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

	spread_rate	flame_length	fireline_intensity	scorch_height	transition_ratio	active_ratio	fire_type	wind_speed	treatment
0	0.035297	0.850504	182.940784	5.005403	0.274758	0.025974	Surface	0	untreated
1	0.036477	0.863471	189.058483	5.150455	0.283946	0.033603	Surface	2	untreated
2	0.038485	0.885015	199.463628	5.391881	0.299574	0.046541	Surface	4	untreated
3	0.040997	0.911142	212.486479	5.685303	0.319133	0.062713	Surface	6	untreated
4	0.043907	0.940336	227.566123	6.013981	0.341781	0.081423	Surface	8	untreated
5	0.047152	0.971693	244.386618	6.367902	0.367044	0.102279	Surface	10	untreated
6	0.050693	1.004603	262.738585	6.740268	0.394606	0.125023	Surface	12	untreated
7	0.054500	1.038631	282.470446	7.126172	0.424242	0.149466	Surface	14	untreated
8	0.058551	1.073456	303.466091	7.521935	0.455775	0.175465	Surface	16	untreated
9	0.062828	1.108839	325.633015	7.924731	0.489067	0.202906	Surface	18	untreated
10	0.067316	1.144599	348.895334	8.332347	0.524005	0.231694	Surface	20	untreated
11	0.072003	1.180595	373.189391	8.743023	0.560492	0.261751	Surface	22	untreated
12	0.076879	1.216721	398.460819	9.155342	0.598447	0.293011	Surface	24	untreated
13	0.081935	1.252892	424.662512	9.568151	0.637799	0.325414	Surface	26	untreated
14	0.087161	1.289045	451.753155	9.980508	0.678487	0.358909	Surface	28	untreated
15	0.092553	1.325129	479.696141	10.391632	0.720454	0.393453	Surface	30	untreated
16	0.098102	1.361104	508.458756	10.800878	0.763653	0.429003	Surface	32	untreated
17	0.103804	1.396940	538.011536	11.207708	0.808038	0.465524	Surface	34	untreated
18	0.109653	1.432613	568.327776	11.611672	0.853570	0.502983	Surface	36	untreated
19	0.115645	1.468107	599.383126	12.012394	0.900212	0.541350	Surface	38	untreated
20	0.121775	1.503406	631.155270	12.409561	0.947930	0.580597	Surface	40	untreated
21	0.128040	1.538500	663.623663	12.802911	0.996695	0.620699	Surface	42	untreated
22	0.241603	3.448728	1474.064719	13.192226	1.046476	0.661632	Torching	44	untreated
23	0.379762	5.160256	2697.956066	13.577327	1.097248	0.703375	Torching	46	untreated
24	0.536191	7.103385	4357.386068	13.958064	1.148986	0.745907	Torching	48	untreated
25	0.711691	9.296938	6524.360652	14.334319	1.201667	0.789210	Torching	50	untreated
26	0.907056	11.754955	9275.974007	14.705996	1.255270	0.833266	Torching	52	untreated
27	1.123074	14.489637	12694.462206	15.073021	1.309773	0.878058	Torching	54	untreated
28	1.360525	17.512343	16867.255868	15.435336	1.365159	0.923571	Torching	56	untreated
29	1.620185	20.833995	21887.031854	15.792902	1.421409	0.969790	Torching	58	untreated

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