Post-fire Scenario Research Articles

Pathological manifestations in a historic building: post-fire scenario at Casarão dos Fabricantes

The objective of this study is to document the pathological manifestations of the Casarão dos Fabricantes, one of the oldest buildings in Fortaleza, which was severely damaged by a major fire in 2020. Despite its historical significance, there are no records detailing the condition of the building either before or after the fire. The internal walls and two facades were the only construction elements that were not destroyed by the fire. The survey of the pathological manifestations was conducted by visual assessment and infrared thermography, revealing different degradation processes across the evaluated structures and providing a systematic view of the extent of the damage to the building. Mapping this damage provided an integrated approach, offering a scientific basis to support the restoration process.

Pre- and post-fire forest canopy height mapping in Southeast Australia through the integration of multi-temporal GEDI data, satellite images, and Convolution Neural Network

ABSTRACT This study leveraged Convolutional Neural Network (CNN) models to estimate canopy height in Southeast Australian forests before and after the 2019–2020 bushfire event, using inputs from Sentinel-1, Sentinel-2, spectral indices, and terrain features and GEDI canopy height (rh99) as target variables. Our research consisted of three primary objectives: (1) an evaluation of GEDI rh99 canopy height in relation to an nDSM derived from airborne LiDAR, (2) the development of two CNN models for pre- and post-fire scenarios, and (3) utilizing the trained CNN models to generate pre- and post-fire canopy height maps and canopy height change maps across the continuous landscape. GEDI rh99 accuracy analysis revealed R 2 = 0.85, RMSE = 7.25 m and nRMSE = 0.23 for pre-fire GEDI and R 2 = 0.78, RMSE = 10.1 m and nRMSE = 0.3 for post-fire GEDI. The pre-fire CNN model achieved R 2 = 0.75, RMSE = 7.29 m and nRMSE = 0.22, and post-fire CNN model achieved R 2 = 0.62, RMSE = 11.67 m, and nRMSE = 0.34 when validated against nDSM. Bias analysis was conducted, revealing that GEDI rh99 underestimated nDSM across all canopy height ranges, and slope has no significant impact on GEDI accuracy. Notably, post-fire GEDI rh99 exhibited significant underestimation in high to extreme fire severity. The CNN models’ prediction displayed overestimation in short forests < 20 m and increasing underestimation in taller forests > 20 m and underestimation in high and extreme fire severity. Subsequent investigation indicated that canopy layer thinning in high fire severity conditions resulted in weak GEDI waveform signals and consequent bias. Additionally, the GEDI rh99 bias was propagated to the CNN models, together with insensitivity of spectral band values to canopy height in dense and burnt forests potentially contributed to models’ bias. Finally, we demonstrated CNN models’ ability to monitor forest recovery by generating canopy height maps spanning East Gippsland from 2019 to 2023.

Post Fire Dynamic Analysis of Steel Buildings Subject to Wind Loadings in South of Iraq

Post-fire analysis of a six-story square steel building under the action of dynamic wind forces in the south of Iraq is presented. The nonlinear time-history analysis using direct integration method is accomplished by SAP 2000 V16 program while geometric nonlinear parameters are included. The post fire deformations values and their configurations along building are based on available literature that related to post fire deformations of steel buildings at 550oCwith reducing of yield stress and modulus of elasticity) by 10% due to fire. In the present study, two post fire scenarios are considered, with wind speed of 42 m/s, according to Iraqi meteorological and IQS.301 standards. The aim of this study is to investigate the post-fire dynamic analysis of a multi-story steel moment-resisting building subjected to dynamic along-wind loads. Variations of base shear, base moment, drift ratio, and displacement are considered for discussion and comparison. Its concluded that the presence of deformation in building after fire and the reduction in yield stress and modulus of elasticity increased the base shear, base moment and drift ratio as average by about 12.5, 20&amp; 64%respectively under the effect wind load. The fire deformations may be critical and the structural decision for the building safety should be done via structural analysis of the building taking into consideration different parameters related to post fire effects.

