TERRAPUB Geochemical Journal

Geochemical Journal, Vol. 51 (No. 5), pp. 439-448, 2017

Estimation of the natural groundwater recharge using tritium-peak and tritium/helium-3 dating techniques in Hungary

László Palcsu,1* László Kompár,2,3 József Deák,4 Péter Szűcs2,5 and László Papp1

1Hertelendi Laboratory of Environmental Studies, Institute for Nuclear Research, Hungarian Academy of Sciences, Bem tér 18/c, 4026 Debrecen, Hungary
2Department of Hydrogeology and Engineering Geology, University of Miskolc, H-3515 Miskolc-Egyetemváros, Hungary
3Isotoptech Ltd., H-4026 Debrecen, Hungary
4GWIS Plc., H-2120 Dunakeszi, Hungary
5MTA-ME Research Group of Geoengineering, H-3515 Miskolc-Egyetemváros, Hungary

(Received February 8, 2016; Accepted March 24, 2017)

Abstract: Quantification of natural groundwater recharge in three study sites within the Great Hungarian Plain was performed using environmental tracer techniques, based on utilization of tritium and helium-3 isotopes in groundwater samples taken from multilevel well-nests. Transport models were calibrated by the measured 3H activities at different depths below surface. The 1963 tritium bomb-peak was used to determine the average natural groundwater recharge. Rates of 48 ± 6 mm/yr, 62 ± 8 mm/yr and 27 ± 3 mm/yr, respectively were obtained. The 3H/3He dating technique was also used to determine age profiles at the three sites, giving recharge rates of 48 ± 6 mm/yr, 63 ± 9 mm/yr and 22 ± 4 mm/yr respectively. Although the recharge rates calculated by the two methods agree well with each other, these two approaches to recovering recharge rates are based on different recharge properties. Modelling of the bomb peak distribution is mainly affected by the position of the bomb peak, hence the recharge rate obtained is not necessarily reliable for recent decades. In contrast, the 3H/3He age-depth profile averages the last 4–5 decades, and therefore may provide a better estimation of long term recharge. A third approach to calculating recharge rates using a simple soil moisture—stable isotope approach was found to only be reliable over the most recent few years.
Key words: groundwater recharge, tritium-peak method, 3H/3He dating, Great Hungarian Plain, transport modelling

*Corresponding author E-mail: palcsu.laszlo@atomki.mta.hu

[Full text] (PDF 815 KB)