Increase in carbon emissions from forest fires after intensive reforestation and forest management programs

This paper shows an example of substantial increase in carbon emissions from forest fires after reforestation on a national scale. It is the first estimation of historical carbon emissions from forest fires in Korea during the last 40 years. Investigation was focused on the recent increase in large forest fires and its closely related factors. A simple modeling approach to estimate carbon emission was applied. The direct carbon emission from forest fires in 2000, ranging from 115 to 300 Gg C, corresponds to 1-3% of the annual carbon uptake by forests. The influence of forest fires on the carbon cycle in Korea is not so significant, but Korean forests have a large potential for generating severe local fires due to increasing forest carbon density and a high forest area ratio (forest area/total land area) of 65%. The carbon emission per area burned (Mg C ha(-1)) clearly reflects the trend toward increases in the number of severe fires. Statistical analyses and the trends of annual temperature and precipitation show that the recent large increase in carbon emissions may be the negative consequences of intensive forest regrowth that is the product of successful reforestation and forest management programs rather than the effect of climate change. These results imply a need for further studies in other countries, where large-scale plantation has been conducted, to evaluate the role of plantation and forest fires on the global carbon cycle.     

The 2007 forest fires in the prefecture of Ilia: the views of citizens with regard to the actions taken before,during and after the fires

In 2007, the prefecture of Ilia, Peloponnese, Greece, was struck by very serious fires which were not only the result of extreme weather but also of human omissions and mistakes. This paper examines the views of the citizens of Ilia with regard to the actions of the Fire Department, the municipal authorities, the Forest Service, the citizens and the state, before, during and after the fires.     

Assessment of gaseous emissions and radiative forcing in Indian forest fires

This paper reports a study of the gaseous emissions from Indian forest fires from 2005 to 2016 and their potential impact on radiative forcing. Initially, forest burned area is quantified using MODIS-MCD45A1 data. Results showed that annual burned area of the study period ranges from 8439 km² to 25,442 km² and the maximum forest area is burned during February, March, and April in any year. Gaseous emissions are estimated using emission factors, the mass of fuel available for combustion, combustion factor, and burned area. CO₂, CO, and CH₄ are the major emissions during forest fires with an annual average of 105 × 10⁶ tonnes, 6 × 10⁶ tonnes, and 3.25 × 10⁵ tonnes, respectively. The average radiative forcing (RF) for CO₂, CH_4, and N₂O is estimated as 1.8 Wm^?2, 0.49 Wm^?2, and 0.177 Wm^?2, respectively. An important finding in the present study is the recurrence of forest fires during the pre-monsoon season.     

Fire whirls in forest fires: An experimental analysis

This work presents a study on the formation of fire whirls with vertical axis on wildfires at laboratory scale. A particularity of the study is the use of typical forest fuels instead of fossil fuels as seen in some of previous studies on this topic. The forest fuels tested in the experiments were dead needles of Pinus pinaster, straw of Avena sativa, dead leaves of Eucalyptus globulus and a mix of shrubs mainly composed by heather (Erica australis) and gorse (Pterospartum tridentatum). The experimental results of the tests with and without forced flow inside a fire whirl generator were compared with tests in similar conditions out of the generator. It was possible to evaluate the effects of fuel bed size, bulk density and external vorticity on several parameters like flame height and diameter, mass decay and heat release rate. The results show that forced flow increases dramatically the burning rate and reduces the time needed to achieve a high rate of energy release. Comparison with results of other sources show that the flames that are generated in the present fire whirl generator are in a transition from fire whirl to pool fire regime and that it is possible to scale up some flow and thermal properties of field scale fire whirls and to derive predictive models on the basis of laboratory scale experiments.     

基于PyroSIM的火灾树木建模研究

通过对树木形态参数的研究,根据FDS的预、后处理的图形软件PyroSIM中建模的特点和FDS计算时对模型的要求,探究了一种适用于FDS火灾模拟软件的树木建模方法.将树木模型简化为树干和树冠两部分,并将树冠分为锥形、纺锤形和半球形三种,分别建立网格模型.     

