Tracing and quantifying lake water and groundwater fluxes in the area under mining dewatering pressure using coupled O and H stable isotope approach

Abstract

Oxygen and hydrogen stable isotopic compositions of precipitation, lake water and groundwater were used to quantitatively asses the water budget related to water inflow and water loss in natural lakes, and mixing between lake water and aquifer groundwater in a mining area of the Lignite Mine Konin, central Poland. While the isotopic composition of precipitation showed large seasonal variations (δ2H from−140 to+13 ‰ and δ18O from−19.3 to+7.6 ‰), the lake waters were variously affected by evaporation (δ2H from−44 to−21 ‰ and δ18O from−5.2 to−1.7 ‰) and the groundwater showed varying contribution from mixing with surface water (δ2H from−75 to−39 ‰ and δ18O from−10.4 to−4.8 ‰). The lake water budget was estimated using a Craig–Gordon model and isotopic mass balance constraint, which enabled us to identify various water sources and to quantify inflow and outflow for each lake. Moreover, we documented that a variable recharge of lake water into the Tertiary aquifer was dependent on mining drainage intensity. A comparison of coupled δ2H–δ18O data with hydrogeological results indicated better precision of the δ2H-based calculations.