scholarly journals Determining Firebrand Generation Rate Using Physics-Based Modelling from Experimental Studies through Inverse Analysis

Fire ◽  
2022 ◽  
Vol 5 (1) ◽  
pp. 6
Author(s):  
Amila Wickramasinghe ◽  
Nazmul Khan ◽  
Khalid Moinuddin
Keyword(s):  
Wind Velocity ◽  
Forest Fire ◽  
Inverse Analysis ◽  
Vegetation Type ◽  
Experimental Studies ◽  
Generation Rate ◽  
Fuel Load ◽  
Potential Threat ◽  
Collection Data ◽  
Vegetation Species

Firebrand spotting is a potential threat to people and infrastructure, which is difficult to predict and becomes more significant when the size of a fire and intensity increases. To conduct realistic physics-based modeling with firebrand transport, the firebrand generation data such as numbers, size, and shape of the firebrands are needed. Broadly, the firebrand generation depends on atmospheric conditions, wind velocity and vegetation species. However, there is no experimental study that has considered all these factors although they are available separately in some experimental studies. Moreover, the experimental studies have firebrand collection data, not generation data. In this study, we have conducted a series of physics-based simulations on a trial-and-error basis to reproduce the experimental collection data, which is called an inverse analysis. Once the generation data was determined from the simulation, we applied the interpolation technique to calibrate the effects of wind velocity, relative humidity, and vegetation species. First, we simulated Douglas-fir (Pseudotsuga menziesii) tree-burning and quantified firebrand generation against the tree burning experiment conducted at the National Institute of Standards and Technology (NIST). Then, we applied the same technique to a prescribed forest fire experiment conducted in the Pinelands National Reserve (PNR) of New Jersey, the USA. The simulations were conducted with the experimental data of fuel load, humidity, temperature, and wind velocity to ensure that the field conditions are replicated in the experiments. The firebrand generation rate was found to be 3.22 pcs/MW/s (pcs-number of firebrands pieces) from the single tree burning and 4.18 pcs/MW/s in the forest fire model. This finding was complemented with the effects of wind, vegetation type, and fuel moisture content to quantify the firebrand generation rate.

Determinants of spatial variation in fire return period in a semiarid African savanna

2011 ◽  
Vol 20 (4) ◽  
pp. 540 ◽  
Author(s):  
T. G. O'Connor ◽  
C. M. Mulqueeny ◽  
P. S. Goodman
Keyword(s):  
Spatial Variation ◽  
Return Period ◽  
Vegetation Type ◽  
Fire Frequency ◽  
Fuel Load ◽  
Annual Rainfall ◽  
Vegetation Types ◽  
Terrestrial Vegetation ◽  
African Savanna ◽  
Data Set

Fire pattern is predicted to vary across an African savanna in accordance with spatial variation in rainfall through its effects on fuel production, vegetation type (on account of differences in fuel load and in flammability), and distribution of herbivores (because of their effects on fuel load). These predictions were examined for the 23 651-ha Mkuzi Game Reserve, KwaZulu-Natal, based on a 37-year data set. Fire return period varied from no occurrence to a fire every 1.76 years. Approximately 75% of the reserve experienced a fire approximately every 5 years, 25% every 4.1–2.2 years and less than 1% every 2 years on average. Fire return period decreased in relation to an increase in mean annual rainfall. For terrestrial vegetation types, median fire return periods decreased with increasing herbaceous biomass, from forest that did not burn to grasslands that burnt every 2.64 years. Fire was absent from some permanent wetlands but seasonal wetlands burnt every 5.29 years. Grazer biomass above 0.5 animal units ha–1 had a limiting influence on the maximum fire frequency of fire-prone vegetation types. The primary determinant of long-term spatial fire patterns is thus fuel load as determined by mean rainfall, vegetation type, and the effects of grazing herbivores.

