Search Results: 1 - 10 of 100 matches for " "
All listed articles are free for downloading (OA Articles)
Page 1 /100
Display every page Item
Integrating Fire Behavior Models and Geospatial Analysis for Wildland Fire Risk Assessment and Fuel Management Planning  [PDF]
Alan A. Ager,Nicole M. Vaillant,Mark A. Finney
Journal of Combustion , 2011, DOI: 10.1155/2011/572452
Abstract: Wildland fire risk assessment and fuel management planning on federal lands in the US are complex problems that require state-of-the-art fire behavior modeling and intensive geospatial analyses. Fuel management is a particularly complicated process where the benefits and potential impacts of fuel treatments must be demonstrated in the context of land management goals and public expectations. A number of fire behavior metrics, including fire spread, intensity, likelihood, and ecological risk must be analyzed for multiple treatment alternatives. The effect of treatments on wildfire impacts must be considered at multiple scales. The process is complicated by the lack of data integration among fire behavior models, and weak linkages to geographic information systems, corporate data, and desktop office software. This paper describes our efforts to build a streamlined fuel management planning and risk assessment framework, and an integrated system of tools for designing and testing fuel treatment programs on fire-prone wildlands. 1. Introduction Wildland fire risk assessment and fuel management activities have become a major activity in the Forest Service as part of efforts to reduce the growing financial and ecological losses from catastrophic wildfires [1–4]. For instance, between 2004 and 2008, 44,000 fuel treatments were implemented across the western US as part of the National Fire Plan [5], with a large proportion of these on national forest land. The importance of fire risk assessments and fuel management will continue with urban expansion into the wildlands and climate-change effects on fire frequency [6, 7]. Fuel treatment activities encompass a wide range of operational methods including thinning (removal of small trees), mechanical treatment of fuel (i.e., mastication, grinding of surface and ladder fuels), and underburning to reduce both surface and canopy fuel to ultimately reduce the frequency of uncharacteristic wildfires [8]. The goal for specific fuel treatment projects vary widely depending on ecological conditions with respect to natural fire regimes and the spatial pattern of values deemed at risk. For instance, some treatments are designed as localized fuel breaks to minimize fire occurrence within highly valued social and ecological values [9] while others are designed to impede the spread of fire over large landscapes [10]. Both wildfire risk assessment and designing fuel management projects are difficult problems, especially on federal land where planners are required to follow complex planning processes while addressing multiple land
Developing the US Wildland Fire Decision Support System  [PDF]
Erin K. Noonan-Wright,Tonja S. Opperman,Mark A. Finney,G. Thomas Zimmerman,Robert C. Seli,Lisa M. Elenz,David E. Calkin,John R. Fiedler
Journal of Combustion , 2011, DOI: 10.1155/2011/168473
Abstract: A new decision support tool, the Wildland Fire Decision Support System (WFDSS) has been developed to support risk-informed decision-making for individual fires in the United States. WFDSS accesses national weather data and forecasts, fire behavior prediction, economic assessment, smoke management assessment, and landscape databases to efficiently formulate and apply information to the decision making process. Risk-informed decision-making is becoming increasingly important as a means of improving fire management and offers substantial opportunities to benefit natural and community resource protection, management response effectiveness, firefighter resource use and exposure, and, possibly, suppression costs. This paper reviews the development, structure, and function of WFDSS, and how it contributes to increased flexibility and agility in decision making, leading to improved fire management program effectiveness. 1. Introduction Wildland fire in the United States carries the most risk and complexity of any discipline in natural resource management. During the last decade, managers have been faced with making increasingly complex decisions—trying to balance ecological objectives, public protection, and greater budget scrutiny. Examples include balancing ecological needs for fire in national parks (e.g., Yosemite National Park, California, USA), fuel hazard reduction benefits of wildfires, protection of the wildland urban interface, and air quality concerns in large urban areas (e.g., Southern California). While the total budgets for federal land management agencies have remained stagnant or decreased, fire-related expenditures for federal, state, and local entities have increased, reducing the proportion of funds available for achieving other land management responsibilities [1, 2]. Additional factors such as changing fire, fuel, and human population dynamics; increasing diversity in land use objectives; and conflicting public views on costs and benefits of wildland fire have further increased the need for better, more informed management actions to address these complexities. As decision complexity has increased, so too has the expectation that decisions will be transparent and communicated in a compressed time frame. To replace multiple processes developed by different agencies and reduce redundancy, senior fire leaders from all wildland fire management agencies concluded that a single decision analysis and documentation system was needed. This system had to be applicable to all wildland fires, regardless of objectives and situations. An effort was
Assimilation of Perimeter Data and Coupling with Fuel Moisture in a Wildland Fire - Atmosphere DDDAS  [PDF]
Jan Mandel,Jonathan D. Beezley,Adam K. Kochanski,Volodymyr Y. Kondratenko,Minjeong Kim
Physics , 2012, DOI: 10.1016/j.procs.2012.04.119
Abstract: We present a methodology to change the state of the Weather Research Forecasting (WRF) model coupled with the fire spread code SFIRE, based on Rothermel's formula and the level set method, and with a fuel moisture model. The fire perimeter in the model changes in response to data while the model is running. However, the atmosphere state takes time to develop in response to the forcing by the heat flux from the fire. Therefore, an artificial fire history is created from an earlier fire perimeter to the new perimeter, and replayed with the proper heat fluxes to allow the atmosphere state to adjust. The method is an extension of an earlier method to start the coupled fire model from a developed fire perimeter rather than an ignition point. The level set method is also used to identify parameters of the simulation, such as the spread rate and the fuel moisture. The coupled model is available from openwfm.org, and it extends the WRF-Fire code in WRF release.
