Open-channel hydraulics are described by hyperbolic equations, derived from laws of conservation of mass and momentum, called Saint-Venant equations. In conjunction with hydraulic structure equations these are used to represent the dynamic behavior of water flowing in rivers, irrigation canals, and sewers. Building on a detailed analysis of open-channel flow modeling, this monograph constructs control design methodologies based on a frequency domain approach. In practice, many open-channel systems are controlled with classical inputoutput controllers that are usually poorly tuned. The approach of this book, fashioning pragmatic engineering solutions for the control of open channels is given rigorous mathematical justification. Once the control objectives are clarified, a generic control design method is proposed, first for a canal pool, and then for a whole canal. The methods developed in the book have been validated on several canals of various dimensions up to a large scale irrigation canal.