Hydrographic network transformations in postglacial areas – a case study of the Krajeński landscape park

The article presents a study on the transformation of hydrographic networks within protected areas. The research is based on the analysis of cartographic materials using GIS software. The temporal scope of the study covers the 19th and 20th centuries — a period marked by the most significant alterations to hydrographic systems due to human activity. The research was conducted within the Krajeński Landscape Park, one of the largest protected areas in the North Polish Lowlands. The results indicate a decrease in the lake surface area and a slight increase in the length of rivers (artificial canals). The primary causes of these changes are attributed directly to human activity, particularly land drainage for agricultural purposes (drainage ditches), and indirectly to the increased eutrophication of waters. The study highlights the sensitivity of young glacial river–lake systems to anthropogenic pressures. Protected areas represent an exceptionally unique part of the natural environment that requires sustainable management aimed at preserving their value for future generations. However, due to human activity and climate change, these areas are increasingly subject to various pressures, including transformations of the hydrographic network. The study aimed to assess the hydrographic network transformation using the example of the Krajeński Landscape Park (northern Poland). Due to the lakeland character of the study area, it constitutes an environment highly sensitive to any changes in water management. The analyses conducted using GIS tools made it possible to identify the main directions of hydrographic network transformation over the past centuries, revealing a strong impact of human activity. A decrease in lake surface area was observed, accompanied by an increase in the length of rivers and drainage ditches. This trend reflects the intensive meliorations carried out in the area in the past, anthropogenic modifications of riverbeds, and the acceleration of eutrophication processes in lakes and wetlands resulting from changes in the entire hydrographic network. The study highlights the need for sustainable management of the landscape park to protect habitats and water-related areas.