A methodological approach to flood dynamics based on satellite-derived spectral indices and altimetric forecast
Ubiratan Joaquim da Silva Junior1, Admilson da Penha Pacheco2, Antonio Miguel Ruiz-Armenteros3
1Department of Civil and Environmental Engineering, Federal University of Pernambuco, Recife, Brazil.
Abstract:
Urban flooding has intensified due to climate change, particularly in rapidly expanding metropolitan regions. This study presents an integrated remote sensing (RS) approach to monitor flood-prone areas in the Porto Alegre Metropolitan Region (Brazil). The methodology combines predictive topographic modeling using the HAND model with post-flood analysis based on water spectral indices. Flood susceptibility was assessed using HAND derived from SRTM data, while flood extent was estimated with NDWI and WNDWI applied to Landsat imagery and validated against HEC-RAS hydrodynamic simulations for the 2015 and 2024 events. HAND effectively identified low-lying, high-risk areas near watercourses but showed limitations in densely urbanized zones. WNDWI mapped up to 2423 km2 flooded in 2024 (22 % of the area), versus 1206 km2 by NDWI. Thematic accuracies for WNDWI reached 98-99 %, with Kappa values of 0.75 (2015) and 0.82 (2024), and AUC of 0.55 and 0.74, indicating strong agreement with HEC-RAS. WNDWI outperformed NDWI in detecting floodwaters in highly turbid and heterogeneous areas, though both indices were less sensitive in transition zones. This study's main contribution is the novel integration of modeling, spectral indices, and hydrodynamic validation, enhancing the reliability of RS-based flood mapping and supporting urban planning, risk management, and implementation of resilient strategies in climate-vulnerable metropolitan areas.
More Related Videos
10:28Investigating the Relationship between Sea Surface Chlorophyll and Major Features of the South China Sea with Satellite Information
Published on: June 13, 2020
07:13Early Detection of Cyanobacterial Blooms and Associated Cyanotoxins using Fast Detection Strategy
Published on: February 25, 2021
Related Concept Videos
Design Example: Analyzing Capacity Contours for Flood Risk Assessment
Precipitation Gravimetry
In determining nickel by gravimetric analysis, a precipitant of ethanolic dimethylglyoxime is added to a hot nickel salt solution. This is quickly followed by the dropwise addition of dilute ammonia solution until precipitation occurs. A...
Precipitation Processes
Applications of GIS: Disaster Management and Emergency Response
Responses to Drought and Flooding
Typical Model Studies