A complex network theory approach for the spatial distribution of fire breaks in heterogeneous forest landscapes for the control of wildland fires  [PDF]
Lucia Russo,Paola Russo,Constantinos I. Siettos
Physics , 2015,
Abstract: Based on complex network theory, we propose a computational methodology that addresses the spatial distribution of fuel breaks for the inhibition of the spread and size of wildland fires on heterogeneous landscapes. This is a two-tire approach where the dynamics of fire spread are modeled as a random Markov field process on a directed network whose edge weights, are provided by a state-of-the-art cellular automata model that integrates detailed GIS, landscape and meteorological data. Within this framework, the spatial distribution of fuel breaks is reduced to the problem of finding the network nodes among which the fire spreads faster, thus their removal favours the inhibition of the fire propagation. Here this is accomplished exploiting the information centrality statistics. We illustrate the proposed approach through (a) an artificial forest of randomly distributed density of vegetation, and (b) a real-world case concerning the island of Rhodes in Greece whose a major part of its forest burned in 2008. Simulation results show that the methodology outperforms significantly the benchmark tactic of random distribution of fuel breaks.
A review of wildland fire spread modelling, 1990-present 2: Empirical and quasi-empirical models  [PDF]
A. L. Sullivan
Physics , 2007, DOI: 10.1071/WF06142
Abstract: In recent years, advances in computational power and spatial data analysis (GIS, remote sensing, etc) have led to an increase in attempts to model the spread and behaviour of wildland fires across the landscape. This series of review papers endeavours to critically and comprehensively review all types of surface fire spread models developed since 1990. This paper reviews models of an empirical or quasi-empirical nature. These models are based solely on the statistical analysis of experimentally obtained data with or without some physical framework for the basis of the relations. Other papers in the series review models of a physical or quasi-physical nature, and mathematical analogues and simulation models. The main relations of empirical models are that of wind speed and fuel moisture content with rate of forward spread. Comparisons are made of the different functional relationships selected by various authors for these variables.
The wildland fire emission inventory: western United States emission estimates and an evaluation of uncertainty
S. P. Urbanski, W. M. Hao,B. Nordgren
Atmospheric Chemistry and Physics (ACP) & Discussions (ACPD) , 2011,
Abstract: Biomass burning emission inventories serve as critical input for atmospheric chemical transport models that are used to understand the role of biomass fires in the chemical composition of the atmosphere, air quality, and the climate system. Significant progress has been achieved in the development of regional and global biomass burning emission inventories over the past decade using satellite remote sensing technology for fire detection and burned area mapping. However, agreement among biomass burning emission inventories is frequently poor. Furthermore, the uncertainties of the emission estimates are typically not well characterized, particularly at the spatio-temporal scales pertinent to regional air quality modeling. We present the Wildland Fire Emission Inventory (WFEI), a high resolution model for non-agricultural open biomass burning (hereafter referred to as wildland fires, WF) in the contiguous United States (CONUS). The model combines observations from the MODerate Resolution Imaging Spectroradiometer (MODIS) sensors on the Terra and Aqua satellites, meteorological analyses, fuel loading maps, an emission factor database, and fuel condition and fuel consumption models to estimate emissions from WF. WFEI was used to estimate emissions of CO (ECO) and PM2.5 (EPM2.5) for the western United States from 2003–2008. The uncertainties in the inventory estimates of ECO and EPM2.5 (uECO and uEPM2.5, respectively) have been explored across spatial and temporal scales relevant to regional and global modeling applications. In order to evaluate the uncertainty in our emission estimates across multiple scales we used a figure of merit, the half mass uncertainty, EX (where X = CO or PM2.5), defined such that for a given aggregation level 50% of total emissions occurred from elements with uEX EX. The sensitivity of the WFEI estimates of ECO and EPM2.5 to uncertainties in mapped fuel loading, fuel consumption, burned area and emission factors have also been examined. The estimated annual, domain wide ECO ranged from 436 Gg yr 1 in 2004 to 3107 Gg yr 1 in 2007. The extremes in estimated annual, domain wide EPM2.5 were 65 Gg yr 1 in 2004 and 454 Gg yr 1 in 2007. Annual WF emissions were a significant share of total emissions from non-WF sources (agriculture, dust, non-WF fire, fuel combustion, industrial processes, transportation, solvent, and miscellaneous) in the western United States as estimated in a national emission inventory. In the peak fire year of 2007, WF emissions were ~20% of total (WF + non-WF) CO emissions and ~39% of total PM2.5 emissions. During the months with the greatest fire activity, WF accounted for the majority of total CO and PM2.5 emitted across the study region. Uncertainties in annual, domain wide emissions was 28% to 51% for CO and 40% to 65% for PM2.5. Sensitivity of ECO and EPM2.5 to the emission model components depended on scale. At scales relevant to regional modeling applications (Δx = 10 km, Δt = 1 day) WFEI estimates