scholarly journals PERFIL DOS INCÊNDIOS FLORESTAIS NO BRASIL DE 1994 A 1997

FLORESTA ◽  
2002 ◽  
Vol 32 (2) ◽  
Author(s):  
Ronaldo Viana Soares ◽  
Juliana Ferreira Santos
Keyword(s):  
Forest Fire ◽  
Vegetation Type ◽  
Secondary Growth ◽  
Minas Gerais ◽  
Size Class ◽  
Fire Season ◽  
Burned Area ◽  
Native Forest ◽  
Fire Statistics ◽  
Fire Control

O conhecimento do perfil dos incêndios florestais é muito importante para o planejamento do controle dos mesmos. O objetivo deste trabalho foi estabelecer o perfil dos incêndios florestais no país através de dados coletados, em áreas protegidas, no período de 1994 a 1997, através de formulários preenchidos por empresas e instituições florestais. Foram registrados e informados 1.957 incêndios e apesar deste número não representar a totalidade dos incêndios ocorridos no período estudado, constituiu-se numa base confiável para se conhecer as principais características dos incêndios. Os resultados mostraram que a área média atingida por incêndio no período analisado foi de aproximadamente 135 ha, sendo Minas Gerais o estado líder, tanto em número de incêndios informados (62,7% do total) como em área queimada (25,2%). O grupo Incendiários foi a principal causa dos incêndios, com 56,6% das ocorrências, vindo a seguir as Queimas para limpeza com 22,1%. Com relação à área queimada o grupo Queimas para limpeza , com 74,1% da superfície atingida, foi a principal causa, ficando o grupo Incendiários em segundo lugar com 19,8%. A principal estação de incêndios no país se estende de julho a novembro, quando ocorreram 79,2% dos incêndios, correspondendo a 98,6% da área atingida. O maior número de incêndios (39,7% das ocorrências) foi registrado em Outro tipo de vegetação, que inclui cerrado, capoeira e campo. Com relação à área atingida, entretanto, 92,5% foi registrada em Florestas Nativas. Quanto à distribuição dos incêndios através das classes de tamanho, 23,9% foi enquadrado na classe I ( 0,1 ha). É importante ressaltar que quanto maior a eficiência no combate aos incêndios, maior é a concentração dos mesmos na classe I. Apesar de corresponder a apenas 2,4% das ocorrências, os incêndios da classe V ( 200,0 ha) foram responsáveis por 94,5% da área queimada. FOREST FIRE STATISTICS IN BRAZIL FROM 1994 TO 1997 Abstract Forest fire statistics knowledge is an important tool for fire control planning. The objective of this research was to collect information on forest fire occurrence in Brazilian protected areas in the period of 1994 to 1997. The analyzed variables were the number of fires and burned areas per state of the federation, monthly distribution, probable causes, affected vegetation, size class distribution, and average burned area per fire. Results showed that the average burned area per fire was approximately 135 ha and Minas Gerais ranked first, both in number of registered fires (62.7%) and burned surface (25.2%). Incendiary, with 56.6% of the occurrences was the leading cause, followed by debris burning with 22.1%. However, as for the affected area, Debris burning was the leading cause (74.1%), followed by Incendiary (19.8%). The fire season extends from July to November, when 79.2% of the fires occurred, corresponding to 98.6% of the burned surface. Miscellaneous, that includes savanna, secondary growth forest, and grassland were the most affected vegetation type (39.7% of the occurrences). In relation to the burned surface, Native Forest (92.5%) ranked first. The distribution of the registered fires through the size classes presented 23.9% of the occurrences in Class I ( 0.1 ha), whereas 94.5% of the burned area were result of Class V ( 200 ha) fires. Size Class II (0.1 to 4.0 ha), with 49.1% of the occurrences, ranked first in number of registered fires during the analyzed period.

scholarly journals Potential threat of southern Moravia soils by wind erosion

2004 ◽  
Vol 52 (2) ◽  
pp. 33-42 ◽  
Author(s):  
Jana Dufková
Keyword(s):  
Wind Velocity ◽  
Wind Erosion ◽  
Linear Trend ◽  
Soil Surface ◽  
Potential Threat ◽  
Soil Humidity ◽  
Average Wind ◽  
Humidity Index ◽  
Southern Moravia ◽  
Average Wind Velocity

