Behavior of experimental grass fires vs. predictions based on Rothermel's fire model

1977 ◽  
Vol 7 (2) ◽  
pp. 357-367 ◽  
Author(s):  
Richard J. Sneeuwjagt ◽  
William H. Frandsen
Keyword(s):  
Combustion Zone ◽  
Fire Behavior ◽  
Fire Spread ◽  
Flame Length ◽  
Fuel Load ◽  
Physical Parameters ◽  
Rate Of Spread ◽  
Least Squares Fit ◽  
Zone Depth ◽  
Positive Agreement

Fire behavior observations with rates of spread up to 20 m/min (66 ft/min) have been recorded on 40 prescribed grass fires in central Washington and northern California. Physical parameters were also recorded describing the grass fuel array (fuel load, moisture content (≤ 15%), etc.), along with the wind speed (up to 8 km/h) and slope (near zero). These data were sufficient to allow a prediction of the fire spread rate, combustion zone depth, and flame length using the Rothermel fire spread model.A least squares fit of the observed versus the predicted results shows that positive agreement (slope = 1, intercept = 0) is supported for rate of spread. Flame length shows positive agreement for the intercept but not for slope. Combustion zone depth does not show positive agreement for either intercept or slope. The authors attribute the lack of positive agreement to less accurate measurements (ocular estimates) of the flame length and combustion zone depth.

Examining fire behavior in mesquite - acacia shrublands

2005 ◽  
Vol 14 (2) ◽  
pp. 131 ◽  
Author(s):  
Tamara J. Streeks ◽  
M. Keith Owens ◽  
Steve G. Whisenant
Keyword(s):  
Flame Temperature ◽  
Fire Behavior ◽  
Fire Spread ◽  
Flame Length ◽  
South Texas ◽  
Fire Intensity ◽  
Rate Of Spread ◽  
Vegetation Shift ◽  
Naturally Occurring ◽  
Behavior Systems

The vegetation of South Texas has changed from mesquite savanna to mixed mesquite–acacia (Prosopis–Acacia) shrubland over the last 150 years. Fire reduction, due to lack of fine fuel and suppression of naturally occurring fires, is cited as one of the primary causes for this vegetation shift. Fire behavior, primarily rate of spread and fire intensity, is poorly understood in these communities, so fire prescriptions have not been developed. We evaluated two current fire behavior systems (BEHAVE and the CSIRO fire spread and fire danger calculator) and three models developed for shrublands to determine how well they predicted rate of spread and flame length during three summer fires within mesquite–acacia shrublands. We also used geostatistical analyses to examine the spatial pattern of net heat, flame temperature and fuel characteristics. The CSIRO forest model under-predicted the rate of fire spread by an average of 5.43 m min−1 and over-predicted flame lengths by 0.2 m while the BEHAVE brush model under-predicted rate of spread by an average of 6.57 m min−1 and flame lengths by an average of 0.33 m. The three shrubland models did not consistently predict the rate of spread in these plant communities. Net heat and flame temperature were related to the amount of 10-h fuel on the site, but were not related to the cover of grasses, forbs, shrubs, or apparent continuity of fine fuel. Fuel loads were typical of South Texas shrublands, in that they were uneven and spatially inconsistent, which resulted in an unpredictable fire pattern.

scholarly journals COMPORTAMENTO DO FOGO, EM CONDIÇÕES DE LABORATÓRIO, EM COMBUSTÍVEIS PROVENIENTES DE UM POVOAMENTO DE Pinus elliottii L.

FLORESTA ◽  
2004 ◽  
Vol 34 (2) ◽  
Author(s):  
Luciana Valle De Loro ◽  
Nelson Akira Hiramatsu
Keyword(s):  
Laboratory Test ◽  
Fire Behavior ◽  
Pinus Elliottii ◽  
Fire Spread ◽  
Flame Length ◽  
Flame Height ◽  
Fire Intensity ◽  
Forest Fuels ◽  
Rate Of Spread ◽  
Fire Laboratory

