiary aquifers, but also Quaternary glaciofluvial aquifer. This could take place in particular areas where aquifers in the upper part of Tertiary interact - in terms of groundwater flow - with the Quaternary glaciofluvial aquifer. This assumption could have been confirmed only by a detailed investigation of the study area's geological setting. Geological investigations have been conducted in several consecutive stages: (1) Processing of all available borehole data from CGS archives and database provided by the Polish Energy Group. In addition, construction of cross-sections provided first insight into geological setting of the study area. (2) Constructing basic 2D contour-line model of main stratigraphic surfaces - top of the basement, base of the Tertiary, bases and tops of the Tertiary coal seams (Cb1, Cb2 and Cb3), base of the Quaternary. Where database did not allow higher resolution, the interpreted geological setting in the resulting model allowed for groundwater flow towards Polish territory. The critical localities without borehole data were selected for field geophysical measurements in the subsequent stage. (3) Field geophysical measurements (in-house ERT). In total, 70 ERT profiles were measured throughout the study area. (4) Construction of the tectonic framework of the study area (cf. Václ 1998). (5) Update of the 2D contour-line model by implementing new geophysical data (ERT profiles, gravity maps). (6) Complex geophysical measurements (VES and seismic profiles) carried out by Geonika, s. r. o., at the localities selected as a result of geological modeling. The main result of the geological part of this project is providing a detailed knowledge of the geological setting of the borderland Hrádek and Frýdlant regions. This was possible by integrating archive as well as newly acquired data into the geological model that would serve as a basis for groundwater modeling and hydrogeological/hydrological balance. The geological model is focused on displaying regional extent and thickness of sedimentary units - carrying the principal groundwater aquifers - represented in the study area by the Tertiary and Quaternary strata (mainly glaciofluvial deposits). In the upcoming stage of the project, a series of exploratory boreholes planned since the spring 2018 is going to be drilled. Geological (cored) as well as hydrogeological boreholes (wells) will serve as a valued database for an ultimate update of the geological model presented herein. [ABSTRACT FROM AUTHOR]

This article represents the executive summary of the Czech Geological Survey report on the urban geology of the Liberec district city in northern Bohemia. This study includes spatial and attribute information on geological units and their lithology, as well as on network of the geological faults, natural magnetic field, natural radioactivity, iron mining, coal mining, quarries of building stones, clay resources ground water and geothermal resources, engineering-geological ground classification, natural outcrops, antropogenous exposures, and road cuts, network of the hydrogeological and geotechnical drill holes, underground objects and sewers, man-made deposits of the industrial and municipal waste, pavement and frontages of building in the Liberec conservation zone, natural seismicity, radon risk, radioactive fallout of caesium 137, soil cover contamination by industrial emissions, Lužická Nisa river inundation area and its geological fundament in the town centre. Data on individual themes were first of all obtained from existing Czech Geological Survey databases, and the new geodata were created by detail mapping (Fig. 4). I This set of information provides data for the municipal government to underpin reliable urban planning and sustainable development of building density. All available information from various data sources have been linked in GIS format to the street plan at the scale of 1 : 13,000, covering the town site of about 40 km2 (Fig.1). An image analysis of the individual data layers and their mutual interferences gives some important information about resources including ground water and geothermal energy, plus environmental hazards that have the potential to impact the town and its residents. The following features of the urban geology model for Liberec may be applicable to other cities in the Czech Republic: - Generation of urban geological maps and spatial models of cities for groundwater and geothermal energy exploitation, and for planning housing and underground constructions. - Use of geological knowledge to assist in protecting the environment of conurbations by identification of man-made infilling, deposits of dangerous waste and air pollutants. - Better informing city dwellers about the environment in which they live and do business, including improving their knowledge of existing and potential geological hazards in their towns. [ABSTRACT FROM AUTHOR]