Changes in the area of the Mazurian Lakes in the light of the cartographic materials at the scale 1:25000

Abstract

The article presents the result of comparative investigations of the areas of the Great Mazurian Lakes. Water decrease was found at the level of 3.1% in the period of approximately seventy years of the twentieth century. Similar tendency was documented with respect to several cases from the latter half of the nineteenth century. The authors draw attention to the role of hydrotechnical build-up (canals, sluices, weirs) constructed to slow down the pace of lake area decline. Several examples of lake area increase and renaturalisation are demonstrated. Most frequent physiographic consequences caused by changes in the lake area include: decrease of bay areas, growth of the extent and number of wetlands, and expansion of islands. The results of the authors’ investigations are compared with other materials and data.