Post-wildfire erosion rates and triggering of debris flows: A case study in Susa Valley (Bussoleno)

Post-wildfires geological hazards are an emerging problem in many places, including areas not typically associated with these events such as the Alpine Region. Hazards connected with post-fire processes such as debris-flows and flood-type events threatens people, infrastructures, services and economical activities. Apart from a few examples, there is a lack of models available to quantify the increase in susceptibility as a result of the modification induced by the wildfires. In this work we test the application of a modified version of the RUSLE, on GIS, to quantify the post-fire erosive phenomena for a case study in the north-western Italian Alps. The results of its application, taking advantage of high-resolution rainfall series and data deriving from field surveys, highlight the marked increase (more than 20 times) in erosion rates, quantified by expressing both the EI (erodibility index), the A (monthly soil loss) and the SL (monthly sediment loss) rise. The months of April, May and June represents the larger share of the total quantities. This is a consequence of the noticeable increase of the Erodibility Index EI, which for the post-fire scenario is more than one order of magnitude higher than the pre-fire one.

Short communication: Maritime pine natural regeneration in Coastal Central Portugal: Effects of the understory composition

Aim of study: To study the natural dynamics of Pinus pinaster natural regeneration in a post-fire scenario in three populations of Coastal Central Portugal, with severe ecological degradation due to plant invasions, and partially affected by the 2017 wildfires.&#x0D; Area of study: Three P. pinaster populations, located along a geographic gradient of about 140 km on Coastal Central Portugal: Mira, Tocha and Leira.&#x0D; Material and methods: The density and establishment success of P. pinaster regeneration was studied in burnt and unburnt forest stands. Special focus was given to the effects of the cover by native and invasive species (mainly Acacia longifolia) on pine regeneration.&#x0D; Main results: Regeneration values considered sustainable (over 0.3 seedlings·m-2) were recorded in all three populations in burnt and unburnt plots, where only one of the three study sites showed signs of establishment difficulty. We recorded high levels of invasion which showed a negative relationship with regeneration density.&#x0D; Research highlights: The cover of invasive flora was negatively correlated with pine regeneration, while the presence of native flora showed positive relations with density and height of pine natural regeneration.

Post-fire seismic behaviour of a self-centring connection with buckling-restrained plates and pre-stressed bars

Fire hazard is regarded as a significant threat to structural systems, not only the resistance during the fire should be concerned but the post-fire assessment of structural performance is also of great importance. The post-fire seismic behaviour is the key metric for evaluating the residual performance of structures mainly serving seismic demands. However, limited research considers whether the self-centring system, one of the seismic-resilient structures, can still resist seismic loadings after fire exposure. Based on that, this study mainly aims to investigate the post-fire seismic response of a self-centring system with buckling-restrained plates and pre-stressed bars. A sequence of the fire exposure and the post-fire cyclic test was conducted on the cross-shaped specimen, and hysteretic behaviour after air-cooling was analysed and compared with the regular seismic response. Results showed that fire exposure not only significantly influences the geometric conditions of the self-centring system, but also completely transforms the original deformation mechanism. Pre-stressed bars were expanded and stretched during the fire so that could not provide self-centring capacity in post-fire conditions, while the energy dissipation of buckling-restrained plates was postponed and weakened because of the slippage at bolted connections. Compared with the regular seismic behaviour, the post-fire hysteretic response appeared sliding and pinching effect rather than the flag-shaped, with a much lower load-carrying capacity and extremely larger residual deformation. To improve the post-fire seismic resistance, the numerical model was established first to reappear the experimental response by the heat transfer analysis and post-fire static analysis, and then extended to simulate the post-fire repair in proposed strategies. According to the repair effect, it is suggested that the high-strength bolts should be replaced with pre-load, and the bars are required at least to provide additional stiffness and re-tensioned if necessary. The findings reveal the considerable influence of fire exposure on the seismic performance of the self-centring system, and highlight the importance of improving residual resistance of seismic-resilient structural systems in post-fire scenarios.

