SEDIMENT BUDGETS BASED ON THE MASS OF SILT AND CLAY ON INTERTIDAL FLAT ADJACENT TO RIVER MOUTH

Abstract

Fine-grained sediment budgets based on the monthly bed level and net sediment flux monitoring during October 2006 to October 2007 are estimated to examine the relative significance of tides and river discharges on mud transport on an intertidal flat adjacent to a river mouth in the semi-closed sound. The intertidal flat accreted during normal discharge conditions mainly due to the alongshore sediment flux toward the river mouth. However, the flat eroded during large discharge conditions at the time of low tides. The offshore sediment transport during the large discharge was four times larger than that during the normal discharge. The spatial variations of tidal currents cause alongshore sediment fluxes toward the river mouth on the intertidal flat adjacent to the river mouth. The proposed fine-grained sediment budgets are useful to understand and assess the transport pathways for silt and clay on the intertidal flat.