Warunki filtracji wód w utworach jury na przykładzie wybranego obszaru w południowej Polsce

Abstract

CONDITIONS OF WATER FILTRATION IN JURASSIC FORMATIONS EXEMPLIFIED BYA SELECTED AREA IN SOUTH POLANDSummaryThe paper presents the results of the research of the groundwater flow conditions of in the catchment area of river R. This area comprises a fragment of the Jurassic upper reaches and the flat form of the river valley R, within the graben. The research has been made by means at electrohydrodynamical analogy method (AEHD). The construction of the electric analog models has been based on electroconductive papers and on electrolytic tank. Boundary conditions of models have been determined on the basis of the field hydrogeological examinations made previously. The purpose of the analog studies was to present on two-layer flat electric models the conditions of formation of hydrodynamic field of the catchment area investigated. The analysis of the conditions of formation of hydrodynamic field allowed t he authors to determine filtration path and to distinguish the individual systems of circulation. Two water-bearing beds have been distinguished within the catchment area investigated; these represent two separate systems of water circulation. The first one is related to the Malm limestones, the second - to the Dogger sandstones, as well as to the Palaeozoic limestones, dolomites and sandstones. Within the graben, the Dogger formations make a separate water-bearing horizon there. Isolation series between the water-bearing beds consists of the Lower Oxfordian marls, locally of the Liassic clays. The formation of the potential pressure field points to the occurrence of local hydraulic relations between the beds considered. The upper water-bearing bed is fed directly by atmospheric precipitations. Locally, within the fault zones of the graben, this bed is fed by the lower water-bearing bed too. The regional direction of water flows runs towards the valley of river R. The arrangement of water table corresponds to the morphology of the area. The bed under consideration is drained mainly by the valleys of the streams which are tributaries of river R. The draining role of the graben is restricted, however, mainly due to a fact that the zone of the faults determining the graben plays a part of a semi-permeable screen. The lower water-bearing bed is fed, in the northern part of the area in study, only indirectly through the feebly permeable marls of Upper Oxfordian age, and the fault zones. Water flow is directed towards the graben. Where the isolating series is absent, the bed may be drained at places by local stream valleys.