SALT DIFFUSION CAUSED BY THE WAKE OF THE BLUFF BODY IN A TIDAL AREA OF ISHIKARI RIVER

Ways to establisha systemo f river transportationo n Ishikari Rivera re currentlyb eing investigated, but there are still many unresolved technical problems. One problem is that a salt wedge extends about 20 km upstream from the mouth of the river in the dry season. The diffusion of salt caused by the passage of a freightboat may have adverse effects on the fishing industry. Moreover, structures such as a bridge pier are in a mouth of the river, and it is necessaryt o also take into considerationth e diffusiono f the saltwaterb y the wake of the bridge pier.This study aims to compare and analyze diffusion of the saltwater induced by both structures and the passage of a freight boat. As a first step, the salt diffusion of two stratified flows induced by structures and the fracture mechanism of two stratified flows will be clarified.