Estimation of an Equilibrium Grain Size Distribution on River Mouth Tidal Flat and a Habitat Assessment for Benthic Animals

Abstract

The aims of this study are the development of methods to evaluate an equilibrium grain size distribution of sediment in a large river mouth and to apply it to a habitat assessment by the HSI model for a fiddler crab Uca arcuata which inhabits on a tidal flat. It was assumed that the sand particles which correspond to the critical shear stress under waves deposit and form a grain size distribution depending on the frequency of disturbance of waves in this model. The particle size distributions which estimated based on a wave statistical data well coincided with field survey data and approached wide areas of environment assessment.