A Hévízi-tó vízháztartásának vizsgálata

Judit Barbara Nagy; Géza Hajnal; Dénes Szieberth; Péter Torma

doi:10.59258/hk.24796

Judit Barbara Nagy Budapest University of Technology and Economics, Department of Hydraulic and Water Resources Engineering https://orcid.org/0009-0007-6613-588X
Géza Hajnal Budapest University of Technology and Economics, Department of Hydraulic and Water Resources Engineering
Dénes Szieberth Budapest University of Technology and Economics, Department of Inorganic and Analytical Chemistry
Péter Torma Budapest University of Technology and Economics, Department of Hydraulic and Water Resources Engineering https://orcid.org/0000-0001-9282-6931

Keywords: Lake Hévíz, water balance, thermal karst, monitoring system, discharge measurement, hydrogeology, hydrometeorology

Abstract

Lake Hévíz is a unique thermal karst lake, fed by springs and featuring a complex water balance system. The unknown discharge of the springs entering through the crater makes it difficult to quantify this balance. This study aims to determine the monthly and annual water balance of the lake for 2024 using available monitoring data. During the analysis, the components of the water balance equation – precipitation, evaporation, discharge through the northern and southern outlets, direct water withdrawals, and water level changes – were determined using measurements and calculations. Evaporation estimation was based on eddy covariance measurements, from which the transfer coefficient was derived. The latent heat flux was subsequently calculated using routine hydrometeorological parameters. Precipitation data were supplemented with data from a meteorological station operated by the Hungarian Meteorological Service. Discharge measurements at both outlet structures were verified on multiple occasions. The results show that the dominant component of the lake’s water balance is the inflow from the thermal karst springs entering through the spring cave, while evaporation and precipitation have a smaller contribution. Based on the 2024 data, water level fluctuations were minor, on the order of approximately 10 cm. The spring discharge could be indirectly estimated by closing the water balance; however, the greatest uncertainties arise from measurement errors in the outflow discharge and from operational characteristics of the sluice structures. To reduce these uncertainties, the development of a self-designed flow measurement device has been initiated, enabling the direct determination of flow velocity at the spring cave outlet. The results contribute to a more accurate understanding of the hydrological functioning of Lake Hévíz and support informed decision-making for sustainable water management.

Author Biographies

Judit Barbara Nagy, Budapest University of Technology and Economics, Department of Hydraulic and Water Resources Engineering

JUDIT BARBARA NAGY obtained her BSc degree in civil engineering in 2021 and her MSc degree in infrastructure civil engineering in 2023 from the Budapest University of Technology and Economics. She is currently a doctoral student at the university's Department of Hydraulic Engineering and Water Management. She began her research activities as an undergraduate student, with investigations related to the Molnár János Cave. The topic of her doctoral research is the hydrogeological investigation of Lake Hévíz and its region. She is a research assistant at the National Laboratory of Water Science and Water Safety. She has been a member of the Hungarian Hydrological Society since 2022.

Géza Hajnal, Budapest University of Technology and Economics, Department of Hydraulic and Water Resources Engineering

GÉZA HAJNAL graduated from the Budapest University of Technology and Economics (BME) in 1993 with a degree in civil engineering, and in 1994 he received a certificate in engineering teaching from the same university. He received his PhD in 2002. Since 2008, he has been an associate professor at the Department of Hydraulic Engineering and Water Management, and was the head of the department between 2017 and 2020. His main research areas are hydrogeology and water balance calculations. He has been awarded the János Bolyai Research Scholarship twice (2004-2006, 2008-2010) for his research in the field of hydrogeology. In 2020, he defended his dissertation in literary studies at the University of Pécs.

Dénes Szieberth, Budapest University of Technology and Economics, Department of Inorganic and Analytical Chemistry

DÉNES SZIEBERTH graduated in chemical engineering in 1997 and received his PhD in 2000. Since completing his studies, he has been working at the Department of Inorganic and Analytical Chemistry of BME, and has been an associate professor since 2011. His original field of expertise is the modeling of the mechanism of chemical reactions. He has researched as a scholarship holder at several universities (Kaiserslautern, Leuven, Antwerp, Edinburgh, Sendai, Turin). Since 2014, his interest has turned to karst waters, and in addition to water analytics, his main research interests include measurements and sampling in underwater caves, as well as the design of custom instruments.

Péter Torma, Budapest University of Technology and Economics, Department of Hydraulic and Water Resources Engineering

PÉTER TORMA obtained an MSc degree in civil engineering in 2011 and a Ph.D. degree in 2016. He has been working at the Department of Hydraulic and Water Resources Engineering at the BME since 2011. Starting 2019, he works as an associate professor. Obtaining a Fulbright Scholarship, he was a visiting researcher at UW-Madison (USA) in the 2017/18 academic year. His field of research is physical limnology, hydrometeorology, in particular the measurement of turbulent exchange processes at the water-air interface based on the eddy-covariance principle, the heat balance of lakes, and numerical hydrodynamic modeling. Member of the Hungarian Hydrological Society since 2023.

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URL1. https://www.met.hu/

Trends in actual evaporation fro Investigation of the water balance of Lake Hévíz

Abstract

Author Biographies

References