Predicting the potential impact of forest fires on runoff and sediment loads using a distributed hydrological modeling approach

Forest fires profoundly affect the nature of watershed responses to precipitation, increases in runoff rate and volume, and post-fire sediment discharge. A post-fire watershed assessment to identify potential trouble spots for soil erosion and flooding can help land managers for decision-making on deploy mitigation, remediation measures, and restoration action plans. Predicting the potential impact of fires on runoff and soil erosion requires distributed hydrological modeling methods. This study used the Soil and Water Assessment Tool (SWAT), a rainfall-runoff model, to investigate the hydrological consequences of forest fires and their impact on sediment load under different burnt scenarios. For the pre-fire (baseline) scenario, the watershed is calibrated by using the measured discharge and suspended sediment concentration data from the weather station during the time step to estimate post-fire changes at the sub-catchment scale. The total water and sediment yield for the selected sub-catchment in the post-fire scenario with the highest spatial distribution of forest fire, due to the excessive surface runoff (an increase of 14.5%) increased significantly, resulted in 6.5 times increase in sediment yield. The results obtained from the study indicate a significant increase in sediment transport into the stream in the post-fire scenario. A large volume of soil losses occurred during the time step. In contrast, due to removing trees and vegetation from the ground, less evapotranspiration and infiltration occurred in selected sub-catchment areas after forest fires. In terms of watershed management, understanding the consequences of forest fires on hydrological services will be an effective method for sediment budget control. Therefore, applying the rainfall-runoff and erosion models for the watershed with developing plausible forest fire scenarios can be a productive method to deal with the threats and hydrological risks such as soil erosion and sediment transfer to the downstream environment.

Unexpected costs of extended phenotypes: nest features determine the effect of fires on leaf cutter ant's demography.

A key principle of the extended phenotype concept is that the benefit of the structures that an animal builds exceeds its cost. However, some contexts may enhance the costs of structures that often represent a benefit, reversing their adaptive nature. In leaf-cutting ant nests, thatched mounds are extended phenotypes that offer a stable microclimate for the growth of the fungus culture. We hypothesized that fires will affect the species that build external, easily flammable thatch mounds (Acromyrmex lobicornis) more than colonies that build subterranean nests in the less-flammable bare ground (Amoimyrmex striatus). We use a stochastic matrix demographic model parameterized with 4 years of data in pre- and post-fire scenarios. Before fires, Ac. lobicornis showed higher stochastic population rate (λs) than Am. striatus. However, fire frequency every 2 years completely reversed this trend, showing population decline only in Ac. lobicornis. Small nests were the stage that most contributed to λs and the most sensitive in all the species and fire scenarios. This illustrates a novel effect of disturbances; the reversion of the adaptive nature of extended phenotypes, which may have strong consequences on population dynamics and assemblage structure through the invert of dominance relationships.

Modelling effects of forest fire and post-fire management in a catchment prone to erosion: Impacts on sediment yield

The present paper contributes to bridging the gaps in modelling post-fire impact and mitigation measures on soil erosion. The specific aims were to predict the effects of forest fires and post-fire mitigation measures on runoff and specific sediment yield (SSY) in a river basin (Celone, S-E Italy). The Soil and Water Assessment Tool model, calibrated with field observations, was used to evaluate runoff and SSY for the current land use (baseline) and six post-fire scenarios. From 1990 to 2011, at the basin scale, the average annual SSY was 5.60 t ha- 1yr−1 (SD = 3.47 t ha-1yr−1). 20% of the total drainage area showed a critical value of SSY (>10 t ha−1 yr−1). The effects of different fire-severity levels were predicted for one year after the fire, acting on a limited area (2.3% of the total basin area). At the basin scale, the post-fire effect on surface runoff was negligible for all scenarios (<0.4%), and the impact on SSY increased from 5.86 t ha−1 yr−1 up to 12.05 t ha−1 yr−1. At the subbasin scale, the post-fire logging scenario showed the highest increase of soil loss (SSY increased from 9.48 t ha−1 yr−1 to 57.40 t ha−1 yr−1). Post-fire mitigation treatments like straw mulching and erosion barriers effectively reduced soil erosion in high- and moderate-severity fires (19.12 t ha-1yr−1 and 20.93 t ha−1 yr−1, respectively). At the hydrological response unit level, the SSY estimated for the forest in the baseline ranged from 1.18 t ha- 1yr−1 to 2.04 t ha−1 yr−1. SSY increased more than one order of magnitude for the high-severity fire scenarios and ranged from 4.33 to 6.74 t ha−1 yr−1 in the very low-severity fire scenario, underlining the scale effect from the HRU to the basin scale.

