RESCUE: A geomorphology-based, hydrologic-hydraulic model for large-scale inundation mapping

Flood mapping is a key stage for detecting vulnerable areas, assessing floods impacts, identifying damages, and mitigation plans. Despite of the available guidelines for flood mapping following EU Floods Directive, coherent and comprehensive official flood hazard maps at the national scale are still missing, at least in the EU. In fact, flood mapping generally requires high economical and computational costs for setup/calibration of hydrological/hydraulic models, leading to partial and fragmented vulnerable areas. Here, we propose RESCUE, a laRgE SCale inUndation modEl; the scope is providing a simple and inexpensive tool for flood mapping at the regional scale, overcoming the current fragmentation. RESCUE takes advantage from coupling geomorphological analysis and simplified hydrologic-hydraulic modeling, providing simple and reliable large scales inundation estimates. It is as parsimonious as purely DTM-based methods and physically based as any hydrodynamic model, yet computationally more efficient. The model allows for parametric uncertainty analysis for a probabilistic assessment of inundation areas. We demonstrate RESCUE potentialities and limitations using two illustrative examples: Paglia-Chiani River system, and Central Apennines District (Central Italy). Notwithstanding the inaccuracies of large scale DTMs and the missed representation of flood-structure interactions, results are promising, suggesting that RESCUE might be an effective tool for preliminary hazard assessment.