Cette thèse est divisée en trois chapitres. Le premier explique comment utiliser la méthode «level-set» de manière rigoureuse pour faire la simulation de feux de forêt en utilisant comme modèle physique pour la propagation le modèle de l'ellipse de Richards. Le second présente un nouveau schéma semi-implicite avec une preuve de convergence pour la solution d'une équation de type Hamilton-Jacobi anisotrope. L'avantage principal de cette méthode est qu'elle permet de réutiliser des solutions à des problèmes «proches» pour accélérer le calcul. Une autre application de ce schéma est l'homogénéisation. Le troisième chapitre montre comment utiliser les méthodes numériques des deux premiers chapitres pour étudier l'influence de variations à petites échelles dans la vitesse du vent sur la propagation d'un feu de forêt à l'aide de la théorie de l'homogénéisation. / This thesis is divided in three chapters. The first explains how to use the level-set method in a rigorous way in the context of forest fire simulation when the physical propagation model for firespread is Richards' ellipse model. The second chapter presents a new semi-implicit scheme with a proof of convergence for the numerical solution of an anisotropic Hamilton-Jacobi partial differential equation. The advantage of this scheme is it allows the use of approximative solutions as initial conditions which reduces the computation time. The third chapter shows how to use the tools introduced in the first two chapters to study the influence of small-scale variations on the wind speed on firespread using the theory of homogenization.

From the Proceedings of the 1971 Meetings of the Arizona Section - American Water Resources Assn. and the Hydrology Section - Arizona Academy of Science - April 22-23, 1971, Tempe, Arizona / The importance of pine forest as a timber and water producing area has led to intensive management, including protection from wildfire. This has resulted in dense stand growth with increased destructive fire potential and transpirational water loss. In Arizona, as in many areas, prescribed forest burning has been used to effectively reduce these fuel hazards. Some question has arisen about the possible side effects of such treatments, particularly air pollution and reduction of infiltration and water yield. In an effort to determine the effects on infiltration, plots receiving various treatments (control, light burn, heavy burn) were fitted with fusion pyrometers before burning, to measure soil surface temperatures during burning. After burning, infiltrometers were installed. Surface temperatures did not exceed 200 degrees f. For the light burns, and ranged over 350-500 degrees f. During heavy burns. Both heavy and light burns produced highly significant decreases in infiltration capacities after burning and the surface 2 inches showed increases in soil pH, carbon and total nitrogen percentages. Infiltration capacities returned to normal after overwintering and were attributed to frost action on soil texture and porosity. The soil chemical changes decreased slowly over 2 years. Soil water repellency also increased and the significance of this is discussed.

Forested watersheds in western North America are subject to significant change from natural and anthropogenic disturbance, including wildfire. Forest canopy changes have subsequent impacts on sub-canopy snow processes. A simple, process-based point energy balance model was developed to quantify differences in energy balance characteristics between a burned and a healthy forest stand. Potential model uncertainties were identified using sensitivity analyses. Simulated snowmelt accurately recreated measured snowmelt, providing confidence in the model’s ability to simulate energy balance processes in subcanopy environments where wind redistribution and sublimation are not major drivers of the local snowmelt energy balance. In the burned stand, sub-canopy snow accumulation was greater but melted more rapidly than in the healthy stand. The removal of forest canopy resulted in more energy available for snowmelt, including higher short-wave and lower long-wave radiation, and increased turbulent fluxes. Burned stands should be considered a separate land cover type in larger scale watershed models. / xii, 129 leaves : ill,, map ; 29 cm

