Occurrence, genetic types, and evolution of lake basins in Poland

Abstract

The territory of Poland includes more than 7,000 lakes (1 ha or larger) with a total surface area of 281,377.0 ha, translating into the lake density index of 0.90%. The territory of Poland is evidently divided into the northern part, including 95% of all lakes, and the southern part poor in lakes. The situation is related to the last Scandinavian glaciation. Due to this, in terms of genesis of basins, the majority of lakes are of postglacial character, where the occurrence and course of channel lakes is an indicator of the maximum range of the ice sheet. Lakes fulfil a number of important functions in the environment. The functions refer among others to the conditions of water circulation (suppressing extreme situations, both floods and draughts), affect the biodiversity, shape climatic conditions, and are of key importance for the development and functioning of many branches of the economy (agriculture, energy engineering, tourism), etc. Both environmental and anthropogenic effects resulting from the occurrence of lakes can soon be lost as a result of the progressing process of their disappearance. The situation is determined by the natural process of evolution, accelerated by human activity related to the regulation of water relations, and an increase in productivity of agriculture, and consequently an increase in supply of nitrogen and phosphorus compounds to water. It is estimated that from the moment of development of lakes until today, approximately 60% of the surface area of lakes disappeared.