Models for Calculating Ice Cover Thickness on Selected Endorheic Lakes of the Upper Radunia (Kashubian Lakeland, Northern Poland)

The paper is an attempt to analyse whether there is or is not a relation between the thickness of ice covers that form on flow-through lakes under constant hydrometric supervision and on endorheic lakes not under constant hydrometric supervision. In order to do so, two benchmark lakes were selected – Raduńskie Górne and Ostrzyckie and six endorheic lakes: Kamionko, Kniewo, Stare Czaple, Zamkowisko, and Żuromino, including one seasonal outflow lake—Boruckie. Additionally, data on air temperature was also taken into consideration so as to determine the thermal characteristics of the analysed period. The data was obtained from the Limnological Station of Gdansk University, collected during patrol research carried out in the winter seasons of 2003–2008. In order to evaluate the formulas, additional measurements were made in 2016. The analysed lakes are located within the water catchment area of the upper Radunia in the central part of the Kashubian Lakeland. The benchmark lakes are located in the Radunia-Ostrzyce tunnel valley while the endorheic ones are located on the postglacial upland. The data analysis has revealed a strong relationship between the ice cover thickness on the benchmark lakes and the endorheic ones. Based on the analysis, models were developed for calculating ice thickness on the small endorheic lakes.