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.
Jacek Barańczuk, Elżbieta Bajkiewicz-Grabowska, Katarzyna Barańczuk and Wojciech Staszek
The paper presents assessment results of the ice dynamics on Lake Raduńskie Górne (Upper Radunia Lake) based on long-term observations of the course of ice phenomena. Interannual changes in lake ice phenology parameters (freeze-onset, ice-on, freeze duration, melt-onset, permanent ice cover duration, ice-off, melt duration) in the years 1961–2010 are discussed. In addition, the ice cover thickness was taken into consideration. The analysed parameters of ice phenology were compared to each other as well as to the mean air and water temperatures of the winter half-year (November–April). The main periods of the ice regime of the lake have been determined and described. The permanent ice cover constitutes on average 79%, freeze-up period 13%, and break-up period 8% of the whole time of ice phenomena. It was shown that the weather parameters crucial for ice formation are the mean air and surface water temperatures. On Lake Raduńskie Górne the ice phenomena can only occur when mean air temperature in the winter half-year, at Borucino wheather station, is lower than 4.9°C, and water temperature (at a depth of 0.4 m) is lower than 5.7°C. In turn permanent ice cover is created when the mean air temperature of the winter half-year is lower than 3.9°C. The maximum and mean ice cover thickness on Lake Raduńskie Górne ranged, respectively, from 0.5 to 50 cm, and from 0.5 to 38.3 cm. These parameters were strongly positively correlated (r = 0.87–0.88, p <0.05) with the duration of the ice cover period.