Fire Ignition Risk Research Articles

Empirical Evidence of Reduced Wildfire Ignition Risk in the Presence of Strong Winds

Anyone who has tried lighting a campfire on a windy day can appreciate how difficult it could be. However, despite real-life experience and despite laboratory experiments which have demonstrated that fire ignition risk dramatically decreases beyond a certain wind threshold, current fire weather indices (FWIs) do not take this effect into account and assume a monotonic relation between wind velocity and ignition risk. In this paper, we perform a global analysis which empirically quantifies the probability of ignition as a function of wind velocity. Using both traditional methods (a logistic regression and a generalized additive model) and machine learning techniques, we find that beyond a threshold of approximately 3–4 m/s, the ignition risk substantially decreases. The effect holds when accounting for additional factors such as temperature and relative humidity. We recommend updating FWIs to account for this issue.

Large-Fire Ignitions Are Higher in Protected Areas than Outside Them in West-Central Spain

Managing protected areas requires knowing what factors control fire ignitions and how likely they are compared to non-protected ones. Here, we modelled fire ignition likelihood in west-central Spain as a function of biophysical and anthropogenic variables in 172 protected areas (PA) of the Natura 2000 network, their buffer zones (BZ, 1500 m area surrounding PA), and non-protected areas (NP). Ignition coordinates from fire statistics (2001–2015 period) were overlaid over maps of relevant biophysical and socioeconomic variables. Models were built for four different fire sizes, small (1–5 ha), medium (5–50 ha), large (50–500 ha), and very large (≥500 ha), using Maxent software. Additionally, PA were classified based on their land use and land cover types by cluster analysis. Mean ignition probabilities were compared between PA, BZ and NP, as well as among different types of PA, by generalized linear models. Maxent models’ accuracy increased as fires were of larger size. Ignitions of small fires were associated with anthropogenic variables, while those of larger fires were more associated with biophysical ones. Ignition likelihood for the small and medium fire sizes was highest in BZ, while being the lowest in PA. Conversely, the likelihood of large and, particularly, very large fires was highest in PA. Mean ignition likelihood varied among types of PA, being highest for very large fires in PA, dominated by pine and mixed forests. Our results support the hypothesis that PAs are at the highest risk of large fire ignition, but BZ were also at high risk for the rest of the fire sizes. This largely reflects the more hazardous nature of PA landscapes. This work provides the needed tools to identify critical fire ignition areas within and nearby protected areas, which should be considered in their conservation and management plans.

Using machine learning algorithms to predict groundwater levels in Indonesian tropical peatlands

Tropical peatlands play a vital role in the global carbon cycle as large carbon reservoirs and substantial carbon sinks. Indonesia possesses the largest share (65 %) of tropical peat carbon, equal to 57.4 Gt C. Human perturbations such as extensive logging, deforestation and canalization exacerbate water losses, especially during dry seasons, when low precipitation and high evapotranspiration rates combine with the increased drainage to lower groundwater levels. Drying and increasing temperatures of the surface peat exacerbate ignition and wildfire risks within the peat soils. As such, it is critically important to know how groundwater levels in peatlands are changing over space and time. In this study, a multilinear regression model as well as two machine learning algorithms, random forest and extreme gradient boosting, were used to model groundwater level over the study period (2010−12) within a peat dome impacted by drainage canals and multiple wildfires in Central Kalimantan, Indonesia. Although all three models performed well, based on overall fit, spatial modeling of groundwater level results revealed that extreme gradient boosting (R2 = 0.998, RMSE = 0.048 m) outperformed random forest (R2 = 0.997, RMSE = 0.054 m) and multilinear regression (R2 = 0.970, RMSE = 0.221 m) near drainage canals, which are key fire ignition risk locations in the peatlands. Our study also shows that, on average, elevation and precipitation are the most important parameters influencing groundwater level spatiotemporally.

