Efficiency evaluation of low impact development practices on urban flood risk

Area of Science:

• Environmental Science
• Urban Planning
• Geographic Information Systems (GIS)

Background:

• Urban flood risk assessment is crucial for effective flood management and risk mitigation in populated areas.
• Shiraz Municipal District 4 faces significant urban flood risks, necessitating detailed vulnerability and hazard mapping.
• Low-impact development (LID) practices are explored as a strategy to reduce urban flood risks.

Purpose of the Study:

• To create a flood risk map for Shiraz Municipal District 4.
• To evaluate the effectiveness of LID practices in mitigating urban flood risks.
• To identify key factors influencing urban flood hazard and vulnerability.

Main Methods:

• Utilized Multi-Criteria Decision Making (MCDM) models (TOPSIS, VIKOR) and data mining (RF) for flood vulnerability and hazard assessment.
• Employed GIS for spatial analysis of thematic layers including rainfall, land use, elevation, and hydrological factors.
• Simulated urban flooding using the Stormwater Management Model (SWMM) to assess LID effectiveness under various rainfall scenarios.

Main Results:

• The study identified 37.8% of the area as having high to very high flood risk.
• The Random Forest (RF) model demonstrated high accuracy in hazard mapping, with curve number, land use, and elevation being critical factors.
• LID practices showed effectiveness for rainfall events with return periods less than 10 years, achieving a 2-22.8% reduction in node flooding in a pilot area.

Conclusions:

• MCDM and data mining models, particularly RF-VIKOR and RF-TOPSIS, accurately identified high-risk flood zones.
• LID practices offer a viable solution for flood risk reduction, especially for frequent, lower-intensity rainfall events.
• Integrated approaches combining data-driven models and physical simulations are essential for robust urban flood risk management.