Fire Danger Conditions Research Articles

Evaluating wildland fire danger and prioritizing vegetation and fuels treatments

We present a decision support application that evaluates danger of severe wildland fire and prioritizes subwatersheds for vegetation and fuels treatment. We demonstrate the use of the system with an example from the Rocky Mountain region in the State of Utah; a planning area of 4.8 million ha encompassing 575 subwatersheds. In a logic model, we evaluate fire danger as a function of three primary topics: fire hazard, fire behavior, and ignition risk. Each primary topic has secondary topics under which data are evaluated. The logic model shows the state of each evaluated watershed with respect to fire danger. In a decision model, we place summarized fire danger conditions of each watershed in the context of the amount of associated wildland–urban interface (WUI). The logic and decision models are executed in EMDS, a decision support system that operates in ArcGIS. We show that a decision criterion such as relationship to WUI can significantly influence the outcome of a decision to determine treatment priorities. For example, we show that subwatersheds that were in the relatively poor condition with respect to fire hazard, behavior, and ignition risk may not be the best candidates for treatment. Additional logistical factors such as proximity to population centers, presence of endangered species, slope steepness, and road access all might be taken into account in selection of specific watersheds within a management area for treatment. Thus, the ecological status of each ecosystem can be placed in one or more social values contexts to further inform decision-making. The application can be readily expanded to support strategic planning at national and regional scales, and tactical planning at local scales.

Estimation of dead fuel moisture content from meteorological data in Mediterranean areas. Applications in fire danger assessment

The estimation of moisture content of dead fuels is a critical variable in fire danger assessment since it is strongly related to fire ignition and fire spread potential. This study evaluates the accuracy of two well-known meteorological moisture codes, the Canadian Fine Fuels Moisture Content and the US 10-h, to estimate fuel moisture content of dead fuels in Mediterranean areas. Cured grasses and litter have been used for this study. The study was conducted in two phases. The former aimed to select the most efficient code, and the latter to produce a spatial representation of that index for operational assessment of fire danger conditions. The first phase required calibration and validation of an estimation model based on regression analysis. Field samples were collected in the Cabañeros National Park (Central Spain) for a six-year period (1998–2003). The estimations were more accurate for litter (r2 between 0.52) than for cured grasslands (r2 0.11). In addition, grasslands showed higher variability in the trends among the study years. The two moisture codes evaluated in this paper offered similar trends, therefore, the 10-h code was selected since it is simpler to compute. The second phase was based on interpolating the required meteorological variables (temperature and relative humidity) to compute the 10-h moisture code. The interpolation was based on European Centre for Medium Range Weather Forecasting (ECMWF) predictions. Finally, a simple method to combine the estimations of dead fuel moisture content with other variables associated to fire danger is presented in this paper. This method estimates the probability of ignition based on the moisture of extinction of each fuel type.

Crown fire behaviour in a northern jack pine – black spruce forest

This paper reports on the behaviour of 10 experimental crown fires conducted between 1997 and 2000 during the International Crown Fire Modelling Experiment (ICFME) in Canada's Northwest Territories. The primary goal of ICFME was a replicated series of high-intensity crown fires designed to validate and improve existing theoretical and empirical models of crown fire behaviour. Fire behaviour characteristics were typical for fully developed boreal forest crown fires, with fires advancing at 15–70 m/min, consuming significant quantities of fuel (2.8–5.5 kg/m2) and releasing vast amounts of thermal heat energy. The resulting flame fronts commonly extended 25–40 m above the ground with head fire intensities up to 90 000 kW/m. Depth of burn ranged from 1.4–3.6 cm, representing a 25%–65% reduction in the thickness of the forest floor layer. Most of the smaller diameter (<3.0 cm) woody surface fuels were consumed, along with a significant proportion of the larger downed woody material. A high degree of fuel consumption occurred in the understory and overstory canopy with very little material less than 1.0 cm in diameter remaining. The documentation of fire behaviour, fire danger, and fire weather conditions carried out during ICFME permitted the evaluation of several empirically based North American fire behaviour prediction systems and models.

Assessment of forest fire danger conditions in southern Spain from NOAA images and meteorological indices

Traditionally, the estimation of fire danger is performed from meteorological danger indices that are computed for single locations, where the weather stations are located. Frequently, these locations are far from forested areas, and there is a need to spatially interpolate danger variables. Methods for spatial interpolation are always prone to error, especially for those variables that show a greater spatial variability (wind, mainly). Satellite images may be considered a good alternative for interpolation of danger values, since they perform a spatially exhaustive observation of the territory. This paper analyses the spatial distribution of the Canadian Drought Code (DC), part of the Canadian Forest Fire Weather Index System (CFFWIS), in the region of Andaluc{@a (south Spain) following two procedures. First, maps of DC values were obtained from spatial interpolation of a network of 30 weather stations using the squared inverse distance algorithm. These results were compared with interpolation based on linear regression analysis, using National Oceanic and Atmospheric Administration (NOAA) Advanced Very High Resolution Radiometer (AVHRR) derived bands as independent variables. The most significant variables found for these empirical fittings were relative greenness, the ratio of Normalized Difference Vegetation Index (NDVI) and surface temperature, and a temporal variable, which accounts for the variations in day length throughout the fire season. After several empirical fittings were obtained, the most precise estimation was found after adjusting the coefficients to the time period considered.