Grazing Intensity Effects on Fire Ignition Risk and Spread in Sagebrush Steppe

Wildfire activity is accelerating on many rangelands worldwide, yet the potential for grazing to be used as a fire management tool remains largely unknown. Particularly, little is known about the influence of grazing on ignition and initial spread of fire, as well as how these vary by differences in grazing management. We investigated effects of grazing intensity (light, moderate, high) on fuel characteristics, fire ignition, and initial spread during the wildfire season in a native-dominated shrub steppe in eastern Oregon. We found that differences in grazing intensity have differential effects on fuel profiles (cover, height, moisture, biomass) with resulting impacts on fire behavior, but these relationships varied across study years. In particular, grazing had a stronger effect on ignition probability in drier years. Fire behavior in lightly grazed plots were similar to ungrazed plots, while moderate grazing was similar to high-intensity grazing. Results of this study highlight that grazing can be useful as a tool for wildfire management, and grazing at moderate and high intensities can reduce the probability of fire propagation in native-dominated sagebrush ecosystems. Further, the effects of grazing are context dependent and therefore may depend on specific objectives and environmental conditions.

Application of Multicriteria GIS Analysis in Derivation of the Wildfire Ignition Index And Optimization of Firefighting Interventions in the NP Krka

This paper demonstrates the possibilities of GIS implementation in the preventive phase of firefighting activities for the Šibenik-Knin County. Multicriteria GIS analysis (GIS-MCDA) was applied in derivation of the wildfire risk ignition index. Four groups of criteria were used: vegetation, geomorphometry, anthropogenic impact, and climate elements. Wildfire risk ignition models were derived based on the decision-maker method through (1) the experience of the local fire commander and (2) following the examples of good practice. Furthermore, the coverage and the passability of the National park (NP) Krka roads were analyzed in relation to the standard intervention time from the competent fire brigades. The nearest fire brigades and the fastest routes to the most endangered zones within the NP Krka have been derived. The results indicate that the area of Šibenik-Knin County belongs to the moderate/moderately high risk of fire ignition and that the coverage of the NP Krka roads within the standard intervention time is not satisfactory.

Post-earthquake fire risk assessment of historic urban areas: A scenario-based analysis applied to the Historic City Centre of Leiria, Portugal

Recent natural and anthropic disasters have aroused the interest of the scientific and governmental community in seeking more efficient and effective risk mitigation strategies. Index-based approaches have received particular attention in the field of disaster risk because of their extraordinary capacity to synthesise and spatially contextualise vulnerability. Motivated by the massive impacts of earthquakes, the seismic risk field has gained popularity over the last few decades. However, little attention has been paid so far to a potentially highly impacting phenomenon: post-earthquake fires. Historical records have shown that fire ignitions triggered by earthquakes present a significant likelihood of ending up in massively destructive urban fires whose consequences are even more dreadful than those of the earthquake itself. This paper aims to contribute to the body of knowledge in the field of post-earthquake fires by presenting a scenario-based analysis in the Historic City Centre of Leiria. Firstly, two seismic vulnerability index methodologies are applied to obtain post-earthquake damage scenarios. Then, a risk matrix is used to identify the buildings that are more prone to suffer post-earthquake fire ignitions. Finally, fire spreading and suppression conditions are examined and discussed through a detailed analysis where fire risk outputs, damages, and the accessibility conditions of the area are combined to obtain an integrated post-earthquake fire analysis. The results show that for a seismic event of intensity IEMS−98 = VIII, 33% of the total surveyed buildings could present a moderate or high risk of post-earthquake fire ignition.

Pneumatic Actuator Controlled by Proportional Valve. Experimental results

In nowadays the pneumatic controlled systems are widely used in industrial applications where valves must be operated, where there is a fire ignition risk, or in different automation systems where a positioning action is desired. The paper presents the experimental results of a pneumatic actuator controlled by a proportional control valve. The goal of the paper is to compare the experimental results with the numerical simulation results and to improve the mathematical model associated with the experiment.