Elevated temperature and post-fire stress-strain modeling of advanced high-strength cold-formed steel alloys

Advanced high-strength cold-formed steels (AHSS) have been developed with yield strengths up to 1250 MPa and ultimate strengths up to 1900 MPa. Accurate stress-strain modeling of these new steel alloys are required for eventual application of AHSS into the building construction industry, including the material behavior of AHSS subjected to elevated temperatures. A series of new constitutive material models are proposed based on the experimental AHSS stress-strain database at elevated temperatures (i.e., steady-state and transient-state test methods) and post-fire scenario (i.e., residual test method). The stress-strain curves from experiments on two families of AHSS, including dual phase steel with nominal yield strengths of 340 MPa and 700 MPa, and martensitic steel with nominal yield strengths of 1030 MPa and 1200 MPa, reported in a previous study are considered. Existing stress-strain models are investigated and fit to the AHSS database, in addition to the development of new material models. The required input parameters of the proposed stress-strain models are determined, and their corresponding predictive expressions are proposed. It is shown the stress-strain behaviors of AHSS could be accurately described by the proposed models. The data generated by this research addresses fire safety design and will be essential in supporting the adoption of these next-generation steels in future infrastructure.

Evaluation of Soil Evolution After a Fire in the Southeast of Spain: A Multiproxy Approach

Fire is considered as part of the ecological dynamic in Mediterranean forests and is strongly related to an anthropogenic origin. The aim of this study is to evaluate the evolution of soil properties after a fire in the short term (20 months) by the use of soil quality indicators. The work is based on a multiproxy approach about three basic aspects: 1) the study of changes in soil properties; 2) the estimation of erosion rates; and 3) the evaluation of colonization evolution by soil arthropods through ichnological analysis. Three sectors were selected for this study: a burned and intervened area, a burned and not intervened area, and a reference area. Soil samples were taken randomly from each plot and their main physico-chemical properties analyzed. The assessment of soil erosion was estimated for each plot from three transects (20 m in length) perpendicular to the maximum slope, and the same transects were used for the ichnological study to identify the different bioturbations and the producers. An increase in pH and K values and C/N ratio, and a decrease in total N, available P, CEC, and respiration rate were observed among the fire-affected areas and the reference area; however, there were no significant differences in soil organic carbon. According to erosion, the hydrological correction measures based on the construction of barriers with trunks and branches favored higher runoff and erosion rates in the intervened areas with respect to the not intervened areas. The ichnological analysis showed that arthropods of Formicidae family and Lycosidae sp. genre were the main organisms that recolonized post-fire scenarios; moreover, a lower ichnodiversity is observed in the not intervened area, although with a greater abundance, with respect to the intervened and reference area. According to our results, 20 months after the fire most soil physical-chemical properties did not experiment significant differences in relation to unburned reference area. Our erosion estimation suggested the hydrological correction measures were not appropriate to reduce erosion rates and led to higher soil losses. Moreover, our ichnological study supports the domination by pioneer and opportunist organisms in the recolonization of burned areas.

Post-fire practices benefits on vegetation recovery and soil conservation in a Mediterranean area

Post-fire practices (PFP) aim to reduce soil erosion and favour vegetation recovery, but their effectiveness is spatially heterogeneous and under debate because of the economic and environmental costs. This study evaluates the different changes (Δ) of canopy cover (CC), sediment connectivity (SC) and local topography in four areas affected by the Pinet fire in eastern Spain (August 8th, 2018) and managed with: totally burnt with tree removal and long log erosion barriers (LEBs) (Pinet-1), partially burnt without PFP (Pinet-2), totally burnt with tree removal and short LEBs (Pinet-3), and totally burnt without PFP (Pinet-4). An unburnt nearby area was used as control site (Pinet-5). High-resolution images obtained before the fire and during two drone flights after the fire (10.5 and 5.5 months after the fire and PFP; and 18 and 13 months after the fire and PFP) were analysed; and LiDAR- and SfM-derived digital elevation models used to compute the Aggregated Index of SC (AICv2). After correcting calculations, because of the different input sources, and excluding the forest roads (x¯=3.6% of the total surface), CC in the first post-fire scenario was of 25.5% (−40.4% with respect to the pre-fire scenario), 14.5% (−68.4%), 23.8% (−43.7%), 26.9% (−26.5%) and 29.6% (−32.7%) in Pinet-1, P-2_totally_burnt, P-2_partially_burnt, P-3 and P-4; and ΔCC among the drone flights were of +2.45%, +0.02% and +10.54% in Pinet-1, Pinet-3 and Pinet-4. The annual CC recovery rate decrease from 27.5% to 19.1% per year between the first and the second post-fire scenario, indicating a quick vegetation recovery, especially in the first year, and considering the surface area covered by rocks (x¯=16.3%). Topographic changes indicated that not install LEBs favoured shorter flow length pathways after the fire, and thus, runoff will flow faster to cover the same area, achieving higher velocity and thus soil detachment capacity. Sediment connectivity increased in all burnt sub-sites after the fire (Δ1¯=+32.4%), but the increments in the two sub-sites with LEBs were 36% lower than the increase in the sub-sites without LEBs. The increase of connectivity in the first and second post-fire scenarios was −32% and −45% in the sub-site with long LEBs compared with the sub-site with short LEBs. Overall, LEBs effectively favoured vegetation recovery, lengthened overland flow pathways, and reduced sediment transport in the early months, but their usefulness was not as pronounced during the second post-fire year, although these results may be influenced by the Mediterranean conditions of the site.

