Knowledge management: An application to wildfire prevention planning

Residential encroachment into wildland areas places an additional burden on fire management activities. Prevention programs, fuel management efforts, and suppression strategies, previously employed in wildland areas, require modification for protection of increased values at risk in this interface area. Knowledge-based computer systems are being investigated as knowledge management tools for the organization, synthesis, and application of information pertinent to fire science utilization. Many such systems contain expertise which has been captured from human experts and symbolically encoded for automatic manipulation by computer. Two systems, fire characteristics prediction and initial-attack force dispatch, have been developed elsewhere using this approach. This paper describes a third project, which is currently being developed for wildfire prevention planning. Initial efforts in elicitation of knowledge from experts have produced several benefits prior to system implementation. Results to date in fire management are encouraging, and provide support for the future potential of these methods for the management of knowledge gained from fire research.     

Wildland fire modeling with an Eulerian level set method and automated calibration

This paper presents the mathematical development of a geospatial model for simulating wildland fire spread. The Eulerian level set method (LSM), a mathematical technique that tracks interfaces between separate regions on a regular grid, is applied here to track the interface between burned (or burning) areas and green areas. Model physics include surface fire spread rate and direction, transition from surface fire to passive or active crown fire, ember lofting, trajectory tracking, and spot fire formation, acceleration from point ignitions, and modifications to fuel strata attributed to suppression activities. A novel aspect of this work involves application of a stochastic optimization algorithm to automatically calibrate baseline model inputs by comparing calculated fire perimeters to observed (target) fire perimeters. The wildland fire model and associated automated calibration technique are assessed by simulating the first 22 h of progression of the 2007 Moonlight Fire in Northern California. Fuels and topography inputs are obtained from the Landfire project while wind and weather inputs are obtained from high resolution numerical weather prediction. Fire areas simulated with the calibrated model agree well with target perimeters.     

Enticing Arsonists with Broken Windows and Social Disorder

In criminology, it is well understood that indicators of urban decay, such as abandoned buildings littered with broken windows, provide criminals with signals identifying neighborhoods with lower crime detection and apprehension rates than better maintained neighborhoods. Whether it is the resident population’s sense of apathy, lack of civic pride, or fear of confrontation that causes criminals to perceive an easy mark, it nevertheless emboldens them to strike. Previous research of wildland arson hints that broken windows (e.g., areas of criminal activity) are partly responsible for arson outbreaks within the wildland–urban interface. We model the incidence of wildland and non-wildland arson ignitions in Michigan from 2001 to 2005 as a function of constructed Broken Windows indices. Our results suggest that crime prevention and urban revitalization programs may be as valuable as fire suppression, fuels management, and law enforcement in limiting incidence and the damage from both wildland and non-wildland arson.     

Wildland fire spot ignition by sparks and firebrands

Wildland and Wildland Urban Interface (WUI) fires are an important problem in many areas of the world and may have major consequences in terms of safety, air quality, and damage to buildings, infrastructure, and the ecosystem. It is expected that with climate changes the wildland fire and WUI fire problem will only intensify. The spot fire ignition of a wildland fire by hot (solid, molten or burning) metal fragments/sparks and firebrands (flaming or glowing embers) is an important fire ignition pathway by which wildfires, WUI fires, and fires in industrial settings are started and may propagate. There are numerous cases reported of wildfires started by hot metal particles from clashing power-lines, or generated by machines, grinding and welding. Once the wildfire or structural fire has been ignited and grows, it can spread rapidly through ember spotting, where pieces of burning material (e.g. branches, bark, building materials, etc.) are lofted by the plume of the fire and then transported forward by the wind landing where they can start spot fires downwind. The spot fire problem can be separated in several individual processes: the generation of the particles (metal or firebrand) and their thermochemical state; their flight by plume lofting and wind drag and the particle thermo-chemical change during the flight; the onset of ignition (smoldering or flaming) of the fuel after the particle lands on the fuel; and finally, the sustained ignition and burning of the combustible material. Here an attempt has been made to summarize the state of the art of the wildfire spotting problem by describing the distinct individual processes involved in the problem and by discussing their know-how status. Emphasis is given to those areas that the author is more familiar with, due to his work on the subject. By characterizing these distinct individual processes, it is possible to attain the required information to develop predictive, physics-base wildfire spotting models. Such spotting models, together with topographical maps and wind models, could be added to existing flame spread models to improve the predictive capabilities of landscape-scale wildland fire spread models. These enhanced wildland fire spread models would provide land managers and government agencies with better tools to prescribe preventive measures and fuels treatments before a fire, and allocate suppression resources and issue evacuation orders during a fire.     

