Monitoring the Variability of Meteorological Drought Characteristics at Multiple Time Scales

Meteorological drought is frequently defined as an extended interval of sub-normal precipitation persisting over a duration of months to multiple years. Drought severity and duration is two important parameters to characterize droughts. In this study, the aim is to monitor the variability of meteorological drought characteristics for selected 3 stations in Mediterranean Region, Türkiye. Initially by taking the mean monthly temperature and monthly total precipitation data for 1950-2024 period from General Directorate of Meteorology of Türkiye, Standardized Precipitation index (SPI) and Standardized Precipitation Evapotranspiration Index (SPEI) have been used to predict drought events at multiple time scales of 1-month and 3-month. For a comprehensive monitoring of meteorological drought, spatial distribution of drought categories has been analyzed using Inverse Distance Weighting (IDW). Secondly, drought characteristics which are severity and duration have been obtained by Theory of Runs. Possible trends in these characteristics have been examined by Mann-Kenndal Test (MKT), Spearman’s Rho (SRT), Wilcoxon Test (WT), Sen’s Slope Test (SST), Innovative Trend Analysis (ITA) and Combination of Wilcoxon Test and Scatter Diagram (CWTSD). Results have shown that many drought events have been observed that indicates many parts of the region were experienced with different drought. Among all categories Normal and Wet (combination of all wet categories) have been most prevalent in the selected stations. Among all determined severity and duration series, the highest drought severity and the longest drought duration have been observed as 58.044 and 49 months during 2019(4)- 2023(4) that have been obtained with SPEI-3 of 17300 station. Trend results by MKT, SRT and WT test considering α=0.01 significance level have put forth that a big part of the series of drought characteristics have been detected with increasing trends. Decreasing trends have been obtained with less amount. However, these trends have been significant only in 9 series out of 24. SST results have shown that there has been mostly increasing trends in severity, while all duration series have shown no trend. The results of ITA and NO-ITA have demonstrated that trends of the characteristics have been increasing in many times. Unlike the MKT, SRT and WT, no trend cases have been observed in a small amount of severity series. In severity series, MKT, SRT, WT, SST, ITA and NO-ITA techniques have a good agreement in 21 series out of 24, in terms of trend type. The findings of this study are expected to be beneficial for local authorities for effective drought action plans in order to keep life, water resources, environment and sustainability.