Fire Extent Research Articles

Amazonian farmers' response to fire policies and climate change

Fires are a major threat to the conservation of the Amazon forest. Despite a large decline in deforestation in the Brazilian Amazon between 2004 and 2012, frequency and extent of forest fires have been increasing over the last two decades. Fires cause huge carbon emissions, biodiversity losses and local economic costs. Fires are anthropogenic and mostly due to the accidental spread of agricultural fires. Yet, there is little data and knowledge about fire mitigation policies' effectiveness. We experimentally assess the impact of two policies under varying drought risk scenarios among Brazilian smallholders. Command and control is more effective than payments for environmental services. We conjecture that the first policy operates through participants' risk aversion (to the fine) and local demand for justice, while payments seem to switch farmers' motivation from normative to monetary payoffs. We also find evidence of a human-mediated, self-reinforcing loop of droughts and fires: droughts increase the exogenous component of fire risk, reducing farmers' incentives to control own fires and to invest in fire-free techniques.

Changes in Fire Activity in Africa from 2002 to 2016 and Their Potential Drivers.

While several studies have reported a recent decline in area burned in Africa, the causes of this decline are still not well understood. In this study, we found that from 2002 to 2016 burned area in Africa declined by 18.5%, with the strongest decline (80% of the area) in the Northern Hemisphere. One third of the reduction in burned area occurred in croplands, suggesting that changes in agricultural practices (including cropland expansion) are not the predominant factor behind recent changes in fire extent. Linear models that considered interannual variability in climate factors directly related to biomass productivity and aridity explained about 70% of the decline in burned area in natural land cover. Our results provide evidence that despite the fact that most fires are human-caused in Africa, increased terrestrial moisture during 2002–2016 facilitated declines in fire activity in Africa.

Detecting historic informal settlement fires with Sentinel 1 and 2 satellite data - Two case studies in Cape Town

Increasing global urbanisation is leading to a rise in the number of people living in informal settlements, challenging our ability to achieve sustainable development goals. As a consequence of high building density, inadequate building methods and flammable building materials, informal settlements are highly vulnerable to the devastating impacts of fire. Databases on historic fire occurrence, location and extent are scarce, especially in the Global South. This paper explores the potential for remote sensing technologies to fill this gap. Two case studies in Cape Town representing fire of different extent and build back characteristics, are used to demonstrate that Sentinel-1 and Sentinel-2 data can be used to detect known historic informal settlement fire. A pixel based approach applied to Sentinel-2 band 2 reflectance and Sentinel 1 backscatter and interferometry are highlighted. The concept of spatial autocorrelation is explored with both Sentinel-2 and 1 data showing that a 3 x 3 pixel standard deviation kernel and hotspot analysis can complement the pixel approach. Further research is required to test these methods within a time series change detection algorithm to identify unknown historic informal settlement fires. .

Relationships between Satellite-Based Spectral Burned Ratios and Terrestrial Laser Scanning

Three-dimensional point data acquired by Terrestrial Lidar Scanning (TLS) is used as ground observation in comparisons with fire severity indices computed from Landsat satellite multi-temporal images through Google Earth Engine (GEE). Forest fires are measured by the extent and severity of fire. Current methods of assessing fire severity are limited to on-site visual inspection or the use of satellite and aerial images to quantify severity over larger areas. On the ground, assessment of fire severity is influenced by the observers’ knowledge of the local ecosystem and ability to accurately assess several forest structure measurements. The objective of this study is to introduce TLS to validate spectral burned ratios obtained from Landsat images. The spectral change was obtained by an image compositing technique through GEE. The 32 plots were collected using TLS in Wood Buffalo National Park, Canada. TLS-generated 3D points were converted to voxels and the counted voxels were compared in four height strata. There was a negative linear relationship between spectral indices and counted voxels in the height strata between 1 to 5 m to produce R2 value of 0.45 and 0.47 for unburned plots and a non-linear relationship in the height strata between 0 to 0.5m for burned plots to produce R2 value of 0.56 and 0.59. Shrub or stand development was related with the spectral indices at unburned plots, and vegetation recovery in the ground surface was related at burned plots. As TLS systems become more cost efficient and portable, techniques used in this study will be useful to produce objective assessments of structure measurements for fire refugia and ecological response after a fire. TLS is especially useful for the quick ground assessments which are needed for forest fire applications.

