Presented at the Role of irrigation and drainage in a sustainable future: USCID fourth international conference on irrigation and drainage on October 3-6, 2007 in Sacramento, California.Includes bibliographical references.Water level in open canal fluctuates with the change of the discharge. The water flow from one steady state to another will take a period of time. For a certain canal, the process of the dynamic response is affected by using different automatic control methods. In order to shorten the response time and limit the fluctuating range of water level, maintain the performance of automatic control canal system stability, proper automatic canal control methods should be adopted. In this study, taking the middle route of China's South-to-North Water Diversion Project as an example, the relationship of operation stability and automatic control methods of open canal is studied by means of numerical simulation of unsteady flow in open canal with different control methods, and some useful results on the automatic canal control system of the middle route of Chinese South-to-North Water Diversion Project are obtained
