Abstract
We conducted the field observations and the calculations on current field by tide and wave to grasp the influence of the formation of the bar on river mouth. Study site is Akashi river mouth, Hyogo Prefecture in Japan. Akashi river is one of the typical urban river, the bar at the river mouth repeat appearance and disappearance. From field observations on recent four years study, it is clarified the right bank bar often developed than left bank one. However, from the result of the past aerial photographs , it turned out opposite result to recent four years study. From the results of the tide calculation, it is clarified that the current velocity by tide has small difference in before and after breakwater construction. On the other hand, the result of the wave simulation, it is clarified the current velocity decreased due to breakwater construction. In addition, it became clear that wave is more remark-able to give the bar of the Akashi river mouth because the tide has very smaller current velocity than wave.