The Dead-Man Zone—a neglected area of firefighter safety

Summary Firefighters engaged in parallel or indirect attack are working in a “dead-man zone” if they do not appreciate the time and space required to find a safe refuge. In this zone, if the wind direction changes, the fire can advance so rapidly that the firefighters have very little time to seek refuge in the burnt area behind a suppressed portion of line, or egress elsewhere, before the fire overwhelms them. We discuss three bushfire incidents in Australia where firefighters were trapped and killed, and the development of fire spread in forest fuels from a line start. A table illustrating the distance that a line fire can travel in five minutes under different fire danger conditions is presented. Factors that affect the speed of the firefighter's reaction to changed circumstances, and safe work practices, arc discussed.

Fire behaviour and fuel reduction burning: Bemm River wildfire, October 1988

Summary On 14 October 1988 a major wildfire occurred in the Bemm River area, 33 km east of Orbost in the East Gippsland region of Victoria. The weather was dominated by wind speeds of gale force strength. The fire burnt under “very high” to “extreme” fire danger conditions with a maximum McArthur fire danger index of 82, a maximum mean forward rate of spread between 3.5 and 4.0 km/h and a maximum mean fireline intensity in the range 31,200 to 35,500 kW/m. The final area of the wildfire was 5,670 ha and the perimeter was 80 km. A highly significant influence on fire behaviour was the layer of aerated, highly flammable shrub fuel. This was combined in the coastal forests of the Bemm River area with high quantities of litter and the high spotting potential of the stringybark eucalypts. Total fine fuel loads averaged about 20 t/ha. The rate of spread predicted by the McArthur Mk 5 Forest Fire Danger Meter during the initial two hour period of the wildfire was 2.0 km/h and the observed mean rate of spread was ...

A chronological overview of the 1989 fire season in Manitoba

In 1989 a new record was established for the number of fires (1147) and area burned (3.28 million ha) in Manitoba. These fires resulted in the unprecedented evacuation of 24,500 people from 32 different communities and cost over $68 million (CDN) to suppress. The first major outbreak of fires occurred in central Manitoba in mid-May and was followed by a second peak of fire activity in northern Manitoba between July 16 and August 2. Both periods were characterized by multiple fire ignitions, severe fire weather and fire danger conditions, and extreme fire behavior. A general description of the events that took place during this historic fire season are presented in this paper.

Prescribed Burning for Stand Conversion in Budworm-killed Balsam Fir: An Ontario Case History

Recent spruce budworm (Choristoneura fumiferana [Clem.]) infestations have resulted in widespread areas of balsam fir (Abies balsamea [L.] Mill.) mortality in Ontario, and there is growing interest in reestablishing these areas quickly as productive forests. One technique being used is prescribed fire after a salvage and bulldozer tramping operation. A 445-ha prescribed burn was carried out under moderate fire danger conditions in northern Ontario. The site, which was covered by balsam fir fuel that had been killed by spruce budworm, was tramped to improve fire spread. Weather, fuel consumption, and fire effects are reported. The burn effectively reduced heavy surface fuel loadings and consequently planting on the site was easier. Key words: Prescribed burning, fire, spruce budworm. Choristoneura fumiferana, balsam fir, Abies balsamea, fuel consumption, site preparation, tramping, stand conversion.

A fire danger rating system for Hawaii

Extremes in rainfall on the Hawaiian Islands make it difficult to judge forest fire danger conditions. The use of an automatic data collection and computer processing system helps to monitor the problem.

ASSESSMENT OF FIRE DANGER CONDITIONS

SUMMARY At the Yallourn and Kiewa undertakings of the State Electricity Commission of Victoria, a simple fire danger meter is being used to assist the fire protection staff in their judgment of fire danger conditions in the surrounding forests. On this meter, the fire danger rating is arrived at by adding a burning index, based on weather conditions on the day, to a season index, based on past weather history for the season. The formulae for calculating these indices are empirical, and are based on a study of recorded weather conditions in relation to actual bush fire and controlled burning history, mainly for the Yallourn area, during the summer seasons from 1938 to 1949. This method of fire danger rating fits past experience over this period, it has been used with reliable results over the past two seasons, and it seems to offer a valuable means whereby the forester can check his judgment of the degree of fire danger and the extent to which fire fighting preparedness needs to over-ride normal forestry a...