Methodology for qualitative urban flooding risk assessment

Area of Science:

• Environmental Science
• Urban Hydrology
• Risk Assessment

Background:

• Pluvial flooding in urbanized areas causes significant damage and disruption.
• Accurate identification of flood consequences and risk assessment is essential.
• Recent advancements in urban flood modeling offer new assessment possibilities.

Purpose of the Study:

• To present and investigate the applicability of a qualitative flood risk assessment methodology in urban settings.
• To demonstrate the integration of dual-drainage modeling concepts for enhanced flood risk analysis.

Main Methods:

• Utilized a qualitative flood risk assessment methodology incorporating dual-drainage modeling.
• Employed one-dimensional automatic overland flow network delineation (AOFD) and 1D/1D models.
• Assessed flood consequences using hydraulic model outputs (water depth, velocity) and likelihood based on historical rainfall return periods.

Main Results:

• The methodology effectively identified the most affected areas during rainfall events.
• Flood risk assessment considered impacts on public transportation, properties, and pedestrian safety.
• The study used rainfall events with 350 and 2-year return periods in Alcântara, Lisbon.

Conclusions:

• The presented flood risk assessment methodology is easy to implement in urban areas.
• The approach is effective for assessing urban flooding risks, even with data acquisition challenges.
• Dual-drainage modeling enhances the accuracy of consequence estimation in flood risk assessments.