The dynamics of forest ground fires in the Saratov region

Abstract

Forest fires are inevitable, as they have pyrological properties, which in turn are associated with weather conditions. Forest fire has a dynamics, i.e. the rate of its spreading under weather conditions and will continue until all available forest fuels are burn out or will extinguished. An important component of forecasting forest fire situations is the assessment of the dynamics of a forest fire, which makes it possible to assess the risk of its spread across the territory. The rate of spread of a forest fire is calculated from the ratio of the increment of area to time. Nevertheless, to obtain an accurate estimate, it is necessary to know the time of its occurrence, which is impossible in practical terms, since in case of careless handling of fire, they are usually not fixed for a while, and in case of deliberate arson, it is difficult to find and interrogate the arsonists. For solving this task, a mathematical model was created that makes it possible to calculate the average rate of development of a forest fire based on the rate of development of a fire (increase in the length of the edge of a forest fire over time) during its extinguishing, as well as the rate of extinguishing a fire. An assumption was made about the additive nature of the rate of increase in the length of the edge and the rate of quenching. Average rate of ground wild fire spread and the estimated time of its occurrence were calculated. The rate of spread of ground wild fire are compared with the data on the wind speed in the study area and the value of the complex indicator of fire danger. It was shown that forest fires spread only when the 3rd class of wild fire conditions is established according to weather, and the wind rate affects the dynamics of a ground wild fire only up to a 10 m s-1.