Interactions among threats affect conservation management outcomes: Livestock grazing removes the benefits of fire management for small mammals in Australian tropical savannas

AbstractConservation scientists and practitioners usually focus on understanding and managing individual threats to biodiversity. However, threats may interact, making management outcomes unpredictable. Here, we investigated whether interactions between fire regimes and introduced livestock affect the conservation goal of population recovery for small mammals in Australia's tropical savannas, using a long‐term and landscape‐scale study. Mammal richness and abundance increased as management reduced the average annual fire extent and frequency at large and medium scales. However, these relationships between fire and richness and abundance were only evident in areas where introduced livestock were removed. This interaction may arise because predation by feral cats is amplified in areas with reduced vegetation ground cover, and cover is reduced over longer periods when livestock have access to burnt areas, because they selectively graze regenerating grass. Fire management for conservation receives substantial investment across northern Australia, and in savannas worldwide; this study shows that without appropriate management of other factors, this investment may be ineffective. More broadly, managing single threats to biodiversity may be compromised if interactions between threats are not explicitly considered. This study provides an example of how such interactions can be evaluated for improved biodiversity conservation.

Holocene savanna dynamics in the seasonal tropics of northern Australia

An environmental history is presented from Girraween Lagoon, Darwin region of the Northern Territory, Australia. Pollen and charcoal analysis of a 5-meter sediment core provides a record of vegetation change, fire history and climate spanning 12,700 cal BP to the present day. This study focusses on tree-grass vegetation dynamics, eucalypt to non-eucalypt plant interactions, and climate–fire–human relationships in an area where few long-term savanna records exist. The dataset suggests wetlands experienced alternating episodes of ephemeral waterlogging and seasonal inundation due to post-glacial monsoon variability up until permanent inundation from approximately 6000 cal BP. The surrounding catchment transformed from a terminal Pleistocene–early Holocene wooded-savanna to a later Holocene open forest. This increase in woody cover was a prominent site feature, primarily driven by climate–moisture availability. In turn, the extent of fire and fire impact, is a function of climate–vegetation feedbacks. Such interplay between fire history, climate change and vegetation pattern was also influenced by more intense human management of the area, in the last 4000 years of the record. It is proposed Girraween may have become a much-socialized and managed human landscape in this late Holocene phase. Results provide essential baseline data describing savanna dynamics linked to contemporary ecological observation, understanding and management goals, and serves as an important resource for the Quaternary sciences and archeology of northern Australia.

Adapting prescribed burns to future climate change in Mediterranean landscapes

Fire regimes are shifting or are expected to do so under global change. Current fire suppression is not able to control all wildfires, and its capability to do so might be compromised under harsher climate conditions. Alternative fire management strategies may allow to counteract predicted fire trends, but we lack quantitative tools to evaluate their potential effectiveness at the landscape scale. Here, we sought to quantify changes in fire regimes induced after the implementation of different fire management strategies. We developed and applied a new version of the model MEDFIRE in Catalonia (Mediterranean region of ~32,000 km2 in NE Spain). We first projected burnt area from 2016 to 2100 resulting from climate change under the Representative Concentration Pathway 8.5 scenario of HadGEM-CC model and under current fire suppression levels. We then evaluated the impacts of four fire management strategies: ‘Let it burn’, fixed effort of prescribed burning with two different spatial allocations, and adaptive prescribed burning dynamically adjusting efforts according to recent past fires. Results predicted the emergence of novel climates associated with similar barometric configurations to current conditions but with higher temperatures (i.e. hot wind events). These novel climates led to an increase in burnt area, which was partially counteracted by negative fire-vegetation feedbacks. All prescribed burning scenarios decreased the amount of high-intensity fires and extreme fire events. The ‘Let it burn’ strategy, although less costly, was not able to reduce the extent of high-intensity fires. The adaptive prescribed burning scenario resulted in the most cost-efficient strategy. Our results provide quantitative evidence of fire management effectiveness, and bring to light key insights that could guide the design of fire policies fit for future novel climate conditions. We propose adaptive landscape management focused on the reduction of fire negative impacts rather than on the elimination of this disturbance from the system.

