Spatial and temporal drought projections of northwestern Turkey

In recent years, natural calamities like droughts have caused disruptive impacts on the environment and society. Drought monitoring and its relations with different climatic parameters have been analyzed with various indices. This study assessed the drought condition with the Standardized Precipitation and Evapotranspiration Index (SPEI) and self-calibrated Palmer Drought Severity Index (sc-PDSI), which were calculated with monthly meteorological measurements between 1971 and 2018 in the northwestern part of Turkey. In addition, the projected drought events of the region were analyzed with the Coordinated Regional Downscaling Experiment (CORDEX) data obtained from five climate models with multi-model ensemble (MME) and under optimistic (RCP 4.5) and pessimistic (RCP 8.5) greenhouse gas and aerosol concentrations for the periods 2019–2050 and 2051–2099. The bias correction of projection data was carried out using meteorological data from the reference period (1971–2000) measurements. Projected drought conditions were analyzed according to the innovative trend analysis (ITA) methods. As a result of the trend analysis of SPEI, it was determined that the drought in the region would increase. Trend analysis of sc-PDSI indicated that drought intensity was different between the stations in RCP 4.5 and 8.5. In addition, the rate of moderate and higher dryness (drought occurrence) in the region was 17.2–30.3% in the measurement period with SPEI and sc-PDSI, respectively. Drought occurrence would increase by 38.3–35.3% in RCP 4.5 and 47–41% in RCP 8.5 for the years 2051–2099, respectively.