Improving rapid flood impact assessment: An enhanced multi-sensor approach including a new flood mapping method based...

Area of Science:

• Remote Sensing and Geospatial Analysis
• Disaster Risk Management
• Environmental Monitoring

Background:

• Accurate flood maps are crucial for effective disaster risk management, including emergency response and recovery planning.
• Existing rapid flood impact assessment methods require complete and precise flood mapping for reliable information.
• There is a need for improved methodologies to enhance the characterization of flood hazards.

Purpose of the Study:

• To develop and present a novel, enhanced satellite multi-sensor approach for rapid flood mapping.
• To improve the accuracy and completeness of flood maps for better disaster risk management.
• To assess flood impacts on buildings, roads, and cropland using multi-source satellite data.

Main Methods:

• Utilized a novel multi-temporal Modified Normalized Difference Water Index (MNDWI) derived from Sentinel-2 time-series data.
• Employed a thresholding technique on multi-temporal statistics to delineate temporary flooded areas for precise flood mapping.
• Integrated Sentinel-1, Sentinel-2, and PlanetScope satellite imagery within a cloud-based environment (Google Earth Engine) for rapid processing.

Main Results:

• The multi-sensor approach provided a more comprehensive flood impact assessment, estimating 57.4 million USD in damages for the 2020 South Sudan flood.
• This multi-sensor estimation was significantly higher than assessments using only Sentinel-1 (24%) or Sentinel-2 (78%) data.
• The methodology proved computationally light and robust, enabling rapid flood map derivation for large areas.

Conclusions:

• Multi-source satellite data integration is highly effective for improving flood mapping accuracy and completeness.
• The enhanced method provides superior flood impact assessment compared to single-sensor approaches.
• This approach significantly enhances disaster risk management by informing better response, recovery, and reconstruction plans.