Wave Set-Up Height and Salinity Intrusion in Yoneshiro River Mouth in Winter

Abstract

Water level rise and salinity intrusion in the mouth of the Yoneshiro River in Akita Prefecture, Japan is investigated. Geographical features of the river mouth are greatly dependent on seasonal variation of major physical forcings. Therefore, the characteristic of wave set-up is assumed to be different according to the season, and seasonal variation of wave set-up is quantified. It is found in winter, the water level rise by wave set-up becomes approximately 10% of the deep water wave height, whereas this ratio decreases rapidly in summer due to flushing of sediment around the river mouth caused by frequent occurrence of floods. In spite of such water level rise due to wave set-up in winter, salinity intrusion was not observed in the river because of the closure of the river entrance caused by severe storms.