Flooding Analysis

Function Overview

Flooding analysis is a common hydrological GIS application used to simulate and predict areas that may be affected by flooding events.

Usage

Click on Terrain > Hydrologic Analysis > Flooding Analysis.

Parameter Settings

• DEM File: Input DEM file. For generation methods, refer to DEM Generation.
• Regions of Interest: Input vector file (optional). If provided, analysis will only be performed on areas within this region.
• Building File: Input vector file containing extracted building vectors (optional). If provided, building damage assessment will be included in the analysis.
• Minimum Slope: Used in the DEM pit filling process. Larger values result in more extensive pit filling.
• Accumulation Method: Methods supported for flow accumulation process: D8, D-Infinity, and MFD.
• Flow Threshold: Used in stream network extraction. Only areas with values above this threshold can form streams.
• Initial Water Level: Water level height based on the base water level value. If both precipitation and drainage are 0, this value will be the final water level. If either precipitation or drainage is not 0, this value serves as the initial level for simulation-based determination of the final water level. Areas with raster values below the water level height are considered flooded.
• Datum Level:
  • RThe Hinimum Value of Raster Data: Uses the minimum elevation value of the current raster as the initial water level. If an area of interest is specified, uses the minimum raster value within that area.
  • Absolute Elevation: Uses a specified value as the initial water level.
• Precipitation: Specifies hourly precipitation in mm/h. Precipitation will cause water level changes in each watershed, ultimately affecting flooded areas.
• Precipitation Duration: Specifies duration of precipitation in hours.
• Water Drainage: Specifies hourly drainage volume. The simulation assumes drainage occurs simultaneously with precipitation (i.e., precipitation duration equals drainage duration).
• Resampling: Performs resampling based on the raster pyramid. Different pyramid levels and resolutions are determined by specific data, with each successive layer downsampled at a 2:1 ratio. If unchecked, original data will be used directly.
  • Resolution: Raster resolution. For rasters with fewer than 1000 rows/columns, lower resolutions won't be displayed. Higher resolutions yield more accurate results but may fail due to insufficient hardware resources.
  • Resampling Method: Raster resampling method.
• Output Path: The algorithm will ultimately output flood analysis results and related analysis reports.