Bed-load transport: advances up to 1945 and outlook into the future

ABSTRACT Fluvial bed-load transport is a fundamental problem in open channel hydraulics and river engineering. It appears that research progress slowed down some 40 years ago, as the advances were too small to generate adequate funding. What are the reasons for these changes in river engineering, and why has bed-load transport not yet received a proper renaissance in research activities? In addition, what are the future research topics in this field? Based on the state-of-the-art up to the end of the Second World War, the author intends to forward reasons for a fresh reconsideration of this fascinating research topic, based on the current knowledge, and particularly on the recent advances in hydraulic experimentation. Given the many questions from the practicing engineering community, it appears that bed-load transport ought to be redeveloped by the modern river engineer. The current knowledge is insufficient to deal with the many questions to be solved not only from the hydraulics community, but also from questions posed by environmental, natural resources, or chemical engineers in dealing with their daily problems. This Forum paper thus does not only attempt to review the origins of bed-load transport, but also would like to foster discussions among experts as to what degree this topic should be reconsidered in the next decade.