Effect of Wind and Slope When Scaling the Forest Fires Rate of Spread of Laboratory Experiments

2010 ◽  
Vol 47 (2) ◽  
pp. 475-489 ◽  
Author(s):  
Yolanda Pérez ◽  
Elsa Pastor ◽  
Alba Àgueda ◽  
Eulalia Planas
Keyword(s):  
Forest Fires ◽  
Laboratory Experiments ◽  
Rate Of Spread

scholarly journals Modelling Forest Fires Using Complex Networks

2021 ◽  
Vol 26 (4) ◽  
pp. 68
Author(s):  
Sara Perestrelo ◽  
Maria C. Grácio ◽  
Nuno A. Ribeiro ◽  
Luís M. Lopes
Keyword(s):  
Forest Fires ◽  
Previous Knowledge ◽  
Time Duration ◽  
Spreading Process ◽  
Multilayer Network ◽  
Major Threat ◽  
Rate Of Spread ◽  
Spreading Dynamics ◽  
Fire Spreading ◽  
Network Of Networks

Forest fires have been a major threat to the environment throughout history. In order to mitigate its consequences, we present, in a first of a series of works, a mathematical model with the purpose of predicting fire spreading in a given land portion divided into patches, considering the area and the rate of spread of each patch as inputs. The rate of spread can be estimated from previous knowledge on fuel availability, weather and terrain conditions. We compute the time duration of the spreading process in a land patch in order to construct and parametrize a landscape network, using cellular automata simulations. We use the multilayer network model to propose a network of networks at the landscape scale, where the nodes are the local patches, each with their own spreading dynamics. We compute some respective network measures and aim, in further work, for the establishment of a fire-break structure according to increasing accuracy simulation results.

scholarly journals Flammability of litter sampled according to two different methods: comparison of results in laboratory experiments

2014 ◽  
Vol 23 (8) ◽  
pp. 1061 ◽  
Author(s):  
Anne Ganteaume ◽  
Marielle Jappiot ◽  
Thomas Curt ◽  
Corinne Lampin ◽  
Laurent Borgniet
Keyword(s):  
Laboratory Experiments ◽  
Sampling Method ◽  
Future Research ◽  
Vegetation Types ◽  
Fire Behaviour ◽  
Rate Of Spread ◽  
Litter Flammability ◽  
Different Types ◽  
Flammability Parameters ◽  
Density Rate

In the laboratory, different types of litter samples (constructed v. intact) can be used in flammability experiments but the sampling method of these litters could affect litter flammability results. To assess this effect, samples of litters were collected in South-eastern France, according to two different methods previously used in other studies, one keeping intact the structure of the litter layers (non-constructed litter) and the other requiring the construction of the litter, using mainly the surface litter layer (constructed litter). The comparison of flammability results showed that the sampling method had a significant effect on litter bulk-density, rate of spread and rate of consumption, intact litter being more flammable than reconstructed litter that was artificially compacted. The type of vegetation had a significant effect on litter depth, ignitability, sustainability, consumability and combustibility (except on rate of spread) and the litter composition could explain in part this fire behaviour. The effect of the construction of litters on flammability parameters and its magnitude also differed according to vegetation types. Intact litter structure appeared to be an important driver of its flammability, especially of combustibility and consumability. The assessment of these flammability components will differ when using constructed litter samples instead of intact litter samples, especially according to vegetation types. Future research on litter flammability should take into account the bias due to the litter sampling method when the litter is constructed.

scholarly journals Automated location of active fire perimeters in aerial infrared imaging using unsupervised edge detectors

2018 ◽  
Vol 27 (4) ◽  
pp. 241 ◽  
Author(s):  
M. M. Valero ◽  
O. Rios ◽  
E. Pastor ◽  
E. Planas
Keyword(s):  
Forest Fires ◽  
Large Scale ◽  
Infrared Imaging ◽  
Weather Conditions ◽  
Automated System ◽  
Rate Of Spread ◽  
Active Fire ◽  
Edge Detectors ◽  
Spatio Temporal ◽  
Manual Tasks