Combining Methods to Estimate Post-Fire Soil Erosion Using Remote Sensing Data

The increasing number of wildfires in southern Europe is making our ecosystem more vulnerable to water erosion; i.e., the loss of vegetation and subsequent runoff increase cause a shift in large quantities of sediment. Fire severity has been recognized as one of the most important parameters controlling the magnitude of post-fire soil erosion. In this paper, we adopted a combination of methods to easily assess post-fire erosion and prevent potential risk in subsequent rain events. The model presented is structured into three modules that were implemented in a GIS environment. The first module estimates fire severity with the Monitoring Trends in Burn Severity (MTBS) method; the second estimates runoff with rainfall depth–duration curves and the Soil Conservation Service Curve Number (SCS-CN) method; and the third estimates pre- and post-fire soil erosion. In addition, two post-fire scenarios were analyzed to assess the influence of fire severity on soil erosion: the former based on the Normalized Difference Vegetation Index (NDVI) and the latter on the Relative differenced Normalized Burn Index (RdNBR). The results obtained in both scenarios are quite similar and demonstrate that transitional areas, such as rangelands and rangelands with bush, are the most vulnerable because they show a significant increase in erosion following a fire event. The study findings are of secondary importance to the combined approach devised because the focal point of the study is to create the basis for a future tool to facilitate decision making in landscape management.

Short-Term Effects of Wildfire Ash on Water Quality Parameters: A Laboratory Approach.

Climate change coupled with inappropriate burning practices has increased large-scale wildfires in Brazilian tropical savannahs (Cerrado). Considering that the effects of ash from wildfires on water parameters are scarcely known in tropical savannahs, this study investigated the chemical changes caused by ash in the soft water, commonly used for bioassays. To this end, ash samples were collected immediately following a fire in a Cerrado area (Federal District, Brazil) and put into water (1:10 ash:soft-water m/v) to check physical parameters under laboratory conditions. Major water-extractable elements (K+, SO42-, Ca2+, PO43-, Na+, Mg2+) from ash strongly altered water quality parameters: elevated total dissolved solids and conductivity levels as well as an increase in pH and decrease in dissolved oxygen concentration were reported over the course of the experiment (15 days) compared to control conditions. Our results point out relevant solubilized compounds from ashes which may potentially impact water quality in post-fire scenarios.

Evaluating the potential of LiDAR data for fire damage assessment: A radiative transfer model approach