Complementing daily fire-danger assessment using a novel metric based on burnt area ranking

Understanding the relationship between fire and weather has important implications for fire danger evaluations, firefighting and fire management. Fire weather indices are mathematical representations of a suite of meteorological variables that are often used as decision-support tools for evaluating the likelihood of fire on a given day. However, these indices are seldom evaluated for their ability to express a probability in terms of final burnt area, which is a very important fire danger component. We propose a new approach for selecting fire weather indices that represent good proxies for both the probability of fire occurrence on a particular day and of the related final burnt area. The novel performance metric was applied to historical data (11 to 31 years) from four European regions with different fire regimes in Switzerland (Canton Ticino) and Italy (Cilento in Campania, Chilivani and Campidano in Sardinia). The results confirm the suitability of the approach for selecting an appropriate fire weather index for a particular region and for providing insight into the regional meteorological control patterns of fire ignition and spread. For three of the six fire regime types analyzed (Campidano, Cilento and winter fire season in Ticino), the prediction power for burnt area of most indices was generally in accordance with estimates of fire ignition risk. For the remaining case studies, fire ignition and burnt area appear to be controlled by different meteorological or non-climatic drivers. In these cases, the selection of the most suitable index should be based on a cutoff that optimizes the two selection criteria according to local needs. From an operational point of view, this novel approach that includes the burnt area aspect can strongly support decisions on firefighting alert and preparedness as well as requested firefighting strategies.

An Experimental Study on the Combustion Characteristics of Pinus densiflora Surface Layer by Slope Condition

본 연구에서는 실내연소실험을 통하여 경사조건이 소나무 지표층 연료의 연소특성에 미치는 영향을 파악하고자 하였다. 경사조건은 0°, 10°, 20°, 30°의 조건을 부여하여 실험하였다. 본 연구결과에 의하면 경사가 급해질수록 확산속도가 증가하여 경사 30°에서의 확산속도는 평지에 비해 최대 약 14배 빠른 것으로 나타났다. 산불강도 분석결과에서는 최소 246.73 kW/m ~ 최대 2,602.96 kW/m의 범위로 나타났으며 경사가 급해질수록 산불강도가 높아지는 경향을 보였다. 연소율 분석결과에서는 경사가 급해질수록 총 연소율이 낮아져 불완전 연소가 진행되었으며, 동일한 경사조건에서 수관연료의 함수율은 지하고가 높아질수록 높게 측정되어 수관연료 발화위험성이 낮을 것으로 판단하였다. 본 연구결과는 추후 경사에 따른 산불행동특성을 규명하는 데 기여할 수 있는 기초자료로 활용될 것이다.In this study, a laboratory burning experiment was conducted to examine the combustion characteristics of Pinus densiflora surface fuel by different slope conditions such as 0°, 10°, 20°, 30° We observed the changes in forest fire behavior after fuel-bed ignition. According to the results of this study, the rate of fire spread increased as the slope angle increased; it was 14 times faster at slope angle of 30° than at 0° The fire intensity also increased as the slope angle increased, ranging from 246.73 kW/m to 2,602.96 kW/m. The flame height and tilt decreased but the length of flame increased, when the slope angle increased. The total combustion rate also decreased as the slope angle increased. Since the moisture content of canopy fuel was measured higher with the increase of the crown base height under the same slope conditions, the risk of forest fire ignition was found to be low. The findings can be used as a basic data for understanding of fire behavior by slope condition.

Logistic Regression Based Arc Fault Detection in Photovoltaic Systems Under Different Conditions

This paper investigates direct current (DC) arc fault detection in photovoltaic system. In order to avoid the risk of fire ignition caused by the arc fault in the photovoltaic power supply, it is urgent to detect the DC arc fault in the photovoltaic system. Once an arc fault is detected, the power supply should be cut off immediately. A lot of field experiments are carried out to obtain the data of arc fault current of the photovoltaic system under different current conditions. Cable length, arc gap, and the effects of different sensors are tested. These three conditions are the most significant features of this paper. Four characteristic variables from both the time domain and the frequency domain are extracted to identify the arc fault. Then the logistic regression method in the field of artificial intelligence and machine learning is originally used to analyze the experimental results of arc fault in the photovoltaic system. The function between the probability of the arc fault and the change of the characteristic variables is obtained. After validating 80 groups of experimental data under different conditions, the accuracy rate of the arc fault detection by this algorithm is proved to reach 100%.