De um povoamento de Pinus elliottii localizado na Fazenda Canguiri-UFPR, foram coletadas seis amostras de material combustível superficial. Este material foi separado em classes, pesado e levado para o laboratório. Efetuou-se a queima da classe acículas num leito de areia no laboratorio, em seis queimas, sendo cada queima com acículas proveniente de cada uma das amostras coletadas. Foram medidas a altura, o comprimento e a velocidade de propagação do fogo. Aplicou-se para cada queima cerca de 746 g de acículas, equivalente a 0,678 Kg/m2, com uma espessura média de 3 cm. Foram obtidos como dados médios: velocidade de propagação de 0,00423 m/s, comprimento da chama de 35,22 cm e altura de 38,79 cm, resultando numa intensidade do fogo igual a 57,07 kW/m. O resíduo médio ficou na ordem de 40,3 %. FIRE BEHAVIOR, IN LABORATORY CONDITIONS, OF FOREST FUELS FROM A Pinus elliottii L. STAND Abstract Pinus elliottii needles from a stand located at Fazenda Canguiri-UFPR were collected to run a laboratory test on fire behavior. The fuel from six samples was separated in classes, weight, and taken to the Federal University of Paraná Forest Fire Laboratory. The pine needles were burned in a sand bed. About 746.0g of each one of the six samples, equivalent to 0.678kg.m-2 and 3cm depth, were used in each fire run. Flame height and length, and rate of spread were measured. The average values obtained were: fire spread, 0,00423 m.s-1, flame length, 35,22cm, and flame height, 38,79cm. Fire intensity was of 57,07 kW.m-1 and residual fuel content about 40,3%.

scholarly journals Meteorological Conditions Conducive to the Rapid Spread of the Deadly Wildfire in Eastern Attica, Greece

2019 ◽  
Vol 100 (11) ◽  
pp. 2137-2145 ◽  
Author(s):  
K. Lagouvardos ◽  
V. Kotroni ◽  
T. M. Giannaros ◽  
S. Dafis
Keyword(s):  
Fire Behavior ◽  
Fire Spread ◽  
High Rate ◽  
Contributing Factors ◽  
Suburban Areas ◽  
Rate Of Spread ◽  
Rapid Spread ◽  
Westerly Flow ◽  
Downslope Flow ◽  
Extreme Fire

AbstractOn 23 July 2018, Attica, Greece, was impacted by a major wildfire that took place in a wildland–urban interface area and exhibited extreme fire behavior, characterized by a very high rate of spread. One-hundred civilian fatalities were registered, establishing this wildfire as the second-deadliest weather-related natural disaster in Greece, following the heat wave of July 1987. On the day of the deadly wildfire, a very strong westerly flow was blowing for more than 10 h over Attica. Wind gusts up to 30–34 m s−1 occurred over the mountainous areas of Attica, with 20–25 m s−1 in the city of Athens and surrounding suburban areas. This strong westerly flow interacted with the local topography and acted as downslope flow over the eastern part of Attica, with temperatures rising up to 39°C and relative humidity dropping to 19% prior to the onset of the wildfire. These weather elements are widely acknowledged as the major contributing factors to extreme fire behavior. WRF-SFIRE correctly predicted the spatiotemporal distribution of the fire spread and demonstrated its utility for fire spread warning purposes.

Got to burn to learn: the effect of fuel load on grassland fire behaviour and its management implications

2018 ◽  
Vol 27 (11) ◽  
pp. 727 ◽  
Author(s):  
Miguel G. Cruz ◽  
Andrew L. Sullivan ◽  
James S. Gould ◽  
Richard J. Hurley ◽  
Matt P. Plucinski
Keyword(s):  
Fire Spread ◽  
Flame Height ◽  
Fuel Load ◽  
Limiting Factor ◽  
Fire Behaviour ◽  
Load Effect ◽  
Fire Propagation ◽  
Rate Of Spread ◽  
Eastern Australia ◽  
Modelling Assumptions

The effect of grass fuel load on fire behaviour and fire danger has been a contentious issue for some time in Australia. Existing operational models have placed different emphases on the effect of fuel load on model outputs, which has created uncertainty in the operational assessment of fire potential and has led to end-user and public distrust of model outcomes. A field-based experimental burning program was conducted to quantify the effect of fuel load on headfire rate of spread and other fire behaviour characteristics in grasslands. A total of 58 experimental fires conducted at six sites across eastern Australia were analysed. We found an inverse relationship between fuel load and the rate of spread in grasslands, which is contrary to current, untested, modelling assumptions. This result is valid for grasslands where fuel load is not a limiting factor for fire propagation. We discuss the reasons for this effect and model it to produce a fuel load effect function that can be applied to operational grassfire spread models used in Australia. We also analyse the effect of fuel load on flame characteristics and develop a model for flame height as a function of rate of fire spread and fuel load.

