Pyrothermel

Model fire rate of spread, intensity, and more for surface fires and crown fires using the extended Rothermel model. Pyrothermel provides a Python interface to the C++ code that underlies Behave, Flammap, and other software tools maintained by the Missoula Fire Lab*.

Please submit bugs and feature requests as Github issues. Note, there may be some API changes in early versions of this package.

*Pyrothermel and its authors are not associated with the Missoula Fire Lab or the US Government.

Dependencies

• Python >= 3.8
• A C++ compiler (conda install -c conda-forge compilers) The C++ compilers used for testing were Visual Studio 2022 and gcc for WSL.

Install

pip install pyrothermel

Quickstart

import pyrothermel
import pandas as pd
import seaborn as sns

Setup Base Fuel Model and Moisture Scenario

moisture = pyrothermel.MoistureScenario.from_existing(dead_fuel_moisture_class='low',live_fuel_moisture_class='moderate')
fuel = pyrothermel.FuelModel.from_existing(identifier='TL8')
canopy_base_height = 2.5 # default unit is m
canopy_bulk_density = .1 # default unit is kg/m^3

# Print some fuel loading values from fuel model TL8
print([fuel.fuel_load_one_hour, fuel.fuel_load_ten_hour, fuel.fuel_load_hundred_hour])
print(fuel.units.loading_units)

[1.300187341185569, 0.31383832373444764, 0.2465872543627803]
LoadingUnitsEnum.KilogramsPerSquareMeter

Run Rothermel Models Across Range of Wind Speeds

results_list = []
for wind_speed in range(0,60,2):
    run = pyrothermel.PyrothermelRun(fuel,moisture,wind_speed,wind_input_mode='ten_meter',canopy_base_height=canopy_base_height,canopy_bulk_density=canopy_bulk_density,canopy_cover=.5,canopy_height=20,canopy_ratio=.6)
    results_surface = run.run_surface_fire_in_direction_of_max_spread()
    results_final = run.run_crown_fire_scott_and_reinhardt()
    results_final['wind_speed'] = wind_speed
    results_final['treatment'] = 'untreated'
    results_list.append(results_final)
    
untreated_crowning_index = run.calculate_crowning_index()
untreated_torching_index = run.calculate_torching_index()
    
df = pd.DataFrame(results_list)
df

Modify Fuel Loading and Recalculate

fuel.fuel_load_one_hour *= .5
fuel.fuel_load_ten_hour *= .5
fuel.fuel_load_hundred_hour *= .75
fuel.fuel_bed_depth *= .5

results_list = []
for wind_speed in range(0,60,2):
    run = pyrothermel.PyrothermelRun(fuel,moisture,wind_speed,wind_input_mode='ten_meter',canopy_base_height=2.5,canopy_bulk_density=.1,canopy_cover=.5,canopy_height=20,canopy_ratio=.6)
    results_surface = run.run_surface_fire_in_direction_of_max_spread()
    results_final = run.run_crown_fire_scott_and_reinhardt()
    results_final['wind_speed'] = wind_speed
    results_final['treatment'] = 'treated'
    results_list.append(results_final)

treated_crowning_index = run.calculate_crowning_index()
treated_torching_index = run.calculate_torching_index()

df_treated = pd.DataFrame(results_list)
df = pd.concat([df,df_treated])

Display Results

sns.lineplot(df,x='wind_speed',y='flame_length',hue='treatment').set(xlabel='Wind Speed (km/hr)',ylabel='Flame Length (m)')

[Text(0.5, 0, 'Wind Speed (km/hr)'), Text(0, 0.5, 'Flame Length (m)')]

print('Wind Speed to initiate crown fire in untreated stand: ', untreated_torching_index, ' km/hr')
print('Wind Speed to initiate crown fire in treated stand: ', treated_torching_index, ' km/hr')
print('Wind Speed to propagate crown fire in untreated stand: ', untreated_crowning_index, ' km/hr')
print('Wind Speed to propagate crown fire in treated stand: ', treated_crowning_index, ' km/hr')

Wind Speed to initiate crown fire in untreated stand:  43  km/hr
Wind Speed to initiate crown fire in treated stand:  98  km/hr
Wind Speed to propagate crown fire in untreated stand:  60  km/hr
Wind Speed to propagate crown fire in treated stand:  60  km/hr