Przeobrażenia systemu wodnego w dolinie Liswarty koło Krzepic w okresie ostatnich 700 lst pod wpływem działalności człowieka

Abstract

The analysis of archival maps and historical sources as well as field stu-dies demonstrate that the Liswarta River water system near Krzepice has undergone significant natural and an-thropogenic transformations in the past 700 years. The broad flat floor of the valley, which only has a slight gra-dient within that reach, is prone to becoming boggy. Within the valley floor, there are two alluvial fans: of the Bieszcza River and of the stream flowing from Kuźniczka. In the past, the Liswarta River channel, which had a small longitudinal gradient, was characterised by considerable sinuousity and a natural tendency to branch out. For military (defence) reasons, a multi-channel river pattern and marshes were maintained there; reservoirs and pol-ders were constructed as well and the current of the Liswarta River was divided in order to optimise flows in mill races. Maps from the first half of the 19th century demonstrate that the construction and operation of water mills in Krzepice had a significant impact on the modification of the river network. Some river channels were artificial canals ranging from 1 to 2.5 km in length. These artificial canals are now subject to naturalisation. The flood plain, where the land is less and less used for agricultural purposes, is modelled by floods. In the study area, there are few large water bodies now: two recreational ponds in the mouth section of the Bieszcza River valley, the over 1,500 m long and 20 m wide channel-type reservoir upstream of the Marcelin mill and a few small landscape ponds and subsistence fish ponds. In the past, there were five channel-type reservoirs used by four mills and a forge, a mill pond and two fish ponds used for commercial purposes in this area. For some time, a large reservoir impounded by dam could also have functioned on the Liswarta River, which occupied a maximum of 3.9 km2 to-gether with the pond in the Bieszcza River valley. This reservoir was supposed to serve primarily defensive pur-poses and it can be considered to have been the model for the Kozłowa Góra-Wesoła hydro-engineering structure within the “Silesia” Fortified Area.