2018 Volume 24 Pages 77-82
Numerical analysis of horizontal two dimensional flow was performed to examine the influence of topographic change on river storage and flow field in mid- and downstream reach of Kinugawa River. Two sets of topographic data in 1974 and 2011 were used. A time series of discharge estimated for flood disaster in September 2015 was imposed at the upstream end of each topography. It is shown that the reduction of peak discharge from the upstream end until Mitsukaidou with 2011’s topography is smaller by 250m3/s than that with 1974’s topography, 790m3/s. It is also indicated that storage rate per unit length is maximum at the upstream zone of the downstream reach with significant longitudinal change in river width, rather than midstream reach mentioned before. In addition, changes of two dimensional flow field with topographic transition at some points are discussed.
