An Estimation Method of Gorge Section at a Small River Mouth

Field measurements have been carried out at the mouth of the Nanakita River, the catchment area being 229 km2, with the object of finding difference of topography change between small and large rivers. Time-variation of the water level inside the river showed remarkable reduction of the amplitude and significant phase shift behind the tidal variation. On assuming a triangular or parabolic section, the width and the maximum depth at the gorge section are determined to minimize the difference between computed and measured water level inside the river mouth.