Climate change: A trend of increasingly frequent droughts in Kakheti Region (East Georgia)

Abstract

Abstract Following the global warming, in Kakheti Region, in East Georgia (by municipalities), the trends of changes (increase or decrease) in agro-climatic characteristics for the development of agricultural crops were identified. Such changes result in the prolonged vegetation period, increased sum of temperatures and mostly, decreased sum of precipitations. Based on the latter indicators, a trend of a decreasing index of the hydrothermal coefficient is observed evidencing more frequent droughts with low or moderate intensity. The data of the 60-year-long period of meteorological observations (1949–2008) were divided into two 30-year-long periods in order to compare them. It was found that in the second period (1979–2008), the indices of a hydrothermal coefficient in all municipalities (except Kvareli) are decreased in the active vegetation period (VI-VIII). The dynamics of the course of a hydrothermal coefficient is shown with trends. Based on the many-year meteorological observation data (1949–2008) in different municipalities, the sums of active annual temperatures (>10 °C) and atmospheric precipitations were calculated. On the background of global warming, the repeated nature of droughts of different types was identified. The nomograms of the frequency of the droughts of the type typical to the study object and moisture evaporation have been drafted. Based on the sums of the annual active temperatures (>10 °C) and atmospheric precipitations, an equation to calculate the hydrothermal coefficient was given. A correlation between the date of the temperature rising over 10 °C and the sum of temperatures was identified (r=0.80) and a regression equation to forecast different types of droughts was designed. Against frequent droughts following the global warming, it is recommended to take relevant adaptation measures to avoid negative events.