Providing accurate information on fire effects is critical to understanding post-fire ecological processes and to design appropriate land management strategies. Multispectral imagery from optical passive sensors is commonly used to estimate fire damage, yet this type of data is only sensitive to the effects in the upper canopy. This paper evaluates the sensitivity of full waveform LiDAR data to estimate the severity of wildfires using a 3D radiative transfer model approach. The approach represents the first attempt to evaluate the effect of different fire impacts, i.e. changes in vegetation structure as well as soil and leaf color, on the LiDAR signal. The FLIGHT 3D radiative transfer model was employed to simulate full waveform data for 10 plots representative of Mediterranean ecosystems along with a wide range of post-fire scenarios characterized by different severity levels, as defined by the composite burn index (CBI). A new metric is proposed, the waveform area relative change (WARC), which provides a comprehensive severity assessment considering all strata and accounting for changes in structure and leaf and soil color. It showed a strong correlation with CBI values (Spearman's Rho = 0.9 ± 0.02), outperforming the relative change of LiDAR metrics commonly applied for vegetation modeling, such as the relative height of energy quantiles (Spearman's Rho = 0.56 ± 0.07, for the relative change of RH60, the second strongest correlation). Logarithmic models fitted for each plot based on the WARC yielded very good performance with R2 (± standard deviation) and RMSE (± standard deviation) of 0.8 (± 0.05) and 0.22 (± 0.03), respectively. LiDAR metrics were evaluated over the King Fire, California, U.S., for which pre- and post-fire discrete return airborne LiDAR data were available. Pseudo-waveforms were computed after radiometric normalization of the intensity data. The WARC showed again the strongest correlation with field measures of GeoCBI values (Spearman's Rho = 0.91), closely followed by the relative change of RH40 (Spearman's Rho = 0.89). The logarithmic model fitted using WARC offered an R2 of 0.78 and a RMSE of 0.37. The accurate results obtained for the King Fire, with very different vegetation characteristics compared to our simulated data, demonstrate the robustness of the new metric proposed and its generalization capabilities to estimate the severity of fires.

A wildfire in an Amazonian canga community maintained important ecosystem properties

Because wildfires alter plant communities, we describe the effects of a single fire event on the composition and diversity of Amazonian ferruginous savannas, locally known as cangas. We installed 20 observation plots in burned and unburned parts of a homogeneous canga site from the Carajás Massif. The single fire event shifted community composition slightly, increased functional richness and the abundance of anemochoric and subshrub species, but did not influence the number of phanerophyte species, highlighting the importance of both seeding and resprouting strategies in the post-fire scenario. In contrast, neither taxonomic nor phylogenetic diversity was affected by the fire event. The absence of differences in the phylogenetic community structure indicated that specific adaptations to fires are widespread within the canga phylogeny, although fires are not an eminent part of these ecosystems, as in other neotropical savannas. As diversity metrics were not negatively affected by a single fire event and only small shifts in species composition were observed, our data indicate maintenance of important ecosystem properties despite an occasional wildfire event in the analysed canga shrubland. Further research should outline how different physiognomies are affected and how different fire regimes influence communities to assist in the design of effective management plans for this ecosystem.

Assessment of superficial water quality of small catchment basins affected by Portuguese rural fires of 2017

Abstract In October of 2017 a series of rural fires affected Portugal’s Central Region, leading to the destruction of 40–60% of the forest area in some districts. A monitoring program was initiated in 5 catchments of the Mondego drainage basin, in order to understand the temporal evolution of the water’s physical and chemical characteristics in a post-fire scenario. This monitoring program was implemented in catchments with sizes between 20 km2 and 160 km2 in areas 60%–99% burnt. For each catchment a gauging point was selected near the mouth of the river. These 5 gauging points were assessed monthly, starting one month after the fire, in November 2017, and ending in June 2018. In each campaign stream water was sampled for laboratory analysis and in-situ physical-chemical proprieties were measured. Major ions in water samples were determined through ion chromatography (IC) and molecular absorption spectroscopy, and inductively coupled plasma optical emission spectrometry (ICP-OES). Trace elements were evaluated through ICP-OES and inductively coupled plasma mass spectrometry. Total organic carbon and dissolved organic carbon were evaluated through the oxidation method and polycyclic aromatic hydrocarbons were determined by high-performance liquid chromatography. The data collected was crossed with the catchment’s morphometric, geological and land use data, including characteristics of the burnt area. Results showed that these fires affected the surface waters in the studied catchments, producing an increase in turbidity, and in the concentrations of Al, Fe, Mn and possibly NO3 and As.

