Examples of Lake Disappearance as an Effect of Reclamation Works in Poland

Glacial lakes undergo evolution with their disappearance as the last stage of it. Natural processes which determine the rate of lake shrinking occur rather slowly but they have been increasing their speed with the stronger human interference in the environment. The most drastic effect of anthropogenic pressure exerted on lake ecosystems is their complete disappearance caused by reclamation works. One can state that this process is a change of rapid character (a lake can disappear within a few years or several decades, in extreme cases even within one year). Drainage works are particularly unfavourable in areas with a shortage of water supplies, where rapid lake shallowing reduces water retention even more. A considerable part of Poland suffers from water supply deficiency. Therefore, draining of lakes should be considered as an adverse operation. This study discusses the examples of eleven lakes located in Poland and subjected to reclamation works. Analyses of those cases lead us to the conclusion that drainage aiming to broaden agricultural areas has not always been proper.