Solar activity as a possible cause of large forest fires--a case study: analysis of the Portuguese forest fires

Fires of large dimension destroy forests, harvests and housing objects. Apart from that combustion products and burned surfaces become large ecological problems. Very often fires emerge simultaneously on different locations of a region so a question could be asked if they always have been a consequence of negligence, pyromania, high temperatures or maybe there has been some other cause. This paper is an attempt of establishing the possible connection between forest fires that numerous satellites registered and activities happening on the Sun immediately before fires ignite. Fires emerged on relatively large areas from Portugal and Spain on August 2005, as well as on other regions of Europe. The cases that have been analyzed show that, in every concrete situation, an emission of strong electromagnetic and thermal corpuscular energy from highly energetic regions that were in geo-effective position had preceded the fires. Such emissions have, usually, very high energy and high speeds of particles and come from coronary holes that also have been either in the very structure or in the immediate closeness of the geo-effective position. It should also be noted that the solar wind directed towards the Earth becomes weaker with deeper penetration towards the topographic surface. However, the results presented in this paper suggest that, there is a strong causality relationship between solar activity and the ignition of these forest fires taking place in South-western Europe.     

Flammability Assessment of Mediterranean Forest Fuels

The time-to-ignition of various dominant Mediterranean forest fuels was measured during laboratory tests, in order to develop a relative flammability classification and determine the moisture of extinction of these fuels. The tests were performed with an ignition apparatus manufactured according to the ISO standards (ISO 5657-1986E) and under a wide gradient of fuel moisture contents, ranging from air-dry to fresh foliage. Moisture content was the single most significant factor that affected fuel flammability. Regression models were developed between the time-to-ignition and the moisture content values of all the fuels tested, and subsequently, were used for the relative flammability ranking of these fuels. Fuel moisture of extinction was assessed to have a threshold value ranging from 40% to more than 140% o.d.w. for the species tested. The flammability ranking of natural fuels can be useful in fuel hazard assessment and fire danger rating, thus facilitating the judicial fire management planning in wildlands and at the rural-urban interface.     

Estimating room temperatures from fires along walls and in corners

Determination of temperatures associated with room fires provides a means of assessing an important aspect of fire hazard: the likelihood of the occurrence of flashover. Layer temperatures in excess of 600°C have been associated with the occurrence of flashover. A data correlation has previously been presented to estimate layer temperatures for fires burning in the center of rooms. For fires in corners and along walls, restricted entrainment results in higher layer temperatures than predicted by the previous correlation. Modification factors for the previous correlation are developed to extend its applicability to wall and corner burning geometries. The present analysis suggests that a fire in a corner may cause flashover with only half the heat release rate necessary for a fire burning in the center of a room. Reference: Frederick Mowrer and Robert Williamson, Estimating Room Temperatures from Fires along Walls and in Corners,Fire Technology, Vol. 23, May 1987, pp. 133–145.     

Forest fires in cork oak (Quercus suber L.) stands in Portugal

Fire and cork can be considered both the most serious problem and the most valuable resource of Portuguese forests. The existence of important areas of burned cork oak stands resulting from severe fire seasons in recent years is an environmental problem which deserves special attention. This paper makes a multidisciplinary survey of the problem of burned cork oak stands focusing on: the dimensions of the problem in Portugal, the remarkable resistance of cork oak to fire, the post‐fire management of cork oak stands, and the economic and ecological effects of fire in cork oak stands. Particular emphasis is given to knowledge gaps in this context.     

