Tom Cova and Phil Dennison, Department of Geography, University of Utah
Setting Wildfire Evacuation Trigger Points
A wildfire has ignited in proximity to a dense canyon community. The fire does not currently threaten the community, but incident commanders (ICs) have concern about whether the community may need to be evacuated should the wind speed increase over the next 24 hours, as expected. Based on a forward-looking scenario for the next 24 hours, they would like to set nested trigger points on the landscape that would initiate protective actions as the fire approaches the community. The first trigger point reached by the fire would result in an evacuation stand-by order, and the second trigger would result in an evacuation order. ICs will be using the Ready-Set-Go strategy where “ready” means there’s a fire in your area, “set” means to prepare to evacuate (i.e. stand-by) and “Go” means to evacuate.
Decision makers (not co-located), fire scouts at the on-site incident command center, community residents, CyberGIS decision support analyst.
Each of the decision makers has access to a shared map-based representation of the fire and area at risk. They need to collaborate to determine about how much time they think the community will need to prepare and subsequently evacuate in addition to how much time they might have available before the fire impacts the community given the short-term weather predictions.
Real world -- fire near an at-risk community, decision makers that are not together, scouts on the ground.
CyberGIS -- A fire-spread model and an evacuation trigger generator with grid computing power and a geo-collaborative interface for remote decision support.
1. The decision makers review the situation through the map-based interface and provide a standby-time (e.g. 3 hours or warning) for the community and a minimum time (e.g. 2 hours of warning) for evacuating the community.
2. The CyberGIS analyst takes the current reported fire location, predicted weather for the next day, and expert estimates of evacuation times and computes a dynamic (short term) estimate of the trigger points for both standby and evacuation warnings.
3. The decision makers review the resulting trigger points and decide whether they are appropriate given the conditions of the community and fire.
4. The decision makers decide to set (or not set) the trigger points as computed, but if they are set then scouts on the ground will report when the triggers have been activated to the incident command center.
The decision makers selected the trigger points and they were tripped or not tripped.
The decision makers did not set trigger points based on the CyberGIS analysis.
The decision makers ask for different weather predictions to be input into the system to test the sensitivity of the trigger points to changes in weather inputs as well as changes in the evacuation time estimates.
The results of the sensitivity analysis might be to: 1) not use the CyberGIS approach because of its heightened sensitivity in this scenario, or 2) to decide that the computed trigger points are sufficiently sound.