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 input–output 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.