scholarly journals Georeferencing Oblique Aerial Wildfire Photographs: An Untapped Source of Fire Behaviour Data

Fire ◽  
2021 ◽  
Vol 4 (4) ◽  
pp. 81
Author(s):  
Henry Hart ◽  
Daniel D. B. Perrakis ◽  
Stephen W. Taylor ◽  
Christopher Bone ◽  
Claudio Bozzini
Keyword(s):  
Fire Behavior ◽  
Fire Spread ◽  
Behavior Prediction ◽  
Empirical Relationships ◽  
Rate Of Spread ◽  
Front Position ◽  
Fire Front ◽  
Initial Work ◽  
The Mean ◽  
Behaviour Data

In this study, we investigate a novel application of the photogrammetric monoplotting technique for assessing wildfires. We demonstrate the use of the software program WSL Monoplotting Tool (MPT) to georeference operational oblique aerial wildfire photographs taken during airtanker response in the early stages of fire growth. We located the position of the fire front in georeferenced pairs of photos from five fires taken 31–118 min apart, and calculated the head fire spread distance and head fire rate of spread (HROS). Our example photos were taken 0.7 to 4.7 km from fire fronts, with camera angles of incidence from −19 to −50° to image centre. Using high quality images with detailed landscape features, it is possible to identify fire front positions with high precision; in our example data, the mean 3D error was 0.533 m and the maximum 3D error for individual fire runs was less than 3 m. This resulted in a maximum HROS error due to monoplotting of only ~0.5%. We then compared HROS estimates with predictions from the Canadian Fire Behavior Prediction System, with differences mainly attributed to model error or uncertainty in weather and fuel inputs. This method can be used to obtain observations to validate fire spread models or create new empirical relationships where databases of such wildfire photos exist. Our initial work suggests that monophotogrammetry can provide reproducible estimates of fire front position, spread distance and rate of spread with high accuracy, and could potentially be used to characterize other fire features such as flame and smoke plume dimensions and spotting.

Slope and Fuel Load Effects on Fire Behavior: Laboratory Experiments in Pine Needles Fuel Beds

1995 ◽  
Vol 5 (3) ◽  
pp. 153 ◽  
Author(s):  
JL Dupuy
Keyword(s):  
Laboratory Experiments ◽  
Pinus Halepensis ◽  
Fire Behavior ◽  
Fuel Load ◽  
Fire Behaviour ◽  
Rate Of Spread ◽  
Load Effects ◽  
Heat Transfers ◽  
Different Levels ◽  
Fire Experiments

Laboratory fire experiments were conducted in both Pinus pinaster and Pinus halepensis litters in order to investigate the effect of slope on fire behaviour for different levels of fuel load. Simulated slopes ranged between -30 degrees and +30 degrees. The results are reported in terms of rate of spread and rate of mass loss when observed fire was quasi-steady. Upslope fires were observed, on the present devices, to be unsteady, and their flame to be three-dimensionnal, when slope and fuel load exceeded certain limits. The heat transfers involved in the explanation of the observed behaviours are discussed, especially on the base of the quite different results obtained in the two tested fuel. beds.

Fire spread in chaparral – a comparison of laboratory data and model predictions in burning live fuels

2016 ◽  
Vol 25 (9) ◽  
pp. 980 ◽  
Author(s):  
David R. Weise ◽  
Eunmo Koo ◽  
Xiangyang Zhou ◽  
Shankar Mahalingam ◽  
Frédéric Morandini ◽  
...  
Keyword(s):  
Laboratory Data ◽  
Slope Angle ◽  
Fire Spread ◽  
Flame Length ◽  
Important Variable ◽  
Rate Of Spread ◽  
Model Predictions ◽  
Physically Based ◽  
Live Fuels ◽  
Physically Based Models

Fire behaviour data from 240 laboratory fires in high-density live chaparral fuel beds were compared with model predictions. Logistic regression was used to develop a model to predict fire spread success in the fuel beds and linear regression was used to predict rate of spread. Predictions from the Rothermel equation and three proposed changes as well as two physically based models were compared with observed spread rates of spread. Flame length–fireline intensity relationships were compared with flame length data. Wind was the most important variable related to spread success. Air temperature, live fuel moisture content, slope angle and fuel bed bulk density were significantly related to spread rate. A flame length–fireline intensity model for Galician shrub fuels was similar to the chaparral data. The Rothermel model failed to predict fire spread in nearly all of the fires that spread using default values. Increasing the moisture of extinction marginally improved its performance. Modifications proposed by Cohen, Wilson and Catchpole also improved predictions. The models successfully predicted fire spread 49 to 69% of the time. Only the physical model predictions fell within a factor of two of actual rates. Mean bias of most models was close to zero. Physically based models generally performed better than empirical models and are recommended for further study.

