Multimethodological Revisit of the Surface Water and Groundwater Interaction in the Balaton Highland Region—Implications for the Overlooked Groundwater Component of Lake Balaton, Hungary

Abstract

The hummocky Balaton Highland is located in western Hungary and is part of the Transdanubian Mountains, the most extensive carbonate aquifer system in Hungary. The study region also encompasses Lake Balaton, the biggest lake in central Europe, which is to the south of Balaton Highland. The surface water–groundwater interaction in the Balaton Highland–Lake Balaton region and the groundwater contribution to Lake Balaton are revisited in this paper. Hydrostratigraphic classification was performed first; then, groundwater flow directions by hydraulic head distribution were analysed, and baseflow indices of surface watercourses were calculated. Regarding hydrochemical characterisation, general hydrochemical facies were identified, natural tracers of temperature, chloride and uranium were applied, and the stable isotopic composition of oxygen and hydrogen was determined. Finally, groundwater flow and heat transport were simulated in a 2D numerical model. A high level of hydraulic interaction was evidenced between surface water and groundwater and the sub-regions of Bakony Mountains, Balaton Highland and Lake Balaton by physical and chemical parameters, numerical simulation and groundwater-flow-related natural manifestations, revealing hydraulic continuity in the study region. Based on the results, the division of legislative water bodies can be reconsidered, especially that surface water and groundwater should be regarded as interconnected, and Lake Balaton can be considered a groundwater-dependent ecosystem in any water-use planning in the region.

The Effect of Horizontal Specific Temperature on the Flow Systems of the Transdanubian Mountains (Hungary)

“…The significance of hydrostatic pressure is indicated by the fact that at sites where no karstic rock occurs in the floor of the bordering basin such as in the areas that border the mountains from the SE (Transdanubian Hills, Mezőföld), no upwelling occurs in spite of the fact that through flow also takes place here into the bordering basin [8,35]. Among the regional flow systems of the Transdanubian Mountains, there occur ascending flows (hypogene branch), formerly ascending flows (paleo hypogene branch), and flows of the outflow type (Figures 3 and 14).…”

“…Preceding karstwater extractions, it emerged not only in karst springs, but also fed karst marshes and karst lakes (Lake Balaton) and flowed into the fill of the basins [1,2]. However, it is also transmitted into the River Danube [8,34,35], and the basin sediments of its environs [36] (Figure 6). The hypogene branch of regional flow was studied in the Buda Hills in a detailed way [6,37] (Figures 7-9).…”