Evolutionary characteristics of river mouth bar in the Shokotsu River

The bar in a river mouth is formed depending on the balance between river dynamics and ocean dynamics,when the river channel curves in a river mouth,the bar maybe evolute most complexly due to channel s curvature.In this paper,by analyzing a great deal of data obtained in-site,the evolutionary characteristics of the Shokotsu River mouth bar were clarified as:(1) due to the coupling action of the bulwark built in the mouth of Shokotsu River and incident wave with the direction of north-east,a river mouth bar occurs in the right bank originally,and gradually develops and extends toward left bank,accordingly the direction of the water flow varies from the right to left bank;(2) no matter river mouth bar exists or not,the elevation of the river bed keeps to a level of 6m after 3 times flood run out,that is,the bed form at the Shokotsu River mouth has been balanced between scouring and sediment in flood season.