Role of Multifunctional Water Reservoirs in the Upper Vistula Basin in Reducing Flood Risk

Multifunctional flood protection reservoirs of regional importance have been controversial for many years due to their significant environmental impact. The impact is especially observed at the implementation stage. Undeniably, properly managed large water reservoirs are the most effective element of active flood protection and significantly reduce the flood wave, thus limiting losses in housing, infrastructure, industry, or agriculture. At the same time, multifunctional reservoirs pursue other goals that are related to reducing shortages and counteracting the effects of drought, water supply, hydropower, or recreation. In the era of rapidly advancing climate and geopolitical changes, their role seems indispensable when it comes to responsible and coordinated water management in Poland. An open question is how to fully use the potential and to what extent it is possible for the system of reservoirs located on different watercourses to work together in the era of the progressive development of the country resulting in significant changes in land use (sealing large catchment areas) in relation to design assumptions. The article presents an analysis of the work of selected water reservoirs located in the basin of the upper Vistula during the floods that took place in the last decade. On the basis of the obtained conclusions, the authors present recommendations on how to effectively manage the network of reservoirs during a flood while minimizing losses of the water retained in them, which should be used to meet other goals of water management.