Impact of Climate Conditions on the Sensitivity of Long-Term Annual River Flow in a Cascade-Dammed River System: The Brda River Case Study (Poland)

Maintaining the sustainable quantity and quality of water resources is crucial for fluvial systems, as well as for human life. This study describes the long-term annual river flow within the Brda River catchment of Poland, a fluvial system subjected to the strong hydrotechnical transformations of a cascade of dams. Our research was based on the following hydrological data (1951–2021), meteorological data (1971–2021), and climate scenarios (2022–50) to determine observed and simulated annual river flows. In this research, rising trends in the mean annual temperature and in the annual precipitation in the Brda River basin have been observed. In addition, significant research findings were the three complete river flow oscillations observed to date, and the further predicted river flow oscillations that have been projected by 2050. We modified the Turc model by linking the forecast of river flow patterns to the precipitation factor. Moreover, we predict a decrease in the river flow in the Brda River catchment of up to 10%. These studies, integrated with river flow scenarios, explicitly indicate that a river flow crisis will occur by 2050. However, it can be reduced through dam operation systems and good environmental practices in river basin management plans. This research contributes to the formulation of a sustainable management model for a cascade-dammed river that considers climate challenges.