EVALUATION OF HYDROGRAPH OF FLOOD DISCHARGE AND ROUGHNESS COEFFICIENT AT THE BRANCHED SECTION IN THE TONE RIVER AND THE EDO RIVER

It is very important to estimate the roughness coefficient distribution and evaluate the hydrograph of flood discharge in a river. Authors have developed a new method that evaluates accurately them in recent studies. However, we must clarify where observation points are proper to obtain the roughness coefficient distribution in a river. This study aims to estimate the discharge hydrograph accurately by the two- dimensional unsteady flow analysis, and examine propriety of observation points and the difference of roughness coefficient distribution in two floods at the branched section in the Tone river and the Edo river. It is shown that we can obtain the accurate discharge hydrograph in the branched section by this method, and the distribution of averaged roughness coefficient is decided based on observed water surface profile at the points that roughness characteristics are appeared.