Toward predictive simulations of pool fires in mechanically ventilated compartments

The objective of this work is to propose an effective modeling to perform predictive simulations of pool fires in mechanically ventilated compartments, representative of a nuclear installation. These predictive simulations have been conducted using original boundary conditions (BCs) for the fuel mass loss rate and the ventilation mass flow rate, which depend on the surrounding environment. To validate the proposed modeling, the specific BCs were implemented in the ISIS computational fluid dynamics (CFD) tool, developed at IRSN, and three fire tests of the PRISME-Door experimental campaign were simulated. They involved a hydrogenated tetrapropylene (HTP) pool fire in a confined room linked to another one by a doorway; the two rooms being connected to a mechanical ventilation system. The three fire scenarios offer different pool fire areas (0.4 and 1 m²) and air change rates (1.5 and 4.7 h⁻¹). For the one square meter pool fire test, the study presents, in detail, the effects of the boundary conditions modeling. The influence of the ventilation and fuel BCs is analyzed using either fixed value, or variable, function of the surrounding environment, determined by a Bernoulli formulation for the ventilation mass flow rate and by the Peatross and Beyler correlation for the fuel mass loss rate. The results indicate that a full coupling between these two BCs is crucial to correctly predict the main parameters of a fire scenario as fire duration, temperature and oxygen fields, over- and under-pressure peaks in the fire compartment. Variable BCs for ventilation and fuel rates were afterward both used to predictively simulate the fire tests with a pool surface area of 0.4 m². The predicted results are in good agreement with measurements signifying that the model allows to catch the main patterns characteristic of an under-ventilated fire.     

Predicting the heat release rates of liquid pool fires in mechanically ventilated compartments

In this paper we perform predictive simulations of liquid pool fires in mechanically ventilated compartments. We show that steady state burning rates are accurately predicted using a detailed model for the liquid phase heat transfer. The effect of lowered oxygen vitiation on the burning rate of pool fires is correctly captured. Simulations were done using the Fire Dynamics Simulator and the experiments considered were conducted in the OECD PRISME project. The main difference between the present study and previous simulation studies is the use of a detailed liquid evaporation model and the direct calculation of the vitiation and thermal environment interactions through the CFD solver.     

Time-dependent smoke yield and mass loss of pool fires in a reduced-scale mechanically ventilated compartment

Technical and pure grades of the combustibles heptane and dodecane were used in a series of small-scale fire tests conducted in a 1 m³ compartment that was mechanically ventilated at 5 and 8 air changes per hour (ACH). Combustible mass loss rates, soot mass concentrations, soot size distributions, several gas species concentrations, and compartment temperatures were measured during the fire. Results for the two pure-grade hydrocarbons were compared with results obtained for their respective technical grades. Technical-grade dodecane produced the highest soot emissions; pure n-heptane produced the lowest. Soot size distributions of all four combustibles attained a steady profile whose modal diameter was about 200 nm. Underventilated fires showed higher carbon monoxide yields than soot yields. Both compartment ventilation rates produced similar results, although the fire self-extinguished earlier for 5 ACH.     

Tenability conditions and filling times for fires in large spaces

Motivated by recent demands on regulatory reform, closed form solutions are developed for the filling times and upper layer temperatures for fires in large spaces including the volume expansion term that was neglected in previous similar efforts. The solutions evolve from (a) utilizing the air entrainment to a buoyant plume from a point source having the same convective heat release as the fire and (b) applying an energy balance for the hot layer. Heat losses to the surfaces of the enclosure and provisions for smoke control by natural ventilation are also considered in an approximate way. Although analytic solutions for the filling times exist in the literature if the volume expansion term is neglected, this work is the first to (a) present analytic solutions for the upper layer temperature including the volume expansion term and (b) incorporate heat losses and smoke control by natural ventilation. The present predictions agree with recent numerical results (Fire Sci. Technol. 19(1) (1999) 27), which agree with experimental data and consequently, the present results in turn agree well with experimental data (Fire Sci. Technol. 19(1) (1999) 27). They are also corroborated by asymptotic analysis worked out in Appendix A. For certain large spaces, the results show that critical times for evacuation or rescue operations from fire brigade depend on the upper layer temperature reaching high enough values to cause harm by radiation to occupants or fire fighting rescuers. Thus, critical times in large spaces do not result from the smoke layer descending below a critical height (e.g. 2.1 m from the floor), as they do for small spaces. The present results for large spaces having high ceiling clearance do not agree with CFAST calculations because the entrainment equation for the fire plume in CFAST is different from the one in this work.     