Thesis (MScBosb)--University of Stellenbosch, 2004. / ENGLISH ABSTRACT: The characteristics and total fuel load of the forest floor (FF) and harvest residue (HR) are needed to develop tools that can be used for fuel load management, fire risk analysis and fire behaviour prediction for P. patula grown in the summer rainfall area of South Africa (SA). Forest floor depth, mass and ash-free mass were measured and there was generally a greater range in depth under sawtimber (ST) stands than under pulpwood (PLP) stands. Forest floor loads, prior to ashing, ranged from 21 - 168 t ha-1 and 27 - 72 t ha-1, for ST and PLP stands, respectively and loads increased linearly with stand age. Sawtimber and PLP stands were analysed together, which resulted in a significant correlation between depth and mass (r2 = 0.78, n = 31). A loss on ignition procedure carried out on sub-samples of the FF improved the relationship between the FF depth and the ash-free mass for the different stands, and provided a more accurate model for the prediction of mass from depth. A multiple regression analysis revealed that age, altitude and mean annual precipitation (MAP) provided the best subset and accounted for 72% of the variation in the FF mass observed. The effect of increasing FF load and increasing moisture content on the fireline intensity (FLI) was examined using the fire behaviour prediction programme, BehavePlus. Harvest residue was quantified and characterised in terms of fuel size classes, under current silvicultural regimes for ST and PLP, for the development of fuel models for this species over its planted range in SA. An investigation into the proportion (by mass) of the 1- (0.0 - 0.6 cm), 10- (0.6 – 2.5 cm), 100- (2.5 – 7.6 cm) and 1000-hr (> 7.6 cm diameter) fuel classes of the total HR mass indicated that there was a significant difference between the mass of the 1-, 10- and 1000-hr fuel classes of the two silvicultural regimes, and no significant difference for the 100-hr fuel class. Two fuel models for P. patula HR and two models for standing timber were developed using the new model (NEWMDL) programme of BEHAVE and tested in BehavePlus. Nutrient concentrations were used with FF layer and HR size class load data to estimate the quantities of nutrients held in the fuel and to describe nutrient distributions in the fuel complex. Significant differences in the nutrient concentration of the FF layers and fuel components were observed which has important implications for fuel management. The concentration of N determined in this study, relative to that determined in other similar studies on P. patula was low. Forest floor loads were predicted and nutrient pools calculated for typical ST and PLP stands at both low and high altitude to provide insight into the nutrient distributions within the fuel complex. / AFRIKAANSE OPSOMMING: Die karaktereienskappe en totale brandstoflading van die bosvloer (FF) en kaalkap oorskot (HR) word benodig om instrumente te ontwikkel wat gebruik kan word vir brandstoflading bestuur, brandgevaar ontleding en brandgedrag voorspelling vir P. patula, wat in die somer reënvalgebied van Suid-Afrika groei. Die bosvloer diepte, massa en asvrye massa is gemeet en daar was oor die algemeen ‘n groter variasie in diepte onder saaghout (ST) opstande as onder pulphout (PLP) opstande. Die bosvloerladings, voor verassing, het varieer van 21 – 168 t ha-1 en 27 – 72 t ha-1 vir ST en PLP opstande respektiwelik. Ladings het linieêr vermeerder met opstand ouderdom. Saaghout en PLP opstande is saam geanaliseer en het tot ‘n betekenisvolle korrelasie gelei tussen diepte en massa (r2 = 0.78, n = 31). ‘n Verliestydens- ontbranding prosedure is uitgevoer op die FF monsters en het die verhouding tussen FF diepte en die asvrye massa van die verskillende opstande verbeter. Dit het ook gelei tot akkurater model vir die voorspelling van massa vanaf diepte. ‘n Veelvoudige regressie analise het aan die lig gebring dat ouderdom, hoogte en gemiddelde jaarlikse reënval (MAP) die beste sub-groep verskaf, en het 72% van die variasie in die FF massa verklaar. Ondersoek is ingestel op die effek van toenemende FF lading en toenemende voginhoud op die brandlyn intensiteit (FLI) deur die brandgedrag program, BehavePlus, toe te pas. Die kaalkap oorskot is gekwantifiseer en gekarakteriseer volgens brandstof grootteklasse, onder die huidige boskultuurstelsels vir ST en PLP, vir die ontwikkeling van brandstofmodelle vir hierdie spesie oor die betrokke groeistreek in SA. ‘n Ondersoek in die verhouding (volgens massa) van die 1- (0.0 – 0.6 cm), 10- (0.6 – 2.5 cm), 100- (2.5 – 7.6 cm) en 1000-uur (> 7.6 cm deursnee) brandstofklasse van die totale HR massa het aangedui dat daar ‘n betekenisvolle verskil is tussen die massas van die 1-, 10- en 1000-uur brandstofklasse van die twee boskultuurstelsels, en geen betekenisvolle verskil vir die 100- uur brandstofklas nie. Twee brandstofmodelle is ontwikkel vir P. patula HR en twee modelle vir staande hout deur gebruik te maak van die nuwe model (NEWMDL) program van BEHAVE en getoets in BehavePlus. Voedingstof konsentrasies is gebruik, tesame met die FF laag en HR klasgrootte ladingdata, om die voedingstof inhoud van die brandstof te skat en om die voedingstof verspreiding te beskryf in die brandstofkompleks. Betekenisvolle verskille is waargeneem in die voedingstof konsentrasies van die FF lae en brandstof komponente wat belangrike implikasies inhou vir brandstofbestuur. Die konsentrasie wat vir N in hierdie studie bepaal is, was laag relatief tot ander soortgelyke studies vir P. patula. Die bosvloer ladings is voorspel en voedingstofpoele bereken vir tipiese ST en PLP opstande vir beide lae en hoë hoogtes om insig te verkry, sodat insig verkry kon word in die voedingstof verspreidings binne die brandstofkompleks.

