# Dry Eucalypt Forest (Vesta)

The Dry Eucalypt Forest (Vesta) rate of spread model was developed by CSIRO for predicting fire spread rates in Eucalyptus Forest. Vesta was published in 2012 in the book Project Vesta, which can be found here.

### Vegetation

Dry Eucalypt Forest

### Fuel inputs

• temp
• rel_hum
• FHSs/FHSns
• Hns
• Temperature (degrees C)
• Relative humidity (%)
• Surface/Near-surface fuel hazard score
• Near-surface fuel height (cm)

### Code

```// Dry Eucalypt model - Project Vesta

// -------------------------------------------
// Model parameters
// These must be defined below, or included as a user-defined layer
//
// 1. Temperature, 'temp' (input)
// 2. Relative humidity, 'rel_hum' (input)
// 3. Surface fuel hazard score, 'FHSs'
// 4. Near-surface fuel hazard score, 'FHSns'
// 5. Near surface height, 'Hns'
// -------------------------------------------

// Backing and flanking coefficients compared to head fire ROS
REAL wind_speed = length(wind_vector);

REAL LBR = 1.0;
if (wind_speed < 5){
LBR = 1.0;
} else if (wind_speed < 25){
LBR = 0.9286 * exp(0.0505 * wind_speed);
} else {
LBR = 0.1143 * wind_speed + 0.4143;
}

// Determine coefficient for flank rank of spread, Rf = cf * Rh, using Andrew's LBR equations
REAL cc = sqrt(1.0-pow(LBR, -2.0));
REAL cb = (1.0-cc)/(1.0+cc);
REAL a_LBR = 0.5*(cb+1.0);
REAL cf = a_LBR/LBR;

// Determine shape parameters
REAL f = 0.5*(1.0+cb);
REAL g = 0.5*(1.0-cb);
REAL h = cf;

// Now calculate a speed coefficient using normal flow formula
REAL speed_fraction = (g*wdot+sqrt(h*h+(f*f-h*h)*wdot*wdot));

// Estimating fuel moisture content using Gould et al. (2007) and Matthews et al. (2010)
// Initialising the fuel moisture variable
REAL Mf;
// Calculating fuel moisture between 12:00 and 16:59 (valid for sunny days from October to March)
if (hour > 11 && hour < 17){
Mf = 2.76 + (0.124*rel_hum) - (0.0187*temp);}

// Calculating fuel moisture for other daylight hours (from 9:00 to 11:59 and 17:00 to 19:59 in this example)
else if ((hour < 12 && hour > 8) || (hour > 16 & hour < 20)){
Mf = 3.6 + (0.169*rel_hum) - (0.045*temp);}

// Calculating fuel moisture for night time hours (from 20:00 to 8:59) in this example
else{
Mf = 3.08 + (0.198*rel_hum) - (0.0483*temp);}

// Calculate moisture coefficients from Burrows (1999)
REAL moisture_coeff = 18.35 * pow(Mf,-1.495);

// Calculate spread rate (in m/s)

if ( wind_speed > 5 )
head_speed = (30.0 + 1.5308 * pow(wind_speed-5,0.8576) *
pow(FHSs,0.9301) * pow(FHSns*Hns,0.6366) * 1.03 ) *
moisture_coeff/3600;
else