边境一线草原火灾风险防控对策

边境一线草原火灾具有发生面广、突发性强、破坏性大等特点,防控难度较大且政治敏感,各级关注度高。高效、快速处置边境一线草原火灾,对维护人民生命财产安全、促进民族团结和社会稳定具有重大意义。     

Extinction of lithium fires: Thermodynamic computations and experimental data from literature

As described in the literature, various substances have been tried as extinguishants for metallic lithium fires. For many of these substances, the equilibrium temperature was computed from the reaction of the substance with hot (1040°C) lithium. For some of these substances, the computed equilibrium temperature was sufficiently low that the substances could be considered good extinguishants, and this was generally borne out by literature data. Some of the more promising substances for use as lithium fire extinguishants are silicon carbide (SiC), magnesium oxide (MgO), liquid argon, and boron nitride. Compounds found both by computation and in the literature to enhance combustion include carbon dioxide, Teflon^TM, Halon 1211, and carbon tetrachloride.     

极端天气条件下山火防控策略分析——以川渝地区山火为例

摘 要：川渝地区位于我国西南部,地处四川盆地及巫山东部,植被以亚热带常绿阔叶林为主,引发山火原因较多。受极端高温干旱天气影响,川渝地区山火的数量和强度持续增加,给当地造成了严重的生态灾难和社会危机。在概括近期川渝地区山火案例的基础上,从氧气、可燃物和引火源3方面分析引发该地山火的主要原因,并从地形、气候和植被方面分析扑救难点,从多角度出发提出相应山火防控策略。     

Thermal characteristics of fires in a noncombustible corner

A series of fire tests were conducted in a full-scale open corner with a ceiling to measure the thermal field generated by fires located in a corner. Fires were produced using different size (0.17, 0.30, and 0.50 m) square and line propane burners with heat release rates ranging from 25 to 300 kW. Burner distance below the ceiling was also considered. Measurements included flame length, gas temperatures, and total incident heat flux onto the noncombustible corner boundaries. Flame lengths were related to Q*, with the burner dimension as the length scale, and were found to be similar to those measured in studies with no ceiling. By dividing the corner into three regions (corner walls (z/H<0.8), top of the walls (z/H>0.8), and ceiling, empirical relations for estimating the gas temperatures and incident heat fluxes were developed. Incident heat fluxes on the corner walls were measured to be similar to those in other studies.     

油罐火灾的统计分析

通过对全国油罐火灾案例的统计，分析并量化了不同罐型的火灾危险性、油罐火灾模式、起火原因。在此基础上研究了不同材料、液位高度、容量对油罐破坏形式的影响，并就油罐火灾的起火原因和火灾危险性影响因素进行探讨。     

Measuring and interpreting flame height in wildland fires

Although advanced technologies are available for measuring and sampling fire intensity, their costs, limitations, or complexity often preclude general use in field experiments. The lack of quality measurements exacerbates the task of relating ecological responses directly to the fires that cause them. In this paper, a new technique for measuring flame height, describing its distribution, and relating it to fire intensity is presented. Flame pulsation in natural fuels is also examined.     

建筑火灾中人的行为反应的调查研究

通过对陕西、山西、河南三省169起火灾274位当事人的问卷调查，统计得到了建筑火灾中人的行为反应频率，以及不同年龄、性别、受教育程度的调查队型的火灾行为反应特征，得出了建筑火灾中人的行为反应的初步数据。