Interacting effects of topography, vegetation, human activities and wildland-urban interfaces on wildfire ignition risk

Effective fire prevention requires a better understanding of the patterns and causes of fire ignition. In this study, we focus on the interacting factors known to influence fire ignition risk, such as the type of vegetation, topographical features and the wildland-urban interface (WUI; i.e. where urban development meet or intermingle with wildland). We also analyze the human activities and motivations related to fires and whether they differ depending on the type of vegetation and the location within/outside WUI. There were significant interactions between topography, type of vegetation and location within/outside WUI. The risk of ignition was in general higher at lower elevations, and this tendency was more marked in forested land covers (all plantations and open woodlands), with the noticeable exception of native forests. North-facing sites had lower fire ignition risk outside the WUI, especially in native forests, while southern aspects showed higher fire ignition risk, especially in open shrublands. However, this effect of the aspect was only significant outside WUI areas. In relation to causes, there were also interactions between human activities/motivations related to fires, the type of vegetation and the location within/outside WUI. All forestry plantations appeared clustered in relation to fire causes, especially in the WUI, with high incidence of deliberately caused fires related to violent or mentally ill people and rekindle fires. In contrast, native forests, despite structural similarities with forestry plantations, showed more similarity with agricultural areas and open woodlands in relation to fire causes. In shrublands, there was a relatively high incidence of fires related to ranching, especially outside the WUI. This pattern of interactions depicts a complex scenario in relation to fire ignition risk and prompts to the importance of taking this complexity into account in order to adjust fire management measures for improved effectiveness.

Lagged cumulative spruce budworm defoliation affects the risk of fire ignition in Ontario, Canada.

Detailed understanding of forest disturbance interactions is needed for effective forecasting, modelling, and management. Insect outbreaks are a significant forest disturbance that alters forest structure as well as the distribution and connectivity of combustible fuels at broad spatial scales. The effect of insect outbreaks on fire activity is an important but contentious issue with significant policy consequences. The eastern spruce budworm (Choristoneura fumiferana) is a native defoliating insect in eastern North America whose periodic outbreaks create large patches of dead fir and spruce trees. Of particular concern to fire and forest managers is whether these patches represent an increased fire risk, if so, for how long, and how the relationship between defoliation and fire risk varies through space and time. Previous work suggests a temporary increase in flammability in budworm-killed forests, but regional and seasonal variability in these relationships has not been examined. Using an extensive database on historical lightning-caused fire ignitions and spruce budworm defoliation between 1963 and 2000, we assess the relative importance of cumulative defoliation and fire weather on the probability of ignition in Ontario, Canada. We modeled fire ignition using a generalized additive logistic regression model that accounts for temporal autocorrelation in fire weather. We compared two ecoregions in eastern Ontario (Abitibi Plains) and western Ontario (Lake of the Woods) that differ in terms of climate, geomorphology, and forest composition. We found that defoliation has the potential to both increase and decrease the probability of ignition depending on the time scale, ecoregion, and season examined. Most importantly, we found that lagged spruce budworm defoliation (8-10yr) increases the risk of fire ignition whereas recent defoliation (1yr) can decrease this risk. We also found that historical defoliation has a greater influence on ignition risk during the spring than during the summer fire season. Given predicted increases in forest insect activity due to global change, these results represent important information for fire management agencies that can be used to refine existing models of fire risk.

Wildfire risk associated with different vegetation types within and outside wildland-urban interfaces

Wildland-urban interfaces (WUIs) are areas where urban settlements and wildland vegetation intermingle, making the interaction between human activities and wildlife especially intense. Their relevance is increasing worldwide as they are expanding and are associated with fire risk. The WUI may affect the fire risk associated with the type of vegetation (land cover/land use; LULC), a well-known risk factor, due to differences in the type and intensity of human activities in different LULCs within and outside WUIs. No previous studies analyse this interaction between the effects of the WUI and the LULC, despite its importance for understanding the patterns of fire risk, an essential prerequisite to undertake management decisions that can influence fire regimes.The aim of this study is to assess the effect of the WUI on fire ignition risk and the area burned, and the interaction between its effect and that of the LULC. We used a database of 26,838 wildfires recorded in 2006–2011 in NW Spain and compared fire patterns in relation to WUI and LULC with a random model, using a Montecarlo approach.There was a clear effect of the WUI on the risk of both fire ignition and spread (higher ignition risk but lower risk of spread in WUIs). The risk of fire was also affected by LULC and, interestingly, the pattern among LULCs differed between WUI and non-WUI areas. This interaction WUI×LULC was particularly important for forestry plantations, which showed the highest increase in ignition risk in WUI compared to non-WUI areas. Native forests and agricultural areas had the lowest ignition risk. Agricultural areas showed the smallest difference in fire size between WUI and non-WUI areas, while shrublands showed much larger fires outside WUIs. Deliberate fires were larger in general than those with other causes, especially outside the WUI.The differences found between LULCs in fire risk, both in WUI and non-WUI areas, have interesting implications for fire management. Promotion of land covers with low fire risk should be considered as a low cost alternative to the usual fire prevention measures based on fuel load reduction, which require the continuous clearing of vegetation. In this regard, the low fire risk in native forests should be taken into account. Native forests naturally colonize many areas in the study region and require low or no management, in contrast with agricultural areas, also with low fire risk but requiring continuous management in order to avoid colonization by natural vegetation.