Les pompiers méditerranéens sont confrontés à des embrasements soudains de la végétation (AFF) dont les mécanismes ne sont pas encore bien compris. La végétation étant l'unique combustible, nous nous sommes penchés sur les gaz qui en proviennent. Nous avons d’abord étudié la dégradation thermique de quatre Composés Organiques Volatils biogéniques (COVb) à l'aide d'une pyrolyse flash et d'un four tubulaire. À partir de cette étude et de la littérature, nous avons choisi un mélange d'étude afin expérimenter ses propriétés de combustion. Nous avons ainsi déterminé l'Énergie Minimale d’Inflammation (EMI) et la vitesse fondamentale de flamme de mélanges d'α-pinène/benzène qui sont respectivement les principaux COV détectés dans les plantes et dans les fumées de feux de forêt. Le dernier chapitre concerne l'étude stationnaire de l'accumulation de gaz dans des vallées à partir d'une maquette de forêt 1/400ème disposée dans une soufflerie. / Mediterranean firefighters cope with powerful accelerations of forest fires (AFF) whose mechanisms are not very well understood. Vegetation is the only fuel of forest fire, then we studied the gases coming from them. First, we studied the thermal degradation of four Biogenic Volatil Organic Compounds (BVOCs) thanks to a flash pyrolysis and a tubular oven. From this study and literature, we chose a representative VOC mixture to study its combustion properties. We determined Minimal Ignition Energy (MIE) and its laminar burning speed of mixtures of α-pinene/benzene that are respectively the main VOC detected in vegetation and forest fire smoke. The last chapter experiment the steady-state gas accumulation above a 1/400 V-shaped forest model.

[ES] El municipio de Serra se asienta en la vertiente meridional de la Sierra Calderona. El término municipal ocupa una superficie de 5.730 hectáreas de las cuales, el 95 % de su territorio se encuentra dentro del ámbito del Parque Natural de la Sierra Calderona y el 85% del territorio corresponde a Suelo Forestal. La estructura económica del municipio ha tenido, desde 1960, al sector de la construcción como eje principal de la economía, quedando el subsector forestal, como actividad residual. Esto ha provocado un flujo de mano de obra desde el sector primario hacia otros más productivos, teniendo como consecuencia un crecimiento desordenado de la masa forestal, provocando un deterioro del paisaje. Esto ha aumentado considerablemente el riesgo de incendios y plagas y amenaza en definitiva el patrimonio forestal del Parque Natural de la Sierra Calderona. Siguiendo las directrices marcadas por las prioridades de la UE en desarrollo rural se ha puesto en marcha un proyecto de investigación dirigido hacia la creación de empleo local mediante el fomento de actividades sostenibles cuyos resultados se reinviertan en la sociedad local generando una economía circular que constituya la base del desarrollo socio económico local. El proyecto consiste en el aprovechamiento energético sostenible de la biomasa forestal, agrícola y de jardinería y su reconversión a un combustible sólido (pélet) empleado en la calefacción de edificios públicos y por otra parte, comercializando el excedente de pélet, con esto se pretende un ahorro económico energético y de gestión del residuo y un beneficio que podrá ser empleado directamente en la creación de empleo local. El proyecto contribuye además a la protección y mejora de los montes de Serra. La presente Tesis trata de estudiar si un adecuado modelo de gestión de la biomasa en zonas de la interfaz urbano forestal de municipios, como Serra, incluidos en el Parque Natural de la Sierra Calderona puede tener efectos directos positivos en la prevención de incendios forestales y la lucha contra el cambio climático, la Tesis estudia además si estos modelos de gestión pueden ser económica y medioambientalmente sostenibles y su capacidad para contribuir a mejorar el desarrollo socioeconómico de estas poblaciones, fijando su población y ofreciendo un verdadero desarrollo rural basado en el aprovechamiento racional de sus recursos naturales. / [CA] El municipi de Serra s'assenta en el vessant meridional de la Serra Calderona. El terme municipal ocupa una superfície de 5.730 hectàrees de les quals, el 95 % del seu territori es troba dins de l'àmbit del Parc Natural de la Serra Calderona i el 85% del territori correspon a Sòl Forestal. L'estructura econòmica del municipi ha tingut, des de 1960, al