Wind erosion is caused by meteorological factors such as wind, precipitation and evaporation that influence the soil humidity. Erosive-climatological factor expresses wind and humidity conditions of particular landscape. This is an index of the influence of average soil surface humidity and average wind velocity on average soil erodibility by wind. On the basis of average wind velocity and Konček’s humidity index, the values of the erosive-climatological factor for three chosen areas of Czech republic (Telč-Kostelní Myslová, Znojmo-Kuchařovice and Brno-Tuřany), where the pro-cesses of wind erosion could exist, were evaluated. Thus, the change of the factor’s value during the period of 1961 – 2000 was studied. The linear trend for the region of Brno and Znojmo (dry areas) shows increasing threat of soils by wind erosion, the contrary situation is at the humid area (Telč). The results prove the influence of soil humidity on the erosive-climatological factor and hereby the influence on wind erosion spreadout.

Bare soil and rill formation following wildfires, fuel reduction treatments, and pine plantations in the southern Sierra Nevada, California, USA

2010 ◽  
Vol 19 (4) ◽  
pp. 478 ◽  
Author(s):  
Neil H. Berg ◽  
David L. Azuma
Keyword(s):  
Sierra Nevada ◽  
Vegetation Type ◽  
Fire Severity ◽  
Reference Conditions ◽  
Bare Soil ◽  
Fuel Load ◽  
Load Reduction ◽  
Fuel Reduction ◽  
Management Options ◽  
Burned Areas

Accelerated erosion commonly occurs after wildfires on forested lands. As burned areas recover, erosion returns towards prefire rates depending on many site-specific characteristics, including fire severity, vegetation type, soil type and climate. In some areas, erosion recovery can be rapid, particularly where revegetation is quick. Erosion recovery is less well understood for many fuel load reduction treatments. The rate of post-disturbance erosion recovery affects management options for forested lands, particularly when considering the combined ramifications of multiple disturbances on resource recovery rates (i.e. cumulative watershed effects). Measurements of percentage bare soil and rilling on over 600 plots in the southern Sierra Nevada with slopes less than 75% and within 1 km of roads were made between 2004 and 2006. Results suggest that after high-, moderate- or low-severity wildfire, rilling was seldom evident more than 4 years after fire. Percentage bare soil generally did not differ significantly between reference plots and wildfire plots greater than 6 years old. Little rilling was evident after treatment with a variety of fuel reduction techniques, including burning of machine- and hand-piled fuel, thinning, mastication, and crushing. Percentage bare soil at the fuel load reduction treatment plots also did not differ significantly from reference conditions. Percentage bare soil at pine plantation plots was noticeably higher than at reference sites.

scholarly journals DISCRIMINATION AND CHARACTERIZATION OF PROMINENT DESERTIC VEGETATIONS USING HYPERSPECTRAL IMAGING DATA

2019 ◽  
Vol XLII-3/W6 ◽  
pp. 363-368 ◽  
Author(s):  
S. L. Borana ◽  
S. K. Yadav ◽  
R. T. Paturkar
Keyword(s):  
Hyperspectral Imaging ◽  
Tree Species ◽  
Vegetation Type ◽  
Spectral Band ◽  
Vegetation Indices ◽  
Hyperspectral Data ◽  
Imaging Data ◽  
Area Index ◽  
Vegetation Species