Review of Vortices in Wildland Fire  [PDF]
Jason M. Forthofer,Scott L. Goodrick
Journal of Combustion , 2011, DOI: 10.1155/2011/984363
Abstract: Vortices are almost always present in the wildland fire environment and can sometimes interact with the fire in unpredictable ways, causing extreme fire behavior and safety concerns. In this paper, the current state of knowledge of the interaction of wildland fire and vortices is examined and reviewed. A basic introduction to vorticity is given, and the two common vortex forms in wildland fire are analyzed: fire whirls and horizontal roll vortices. Attention is given to mechanisms of formation and growth and how this information can be used by firefighters. 1. Introduction Large fire whirls are often one of the more spectacular aspects of fire behavior. Flames flow across the ground like water feeding into the base of the vortex, the lowest thousand feet of which often takes on an orange glow from combusting gases rising within the vortex core. Burning debris lofted within the vortex can lead to a scattering of spot fires some distance from the main fire. With their sudden formation, erratic movement, and often sudden dissipation, fire whirls are a good example of extreme fire behavior. However, other forms of vortices are actually quite common on wildland fires and receive less attention despite their potential to dramatically alter fire behavior. This paper is designed to provide a better understanding of vortices associated with wildland fires, both fire whirls, and horizontal roll vortices. A key point will be providing a basic understanding of what aspects of the fire environment contribute to the development and growth of these vortices. The next section supplies a brief introduction to vorticity, a measure of the atmosphere's tendency to spin or rotate about some axis. With this basic understanding of vorticity, we will examine the common vortex forms described in the fire behavior literature, fire whirls, and horizontal roll vortices. 2. Vorticity Basics Simply stated, vorticity is the measure of spin about an axis. That axis can be vertical, as in the case of a fire whirl, or horizontal for a roll vortex, or somewhere in between. Mathematically, vorticity is a vector quantity (it has both magnitude and directional information) that is defined as the curl of the wind field: or in component form: As a simple hypothetical example, take a vertical cross-section through a fire with no ambient horizontal winds (Figure 1). The vertical winds near the ground can be characterized by a strong updraft over the fire and descending air outside of the fire area. The change in the vertical velocity along the x-axis imparts rotation to the flow field about the
Modeling Wildland Fire Propagation with Level Set Methods  [PDF]
V. Mallet,D. E. Keyes,F. E. Fendell
Mathematics , 2007,
Abstract: Level set methods are versatile and extensible techniques for general front tracking problems, including the practically important problem of predicting the advance of a firefront across expanses of surface vegetation. Given a rule, empirical or otherwise, to specify the rate of advance of an infinitesimal segment of firefront arc normal to itself (i.e., given the firespread rate as a function of known local parameters relating to topography, vegetation, and meteorology), level set methods harness the well developed mathematical machinery of hyperbolic conservation laws on Eulerian grids to evolve the position of the front in time. Topological challenges associated with the swallowing of islands and the merger of fronts are tractable. The principal goals of this paper are to: collect key results from the two largely distinct scientific literatures of level sets and firespread; demonstrate the practical value of level set methods to wildland fire modeling through numerical experiments; probe and address current limitations; and propose future directions in the simulation of, and the development of decision-aiding tools to assess countermeasure options for, wildland fires. In addition, we introduce a freely available two-dimensional level set code used to produce the numerical results of this paper and designed to be extensible to more complicated configurations.
