斐伊川における洪水観測について一水面流況と河床形状の同時計測一

Abstract

The three-dimensional river-bed configurations were measured by a echo sounder, and, almost at the same time, time series of photographs were taken of the patterns on the flow surface during a flood stage in the Hii River.Photograph data were analyzed by picture processing technique to obtain velocity vectors.The streamlines, vorticity and divergence calculated from the obtained velocity vectors were examined to clarify the boil structure.The time variation of wave height and wave length of dunes and small scale bars during the decreasing stage of flood flow are examined.In the Sept. 5-6 flood, the height of small scale bars increases while one of dunes decreases during the stage.