Flood characterization based on forensic analysis of bridge collapse using UAV reconnaissance and CFD simulations

Area of Science:

• Hydrology and Water Resources
• Civil Engineering
• Natural Hazards

Background:

• Flash floods are frequent extreme weather events causing significant fatalities and economic losses.
• Climate change is increasing the severity of flash floods.
• Lack of flow intensity data hinders flash flood documentation and risk assessment.

Purpose of the Study:

• To estimate the undocumented magnitude of an extreme flash flood event.
• To reproduce flood-induced bridge abutment failure using numerical modeling.
• To provide valuable input for flood risk re-assessment in Central Greece.

Main Methods:

• Field investigation including UAV-based 3D mapping and on-site material testing.
• Numerical study combining 3D flow-structure interaction and nonlinear structural response modeling.
• Back-analysis of a bridge abutment failure to estimate flow velocity.

Main Results:

• A lower bound value for flow velocity at the studied location was estimated.
• The numerical model successfully reproduced the flood-induced fracture of a bridge abutment.
• The study provides a methodology for a posteriori estimation of flood intensity.

Conclusions:

• The developed approach using disaster forensics and engineering analysis can fill data gaps for extreme events.
• The findings are valuable for understanding downstream damage and re-assessing flood risk.
• This case study can validate future numerical/experimental methods for flow-soil-structure interaction.