Statistical Analysis of Angstrom Fire Index for Kutaisi, Georgia

Abstract

The problem of fires, including forest fires, is actual for many countries of world. This problem is also important for Georgia, where forest fires are frequent. In recent years this problem is aggravated by the global and local climate warming which facilitates an increase in the fire hazard. In Georgia, the top 3 regions were responsible for 53% of all tree cover loss between 2001 and 2020. Samtskhe-Javakheti had the most tree cover loss at 3.24 kha, then Kakheti (1.24 kha) and Imereti (1.01 kha) [https://www.globalforestwatch.org/dashboards/country/GEO]. For evaluating the fire hazard in locality the set of indices is developed. One of the simple of these indices is the Swedish Angstrom Fire Index (AFI). Earlier, data on AFI for Tbilisi and Telavi were presented. In this work results of a statistical analysis of daily values of AFI for Kutaisi are presented. AFI = (R/20) + (27-T)/10, where R is the minimum relative humidity, T is the maximum air temperature. Data of the about daily values of T and R in the period 2011-2020 are used [http://www.pogodaiklimat.ru/archive.php?id=ru®ion=07]. The gradations of the values of AFI are as follows: I. AFI ≥ 4.1 – Low, II. AFI = 4.0 ÷ 3.0 - Moderate, III. AFI = 2.9 ÷ 2.5 - High, IY. AFI = 2.4 ÷ 2.0 – Very High, Y. AFI = <2.0 - Extreme. In particular, it was found that an Extreme fire hazard in Kutaisi is observed on average within 59 days a year (16.0 % of cases), Very High – 46 days a year (12.7 % of cases), High - 64 days a year (17.6 % of cases), Moderate – 100 days a year (27.5 % of cases), Low – 96 days a year (26.2 % of cases). The highest repeatability of AFI values for its various gradations is as follows: Extreme – 33.3 % (September), Very High – 22.6 % (August), High – 30.3 % (July), Moderate – 37.3 % (November), Low 48.7 % (January). The values of AFI in Kutaisi are compared with their values in Tbilisi and Telavi. In particular, it was found that a repeatability of Extreme fire hazard in Kutaisi is lower, than in Tbilisi (19.1 % of cases) and Telavi (18.5 % of cases). This result is in good agreement with the data on loss of forest cover from fires in Kakheti and Imereti, indicated above. Further, it is planned to expand work on this issue (using other more complex fire hazard indices, studying their trends in connection with climate change, determining these indices for other points in Georgia, etc.).