Temperature-controlled tundra fire severity and frequency during the last millennium in the Yukon-Kuskokwim Delta, Alaska

Wildfire is an important disturbance to Arctic tundra ecosystems. In the coming decades, tundra fire frequency, intensity, and extent are projected to increase because of anthropogenic climate change. To more accurately predict the effects of climate change on tundra fire regimes, it is critical to have detailed knowledge of the natural frequency and extent of past wildfires and how they responded to past climate variability. We present analyses of fire frequency and temperature from a lake sediment core from the Yukon-Kuskokwim (YK) Delta. Our ca. 1000 macroscopic charcoal record shows more frequent but possibly less severe tundra fires during the first half of the last millennium, whereas less frequent, possibly more severe fires characterize the latter half. Our temperature reconstruction, based on distributional changes of branched glycerol dialkyl glycerol tetraethers (brGDGTs), shows slightly warmer conditions from ca. AD 1000 to 1500, and cooler conditions thereafter (ca. AD 1500 to 2000), suggesting that fire frequency increases when climate is relatively warmer in this region. When wildfires occur more frequently, fire severity may decrease because of limited biomass (fuel source) accumulating between fires. The data suggest that tundra ecosystems are highly sensitive to climate change, and that a warmer climate, which is predicted to develop in the near future, will result in more frequent tundra wildfires.

Post-burn and long-term fire effects on plants and birds in floodplain wetlands of the Russian Far East

Wildfires affect biodiversity at multiple levels. While vegetation is directly changed by fire events, animals are often indirectly affected through changes in habitat and food availability. Globally, fire frequency and the extent of fires are predicted to increase in the future. The impact of fire on the biodiversity of temperate wetlands has gained little attention so far. We compared species richness and abundance of plants and birds in burnt and unburnt areas in the Amur floodplain/Russian Far East in the year of fire and 1 year after. We also analysed vegetation recovery in relation to time since fire over a period of 18 years. Plant species richness was higher in burnt compared to unburnt plots in the year of the fire, but not in the year after. This suggests that fire has a positive short-term effect on plant diversity. Bird species richness and abundance were lower on burnt compared to unburnt plots in the year of the fire, but not in the year after. Over a period of 18 years, high fire frequency led to an increase in herb cover and a decrease in grass cover. We show that the effects on biodiversity are taxon- and species-specific. Fire management strategies in temperate wetlands should consider fire frequency as a key driving force of vegetation structure, with carry-over effects on higher trophic levels. Designing fire “refuges”, i.e., areas that do not burn annually, might locally be necessary to maintain high species richness.

Historical patterns of fire severity and forest structure and composition in a landscape structured by frequent large fires: Pumice Plateau ecoregion, Oregon, USA

Lack of quantitative observations of extent, frequency, and severity of large historical fires constrains awareness of departure of contemporary conditions from those that demonstrated resistance and resilience to frequent fire and recurring drought. Compare historical and contemporary fire and forest conditions for a dry forest landscape with few barriers to fire spread. Quantify differences in (1) historical (1700–1918) and contemporary (1985–2015) fire extent, fire rotation, and stand-replacing fire and (2) historical (1914–1924) and contemporary (2012) forest structure and composition. Data include 85,750-ha tree-ring reconstruction of fire frequency and extent; > 375,000-ha timber inventory following > 78,900-ha fires in 1918; and remotely-sensed maps of contemporary fire effects and forest conditions. Historically, fires > 20,000 ha occurred every 9.5 years; fire rotation was 14.9 years; seven fires > 40,469 ha occurred during extreme drought (PDSI 15 cm dbh exceeded 120 trees/ha on 40,469 ha (minimum size of contemporary “megafires”) during extreme drought. In this frequent-fire landscape, mixed-severity fire historically influenced lodgepole and adjacent forests. Lack of large, frequent, low-severity fires degrades contemporary forest ecosystems.