sector de la construcció com a eix principal de l'economia, quedant el subsector forestal, com a activitat residual. Açò ha provocat un flux de mà d'obra des del sector primari cap a uns altres més productius, tenint com a conseqüència un creixement desordenat de la massa forestal, provocant una deterioració del paisatge. Açò ha augmentat considerablement el risc d'incendis i plagues i amenaça en definitiva el patrimoni forestal del Parc Natural de la Serra Calderona. Seguint les directrius marcades per les prioritats de la UE en desenvolupament rural s'ha engegat un projecte de recerca dirigit cap a la creació d'ocupació local mitjançant el foment d'activitats sostenibles els resultats de les quals es reinverteixen a la societat local generant una economia circular que constituïsca la base del desenvolupe soci econòmic local. El projecte consisteix en l'aprofitament energètic sostenible de la biomassa forestal, agrícola i de jardineria i la seua reconversió a un combustible sòlid (pélet) emprat en la calefacció d'edificis públics i d'altra banda, comercialitzant l'excedent de pélet, amb açò es pretén un estalvi econòmic energètic i de gestió del residu i un benefici que podrà ser emprat directament en la creació d'ocupació local. El projecte contribueix a més a la protecció i millora de les muntanyes de Serra. La present Tesi tracta d'estudiar si un adequat model de gestió de la biomassa en zones de la interfície urbà forestal de municipis, com Serra, inclosos en el Parc Natural de la Serra Calderona pot tenir efectes directes positius en la prevenció d'incendis forestals i la lluita contra el canvi climàtic, la Tesi estudia a més si aquests models de gestió poden ser econòmica i mediambientalment sostenibles i la seua capacitat per a contribuir a millorar el desenvolupament socioeconòmic d'aquestes poblacions, fixant la seua població i oferint un vertader desenvolupament rural basat en l'aprofitament racional dels seus recursos naturals. / [EN] The municipality of Serra sits on the southern slope of the Sierra Calderona mountains. The municipality occupies an area of 5,730 hectares of which, 95% of its territory is within the Sierra Calderona Natural Park and 85% of the territory corresponds to forest land. The economic structure of the municipality has had, since 1960, the construction sector as the main axis of the economy, leaving the forestry sub-sector as a residual activity. This has caused a labor flow from the primary sector to more productive ones, resulting in a disorderly growth of the forest mass, causing a deterioration of the landscape. This has considerably increased the risk of fire and pests and ultimately threatens the forest heritage of the Sierra Calderona Natural Park. Following the guidelines set by the EU priorities for rural development, a research project aimed at the creation of local jobs has been launched through the promotion of sustainable activities whose results are reinvested in the Local society generating a circular economy that constitutes the basis of the local socio-economic development. The project consists of the sustainable energetic use of forest, agricultural and garden biomass and its conversion to a solid fuel (wood pélet) used in the heating of public buildings and on the other hand, marketing the surplus of this wood pélet, this aims to a saving of energy bills and waste management costs and brings a benefit that can be used directly in the creation of local employment. The project also contributes to the protection and improvement of the Serra Mountains. This thesis aims to study whether an adequate model of management of biomass in the municipal urban forest interface, such as Serra, included in the Natural Park of the Sierra Calderona can have direct positive effects on the prevention of forest fires and the fight against climate change, the thesis also studies whether these management models can be economically and environmentally sustainable and their ability to contribute to improving the socioeconomic development of these populations, setting their Population and offering a true rural development based on the rational use of their natural resources. / Mayans Díaz, JJ. (2021). Gestión integral de la biomasa en la interfaz urbano-forestal, en ámbito supramunicipal y sus efectos en la lucha contra el cambio climático, Red Natura 2000 y prevención de incendios forestales [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/166094