Analysis of a fatal electrical accident due to the contact of an overhead line conductor with a guy wire

The analysis carried out in this paper refers to a non-occupational accident that occurred in Greece few years ago, in which a man suffered a fatal electric shock, when coming into contact with the metallic protective cover of an energised guy wire of a medium voltage line. From this specific analysis a new class of electrical accident is presented and investigated in which the contact between a medium voltage conductor and a guy wire (or other metallic surface) does not cause the de-energisation of the line (for a variety of reasons), and can result in an energised guy wire which presents an electrocution risk and a fire ignition risk. Proposals of technical and informational measures are made in order to prevent similar future accidents.

Use and performance of the Forest Fire Weather Index to model the risk of wildfire occurrence in the Alpine region

Assessing a territory’s fire proneness is fundamental when planning and undertaking effective forest protection and land management. Accurate methods to estimate the risk of fire ignition in natural environments have been proposed over the last decades and digital mapping has been used to identify critical areas. The Canadian Forest Fire Weather Index is a well-known fire danger rating index created and improved during the last 45 years by the Canadian Forest Service. The goal of this paper is twofold. Firstly, we evaluated whether the Forest Fire Weather Index is an adequate instrument to predict fire ignition in Alpine and sub-Alpine areas using quite a large dataset of meteorological and forest fire data collected in the Lombardy region (Northern Italy) between 2003 and 2011. By means of a spatial binary regression model, we demonstrated that Forest Fire Weather Index has a significant impact on the probability of fire ignition. Since this approach allows us to account for other characteristics of the territory in order to provide a more accurate estimate of the spatial wildfire dynamics at a moderately large scale, the second goal of the paper aims at creating a model to assess fire risk occurrence using the Forest Fire Weather Index and land use information. It has been found that ignition can easily occur in large forested areas whereas denser urban areas are less exposed to fire since they usually have no fuels to ignite. Nevertheless, since human activity has a direct impact on fire ignition human presence, it fosters ignition in forested areas. Finally, the model, including these spatial dimensions, has been employed to derive a probability map of fire occurrences at 1.5 km resolution, which is a fundamental instrument to develop optimal prevention and risk management policy plans for the decision maker.

A multivariate approach for mapping fire ignition risk: the example of the National Park of Cilento (southern Italy).

Recent advances in fire management led landscape managers to adopt an integrated fire fighting strategy in which fire suppression is supported by prevention actions and by knowledge of local fire history and ecology. In this framework, an accurate evaluation of fire ignition risk and its environmental drivers constitutes a basic step toward the optimization of fire management measures. In this paper, we propose a multivariate method for identifying and spatially portraying fire ignition risk across a complex and heterogeneous landscape such as the National Park of Cilento, Vallo di Diano, and Alburni (southern Italy). The proposed approach consists first in calculating the fire selectivity of several landscape features that are usually related to fire ignition, such as land cover or topography. Next, the fire selectivity values of single landscape features are combined with multivariate segmentation tools. The resulting fire risk map may constitute a valuable tool for optimizing fire prevention strategies and for efficiently allocating fire fighting resources.

