How to create an evacuation routes overlay

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Combine Water Overlay height results with the Travel Distance Overlay to model valid evacuation routes during floods.

How to create an Overlay for calculated evacuation routes:
  1. Add a Water Overlay.
  2. Set the amount of rainfall of the Water Overlay to a total of 60mm in 60 minutes, followed by 0 minutes of dry period.
  3. Add a Combo Overlay, with the Water Overlay set to input A, and a formula of "GT(AT, 0.2)". This computes all places where a route would be blocked (1) or not (0), by having more than 20cm of water stress, for each timeframe.
  4. Add an Area, and draw it anywhere in the project map and with an Attribute named DESTINATION_AREA set to 1. This location will be the evacuation point.
  5. Add a Travel Distance Overlay.
  6. Under "Keys", opt to use a "blocking input", and select the Combo Overlay created earlier. This will disqualify certain routes from being traversed.
  7. Recalculate, and play the Travel Distance Overlay
  8. As the simulation progresses, green evacuation routes will turn red to indicate excessive water stress.

Notes

  • Expand this setup with another Combo Overlay to highlight locations that lose their valid evacuation routes over time.

See also

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