This book grew out of lectures on unsteady flow in open channels in the Civil Engineering Department of the Delft University of Technology for senior BSc students and firstyear MSc students in hydraulic and coastal engineering, water resources management, hydrology and sanitary engineering. It deals with gradually varying, unsteady flows, or long waves, in natural channels such as rivers, estuaries and tidal channels, as well as manmade canals for various purposes such as drainage and irrigation systems and shipping.

Most existing books on open channel flow deal mainly with steady flows, unsteady flows typically being diverted to a single chapter. In practice, unsteady flows are the rule rather than the exception. Therefore, a unified introduction was deemed necessary, in which the unsteadiness and the important associated notion of wave propagation are essential ingredients from the start. The intended readership consists of students in the above-mentioned disciplines as well as practitioners.

Subject

The subject of this book is the mathematical modelling of gradually varying unsteady flows, or long waves, in open channels. Various classes of long waves are distinguished, depending on their origin and the associated time scale, varying from the relatively rapid translatory waves to the sluggish flood waves in lowland rivers. A chapter on steady flow summarizes some relevant results within this subclass. Transport of dissolved or suspended matter in open channels is briefly dealt with as well. Lastly, the numerical modelling of flow in conduits is covered in a separate chapter.

Pressurized flow in pipelines falls formally outside the scope of this book, but it is included nonetheless because pipe flow often is an integral part of water transport systems, and the mathematical equations describing pressurized flow and those describing open channel flow are quite similar. For these reasons, a summary is presented in Appendix A.

Aim

This book offers a unified presentation of the mathematical modelling of various classes of unsteady flows that can be expected in the context of design and operation of hydraulic engineering works in tidal areas, estuaries, rivers, canals etc., e.g. dredging or the construction and operation of control structures or dams. The engineer should be able to foresee consequences of the works being designed, both qualitatively and quantitatively.