Integration of a Shallow Soda Lake into the Groundwater Flow System by Using Hydraulic Evaluation and Environmental Tracers

Abstract

Lake Velence is a shallow soda lake whose water level and water quality show a severely deteriorating tendency in recent years. Until recently, the groundwater component in the lake’s water budget has not been taken into consideration. To integrate the lake into the groundwater flow system at the regional scale, methods of “basin hydraulics” were applied. In addition, 17 water samples were collected for δ2H and δ18O, and for ΣU, 226Ra and 222Rn activity measurements to use these parameters as environmental tracers of groundwater contribution. Groundwater mapping revealed that groundwater recharges in Velence Hills and the local elevations south of the lake, whereas discharge occurs by the lake’s shoreline and along surface watercourses. The results indicated that Lake Velence is the discharge point of local groundwater flow systems known to be more sensitive to climate changes and anthropogenic activities (e.g., contamination, overexploitation). Groundwater and lake water have similar uranium activity concentrations serving as another sign of groundwater inflow into the lake. Therefore, it is necessary to consider both the groundwater component in the lake’s water management and its vulnerability regarding local and short-term changes in the catchment area.

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

“…Water samples for uranium analysis were collected in 0.25 L PP bottles at fewer sites, altogether 16 sites: 12 springs, 1 creek and 3 locations in Lake Balaton (Figure 5). Total uranium activity, ΣU = 234 U + 235 U + 238 U, was determined by alpha spectrometry using NucFilm discs (see measurement details in Baják et al [11,92] and Surbeck [93]).…”

“…Therefore, evaporated waters, such as lakes and rivers, will plot below the GMWL. Waters infiltrated during different climatic conditions, such as deep groundwater, may be depleted in these stable isotopes and reflect a more negative isotope composition [11,105,111,112].…”

“…Studies from all over the world have proven vital surface water-groundwater interaction [4][5][6][7][8], and these two types of water form an interconnected resource [9,10]. Meanwhile, the surface waters of Hungary, including Lake Balaton, remain groundwater-intact and are handled as separate entities without a single mention of groundwater in their budget [11,12]. However, several authors have hypothesised and claimed the opposite.…”

Description of Saprolegnia velencensis sp. n. (Oomycota), a novel water mold species from Lake Velence, Hungary

“…The water temperature is relatively high; in the summer it can reach the 26–28°C. The water has considerably high pH as well (7.8–9.2) and contains a high concentration (1–3 g/L) of dissolved salts (mainly Na- and Mg-hydrogen-carbonates and sulphates) [ 26 , 27 ]. The sampling took place in a public area, and no permission was required for collecting water samples.…”

“…In addition, Tandel et al [42] experimentally confirmed that S. australis could not grow at temperatures below +7˚C, whereas S. parasitica could tolerate a wider range of temperatures (+4-20˚C). Meanwhile, other studies have found that decreasing water depth and higher water temperatures favour bacteria which can suppress the growth of water mold, suggesting that water temperature only plays an indirect role in regulating water mold abundance [11,26]. Besides water temperature and salinity, the human factor should also be considered.…”