Evaluating the effects of forest fire on water balance using fire susceptibility maps

Abstract Sudden and long term changes in the landscape can be attributed to periodic wildfires which, is a cyclic occurrence at Kudremukh national forest in Western Ghats of India. These land-use changes influence the hydrology of landscape, causing disintegration of soil, loss of biodiversity, changes in stream and flooding. To understand and account for these land-use changes, a new approach was implemented by developing fire susceptibility map from topographic, climatic and human-induced factors and validating it with MODIS (Moderate-resolution Imaging Spectro-radiometer) fire points for discretising accuracy. The fire susceptibility map can be used for studying the long-term (year or more) effects of fire on water balance systems. The fire susceptibility map generated for the years 2005 and 2017 was overlaid with MODIS LULC (Land Use Land Cover) for establishing the post-fire scenario whereas MODIS LULC MCD12Q1 (2005 and 2017) was considered as the no-fire scenario to analyse the intensity of the fire and its effect on streamflow and infiltration. These maps along with historical satellite hydro-climatic datasets, were used to assess the effect of forest fire on hydrological parameters using the SWAT (Soil and Water Assessment Tool) model. No-fire and post-fire conditions were established by modifying SCS-CN (Soil Conservation Service-Curve Number) based on previous works of literature to represent the catchment as unburnt and burnt area. The SWAT model was calibrated (2002–2008) and validated (2009–2012) for establishing a baseline scenario. The sensitive parameters obtained from SUFI-2 (Sequential Uncertainty Fitting) algorithm in SWAT-CUP (Calibration and Uncertainty Programs) were used to simulate stream flows till 2017 due to lack of observed streamflow data for the year 2017. It was inferred that the effect of wildfire on flows in recent years (2017) had increased radically when compared to the flows before a decade (2005), diminishing the rate of infiltration and causing the deficit in groundwater to energise. The methodology can further be executed in any forest area for distinguishing fire hazard zones and implementing prior actions in those areas for mitigation of forest fires and maintaining sustainable water balance.

Evaluation of hydrological and erosive effects at the basin scale in relation to the severity of forest fires

This study aimed to assess the hydrological and erosive effects of different levels of the fire severity in the drainage basin of the Trionto River (Calabria, southern Italy), which was partially burned by intense fires during the summer 2017. The analysis focused on the identification of wildfire areas using a supervised classification of remote sensing images with the minimum distance algorithm. The level of severity of each fire was then discriminated based on a procedure proposed by the U.S. Department of Agriculture and adapted to the study area. To evaluate how wildfire occurrence affects the hydrological behaviour at the basin scale, the SCS-Curve Number model was used to document pre- and post-fire conditions in relation with the level of fire severity. Finally, the influence on erosion was analysed for analogous conditions at the basin scale using the RUSLE equation. The effects on hydrological balance and soil loss were evaluated by comparing the pre-fire value with three different post-fire scenarios: (a) different levels of severity on the surface covered by the fire (real case); (b) maximum level of severity on the surface covered by the fire; (c) total loss of the canopy and formation of a hydrophobic layer on the surface soil. The results confirmed that the level of severity of the forest fires, combined with climatic factors, morphological conditions, and the pedological characteristics of the basin, significantly influence changes to the hydrology and rates of erosion. Moreover, these impacts proved to be mainly dependent on the consequent, often notable, heterogeneity in the spatial distribution of burned areas with different severity.

POST-FIRE FORESTRY RECOVERY MONITORING USING HIGH-RESOLUTION MULTISPECTRAL IMAGERY FROM UNMANNED AERIAL VEHICLES

Abstract. In recent years unmanned aerial vehicles (UAVs) have been used in several applications and research studies related to environmental monitoring. The works performed have demonstrated the suitability of UAVs to be employed in different scenarios, taking advantage of its capacity to acquire high-resolution data from different sensing payloads, in a timely and flexible manner. In forestry ecosystems, UAVs can be used with accuracies comparable with traditional methods to retrieve different forest properties, to monitor forest disturbances and to support disaster monitoring in fire and post-fire scenarios. In this study an area recently affected by a wildfire was surveyed using two UAVs to acquire multi-spectral data and RGB imagery at different resolutions. By analysing the surveyed area, it was possible to detect trees, that were able to survive to the fire. By comparing the ground-truth data and the measurements estimated from the UAV-imagery, it was found a positive correlation between burned height and a high correlation for tree height. The mean NDVI value was extracted used to create a three classes map. Higher NDVI values were mostly located in trees that survived that were not/barely affected by the fire. The results achieved by this study reiterate the effectiveness of UAVs to be used as a timely, efficient and cost-effective data acquisition tool, helping for forestry management planning and for monitoring forest rehabilitation in post-fire scenarios.