Groundwater supply of lakes: the case of Lake Raduskie Gorne (northern Poland, Kashubian Lake District)

The aim of the study was to locate and describe groundwater outflows in a selected lake basin and measure the spring output of water and the physical characteristics of the studied waters (temperature and conductivity). The final aim was to gauge the effects of the spring output on the lake hydrology. The time scope of the work included the period from January 2011 to September 2012. The spatial scope of the work included the area of Lake Raduskie Gorne and its direct catchment located in the Kashubian Lake District in northern Poland. Four groundwater outflows were located in the course of the study. Their total output was 4.6 Ls(-1) and ranged between 0.5 and 2.5 Ls(-1). This produces an annual yield of about 145 000m(3) year(-1). These results confirm that one of the forms of supply to the lakes are the under-lake springs. For lakes located in the area of young glacial accumulation this can be decisive.