Ice Cover Thickness Formulas for Selected Flow-Through Lakes of the Upper łeba River (Kashubian Lakeland, Northern Poland) and an Overview of GIS Methods, Models for Determining the Thickness of Ice Cover on the Selected Examples

The lakes selected for the analysis are situated in the Kashubian Lakeland which is a proper research area as there is a benchmark lake with a long data series within the region. This lake is located in the central part of the lakeland, in the upper Radunia water catchment area, while the lakes not being hydrometrically supervised constitute part of the upper Łeba water catchment area. The main objective of this study is to determine the relationship between ice cover thickness on the flow-through lake undergoing constant hydrometric supervision and some selected flow-through lakes not being monitored. The following lakes were selected for the study: Lake Raduńskie Górne (the benchmark lake) and four hydrometrically unmonitored lakes: Długie, Wielkie, Reskowskie and Łapalickie. The fieldwork research was done in the period of 2003–2008. Moreover, in order to evaluate the data calculated with the use of empirical formulas, additional fieldwork research was carried out in 2016. The analysis made it possible to develop formulas that allowed the thickness of the ice covering the selected flow-through lakes of the upper Łeba water catchment area to be assessed with decent accuracy.