A variety of remote sensing techniques have been applied to forest fires. However, there is at present no system capable of monitoring an active fire precisely in a totally automated manner. Spaceborne sensors show too coarse spatio-temporal resolutions and all previous studies that extracted fire properties from infrared aerial imagery incorporated manual tasks within the image processing workflow. As a contribution to this topic, this paper presents an algorithm to automatically locate the fuel burning interface of an active wildfire in georeferenced aerial thermal infrared (TIR) imagery. An unsupervised edge detector, built upon the Canny method, was accompanied by the necessary modules for the extraction of line coordinates and the location of the total burned perimeter. The system was validated in different scenarios ranging from laboratory tests to large-scale experimental burns performed under extreme weather conditions. Output accuracy was computed through three common similarity indices and proved acceptable. Computing times were below 1 s per image on average. The produced information was used to measure the temporal evolution of the fire perimeter and automatically generate rate of spread (ROS) fields. Information products were easily exported to standard Geographic Information Systems (GIS), such as GoogleEarth and QGIS. Therefore, this work contributes towards the development of an affordable and totally automated system for operational wildfire surveillance.

A Numerical Study of Forest Fire Progression and Fire Suppression by Aerial Fire Fighting

2004 ◽  
Author(s):  
Kohyu Satoh ◽  
Kunio Kuwahara ◽  
K. T. Yang
Keyword(s):  
Forest Fire ◽  
Forest Fires ◽  
High Speed ◽  
Laboratory Experiments ◽  
Numerical Study ◽  
Water Drop ◽  
Fire Suppression ◽  
Critical Issue ◽  
Fire Fighting ◽  
Cfd Simulations

Forest fires are of common occurrence all over the world, which cause severe damages to valuable natural resources and human lives. In the recent California Fire, which burned 300,000 hectors of land, the disaster danger could reasonably be predicted, but early control of fires by means of aerial fire fighting might have been failed in that situation. Also in Japan, there are similar problems in the aerial fire fighting. Most forest fires occur in the daytime and the fires are freely in progress without any control during the nighttime. Therefore, it is important to attack the fires when there is daylight. The water dropped by helicopters is not always sufficient to control fires, since the quantity of water that can be carried aloft is a critical issue. Large amount of water can be dropped from aircrafts, but the high-speed flight of aircrafts may be dangerous in the mountain, where tall trees and steel towers with electric wires may exist. Therefore, those aircrafts have to fly at much higher altitudes than helicopters, while the water drop at high altitudes changes water into mist in the air. The objective of this study is to examine the methods to prevent the ignition by firebrands in the downwind area by applying water through the aerial fire fighting. However, tests by real aircrafts to obtain such information would be too costly. Therefore, the patterns of water drop from aircrafts were examined in CFD simulations, together with the investigation of needed water drop rate based on the forest fire statistics, the previous real aircraft tests and laboratory experiments. It has been found in the simulations that the water supply with the water density of 2 L/m2 is effective to control fires and the patterns of dropping water are reasonable.

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.

Seasonal Changes in Fire Behaviour in a Tropical Savanna in Northern Australia

1998 ◽  
Vol 8 (4) ◽  
pp. 227 ◽  
Author(s):  
RJ Williams ◽  
AM Gill ◽  
PHR Moore
Keyword(s):  
Leaf Litter ◽  
Forest Fires ◽  
Heat Content ◽  
Dry Season ◽  
Fire Intensity ◽  
Southeastern Australia ◽  
Rate Of Spread ◽  
Open Forest ◽  
Annual Grasses ◽  
Scale Experiment

In a landscape-scale experiment, fires were lit in replicate catchments 15-20 km2 in area, either early in the dry season (June) or late in the dry season (September) between 1990 and 1994. For each fire, Byram-intensity was determined in representative one ha areas of Eucalyptus miniata – E. tetrodonta open-forest, with a ground stratum dominated by annual grasses. Fuel weights were measured by harvest, fuel heat content was assumed to be constant, and the rate of spread was determined using electronic timers. Fuels consisted primarily of grass and leaf litter, and ranged from 1.5 to 13 t ha-1; in most years, average fuel loads were 2-4 t ha-1. Rates of spread were generally in the range of 0.2-0.8 ms-1. The mean intensity of early dry season fires (2100 kW m-1) was significantly less than that of the late dry season fires (7700 kW m-1), primarily because, in the late dry season, there was more leaf litter, fuels were drier, and fire weather was more extreme. Crown fires, a feature of forest fires of high intensity in southeastern Australia, were not observed in the Kapalga fires. Fire intensity was a very good predictor of both leaf-char height and leaf-scorch height for fires between 100 kW m-1 and 10,000 kW m-1, the range in which the majority of experimental fires fell.