Forest Fire Risk Assessment: An Illustrative Example from Ontario, Canada  [PDF]
W. John Braun,Bruce L. Jones,Jonathan S. W. Lee,Douglas G. Woolford,B. Mike Wotton
Journal of Probability and Statistics , 2010, DOI: 10.1155/2010/823018
Abstract: This paper presents an analysis of ignition and burn risk due to wildfire in a region of Ontario, Canada using a methodology which is applicable to the entire boreal forest region. A generalized additive model was employed to obtain ignition risk probabilities and a burn probability map using only historic ignition and fire area data. Constructing fire shapes according to an accurate physical model for fire spread, using a fuel map and realistic weather scenarios is possible with the Prometheus fire growth simulation model. Thus, we applied the Burn-P3 implementation of Prometheus to construct a more accurate burn probability map. The fuel map for the study region was verified and corrected. Burn-P3 simulations were run under the settings (related to weather) recommended in the software documentation and were found to be fairly robust to errors in the fuel map, but simulated fire sizes were substantially larger than those observed in the historic record. By adjusting the input parameters to reflect suppression effects, we obtained a model which gives more appropriate fire sizes. The resulting burn probability map suggests that risk of fire in the study area is much lower than what is predicted by Burn-P3 under its recommended settings. 1. Introduction Fire is a naturally occurring phenomenon on the forested landscape. In Canada's boreal forest region, it plays an important ecological role. However, it also poses threats to human safety and can cause tremendous damage to timber resources and other economic assets. Wildfires have recently devastated parts of British Columbia, California, and several other locations in North America, Europe, and Australia. The economic losses in terms of suppression costs and property damage have been staggering, not to mention the tragic loss of human life. Many of these fires have taken place at the wildland-urban interface—predominantly natural areas which are increasingly being encroached upon by human habitation. As the population increases in these areas, there would appear to be potential for increased risk of economic and human loss. A wildland-urban interface is defined as “any area where industrial or agricultural installations, recreational developments, or homes are mingled with natural, flammable vegetation” [1]. The Province of Ontario has several areas which could be classified as wildland-urban interface. These areas include the Lake of the Woods region, the Thunder Bay region, the region surrounding Sault St. Marie, and North Bay among others. One of the most significant of these is the District of Muskoka
Experimental Investigation of Radiation Emitted by Optically Thin to Optically Thick Wildland Flames  [PDF]
P. Boulet,G. Parent,Z. Acem,A. Kaiss,Y. Billaud,B. Porterie,Y. Pizzo,C. Picard
Journal of Combustion , 2011, DOI: 10.1155/2011/137437
Abstract: A series of outdoor experiments were conducted in a fire tunnel to measure the emission of infrared radiation from wildland flames, using a FTIR spectrometer combined with a multispectral camera. Flames of different sizes were produced by the combustion of vegetation sets close to wildland fuel beds, using wood shavings and kermes oak shrubs as fuels. The nongray radiation of the gas-soot mixture was clearly observed from the infrared emitted intensities. It was found that the flame resulting from the combustion of the 0.50?m long fuel bed, with a near-zero soot emission, may be considered as optically thin and that the increase in bed length, from 1 to 4?m, led to an increase in flame thickness, and therefore, in flame emission with contributions from both soot and gases. A further analysis of the emission was conducted in order to evaluate effective flame properties (i.e., emissivity, extinction coefficient, and temperature). The observation of emission spectra suggests thermal nonequilibrium between soot particles and gas species that can be attributed to the presence of relatively cold soot and hot gases within the flame. 1. Introduction Radiation heat transfer plays an important role in the ignition, spread, and intensity of wildland fires. The experimental characterization of radiation from wildland flames is a very active field of research, as demonstrated by recent contributions (e.g., Chetehouna et al. [1], Butler et al. [2], Dupuy et al. [3], Boulet et al. [4], Agueda et al. [5], and Parent et al. [6]). These contributions raise some important issues, such as those related to the uncertainties and interpretation of results and to the importance of flame scale. A commonly used simplified approach consists in evaluating effective flame properties, modeling the flame as a radiating surface with constant temperature and emissivity. However, neglecting the distributions of temperature and species concentrations and the wavelength dependence and ignoring that emission comes from the volume of flame (or a part of it) can cause noticeable errors. Moreover, temperature and emissivity are two unknowns that must be determined from a single emission acquisition. An alternative approach to estimating flame emission is to determine an extinction coefficient that includes the contributions of both gas species and soot and to consider radiation coming from a volumetric domain representing the flame. When dealing with radiation measurements, special attention to the spectral range is required. Water vapor is known to produce emission bands in the ranges
Page 1 /100
Display every page Item

Copyright © 2008-2017 Open Access Library. All rights reserved.