Mediterranean fuel models and potential fire behaviour in Greece

2002 ◽  
Vol 11 (2) ◽  
pp. 127 ◽  
Author(s):  
A. P. Dimitrakopoulos
Keyword(s):  
Fire Behavior ◽  
Pine Forests ◽  
Fuel Load ◽  
Average Height ◽  
Litter Layer ◽  
Data Set ◽  
Rate Of Spread ◽  
Fuel Models ◽  
Tall Shrub ◽  
Mediterranean Pine

The Mediterranean vegetation types of Greece were classified into typical fuel models by measuring the following fuel parameters in 181 representative natural fuel complexes: 1-h, 10-h, 100-h and 1000-h fuel loads; foliage load; litter load and depth; total fuel load; average height and soil cover of the herbaceous, small shrub (up to 0.5 m) and tall shrub (0.5-3.0 m) vegetation layers. The data set was statistically analysed by a two-stage clustering procedure that produced seven distinct fuel models: two for evergreen-sclerophyllous shrublands (maquis), one for kermes oak shrublands, two for phrygana, one for grasslands and one for the litter layer of Mediterranean pine forests. The indicative range (upper and lower limit) of potential fire behavior for every fuel model was calculated with the BEHAVE fire behavior prediction system, using as inputs the specific fuel parameter values of every model. The shrubland fuel models resulted in fires with high intensity and rate of spread, while the phrygana and grassland models in fast fires of medium to low intensity. The litter layer of the pine forests provided the least severe burning conditions.

Testing the Effect of Fuel Consumption on Fire Spread Rate

1995 ◽  
Vol 5 (3) ◽  
pp. 143 ◽  
Author(s):  
RS McAlpine
Keyword(s):  
Fuel Consumption ◽  
Fire Behavior ◽  
Fire Spread ◽  
Data Sets ◽  
Behavior Prediction ◽  
Spread Rate ◽  
Data Set ◽  
Weak Relationship ◽  
Rate Of Spread ◽  
Fire Front

It has been theorized that the amount of fuel involved in a fire front can influence the rate of spread of the fire. Three data sets are examined in an attempt to prove this relationship. The first, a Canadian Forest Service database of over 400 experimental, wild, and prescribed fires showed a weak relationship in some fuel complexes. The second, a series of field experimental fires conducted to isolate the relationship, showed a small effect. The final data set, from a series of 47 small plots (3m x 3m) burned with a variety of fuel loadings, also show a weak relationship. While a relationship was shown to exist, it is debatable whether it should be included in a fire behavior prediction system. Inherent errors associated with predicting fuel consumption can be compounded, causing additional, more critical, errors with the derived fire spread rate.

An effective wind speed for models of fire spread

2002 ◽  
Vol 11 (2) ◽  
pp. 153 ◽  
Author(s):  
Ralph M. Nelson, Jr.
Keyword(s):  
Wind Speed ◽  
Slope Angle ◽  
Fire Behavior ◽  
Fire Spread ◽  
Spread Rate ◽  
Ambient Wind ◽  
Rate Of Spread ◽  
Spread Model ◽  
The Difference ◽  
Fire Spread Model

In previous descriptions of wind-slope interaction and the spread rate of wildland fires it is assumed that the separate effects of wind and slope are independent and additive and that corrections for these effects may be applied to spread rates computed from existing rate of spread models. A different approach is explored in the present paper in which the upslope component of the fire's buoyant velocity is used with the speed and direction of the ambient wind to produce effective values of wind speed and direction that determine the rate of spread vector. Thus the effective wind speed can replace the ambient wind speed in any suitable fire spread model and provide a description of the combined effects on the fire behavior. The difference between current and threshold values of the effective wind speed also can be used to determine whether fire will spread in a given fuel type. The model is tested with data from experiments reported by Weise (1993) in which fire spread was in response to variation in both wind speed and slope angle. The Weise spread rate data were satisfactorily correlated using dimensional methods and the observed spread rate was reasonably well predicted with an existing rate of spread model. Directional aspects of the model were not tested because the Weise (1993) study did not include winds with a cross-slope component.

Sign in / Sign up

Export Citation Format

Share Document