Fire spread in canyons

2004 ◽  
Vol 13 (3) ◽  
pp. 253 ◽  
Author(s):  
Domingos Xavier Viegas ◽  
Luis Paulo Pita
Keyword(s):  
Forest Fires ◽  
Numerical Study ◽  
Fire Spread ◽  
Laboratory Scale ◽  
Experimental Program ◽  
Small Scale ◽  
Geometrical Parameters ◽  
Fire Behaviour ◽  
Fatal Accidents ◽  
Rate Of Spread

Canyons or ridges are associated with a large number of fatal accidents produced during forest fires all over the world. A contribution to the understanding of fire behaviour in these terrain conditions is given in this paper. The basic geometrical parameters of the canyon configuration are described. An analytical model assuming elliptical growth of point ignition fires and constant values of rate of spread is proposed. A non-dimensional formulation to transfer results from analytical, numerical, laboratory or field simulations to other situations is proposed. An experimental study at laboratory scale on a special test rig is described. A wide set of canyon configurations were covered in the experimental program. In spite of the relatively small scale of the experiments they were able to put in evidence some of the main features found in fires spreading in this type of terrain. They show that in practically all cases the rate of spread of the fire front is non-constant. On the contrary, the fire has a dynamic behaviour and its properties depend not only on the canyon geometry but on the history of fire development as well. The convection induced by the fire is enhanced by terrain curvature and the fire accelerates causing the well-known blow-up that is associated with canyon fires. The rate of spread of the head fire increases continuously even in the absence of wind or any other special feature or change of boundary conditions that are sometimes invoked to justify such fire behaviour. The results of the present study confirm the predictions of a previous numerical study of the flow and fire spread in canyons that showed the important feedback effect of the fire on the atmospheric flow and how this affects fire behaviour in canyons. Results from a field experiment carried out in a canyon-shaped plot covered by tall shrubs were used to validate the laboratory scale experiments. Case studies related to fatal accidents that occurred in canyon-shaped configurations are analysed and recommendations to deal with this problem are made. It is shown that these accidents may occur even in the absence of special fuel or atmospheric conditions as they are intrinsically related to terrain configuration.

scholarly journals DESCRIBING FOREST FIRES — OLD WAYS AND NEW

1965 ◽  
Vol 41 (3) ◽  
pp. 301-305 ◽  
Author(s):  
C. E. van Wagner
Keyword(s):  
Forest Fires ◽  
Quantitative Measure ◽  
Verbal Description ◽  
Energy Output ◽  
Fire Behaviour ◽  
Fire Control ◽  
Linear Rate ◽  
Rate Of Spread ◽  
Fire Front ◽  
In Fire

This article deals with several ways of describing forest fires and their limitations. The simplest and oldest way is by simple verbal description. Then came the combination of rate of spread and resistance to control. The best quantitative measure of fire behaviour, however, is the rate of energy output per unit of fire front, quoted in conjunction with the linear rate of spread. If the full benefits of advances in fire control technology are to be realized, wider use of the energy output concept will probably be necessary, first among fire researchers and eventually among fire control people.

Comparison of three methods to quantify the fire spread rate in laboratory experiments

2017 ◽  
Vol 26 (10) ◽  
pp. 877 ◽  
Author(s):  
J. S. Gould ◽  
A. L. Sullivan ◽  
R. Hurley ◽  
V. Koul
Keyword(s):  
Wind Tunnel ◽  
Laboratory Experiments ◽  
Visible Spectrum ◽  
Forest Litter ◽  
Fire Spread ◽  
Time Of Arrival ◽  
Spread Rate ◽  
Eucalypt Forest ◽  
Rate Of Spread ◽  
Selection Of

Different methods can be used to measure the time and distance of travel of a fire and thus its speed. The selection of a particular method will depend on the experimental objectives, design, scale, location (in the laboratory or field), required accuracy and resources available. In this study, measurements from ocular observation (directly by eye), visible spectrum video imagery and thermocouple instrumentation were used to compare their performance in quantifying the time of arrival and rate of spread of a fire burning across a eucalypt forest litter fuel bed in a combustion wind tunnel. All methods gave similar results, but there were some significant differences depending on the dryness of the fuel and speed of the wind.

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