The chapter presents the results of experimental-analytical modeling of the surface forest fire dynamics and the process of forest fuel ignition when exposed to thermal radiation from the fire line. The regularities are established for the occurrence and spread of fires in natural ecosystems of the temperate climatic zone. Analytical solutions have been obtained that make it possible to predict the level of heat load on the soil cover of coniferous stands. The special computer program has been developed to calculate the heat load during fires. The methods of field and laboratory modeling revealed patterns of forest fuel heating and ignition depending on moisture content. A practice-oriented method is proposed to calculate the width of fire barriers that limit the spread of forest fires. The methods for creating fire barriers are proposed.
Top1. Introduction
In recent years, due to global warming in a number of countries around the world, the situation with forest fires has become especially aggravated. As a result of fires, the ecology of the regions is deteriorating, natural ecosystems and settlements are being destroyed, rescuers and people are dying. In addition, layers of dust and soot from fires lead to the melting of glaciers, which affects the rise in sea level and creates the likelihood of flooding vast coastal areas around the world.
The largest forest fires of the last decade include the fires that occurred in 2009 in Australia, which destroyed about 450 thousand hectares of forest and led to the death of 173 people. In Russia in 2010, as a result of the abnormal heat, forest fires covered an area of about 2 million hectares, more than 60 people died, 2.5 thousand families were left homeless. 111 people became victims of forest fires in Portugal in 2017. A significant part of the victims were motorists who tried to evacuate to safe areas, but fell into a fire trap on one of the roads (Figure 1). Forest fires in California in 2018 were the largest in the entire history of the state. As a result of fires, 85 people died, about 250 people are missing. The fire destroyed about 14 thousand houses (Abduragimov, 2012; Bondur, 2011; Artsybashev, 2014; Lasuta & Goman, 2019).
Special danger is represented by fires in radiation-polluted territories, the situation with which has also aggravated in recent years. So in 2015, 2017 and 2018 large fires occurred in the Chernobyl Exclusion Zone in Ukraine(Lasuta & Goman, 2019; Bogorad et al., 2016). In these forest plantations, due to the restriction of forestry activities, a large amount of combustible material is accumulated, which increases the fire hazard and the risk of fire. Fires on this category of land lead to the re-migration of radionuclides over considerable distances, which causes deterioration of the environmental situation in several countries and is a serious international problem (Figure 2).
In this situation, to increase the level of fire safety of natural ecosystems and reduce the number and size of fires, scientific research related to the study of the emergence and spread of forest fires in conditions of global climate warming is of particular importance. These studies should mainly be aimed at predicting the occurrence and early detection of fires, creating conditions for limiting the spread of fires and developing modern ways to extinguish them.
Top2. Review Of Literature
The problem of forest fires are actively engaged in specialists from around the world. On the territory of the post-Soviet space, a significant contribution to the fight against fires in natural ecosystems was made by Usenya V.V., Gusev V.G., Grishin A.M., Dorrer G.A., Artsybashev E.S., Ovsyannikov I.V., Baranovsky N.V., Zharikova M.V. and a number of other researchers (Usenya, 2002; Gusev, 2005; Grishin, 1981; Dorrer, 2008; Artsybashev, 1974; Ovsyannikov, 1978; Kuznetsov & Baranovsky, 2009; Khodakov & Zharikovа, 2011). These authors obtained significant results in improving the fire safety of natural ecosystems (Usenya, 2002; Artsybashev, 1974; Ovsyannikov, 1978), predicting the occurrence of forest fires and their environmental consequences (Kuznetsov & Baranovsky, 2009), physico-mathematical modeling of fire spread (Gusev, 2005; Grishin, 1981; Dorrer, 2008), creating modern fire extinguishing and fire-retarding compounds (Usenya, 2002).