Flood Inundation Assessment in the Low-Lying River Basin Considering Extreme Rainfall Impacts and Topographic Vulnerability

This study aims to evaluate the change in flood inundation Chitose River basin (CRB), a tributary of Ishikari River, considering extreme rainfall impacts and topographic vulnerability. The changing were assessed using large-ensemble dataset with high resolution 5 km (d4PDF) as input data for rainfall–runoff–inundation (RRI) model. Additionally, prediction time differences between peak discharge water levels at confluence point intersecting improved compared previous study. Results indicate that due climatic changes, river floods are expected increase by 21–24% (IRB), while is be severe higher CRB, increases 24.5, 46.5, 13.8% area, volume, depth, respectively. Flood likely occur CRB downstream area frequency 90–100%. duration 5–10 h here. Moreover, short difference (0–10 h) predicted significantly CRB. provides useful information policymakers mitigate damage vulnerable areas.