279 Association of Personal Protective Equipment Use and Maintenance with Burn Injury: A Pilot Survey of Firefighters

Thermal injury remains a persistent occupational hazard for both volunteer and career firefighters. While advances in personal protective equipment (PPE) offer improved safety and reported rates of compliance are high, injuries still occur. The purpose of this pilot project was to investigate the correlation between PPE use and damage with injury characteristics. A structured questionnaire was distributed to a convenience sample of firefighters undergoing initial outpatient evaluation in a burn clinic. Data were collected regarding fire experience, incident circumstances and extent of injury sustained, as well as PPE use and post-injury damage and PPE integrity monitoring history. Chi-square tests were used to evaluate the relationship between PPE use, damage and monitoring with injury. There were 45 respondents included in this analysis. Firefighters were on average 31.8 ± 7.5 years with 10.8 ± 8.9 mean years of experience (range 1-32 years). The majority of respondents identified as career firefighters (72.4%). Injuries were sustained primarily in structure fires (93.3%), and 22.0% were in a training setting. Ears were the most commonly burned area (n=25) followed by arms, hands, and wrists. Nearly all injuries were small (< 5% TBSA) and managed in an outpatient setting. Only one patient requiring grafting, though 60.0% reported missing at least one shift. The majority reported use of most PPE elements at the time of injury, although more than 25% indicated not using suspenders. Eight individuals had not been sized for PPE in the last two years, two of whom indicated never having been properly sized. Although ear burns were not significantly associated with use of helmets or earflaps, there was a significant association with helmet damage (p = 0.04), with a trend toward significance for visible gear damage (p = 0.05) and hood damage (p = 0.09). Arm burns were significantly associated with visibly damaged gear (p = 0.003), damaged gloves (p = 0.012), and damaged coats (p < 0.001). Given the association of PPE damage and injury identified in this pilot study, further training directed towards improved frequency of resizing and inspection of PPE post-injury may be warranted. These findings necessitate further investigation, which is planned via more extensive questionnaire distribution within the firefighting community. Further significant associations may be revealed within a larger sample size. Thermal injury will continue to be an occupational hazard for firefighters. Better understanding of associated factors can help target training and prevention strategies to mitigate risk.

Determination of Fire Extent in Forest Zones Using Remote Sensing Data Case Study: Golestan Province of Iran

Fire is one of the most serious hazards, which causes many economic, social, ecological, and human damages every year in the world. Fire in forests and natural ecosystems destroys wood, regeneration, forest vegetation, as well as soil erosion and forest regeneration problems (due to the dryness of the weather and the weakness of the soil). Awareness of the extent of the zones that have been fired is important for forest management. On the other hand, the difficulty of fieldwork due to the high cost and inaccessible roads, etc. reveals the need for using remote sensing science to solve this problem. In this research, MODIS satellite images were used to detect and determine the fire extent of Golestan province forests in northern Iran. MID13q1 and MOD13q1 images were used to detect the normal conditions of the environment. The 15-year time series data were provided for the NDVI and NDMI indicators in 2000-2015. Then, the behavior of indicators in the fire zone was studied on the day after the fire. The burned zones by the fire were specified by determining the appropriate threshold and then, they were compared to long-term normals. In the NDMI and NDVI indicators, the mean of the numeric value threshold limit for determining the burnt pixels was respectively 1.865 and 0.743 of the reduction in their normal long-term period, which are selected as fire pixels. The results showed that the NDMI index could determine the extent of the burned zone with the accuracy of 95.15%.