<p><strong>Abstract.</strong> Imaging Hyperspectral data are advent as potential solutions in modeling, discrimination and mapping of vegetation species. Hyperspectral remote sensing provides valuable information about vegetation type, leaf area index, chlorophyll, and leaf nutrient concentration. Estimation of these vegetation parameters has been made possible by calculating various vegetation indices (VIs), usually by ratioing, differencing, ratioing differences and combinations of suitable spectral band. This paper presents a ground-based hyperspectral imaging system for characterizing vegetation spectral features. In this study, a ground-based hyperspectral imaging data (AISA VNIR 400&amp;ndash;960&amp;thinsp;nm, Spectral Resolution @ 2.5&amp;thinsp;nm) was used for spectral vegetation discrimination and characterization of natural desertic tree species. This study assessed the utility of hyperspectral imagery of 240 narrow bands in discrimination and classification of desert tree species in Jodhpur region using ENVI software. Vegetation indices derived from hyperspectral images used in the Analysis for tree species classification discrimination study. Prominent occurring two desertic tree species, viz., Neem and Babul in Jodhpur region could be effectively discriminated. Study demonstrated the potential utility of narrow spectral bands of Hyperspectral Imaging data in discriminating vegetation species in a desertic terrain.</p>

scholarly journals Non-Additive Effects of Forest Litter on Flammability

Fire ◽  
2020 ◽  
Vol 3 (2) ◽  
pp. 12 ◽  
Author(s):  
Angela G. Gormley ◽  
Tina L. Bell ◽  
Malcolm Possell
Keyword(s):  
Vegetation Type ◽  
Forest Litter ◽  
Flame Height ◽  
Fuel Load ◽  
Additive Effects ◽  
Forest Types ◽  
Fuel Component ◽  
Hazard Reduction ◽  
Sclerophyll Forest ◽  
Optimisation Methods

Forest litter is a fuel component that is important for the propagation of fire. Data describing fuel load, structure and fuel condition were gathered for two sites of Sydney Coastal Dry Sclerophyll Forest, a common vegetation type in the Sydney Basin, Australia. Surface litter from the sites was sorted into its constituent components and used to establish which component or mixture of components were the most flammable using several metrics. A general blending model was used to estimate the effect the different mixtures had on the response of the flammability metrics and identify non-additive effects. Optimisation methods were applied to the models to determine the mixture compositions that were the most or least flammable. Differences in the flammability of the two sites were significant and were driven by Allocasuarina littoralis. The presence of A. littoralis in litter mixtures caused non-additive effects, increasing the rate of flame spread and flame height non-linearly. We discuss how land managers could use these models as a tool to assist in prioritising areas for hazard reduction burns and how the methodology can be extended to other fuel conditions or forest types.

Relating fuel loads to overstorey structure and composition in a fire-excluded Sierra Nevada mixed conifer forest

2015 ◽  
Vol 24 (4) ◽  
pp. 484 ◽  
Author(s):  
Jamie M. Lydersen ◽  
Brandon M. Collins ◽  
Eric E. Knapp ◽  
Gary B. Roller ◽  
Scott Stephens
Keyword(s):  
Sierra Nevada ◽  
Predictive Models ◽  
Vegetation Type ◽  
Fuel Load ◽  
Small Scale ◽  
Conifer Forest ◽  
Fire Behaviour ◽  
Mixed Conifer ◽  
Fuel Loads ◽  
Mixed Conifer Forest

Although knowledge of surface fuel loads is critical for evaluating potential fire behaviour and effects, their inherent variability makes these difficult to quantify. Several studies relate fuel loads to vegetation type, topography and spectral imaging, but little work has been done examining relationships between forest overstorey variables and surface fuel characteristics on a small scale (<0.05 ha). Within-stand differences in structure and composition would be expected to influence fuel bed characteristics, and thus affect fire behaviour and effects. We used intensive tree and fuel measurements in a fire-excluded Sierra Nevada mixed conifer forest to assess relationships and build predictive models for loads of duff, litter and four size classes of downed woody fuels to overstorey structure and composition. Overstorey variables explained a significant but somewhat small percentage of variation in fuel load, with marginal R2 values for predictive models ranging from 0.16 to 0.29. Canopy cover was a relatively important predictor for all fuel components, although relationships varied with tree species. White fir abundance had a positive relationship with total fine woody fuel load. Greater pine abundance was associated with lower load of fine woody fuels and greater load of litter. Duff load was positively associated with total basal area and negatively associated with oak abundance. Knowledge of relationships contributing to within-stand variation in fuel loads can increase our understanding of fuel accumulation and improve our ability to anticipate fine-scale variability in fire behaviour and effects in heterogeneous mixed species stands.

