A study on drought analysis using time series, standardized precipitation index (SPI) and standardized precipitation evapotranspiration index (SPEI) in Bursa region

Abstract

All agricultural activities are directly related to the climate. In recent years, temperature increases and changes in precipitation regimes adversely affect the Mediterranean Basin, including Türkiye. While increasing temperatures and irregular precipitation rise the need for irrigation in crop production in some regions, excessive and irregular rainfall in some areas seriously damages production. Nowadays, climate change has been accepted by many climate scientists as a problem that cannot be ignored. In our country, drought is one of the natural disasters that will affect agricultural production the most. In this study, a drought analysis was made for Bursa, one of Türkiye’s important cities in agricultural production. In addition, non-parametric Mann-Kendall and Sen's Trend Analyzes were conducted between 1990 - 2019 for precipitation and temperature values. According to the trend analysis results, statistically significant trends could not be reached in the precipitation data; increasing trends were observed in the temperature data. SPI (Standardized Precipitation Index) and SPEI (Standardized Precipitation and Evapotanspiration Index) methods were used for drought analysis; although extreme values were reached for the years 1960 – 2019 due to both ways, it was determined that normal drought levels were dominant in general.