Przemiany środowiskowe związane z antropopresją w ujściowym odcinku Warty

This article is an attempt at presenting environmental changes within the Warta valley during the last 250 years on the basis of existing archives, i.e. historical sources and old hydrographic hand-drawn maps, compiled in 1773 and 1786. Correlation with a modern map illustrates how much the hydrographic network and water conditions has changed in this area. The area under discussion by the author covers the valley of the lower Warta river from the mouth of Noteć river to the mouth of the Warta into the Odra river. First of all, an attempt was mode to reconstruct the initial environmental conditions. The greatest changes were connected with river regulation work in the Warta valley, including irrigation channels and discharge ditches draining the water from swampy valleys parts. These field works were for the most part of valley carried out towards the end of the 18-th century and the early part of the 19-th century. In this period the changes of hydrographic conditions were greatest. The present hydrographic pattern in the Warta Valley is artificial regulated with strengthened nearly straight line banks. This works provided for its stability, whereas in its other segments of Warta river often changed its course creating new meanders or arms. The dominance of drainage works in this area, liquidation of wet areas and river patterns made this terrain periodically dry, completely different than in the middle Ages. The Warta also lost its significance as a water route, and its water are polluted. In the Warta valley also the transformation of relief is caused by the development of transport routes, building the flood dam and another type of anthropogenic forms. In area under consideration as a result of human activity, practically all physiographic elements were changed – waters, swamps, relief, soils and topoclimate