Parametric study of urban fire spread using an urban fire simulation model with fire department suppression

Although urban conflagrations are rare now, the threat still exists in two situations—following an earthquake and when a wildland fire reaches an urban area. In this paper, we first extend a previously developed urban fire simulation model to include fire department suppression, making it a complete, integrated ignition-spread-suppression model that can now better estimate urban fire risk and help understand the effectiveness of fire department efforts. We then apply this Urban Fire Simulation model (UFS2) to a case study area in California and conduct a parametric study to examine the key factors that influence fire spread and the interactions among them. The results suggest that urban fire spread is highly variable and under the right combination of unlucky but possible circumstances—many ignitions, high wind speeds, and limited water availability—the losses can be very high, much higher than observed in recent earthquakes. In addition to the three factors mentioned, the locations of the ignitions (relative to wind direction and fire breaks), number of engines, and engine arrival times are shown to be important. Strong interactions are evident between wind speed and number of ignitions, and between water availability and number of engines.     

Applying building information modeling to support fire safety management

Building information modeling (BIM) is useful in three-dimensional (3D) visualization and data/information storage for planning and maintaining building projects. Recently, researchers globally have been exploring the applications of BIM. In this work, a BIM-based model is designed to support fire safety management of buildings. The model comprises four modules — evacuation assessment, escape route planning, safety education, and equipment maintenance. The evacuation assessment module integrates BIM with a Fire Dynamics Simulator to calculate the required safety egress time and the available safety egress time to evaluate the ability to evacuate in case of fire. The escape route planning module utilizes BIM to determine whether the distance of an escape route is acceptable. The safety education module presents hazardous areas, videos of escape routes and directional maps, all in three dimensions, to educate the occupants of the building about fire safety. The equipment maintenance module is implemented in a web-based prototype to support maintenance tasks in a remote management manner. The results of applying BIM have demonstrated that BIM can effectively provide 3D geometric data to support the assessment and planning of fire safety (using the first three modules), and it can store information in support of safety management and property management in a web-based environment (using the equipment maintenance module).     

Optinum suppression tactics—A model and some theorems

The author presents an analytic model of tactical decision making for wildland fire suppression, which emphasizes the control line concept. After determining solutions for several representations of practical constraint conditions, he concludes that control tactices can be simulated mathematically. However, he also outlines areas requiring further work.     

Establishing safety distances for wildland fires

In wildland fires, safety zones should be considered concerning people who are intervening in the emergency or attempting evacuation. To establish such zones, the solid flame model, together with the view factor calculated from a previously selected equation, was used to estimate the thermal radiation emitted by the flame front of a wildland fire. After determining the flame heights yielded by the 13 fuel types in the Rothermel classification for surface fires, and for crown fires in various Mediterranean forests, the thermal radiation was calculated for each scenario as a function of the distance. These data, together with threshold values for the vulnerability of people (protected or unprotected) and houses to thermal radiation, allowed for a set of safety distances for different situations to be obtained. These safety distances can be applied both in territory planning and in emergency situations.     

Fire protection in the urban/wildland interface: Who plays what role?

The problem of fire protection in the urban/wildland interface is a complex combination of three components: fire behavior and combustion, social and political factors, and the cooperation of property owners. By examining the problem's component parts, it is easier to understand its complexity and to integrate often quite diverse factors relating to interface fire protection.     

