Hydrogeological conditions of the Cracow sandstone series in Upper Silesian Coal Basin influenced by mining activity

The Cracow Sandstone Series (CSS), consisting mainly of coarse-grained clastic rocks (>75%), form upper lithostratigraphic series of the coal-bearing Carboniferous formations in the Upper Silesian Coal Basin (USCB). CSS covers the area of 1,500 km2. Thicknes of a formation varies from tens to 1,140 m. Exploitation of coal deposits on industrial scale of production has started since the turn of the XVIII and XIX century. Intensity of water inflows to individual mines ranging from 4.3 to 52.8 m3/min, depends on morphological, geogenic and mining factors. Within the CSS hydrogeological complex typical for sedimentary basins hydrodynamic and hydrogeochemical vertical zoning occurs. Hydrochemical as well as isotope research revealed appearance of varied zones of infiltration, mixed waters and relict brines. Prevailing significance in hydrodynamic conditions forming within the CSS have hydrodynamic barriers: overlying isolating Miocene aquitard and increasing with depth diagenesis of the Carboniferous formation. The mining activity increases the rock permeability and causes the disturbance of the natural hydrodynamic field and hydrogeochemical conditions of the CSS.