Abstract
Understanding of the propagation mechanisms of the discharge and water level hydrographs in river channels is important for proper river management. It has been known that discharge hydrographs of flood flows passing through channel contractions are distorted by longitudinal difference of the storage volume of water in the channel. In this case, propagation mechanisms of the discharge and water level hydrographs are different, unlike in the case of the flood flow through a uniform channel. This paper characterize a part of the storage volume of water that causes the distortion of a discharge hydrograph as retarding storage volume of water and its evaluation method is proposed. We apply this method to a large flood through the valley of the Kitakami River and propagation mechanisms of the discharge and water level hydrographs are explained with relation to the storage volume and retarding storage volume of flood water.