孤立森林算法的灭火救援疏散路径规划方法

针对建筑火灾中人员疏散路径规划问题,提出基于孤立森林算法的灭火救援疏散路径规划的方法。运用布置在火灾现场的无线传感器网络采集火灾环境信息,构建火灾数据样本,随机分割并训练火灾数据样本,创建多个孤立二叉树组建孤立森林,识别火灾异常数据,获得着火点及障碍物位置,并以栅格法构建火灾救援环境动态地图为基础,通过更新位置节点当量距离、信息素浓度以及信息素挥发因子的改进蚁群算法,构建救援疏散路径组合优化模型,规划出最佳灭火救援疏散路径。测试结果表明：该方法可准确检测火灾中的着火点位置,可在多起点、多终点的救援疏散路径规划中更好地避开着火点和障碍物,快速、合理地规划出最佳灭火救援疏散路径。     

Flammability characterisation of grassland species of Songhua Jiang-Nen Jiang Plain (China) using thermal analysis

The aim of this work was to study the flammability of grassland fuels of the Songhua Jiang-Nen Jiang Plain in China. A Pyris Diamond TG-DTG was used, and the grassland materials examined were Aneurolepidium chinense, Chloris virgata, Phragmites communis, Suaeda corniculata, Lathyrus quinquenervius, Hemarthria japonica, Puccinellia chinampoensis, Calamagrostis epigejos, Medicago ruthenica and Lespedeza davurica. These species are very common in the Songhua Jiang-Nen Jiang Plain, and are frequently devastated by wildland fires. Mass loss is an important index for modelling wildland fires and for fire hazard studies on biomass fuels. In the TG-DTG curves, evaporation of a moisture peak and two dominating thermal oxidative degradation peaks were recorded. The relative data determined was used to compare the ignitability, combustibility and sustainability of the species. An index of integrated flammability was calculated for the examined species, and the relative flammability was ranked in the order: Medicago ruthenica>Suaeda corniculata>Lespedeza davurica>Lathyrus quinquenervius>Chloris virgata>Hemarthria japonica>Puccinellia chinampoensis>Phragmites communis>Calamagrostis epigejos>Aneurolepidium chinense. The flammability ranking of these natural fuels can be used in grassland fire management planning, fire behaviour modelling and fire hazard assessment.     

Protecting Lives and Property in the Wildland–Urban Interface: Communities in Montana and Southern California Adopt Australian Paradigm

Threats to people and property in the wildland–urban interface have taken on global proportions. It is becoming increasingly rare to have a wildland fire incident that does not involve people and their homes. In addition to Australia and North America, people have died in interface fires in Europe, Africa, and Asia, including 212 people who died in the devastating forest fires in northeastern China in May 1987. The prevailing interface model is one that attempts to evacuate people away from fire areas to get them out of harm’s way. This traditional approach in the U.S. has been preferred by law enforcement agencies and fire services. The problem with this model is that evacuation warnings are often late to non-existent, leading to the deaths of interface residents entrapped by fires on highways as they try to escape. For example, 16 people suffered lethal burns when the 2003 Cedar and Paradise Fires in California overran them as they were trying to evacuate. Two communities in the United States have adopted variations of the Australian model of Prepare, Go Early, or Stay and Defend (P/GE/SD). Officials in the Painted Rocks Fire District, Montana, and Rancho Santa Fe, California, were interviewed to determine how the Australian model was being implemented. Two of the authors have firsthand experience with these two case examples. P/GE/SD has been tested successfully at both locations. The Australian model, however, is under review following the Black Saturday fires of February 2009 in Victoria, Australia. The objective of this paper is to present specific ideas that can be used to reform and improve fire policy, planning, and performance in the Wildland–Urban Interface in the United States.     