scholarly journals An Empirical Model for the Effect of Wind on Fire Spread Rate

Fire ◽  
2018 ◽  
Vol 1 (2) ◽  
pp. 31 ◽  
Author(s):  
Carlos Rossa ◽  
Paulo Fernandes
Keyword(s):  
Empirical Model ◽  
Vegetation Type ◽  
Fire Spread ◽  
Fuel Load ◽  
Wind Effect ◽  
High Moisture ◽  
Independent Laboratory ◽  
Live Fuels ◽  
Released Energy ◽  
Good Agreement

Predicting wind-driven rate of fire spread (RoS) has been the aim of many studies. Still, a field-tested model for general use, regardless of vegetation type, is currently lacking. We develop an empirical model for wind-aided RoS from laboratory fires (n = 216), assuming that it depends mainly on fire-released energy and on the extension of flame over the fuel bed in still air, and that it can be obtained by multiplying RoS in no-wind and no-slope conditions by a factor quantifying the wind effect. Testing against independent laboratory and field data (n = 461) shows good agreement between observations and predictions. Our results suggest that the fuel bed density effect detected by other work may be a surrogate for the amount of fuel involved in combustion, which depends on fuel load. Because RoS under windless conditions is unaffected by fuel load, the involved mechanisms differ from wind-aided propagation. Compared to shallow fuel beds, the wind effect is usually modest in deep vegetation, because tall fuel complexes are dominated by live fuels (high moisture content) and flames extend less above the vegetation when fuel moisture is high. The present work warrants further inspection in a broader range of field conditions.

Wall Shear-Stress as a Parameter to Correlate the Rate of Spread of a Wind Induced Forest Fire.

1991 ◽  
Vol 1 (3) ◽  
pp. 177 ◽  
Author(s):  
DX Viegas ◽  
LPC Neto
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
Flame Front ◽  
Wind Velocity ◽  
Forest Fire ◽  
Flame Height ◽  
Wind Effect ◽  
Alternative Formulation ◽  
Rate Of Spread ◽  
Wall Shear

Modelling of the wind effect on the rate of spread of a flame in a forest fire usually employs a wind velocity measured at mid-flame height. An alternative formulation is proposed in this paper, based on the wall shear-stress produced by the wind on the fuelbed in the absence of combustion. Some tests performed on a labo ratory scale are described and the results obtained to gether with those from other sources confirm the possi bility of using wall shear-stress to correlate the rate of spread of a flame front.

scholarly journals Potential threat of the international aquarium fish trade to silver arawana Osteoglossum bicirrhosum in the Peruvian Amazon

Oryx ◽  
2006 ◽  
Vol 40 (2) ◽  
pp. 152-160 ◽  
Author(s):  
Marie-Annick Moreau ◽  
Oliver T. Coomes
Keyword(s):  
Experimental Studies ◽  
Rural Poor ◽  
Peruvian Amazon ◽  
Potential Threat ◽  
Aquarium Fish ◽  
Foreign Earnings ◽  
Catch And Release ◽  
Part Time ◽  
Management Schemes ◽  
Government Statistics

Silver arawana Osteoglossum bicirrhosum are increasingly popular on the international aquarium fish market, but the routine killing of mouth brooding adults to collect juveniles for the trade may threaten wild populations. We describe the aquarium trade and fishery for silver arawana in the Peruvian Amazon. This is the first such report on the species for South America, and is based on field interviews with trade participants and fishermen, and on a review of government statistics. The regional trade is large, expanding and valuable (over 1 million juveniles worth USD 560,000 exported in 2001), of considerable economic importance to the rural poor, and in urgent need of research, monitoring and management. Outright bans on arawana fishing are likely to be ineffective and to destabilize an export fishery that provides significant part-time employment for the rural poor and substantial foreign earnings. Experimental studies are called for that compare the impacts on arawana yields of alternate fishing techniques, such as catch and release of brooding males, as a basis for developing more effective management schemes in Amazonia.

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