Author(s): Keisuke Yoshida; Tadaharu Ishikawa
Linked Author(s): Keisuke Yoshida
Keywords: Data assimilation; Discharge estimation; Adjoint shallow-water model; Compound open-channel
Abstract: This study describes an estimation of a flood discharge hydrograph in compound open-channels with floodplains by using a data assimilation method. The hydrograph is iteratively identified using an adjoint shallow-water model with data of time-series of observed water levels. The data assimilation was applied to the flood event in a 20km-long lower reach of the Tone River, which occurred in mid-September, 1998. Not only the estimated hydrograph but also the flow field simulated by using the hydrograph were verified by comparing them with the results of the aerial photo analysis. The solution showed that the observed hydrograph was overestimated and it was revised reasonably by the present data assimilation, and that the hysteresis-loop characteristic, which is typically observed in the compound open-channel flows, was obtained in the stage-discharges relationship during the flood event.