A Review of Pathways for Building Fire Spread in the Wildland Urban Interface Part II: Response of Components and Systems and Mitigation Strategies in the United States

Structure loss in wildland fires has significantly increased over the past few decades, affected by increased development in rural areas, changing fuel management policies, and climate change, all of which are projected to increase in the future. This paper is Part II of a two-part review, which presents a summary of fundamental and applied research on pathways to fire spread in the wildland urban interface. Part I discussed the fundamentals of wildland fire spread via radiative heat transfer, direct flame contact, and firebrand exposure. Here in Part II, we cover the response of building components and systems, as well as mitigation strategies used to prevent fire spread into and within communities in the United States. Post-fire investigations, full-scale structural testing, individual component testing, and combined systems or assembly testing have been used to identify building component and system vulnerabilities such as roofs, vents, siding, decks, fences, and mulch. Using results from these tests and investigations at different scales, some knowledge has been gained on specific vulnerabilities and the effectiveness of mitigation strategies, but a quantitative framework has not yet been established. On a community level, the layout of structures and the space between them has been shown to be incredibly important in mitigating wildfire risk. More locally, defensible space around homes has been effective in mitigating exposure from both radiation and direct flame contact. Firebrands still remain a challenge; however, many design recommendations have been proposed to harden structures against firebrand exposures. Recommendations for future research and development are also presented.     

Review of Pathways for Building Fire Spread in the Wildland Urban Interface Part I: Exposure Conditions

While the wildland–urban interface (WUI) is not a new concept, fires in WUI communities have rapidly expanded in frequency and severity over the past few decades. The number of structures lost per year has increased significantly, due in part to increased development in rural areas, fuel management policies, and climate change, all of which are projected to increase in the future. This two-part review presents an overview of research on the pathways for fire spread in the WUI. Recent involvement of the fire science community in WUI fire research has led to some great advances in knowledge; however, much work is left to be done. While the general pathways for fire spread in the WUI (radiative, flame, and ember exposure) are known, the exposure conditions generated by surrounding wildland fuels, nearby structures or other system-wide factors, and the subsequent response of WUI structures and communities are not well known or well understood. This first part of the review covers the current state of the WUI and existing knowledge on exposure conditions. Recommendations for future research and development are also presented for each part of the review.     

Concepts of Wildland Fire Protection of Cultural Monuments and National Parks in Greece. Case Study: Digital Telemetry Networks at the Forest of Ancient Olympia

The concepts and particularities of fire protection planning for monuments of cultural heritage that are surrounded by national parks and other public wildlands are outlined, in the context of the general wildland fire problem of Greece. Typical examples of cultural monuments that were threatened by wildland fires in Greece are reported. A conceptual flowchart that combines optimal fire protection objectives with the protected values and functions of the national parks and cultural monuments is analyzed. A case-study presents the development of an electronic forest fire protection support system in the forest around the Ancient Olympia site in Greece, as an example of the potential deployment of innovative technologies in wildland fire protection. The aim of the system is twofold. First, the system supports remote monitoring of an extensive hydraulic network of pipelines, pumps and water-storage tanks build in the vicinity of the site. Second, the system provides means for remote operation of numerous revolving water-jets installed on top of heavy-duty tree-high metal towers, spread at key-locations inside the surrounding forest. All system telemetry data and command signals are transmitted through a single underground wire link requiring no external electric power at sensor/actuator locations inside the forest. Special user interfaces allow immediate system deployment either from a central graphics-based console screen or from purpose-build remote consoles installed at selected locations in the forest, thus achieving a high degree of readiness.     

