This book is a monograph on the open-channel turbulence. Former part covers the basic characteristics including derivation of governing equations. The latter part focuses on various topics related to environmental management and disaster problem in river turbulence. The turbulent flow is a momentary phenomenon, but there are also organized motions, not just random. How to feedback this fundamental knowledge to the practice of hydraulic engineering including mass and sediment transport is a big issue. This book explains in detail the basic points and various specific problems of river turbulence in order for abecedarians to easily learn for themselves. By including application examples, the understanding of readers is more deepened. In addition, it also outlines the methods of hydraulics experiments and turbulence measurements. So, it will be very useful for readers themselves to measure turbulence with their own hands in future. It is intended for a wide range of readers, from students studying hydraulics to graduate students who want to know more about the essence of phenomena, and engineers using it as a reference for hydraulic works and practice.