우리나라의 기후변화와 산불발생의 방재적 방안 연구

Abstract

In this study, the general characteristics of forest fires, the changes in the meteorological environment of the Gangwon area due to climate change and the relationship between the occurrence of forest fires and the meteorological elements were analyzed to propose a new forest fire danger index (FFDI) using a new meteorological element and to verify it. On the general characteristics of forest fires, wood always contains some moisture, combustion depends on the moisture content of the wood, and the drying time of wood in a forest is determined by the soil moisture content. In addition, the moisture content of wood varies according to the air temperature and the type of wood. Therefore, a combustible can be ignited with small embers when its moisture content is less than approximately 15% of its total weight, but it cannot be ignited when its moisture content is greater than 15%. However, in a large fire, the moisture content does not matter, and a combustible with a 50% or higher moisture content burns well. The moisture content of fallen leaves also influences forest fires. A 10% or lower leaf moisture content is a good condition for a forest fire, and a forest fire rarely occurs with a 25% or higher moisture content. In addition, the production of fire and the ignition temperature vary according to the type of forest. Because the type of forest is determined by the weather, it can be said that a change in the weather environment affects the occurrence and spread of fires. The combustion speed is also influenced by the air temperature. When the air temperature is high, the combustion speed significantly varies according to the moisture content; but when the air temperature is approximately 0°C, the change in the combustion speed according to the moisture content is small. In addition, high air humidity leads to a slower combustion speed; and in the case of combustion as large as a forest fire, a higher wind speed leads to a more active combustion. The topography of a mountain also significantly influences the development of forest fires. A different slope direction leads to a different amount of sunshine, wind direction, wind velocity and degree of dryness of fuel materials. Therefore, the Yeongdong area, the slope of which is steeper than that of the Yeongseo area, has a larger damaged area than other sites. The changes in the climate in the Gangwon area are characterized by a clear rise in the air temperature and the amount of precipitation, and a fall in the relative humidity and the wind velocity. The wind velocity significantly varies according to seasonal changes. Among the changes in the climate elements, the decrease in the relative humidity is an important factor of the frequency of forest fires. Multiple examinations via one-way ANOVA using the daily weather data of the 10 observatories in Gangwon-do and significance verification showed that the meteorological elements such as the air temperature, humidity and wind velocity varied according to the area. The meteorological elements of the east coast area in Gangwon-do (Gangneung, Samcheok, Donghae and Sokcho), which has been the most damaged by forest fires, were compared with those of the other areas in the Yeongseo area. The daily mean temperature and wind velocity were higher in the east coast area than in the inland areas such as Wonju and Chuncheon. Thus, the air temperature and the wind velocity were higher in Gangneung, Sokcho and Donghae, which were severely damaged by large-scale forest fires in the 2000s, than in the other areas. Considering that forest fires from a military firing range are significantly related to the soil moisture content, a new FFDI was proposed via indexing through correlation analysis by including the soil moisture content, which had not been considered for the FFDI. The new FFDI was evaluated and was found to be highly correlated with the number of forest fires and the size of the damaged area in Gangwon-do for the last 10 years, from 2003 to 2012.