A Case Study of a Community Affected by the Witch and Guejito Wildland Fires

Wildland-urban interface (WUI) fires occur when fire spreads through both wildland and community (structures and vegetation) fuels. These fires are capable of causing significant destruction to both the built and the natural environments. When these fires occur under extreme fire danger conditions (e.g., high winds, low humidity) and in areas of significant population (e.g., San Diego, California) firefighters, and other emergency responders, are significantly challenged by the combination of firefighting and aiding the public. This paper presents the results of an in-depth case study of a community of 274 residences which was subjected to two wildland fires (within 2.5 h of each other) during the October 2007 firestorm in southern California. A significant amount of effort was spent obtaining information from residents and emergency responders to determine the fire spread timeline, structure ignition mechanisms, and defensive actions. Of the 274 residences, 245 were within the fire perimeter, 74 were destroyed, and 16 were damaged. When the first fire front arrived, the rate of structure ignitions peaked at 21 per hour. Direct and indirect ember, or firebrand, attack was responsible for the ignition of 2/3 of the destroyed homes. Defensive actions were taken on one of every three homes. Of the 16 damaged homes, 15 were successfully defended. Further study of this community is ongoing to investigate what currently recommended pre-fire hazard reduction actions could be, and were, implemented and their effectiveness at reducing the likelihood of structure ignition.     

A methodology for comparing the relative effectiveness of suppressant enhancers designed for the direct attack of wildfires

Suppressant chemicals are often added to water for use in the direct attack of wildfires to extend the longevity and suppression effects of the water. There are a range of suppressants available, however there has been limited testing to determine which are the most effective. This paper presents an experimental methodology designed to enable the comparison of the relative effectiveness of wildfire suppressants applied in direct attack to fires in forest fuels. The method involves suppressants being applied onto the flaming fronts of standardised laboratory fires burning in uniform forest litter fuels within a wind tunnel through a pressurised system mounted above the burning fuel. The minimum volume of suppressant required to extinguish a standard fire is determined and used to quantify suppressant effectiveness. Examples of the method are presented for plain water and water with three types of wildland fire suppressant. Results show that repeated tests conducted with the same suppressants have low variability (coefficient of variation ~10.8%) and thus high reliability. In order to minimise effects of non-controlled variation in fire behaviour between tests, results can be normalised to produce relative values for comparison across datasets.     

Integration of field chemical data in initial risk assessment of forest fire smoke

A risk assessment framework was used to assess the risks of forest fire smoke (ffs) to the exposed communities, critical infrastructures and the environment. The present work is focused on the planning and problem formulation phases of this risk assessment procedure. Specifically, as part of the problem formulation phase, integration of the available ffs chemical data was carried out by answering critical questions regarding the ffs. In this way, critical factors have been identified, which mostly define and characterize ffs as a cause of problems and possible symptoms. The integrated information can be used in order to determine assessment endpoints, conceptual models, and risk hypotheses, as presented in an indicative example referred to a simple risk scenario. This work, enhanced with additional risk scenarios, can be used for the next phases of the risk assessment procedure, such as risk analysis and risk characterization. Future research needs for adequate evaluation of ffs impacts on communities, infrastructures, and the environment are also discussed.     

Ignition of Combustible Fuel Beds by Hot Particles: An Experimental and Theoretical Study

The process of spotting occurs in wildland fires when fire-lofted embers or hot particles land downwind, leading to ignition of new, discrete fires. This common mechanism of wildland fire propagation can result in rapid spread of the fire, potentially causing property damage and increased risk to life safety of both fire fighters and civilians. Despite the increasing frequency and losses in wildland fires, there has been relatively little research on ignition of fuel beds by embers and hot particles. In this work, an experimental and theoretical study of ignition of homogeneous cellulose fuel beds by hot metal particles is undertaken. This type of well-characterized laboratory fuel provides a more controllable fuel bed than natural fuels, and the use of hot metal particles simplifies interpretation of the experiments by reducing uncertainty due to unknown effects of the ember combustion reaction. Spherical steel particles with diameters in the range from 0.8 mm to 19.1 mm heated to temperatures between 500°C and 1300°C are used in the experiments. A relationship between the size of the particle and temperature required for flaming or smoldering ignition is found. These results are used to assess a simplified analysis based on hot-spot ignition theory to determine the particle size-temperature relationship required for ignition of a cellulose fuel bed.