30 m Resolution Global Annual Burned Area Mapping Based on Landsat Images and Google Earth Engine

Heretofore, global Burned Area (BA) products have only been available at coarse spatial resolution, since most of the current global BA products are produced with the help of active fire detection or dense time-series change analysis, which requires very high temporal resolution. In this study, however, we focus on an automated global burned area mapping approach based on Landsat images. By utilizing the huge catalog of satellite imagery, as well as the high-performance computing capacity of Google Earth Engine, we propose an automated pipeline for generating 30-m resolution global-scale annual burned area maps from time-series of Landsat images, and a novel 30-m resolution Global annual Burned Area Map of 2015 (GABAM 2015) was released. All the available Landsat-8 images during 2014–2015 and various spectral indices were utilized to calculate the burned probability of each pixel using random decision forests, which were globally trained with stratified (considering both fire frequency and type of land cover) samples, and a seed-growing approach was conducted to shape the final burned areas after several carefully-designed logical filters (NDVI filter, Normalized Burned Ratio (NBR) filter, and temporal filter). GABAM 2015 consists of spatial extent of fires that occurred during 2015 and not of fires that occurred in previous years. Cross-comparison with the recent Fire_cci Version 5.0 BA product found a similar spatial distribution and a strong correlation ( R 2 = 0.74) between the burned areas from the two products, although differences were found in specific land cover categories (particularly in agriculture land). Preliminary global validation showed the commission and omission errors of GABAM 2015 to be 13.17% and 30.13%, respectively.

Boreal Forest Floor Greenhouse Gas Emissions Across a Pleurozium schreberi-Dominated, Wildfire-Disturbed Chronosequence

The boreal forest is a globally critical biome for carbon cycling. Its forests are shaped by wildfire events that affect ecosystem properties and climate feedbacks including greenhouse gas (GHG) emissions. Improved understanding of boreal forest floor processes is needed to predict the impacts of anticipated increases in fire frequency, severity, and extent. In this study, we examined relationships between time since last wildfire (TSF), forest floor soil properties, and GHG emissions (CO2, CH4, N2O) along a Pleurozium schreberi-dominated chronosequence in mid- to late succession located in northern Sweden. Over three growing seasons in 2012–2014, GHG flux measurements were made in situ and samples were collected for laboratory analyses. We predicted that P. schreberi-covered forest floor GHG fluxes would be related to distinct trends in the soil properties and microbial community along the wildfire chronosequence. Although we found no overall effect of TSF on GHG emissions, there was evidence that soil C/N, one of the few properties to show a trend with time, was inversely linked to ecosystem respiration. We also found that local microclimatic conditions and site-dependent properties were better predictors of GHG fluxes than TSF. This shows that site-dependent co-variables (that is, forest floor climate and plant-soil properties) need to be considered as well as TSF to predict GHG emissions as wildfires become more frequent, extensive and severe.

Are reptile responses to fire shaped by forest type and vegetation structure? Insights from the Mediterranean basin

Socioeconomic factors (e.g. rural abandonment, monoculture plantations) and global warming are changing fire regimes (fire intensity, extent, and frequency) in fire-prone regions such as the Mediterranean Basin. Understanding the factors that shape responses of animal communities to fire is a key objective for biodiversity conservation. Given the substitution of native forests to pine plantations in many regions of the world, we studied whether forest type influences the responses to fire of reptile communities, in the African rim of the Western Mediterranean. Reptiles were sampled and vegetation structure measured in 2015 and 2016. We used generalized linear mixed models to examine the influence of fire, forest type (cork oak and pine), habitat structure and climate factors on two reptile-community metrics (abundance, species richness). Given possible differences in reptile detectability between unburnt and burnt transects, we used distance sampling models to estimate the density of the five commonest reptile species. The response of reptiles to fire varied between the two forest types: reptile abundance did not change with fire in cork oak forest, and increased with fire in pine plantation. Species richness was higher in cork oak forests, and increased from unburnt to burnt areas. Two out of five commonest lizards in the region, Acanthodactylus erythrurus and Podarcis vaucheri, responded positively to fire in pine plantation and remained similar in cork oak forest. Reptile communities were more similar between burnt and unburnt cork oak forests than between burnt and unburnt pine plantations, due to the reduced effect of fire on the former tree (a resprouter species) than on the latter (a seeder species). This work is the first field-based study examining the effects of fire on animal communities from north-western Africa. Overall, our results show that the response of reptiles to fire is shaped by forest type, and this conclusion has to be considered in fire-prone regions.

