The Role of Lakes in Natural Groundwater Drainage

In the paper it is shown that the lakes of the North-Eastern Poland fulfil various functions in the groundwater phase of the water circulation. The value of the resultant of the groundwater supply to the lake, and in some cases also its direction, depend on the volume of the water undergoing a total exchange in the reservoir in the given year. In through-flow lakes the runoff increase coefficient also influences this value.