Analysis of Water Retention Changes in Selected Lake-Wetland Catchments of West Polesie Based on Historical Documents

The paper presents analysis results concerning changes in the range of areas of surface and transitional retention, here corresponding with wetlands, in two small lake catchments in the western part of West Polesie. The cartometric research was performed on maps covering the period from the 19th to the early 21st century. The analyses were referred to the modern state of investigation recorded on orthophotomaps in data bases disclosed in Geoportal Krajowy and in the Google Earth Pro application. Lake surface retention showed no substantial changes, and the differences result from the scale of maps used in the study, and therefore from the degree of detail of the presented objects. In the catchment of Lake Czarne Gościnieckie it occupied from 13.61 to 15.64% of its area, and in the catchment of Lake Brzeziczno from 0.96 to 1.28%. The greatest discrepancies in the area of wetlands result from the cartographic method of presentation, and generalisation of maps. In the catchment of Lake Czarne Gościnieckie, areas of transitional retention could be identified on 11 out of 13 maps, and in the catchment of Lake Brzeziczno on 12. In the case of the former catchment, transitional retention occupies from 17.35 to 34.00% of its area, and in the catchment of Brzeziczno from 4.81 to 24.00%. Such different surface areas of wetlands measured on maps, however, do not signify evident tendencies for change. Over the last 200 years, no substantial changes occurred in the studied catchments regarding the range of surface waters and wetlands, as confirmed by field research conducted in the years 2006-2012. The quantity and quality of maps and the variability of their scales encourage a careful interpretation of obtained information. In such a case, it is necessary to supplement cartographic analyses with investigating procedures of map preparation, and also to collect written documents concerning the entire area.