EXAMINATION OF VEGETATION MANAGEMENT AROUND A FIXED WEIR AT THE BIFURCATION POINT OF THE HYAKKEN RIVER TO CONTROL A PROPER DIVERSION DISCHARGE

Abstract

 Improvement works of The Hyakken River, a diversion channel of the Asahi River flowing north to south through Okayama city, have been carried under the river improvement planning. Construction of the fixed overflow weir have been conducted at the bifurcation point and will be completed in 2019. However, because the Asahi River is a rather vegetated river, diversion discharge may exceed designed amount under attack of the designed scale flood due to over growth of vegetation. In this study, vegetation management methods to control a proper diversion discharge considering three separating management zone were examined using two dimensional flow analysis with the effect of vegetation. As a results, standard vegetation heights to be controlled in the each management zone were proposed.