Climate-Driven Flood Risks and Damages: A Case Study of the Kashkan River Floodplain

Flood losses in semi-arid Iran are rising and are widely expected to accelerate under climate change, yet quantitative projections for many interior basins remain sparse. Here we combine statistically-downscaled CMIP6 projections, a hybrid HEC-HMS–LSTM rainfall–run-off model, one-dimensional HEC-RAS hydraulics and the Damage Scanner module to appraise potential future fluvial-flood damage and risk in the Kashkan River basin, a region that is highly prone to flooding. In this study, we analyzed impacts of climate change on changes in rainfall, flood severity and frequency and inundation extent and depth, as well as flood damages in Kashkan River basin. The study utilized CMIP6 climate models under two climate scenarios, SSP1-2.6 and SSP5-8.5, which covers the near (2030–2060) and far future (2060–2090) periods.The findings reveal that both scenarios project a notable increase in the frequency, intensity, and extent of flooding, particularly under the SSP5-8.5 scenario. SSP5-8.5 scenario indicates a more accelerated and severe impact, mostly in the far future. The projected flood hazards are expected to cause substantial economic losses, with the expected annual damage (EAD) estimated to escalate dramatically by 2090. expected annual damage (EAD) grows from a 2015 baseline of US $1 m to US $7.5 m (SSP1-2.6) and US $18 m (SSP5-8.5) by 2090. Losses concentrate along the densely settled east bank of Pole-Dokhtar. The findings of the study can provide a basis for planners and policymakers to make decisions to adapt to the changing climate, and floods. Results show without decisive action; fluvial flooding could erase decades of socio-economic gains in Lorestan Province. Integrating the present maps into local development plans, prioritizing river-side hot-spots for investment, is pragmatic steps towards safeguarding Pole-Dokhtar against a climate-intensified flood future.