BASIN-SCALE FLOOD DISTURBANCE ASSESSMENT BY HYDROLOGICAL MODEL

Abstract

 This study aims to develop a method to evaluate flood disturbances acting on each river segment in a river system from basin-scale. A flood disturbance evaluation index based on dimensionless scavenging forces for representative grain sizes is proposed. The rainfall-runoff-inundation model (RRI model) was extended to calculate this index for the entire river basin. The method was applied to the evaluation of flood disturbance during the 2020 runoff period in the Nagara River basin of the Kiso River system, and compared with the evaluation method using specific discharge as an indicator reported in previous studies. The proposed indices are capable of discussing the substantial disturbance occurring in the river channel from sediment hydraulics perspective. Although the usefulness of the indices was recognized, many issues were identified that need to be resolved regarding the calculation method.