Characterisation of aerosol constituents from wildfires using satellites and model data: a case study in Knysna, South Africa

ABSTRACTStrong winds and dry conditions make it difficult to contain wild fires worldwide. Such fires could cause devastating effects on landscape structures around many urban/peri-urban areas. The greater impact of such fires is commonly felt when landscape elements such as forest vegetation biomass fuel increase the wild fire risk to people and their properties. In order to mitigate the impact of a wild fire at local level, it is imperative to understand its spatial distribution and fuel load dynamics surrounding it. This study aimed at exploring the possibility of integrating various satellites and model data to characterise the aerosols emissions from wild fires which occurred at Knysna (South Africa). The Moderate Resolution Imaging Spectroradiometer (MODIS), the Sentinel-2 normalized difference vegetation index (NDVI), the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO), the Hybrid Single-Particle Lagrangian Intergrated trajectory (HYSPLIT) model and the Modern-Era Retrospective Analysis for Research and Applications version 2 (MERRA-2) model were employed to characterise the Knysna fires, and the resultant atmospheric conditions that prevailed at altitudes lower than 10 km. Large flames and high amounts of smoke were observed at the Knysna forests by the Sentinel-2 optical data. Our findings showed that there was an apparent reduction in the green vegetation biomass coverage of up to 20.2% following the wildfires as observed by Sentinel-2 data analysis. Biomass burning (BB) aerosols and smoke were observed to reach high altitudes of 2–4 km by CALIPSO. Pyrocumulus clouds were also observed at altitudes of 7.2 km. These clouds were a result of the mixing of the smoke and clouds in the mid-troposphere. The HYSPLIT model and MERRA-2 model showed that the emitted BB aerosols and smoke did not travel inland but rather dispersed in an eastward and south-eastward direction into the Indian Ocean from the source. A multi-satellite data approach proved to be a valuable resource to study the extent of wild fires and to determine their atmospheric impact and thus contributing to climate change. The transport models data was resourceful in determining the destination of the wild fires emissions.

Illegal Selective Logging and Forest Fires in the Northern Brazilian Amazon

Illegal selective logging and forest fires occur on a large scale in the northern Brazilian Amazon, contributing to an increase in tree mortality and a reduction in forest carbon stock. A total of 120 plots of 0.25 ha (30 ha) were installed in transitional ecosystems or ecotones (LOt) between the forested shade-loving campinarana (Ld) and dense-canopy rainforest, submontane (Ds), in the National Forest (Flona) of Anauá, southern Roraima. Measuring the diameters at breast height (DBH ≥ 10 cm) and the heights of 171 dead trees (fallen naturally, illegally exploited, and affected by forest fires), enabled the estimation of carbon content from the application of a biomass equation developed at Manaus, and the calculation of a correction factor, using the average height of the largest trees. From 2015–2017, we mapped the real extent of illegal selective logging and forest fires across the region with CLASlite and INPE/Queimadas. From measurements of 14,730 live and dead trees across 30 hectares (491 ± 15 trees·ha−1), the illegal selective logging and associated forest fires, and aggravation by severe El Niño droughts resulted in an 8.2% mortality of trees (40 ± 9 dead trees·ha−1) and a 3.5% reduction in forest carbon stock (6 ± 3 Mg·ha−1) in the short-term. The surface area or influence of forest fires of very high density were estimated in the south-central region of Roraima (8374 km²) and the eastern region of the Flona Anauá (37 km²). Illegal selective logging and forest fires in forest areas totaled 357 km² in the mosaic area, and 6 km² within Flona Anaua. Illegal selective logging and forest fires in the years of severe El Niño droughts threatened the maintenance of environmental services provided by Amazonian forests.

