Bank Erosion of A Main Channel and Scouring of A Side Channel in A River in An Alluvial Fan Reach

The cross section of a river channel in an alluvial fan reach is originally simple, but in many rivers it has been changed into a compoud-section by dredging a main channel because of its larger capacity to handle floods and the multipurpose utilization of a side channel. However, many troubles such as bank erosion in a main channel and scouring of a side channel occur during floods. The mechanisms of the problems in some Japanese rivers are analyzed by field studies using aerophotos and survey data and by experiments conducted in the laboratory.