Increases in fire risk due to warmer summer temperatures and wildland urban interface changes do not necessarily lead to more fires

Forest fire frequency in Mediterranean countries is expected to increase with land cover and climate changes as temperatures rise and rainfall patterns are altered. Although the cause of many Mediterranean fires remains poorly defined, most fires are of anthropogenic origin and are located in the wildland urban interface (WUI), so fire ignition risk depends on both weather and land cover characteristics. The objectives of this study were to quantify the overall trends in forest fire risk in the WUI of the Alpes-Maritimes department in SE France over a period of almost 50 years (about 1960–2009) and relate these to changes in land cover and temperature changes. Land cover for two contrasting reference catchments (236 km2 and 289 km2, respectively) was mapped from available aerial photographs. Changes in fire risk over time were estimated using statistical relationships defined for each type of WUI, where isolated and scattered housing present a greater risk than dense and very dense housing. Summer monthly temperatures and spring and summer precipitation were quantified over the same temporal period as land cover. Finally, trends in fire frequency and burned area were analyzed over a shorter 37 year period (1973–2009) due to the lack of available fire data before 1973. Fire risk associated with WUI expansion increased by about 18%–80% over the 1960–2009 period (depending on the catchment). Similarly, mean summer minimum and maximum monthly temperatures increased by 1.8 °C and 1.4 °C, respectively, over the same period. Summer rainfall appears to decrease over time since about the 1970's but remains highly variable. Land cover and weather changes both suggest an overall increase in fire risk. However, the number of fires and burned area have decreased significantly since about 1990. This paradoxical result is due to a change in fire-fighting strategy which reinforced the systematic extinction of fires in their early stages. Technical support in the form of improved radio communication and helicopters contributed greatly to reducing fire frequency and burned area. Surveillance and legal reforms included the introduction of field patrols and restricted access to forests during high risk periods. Although this has proven highly successful in the short term, the risk of fuel load accumulation over time remains a risk which might contribute to the development of mega-fires in extreme climatic conditions in the future.

Deriving forest fire ignition risk with biogeochemical process modelling

Climate impacts the growth of trees and also affects disturbance regimes such as wildfire frequency. The European Alps have warmed considerably over the past half-century, but incomplete records make it difficult to definitively link alpine wildfire to climate change. Complicating this is the influence of forest composition and fuel loading on fire ignition risk, which is not considered by purely meteorological risk indices. Biogeochemical forest growth models track several variables that may be used as proxies for fire ignition risk. This study assesses the usefulness of the ecophysiological model BIOME-BGC's ‘soil water’ and ‘labile litter carbon’ variables in predicting fire ignition. A brief application case examines historic fire occurrence trends over pre-defined regions of Austria from 1960 to 2008. Results show that summer fire ignition risk is largely a function of low soil moisture, while winter fire ignitions are linked to the mass of volatile litter and atmospheric dryness.

Controls on the spatial pattern of wildfire ignitions in Southern California

Wildfire ignition requires a combination of an open spark, and suitable weather and fuel conditions. Models of fire occurrence and burned area provide a good understanding of the physical and climatic factors that constrain and promote fire spread and recurrence, but information on how humans influence ignition patterns is still lacking at a scale compatible with integrated fire management. We investigated the relative importance of the physical, climatic and human factors regulating ignition probability across Southern California’s National Forests. A 30-year exploratory analysis of one-way relationships indicated that distance to a road, distance to housing and topographic slope were the major determinants of ignition frequency. We used logistic and Poisson regression analyses to model ignition occurrence and frequency as a function of the dominant covariates. The resulting models explained ~70% of the spatial variability in ignition likelihood and 45% of the variability in ignition frequency. In turn, predicted ignition probability contributed to some of the spatial variability in burned area, particularly for summer fires. These models may enable estimates of fire ignition risk for the broader domain of Southern California and how this risk may change with future population and housing development. Our spatially explicit predictions may also be useful for strategic fire management in the region.

Mapping fire ignition risk in a complex anthropogenic landscape

The progressing spread of urban development into the surrounding fuel-loaded wildland creates a particular landscape structure where the co-occurrence of human activities and flammable fuel greatly increases the fire ignition risk. In this framework, land use and land cover (LULC) maps derived from remotely sensed images represent a useful tool for assessing fire risk. The aim of this letter is thus to use a LULC map derived from QuickBird satellite imagery for assessing ignition risk at the rural–forest interface in Sardinia (Italy). Our results show that fire risk is strongly positively correlated with anthropogenic land use and negatively correlated with semi-natural and natural vegetation cover, such as shrubland or forest.