Multi-century periods since fire in an intact woodland landscape favour bird species declining in an adjacent agricultural region

Habitat modification by fire and habitat loss via anthropogenic vegetation clearance and fragmentation both impact animal populations. Yet, there has been limited investigation as to whether animals that decline under one of these types of habitat change also decline under the other, and how their cumulative impacts affect the status of species and communities. Using a ~400-year chronosequence in the world's largest extant temperate woodland in south-western Australia, we examine how time since fire affects bird community richness, reporting rates and composition, and whether taxa grouped on the basis of responses to vegetation clearance and fragmentation in an adjoining agricultural landscape are associated with either recently-burnt or long-unburnt woodlands. Consistent with substantial changes in vegetation composition and structure after fire in obligate-seeder eucalypt woodlands, woodland bird communities were strongly affected by fire. Species richness and total reporting rates increased with time since fire, and community composition changed across the entire multi-century span of the chronosequence. Woodland birds most negatively impacted by vegetation clearance and fragmentation were strongly associated with long-unburnt woodlands. In a regional south-western Australian context, where extensive vegetation clearance has substantially reduced the range and populations of many woodland bird species, the ability of remaining unfragmented woodlands to support populations of these species will be strongly contingent on appropriate fire management. Specifically, as stand-replacement fires have affected 25–30% of extant woodland over recent decades, management to limit the extent of fire in remaining long-unburnt woodlands would appear a priority for conservation of woodland bird diversity.

Estimating the extent of fire induced soil water repellency in Mediterranean environment

The fire occurrence in Mediterranean climate regions and the area affected by fire in general are rising due to prolonged drought periods and redistribution of rainfall. This can have effect on soil properties and local scale hydrology by increasing fire induced soil water repellency (SWR). The main objective of our research was to assess the degree of fire induced SWR in the Mediterranean karst area using multiple easy-to-perform field and laboratory methods. The field infiltration measurements were performed with a tension disc infiltrometer (TI) and a minidisc tension infiltrometer (MD) using water and ethanol as an infiltrating liquid on two locations: burnt (B) and control (C, unaffected by fire). Additionally, water drop penetration time test (WDPT), and molarity of ethanol droplet time test (MED) were applied at the laboratory on disturbed and undisturbed soil samples at various depths. All measurements revealed significant differences between burnt and control plots. Infiltration and hydraulic conductivity were reduced and repellency index (RI) was increased at the fire affected sites. The SWR decreased with depth which can be associated with decreasing organic matter and fire burning effect. The WDPT and MED methods in combination with mini disc tension infiltrometer measurements were found useful for the determination of sub-critical SWR. Further research is needed to develop a framework for the quantitative SWR classification, as well as subsequent estimation of the relevance of SWR on critical hydrological processes such as infiltration, runoff, and preferential flow.

A Finite Element (FE) simulation of naked solid steel beam at elevated temperature

This paper presents the numerical analysis of temperature distribution of a simply supported naked solid steel beam under fire exposure. Prescriptive based approach particularly is the safest and easiest approach to determine the level of strength of structural member when expose to elevated temperature. However, this method assuming uniform fire exposure through the overall cross section of the structural member which may leads to over design. The outcome of the design may not reflect the real fire scenario. Performance based approach is a realistic approach which can predict the structural steel behavior. In this method, three main components were considered, namely fire exposure behavior, heat transfer analysis and mechanical reaction. Fire exposure behavior dealing with types or severity fire load exposed to structural member. There are few options available to determine the fire extent, namely nominal fire models, compartment fires, localized fires, zone models and computational fluid dynamics (CFD) models. Meanwhile, heat transfer analysis estimates the energy dissipation (initiate from fire) between structural elements due to temperature variation. Structural response incorporates finite element modeling that predicts the structural element behavior, namely stresses and deformation. This method considers the prime factors such as shadow effect, support condition, loading condition, boundary conditions and interaction properties between different structural elements which can optimize the structural behavior analysis. However, there are still lack of research that consider those factors that might jeopardize the behavior of steel beam. Owing to this, a performance based approach method was introduced in this research. Experimental investigation was retrieved from the readily available data of Compendium of UK Standard Fire Test Data. One sample of naked solid steel beam was selected from the wide range of naked solid beam available from the Compendium. Standard fire curve of ISO 834 was used during numerical simulation to correlate with the experimental investigation. From the results of the finite element simulation, the predicted member temperature agrees well with the experimental investigations. Hence, future works of cellular steel beam (CSB) with various web opening shapes can be initiate due to its limited researches related to CSB at elevated temperatures