EFFECT OF SALTWATER INTRUSION ON WATER DISTRIBUTION AT THE CONFLUENCE OF CHIKUGO ESTUARY

Abstract

 To clarify the effect of saltwater intrusion on the freshwater distribution at the X-shaped confluence point of the Chikugo River estuary, cross-sectional flow velocity and salinity distribution were observed for one diurnal tidal cycle. This study made the following conclusions: (1) The estuary was well-mixed during spring tide and that the flow rate ratio and cross-sectional area ratio between the tributary and main channels are not significantly different; (2) Vertical distributions of velocity and salinity confirm saltwater retention at the confluence point of Chikugo and Hayatsue Rivers at the start of ebb tide; (3) These findings can be generally explained by the difference in river lengths considering this as the limiting morphometric parameter.