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Alvarez, C., Moreno, G., Valenzuela, F., Rivera, J. I., Ebensperger, F., Reszka, P., et al. (2023). Use of an electric heater as an idealized firebrand to determine ignition delay time of Eucalyptus globulus leaves. Fire Saf. J., 141, 103923.
Abstract: The Idealized-Firebrand Ignition Test (I-FIT) protocol was used to evaluate the piloted ignition delay times of fuel beds composed of leaves of Eucalyptus globulus (Labill.). The amount of fuel layer used for evaluation ranged between the fraction volume (������) of 0.03 to 0.07 which are values expected to be found in forest bed fuels. A theoretical model was developed to describe the heating and ignition of the fuel beds, based on the thermal ignition theory. The model, which was originally developed for pine needle beds, considers the penetration of radiation to the porous matrix. The model is able to accurately predict the ignition delay time for different values of ������, but shows a poorer accuracy for the temperature evolution. This is explained by the large variability observed for the Eucalyptus leaves.
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Baselli, G., Contreras, F., Lillo, M., Marin, M., & Carrasco, R. A. (2020). Optimal decisions for salvage logging after wildfires. Omega-Int. J. Manage. Sci., 96, 9 pp.
Abstract: Strategic, tactical, and operational harvesting plans for the forestry and logging industry have been widely studied for more than 60 years. Many different settings and specific constraints due to legal, environmental, and operational requirements have been modeled, improving the performance of the harvesting process significantly. During the summer of 2017, Chile suffered from the most massive wildfires in its history, affecting almost half a million hectares, of which nearly half were forests owned by medium and small forestry companies. Some of the stands were burned by intense crown fires, which always spread fast, that burned the foliage and outer layer of the bark but left standing dead trees that could be salvage harvested before insect and decay processes rendered them unusable for commercial purposes. Unlike the typical operational programming models studied in the past, in this setting, companies can make insurance claims on part or all of the burnt forest, whereas the rest of the forest needs to be harvested before it loses its value. This problem is known as the salvage logging problem. The issue also has an important social component when considering medium and small forestry and logging companies: most of their personnel come from local communities, which have already been affected by the fires. Harvesting part of the remaining forest can allow them to keep their jobs longer and, hopefully, leave the company in a better financial situation if the harvesting areas are correctly selected. In this work, we present a novel mixed-integer optimization-based approach to support salvage logging decisions, which helps in the configuration of an operational-level harvesting and workforce assignment plan. Our model takes into account the payment from an insurance claim as well as future income from harvesting the remaining trees. The model also computes an optimal assignment of personnel to the different activities required. The objective is to improve the cash position of the company by the end of the harvest and ensure that the company is paying all its liabilities and maintaining personnel. We show how our model performs compared to the current decisions made by medium and small-sized forestry companies, and we study the specific case of a small forestry company located in Cauquenes, Chile, which used our model to decide its course of action. (C) 2019 Elsevier Ltd. All rights reserved.
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Miranda, A., Mentler, R., Moletto-Lobos, I., Alfaro, G., Aliaga, L., Balbontin, D., et al. (2022). The Landscape Fire Scars Database: mapping historical burned area and fire severity in Chile. Earth Syst. Sci. Data, 14(8), 3599–3613.
Abstract: Achieving a local understanding of fire regimes requires high-resolution, systematic and dynamic databases. High-quality information can help to transform evidence into decision-making in the context of rapidly changing landscapes, particularly considering that geographical and temporal patterns of fire regimes and their trends vary locally over time. Global fire scar products at low spatial resolutions are available, but high-resolution wildfire data, especially for developing countries, are still lacking. Taking advantage of the Google Earth Engine (GEE) big-data analysis platform, we developed a flexible workflow to reconstruct individual burned areas and derive fire severity estimates for all reported fires. We tested our approach for historical wild-fires in Chile. The result is the Landscape Fire Scars Database, a detailed and dynamic database that reconstructs 8153 fires scars, representing 66.6% of the country's officially recorded fires between 1985 and 2018. For each fire event, the database contains the following information: (i) the Landsat mosaic of pre- and post-fire images; (ii) the fire scar in binary format; (iii) the remotely sensed estimated fire indexes (the normalized burned ratio, NBR, and the relative delta normalized burn ratio, RdNBR); and two vector files indicating (iv) the fire scar perimeter and (v) the fire scar severity reclassification, respectively. The Landscape Fire Scars Database for Chile and GEE script (JavaScript) are publicly available. The framework developed for the database can be applied anywhere in the world, with the only requirement being its adaptation to local factors such as data availability, fire regimes, land cover or land cover dynamics, vegetation recovery, and cloud cover. The Landscape Fire Scars Database for Chile is publicly available in https://doi.org/10.1594/PANGAEA.941127 (Miranda et al., 2022).
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Valenzuela, F., Rivera, J. I., Ebensperger, F., Alvarez, C., Reszka, P., Auat Cheein, F., et al. (2023). Ignition of Wildland Fuels Exposed to a Time-Decreasing Incident Heat Flux. Combust. Sci. Technol., 195(14), 3596–3611.
Abstract: The effect of decreasing incident heat fluxes on the ignition delay time of dry pine needles is addressed in the present study. A customized modular instrument (I-FIT) that uses radiant heaters to simulate idealized firebrands ensures experimental repeatability for combustion experiments. Linear incident heat flux ramps are obtained by controlling the power of the heating element, thus simulating idealized firebrands. An analytical model based on the thermal ignition theory was developed and solved analytically using an integral approach. This model includes convective losses and in-depth penetration of radiation. Radiation was modeled using the P1 approximation. The theoretical model is complemented and validated by experimental data, showing increments of the ignition delay times when the negative slope steepness over time increases for the same heat flux. For given values of the initial incident heat flux on the sample, a critical slope beta(cri) is observed. For slopes steeper than this critical value, ignition is not attained.
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