Short overview of basin-scale hydrogeological research conducted at ELTE in the last two decades

Abstract

The research and educational activity of the hydrogeological group (József & Erzsébet Tóth Endowed Hydrogeology Chair) of the Department of Physical and Applied Geology of the Eötvös Loránd University (ELTE, Budapest, Hungary) focuses on the basin-scale system approach of groundwater flow and the related natural phenomena based on the theory of hydraulic continuity. The paper presents this approach with its historical background as compared to the earlier aquiferbased artesian paradigm. The background of basin-scale hydrogeological research approach and methodology under continuous development is shortly explained, while less emphasis is placed on technical minutiae. Among the methods,
basin hydraulics are fundamental as these provide the “real groundwater flow system model” based on the basin-scale analysis and interpretation of measured hydraulic data from wells. Accordingly, the basin-scale and particularly the basin hydraulics’ results of our research history are reviewed, but the related phenomena investigated by other methods are also mentioned. Our studies covered most areas of Hungary and revealed everywhere the hydraulic continuity of the rock framework and the existence of gravity-driven regional groundwater flow systems irrespectively of the topography and rock type (i.e., siliciclastic or carbonate). The pressure regime in these flow systems is near to hydrostatic, while the flow field is regionally unconfined and recharged from rainwater. In the deeper sub-basins, the gravitational regime is underlain by an overpressured regime (e.g., in the Duna–Tisza Interfluve, Derecske Trough, Békés Basin, Battonya High, Dráva Basin) or underpressured regime (e.g., in the Hungarian Paleogene Basin). Both anomalous pressure regimes are confined with nonrenewable resources (overpressured) or with limited recharge (underpressured). This complex hydraulic situation, as well as the geologic and environmental agency of groundwater flows account for several surface (e.g., salinization, groundwater dependent ecosystems (GDEs)) and subsurface (e.g., hypogene caves, hydrocarbon entrapment) phenomena and processes.