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Table of contents
- Introduction
- Development philosophy of PHOENIX
- The Fire Grid
- Inputs
- Fire Behaviour
- Fire Perimeter Propagation
- Asset Impact
- Outputs
1. Introduction
1.1 Purpose of this document
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In order to gain an overview of how the simulation process in PHOENIX works, an overview is offered below based on Figure 1. A more detailed explanation is offered in Appendix 3: The Simulation Process.
Figure 1.Simulation process used in PHOENIX RapidFire
To trigger a simulation the user specifies an ignition time and location. This is used to access the underlying input layers such as fuel, terrain and weather, in order to start the fire behaviour calculations.
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Table 1 offers a brief description of the purpose of each component. Later chapters describe these components in detailed.
Figure 2. Overview of the PHOENIX components including inputs, data representation, models and outputs. The numbers against each element refer to chapters or sections within this document.
Table 1. Purpose of each component of PHOENIX
Chapter / Section | Chapter Name | Component Name | Purpose |
|---|---|---|---|
3 | FIRE GRID | The Fire Grid is central to PHOENIX in that it is used to manage and represent data. It is used for inputs, to feed data to the models and to store outputs. | |
4 | INPUTS | Inputs are the underlying spatial or temporal data layers provided by the user that power PHOENIX. | |
4.1 | Fuel Types | Fuel type is a mandatory input layer required by PHOENIX to generate fine fuel levels for each fuel stratum. | |
4.2 | Wind Reduction Factors | Forecast wind data is provided at 10 m above ground. PHOENIX takes this data and converts it to wind speeds at 1.5 m above ground for use by various PHOENIX models. | |
4.3 | Fire History | Fuel types are used in conjunction with the fire history layer to generate fuel levels at the time of the simulation. | |
4.4 | Topography | A digital elevation model (DEM) is required by PHOENIX to support various models, such as slope correction, wind field models and map reprojection. | |
4.5 | Asset and Values | The user can provide data about asset types, value and vulnerability in order to support the Asset Impact PHOENIX model. | |
4.6 | Road Proximity | PHOENIX uses the road proximity layer to assess how much, if any, roads will assist in suppression efforts. | |
4.7 | Fuel Disruptions | The Fuel Disruption Layer defines the location and width of linear features such as roads, streams, firebreaks and railway lines that are generally devoid of fuel and may act as barriers to the progress of a fire. | |
4.8 | Weather | PHOENIX requires weather data to support various fire spread models. | |
4.9 | Suppression Resources | To provide the data necessary to run the PHOENIX suppression simulation model. | |
5 | FIRE BEHAVIOUR | The various models that drive underlying fire behaviour, including fire behaviour models, slope correction, convection, ember generation, fuel moisture and breaks in fuel. | |
5.1 | Behaviour Models | Fire behaviour models form the basis of simulations of fire spread and other fire characteristics within PHOENIX. | |
5.2 | Spotting / Embers | Simulates ember generation, lofting, transport and distribution. | |
5.3 | Slope Correction | Slope is derived by PHOENIX from the digital elevation model and is used to modify the outcomes of fire behaviour models. | |
5.4 | Wind Field Models | PHOENIX can incorporate a wind modification layer that represents the deviation in wind speed and direction caused by local topography, to modify the outcomes of fire behaviour models. | |
5.5 | Road / River / Break Impact | Linear fuel elements with no fuel such as roads and streams can be highly disruptive to fire spread, with their effect far exceeding the area they represent. PHOENIX implements a process that attempts to capture this effect. | |
5.6 | Solar Radiation Model | PHOENIX incorporates a solar radiation model to determine the amount of solar radiation at each cell of the Fire Grid. Solar radiation is required as an input into the fuel moisture and suppression models. | |
5.7 | Fuel Accumulation | Fuel levels are considered in a dynamic manner, using the time since the last fire to moderate total fuel levels for each stratum. These are then used in fire behaviour calculations. | |
5.8 | Fuel Moisture | Fine fuel moisture is an important component for fire behaviour calculations. PHOENIX incorporates a fine fuel moisture model. | |
5.9 | Convection / Heat Centres | The outputs of the convection model are used in conjunction with wind speed and direction to support simulation of ember lofting and distribution. | |
6 | FIRE PERIMETER PROPAGATION | Includes models that deal with the spread of the fire perimeter. This includes perimeter expansion, spot fire generation and how fire spread is ameliorated through suppression efforts. | |
6.1 | Point Spread Modelling | This model simulates the movement of the active fire perimeter. | |
6.2 | Self-Extinction | A self-extinction process is incorporated into PHOENIX, in which parts of the perimeter are predicted to extinguish if heat output is less than a threshold value. | |
6.3 | Reprojection on Map | During the perimeter modelling process, a surface-to-plan conversion of point spread is carried out to accurately capture the fire perimeter in three-dimensional space. | |
6.4 | Suppression Model | The suppression model modulates fire spread based on suppression resources provided by the user. | |
6.5 | Spot Fires | Starts new fires outside of the fire perimeter where burning embers land in suitably flammable fuels. | |
7 | ASSET IMPACT | PHOENIX provides for the intersection of fire attributes with maps of assets to allow estimates of fire damage. Characterising fires by asset impact provides an additional means of comparing fire management options. | |
8 | OUTPUTS | PHOENIX produces a wide range of outputs. Vector perimeter isochrones are a standard output, produced both as ESRI Shapefiles and Google Earth KMZ files. In addition, a wide range of gridded cell values about fire characteristics can be outputted in various formats. |
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