This book contains the written, thoroughly reviewed versions of both invited lectures and regular presentations given at the 36th International School of Hydraulics, held at Jachranka in Poland on May 23¿26, 2017. The contributions cover recent findings in the areas of mathematical modeling as well as experimental investigations related to free surface flows and pollution, sediment and heat transport processes in rivers. Better understanding of environmental flows requires cognition of physical, chemical and biological attributes of flowing water and therefore hydraulic research becomes strongly interdisciplinary field of science. The authors also realize that fundamental knowledge of environmental hydraulics problems is absolutely essential for planning and design