Flood Susceptibility Analysis#

Terrain-based flood susceptibility analysis using TWI, log-transformed flow accumulation, inverse slope, inverse stream distance, and inverse TPI. Produces a Flood Susceptibility Index (FSI) scaled 0-100 with 5-level classification.

Inputs:

  • Terrain Analysis Package (ZIP). ZIP file from terrain_analysis containing DEM, slope, TWI, flow accumulation, TPI, streams, flow direction, and manifest.json

  • Weight: TWI. Weight for the Topographic Wetness Index indicator (default: 0.30)

  • Weight: Flow Accumulation. Weight for the log-transformed flow accumulation indicator (default: 0.25)

  • Weight: Slope (inverted). Weight for the inverted slope indicator — flat areas have higher flood risk (default: 0.20)

  • Weight: Stream Distance (inverted). Weight for the inverted stream distance indicator — closer to streams means higher risk (default: 0.15)

  • Weight: TPI (inverted). Weight for the inverted TPI indicator — depressions have higher flood risk (default: 0.10)

  • Hotspot Threshold. FSI value above which areas are classified as flood hotspots (default: 70)

  • Spectral Indices Package (ZIP). Optional ZIP from spectral_indices with vegetation index aggregates. When provided, a vegetation indicator is added to the weighted overlay.

  • Weight: Vegetation Index. Weight for the vegetation index indicator (default: 0.10). Only used when spectral_zip is provided. Other weights are scaled down proportionally.

Outputs:

  • Flood Analysis Package (ZIP). ZIP archive with flood susceptibility rasters, vectors, statistics, and manifest

  • Summary. Human-readable summary of the flood analysis results

  • Manifest JSON. JSON manifest string describing all outputs

Launch the tool: https://toolbox.nextgis.com/t/flood_analysis

Example:

../../_images/analysis_input_en.png

Fig. 139. Example input#

../../_images/flood_analysis_result_en.png

Fig. 140. Example output#

Try the tool in action

  1. Click on the Demo button above the tool form. The fields are filled in with demo values.

  2. Click on the Run button.

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