Trend Analyses of Extreme Precipitation Indices Based on Downscaled Outputs of Global Circulation Models in Western Black Sea Basin, Turkey

In this study, the impacts of climate change on the extreme precipitation indices in the Western Black Sea Basin, Turkey, were investigated in terms of trend analyses based on the historical and projected daily precipitation data. Eight extreme precipitation indices were computed using the reference period data obtained from nine meteorological stations and dynamically downscaled outputs of GFDL-ESM2M, HadGEM2-ES and MPI-ESM-MR global circulation models (GCMs) under RCP4.5 and RCP8.5 emission scenarios. The biases in the outputs of GCMs were corrected by using the linear scaling method. The Mann–Kendall and Spearman’s rho tests were utilized to detection of the trend in the precipitation indices during the reference (1971–2000) and future periods (2020–2099). The results of the analyses for the reference period showed a strong increasing trend in indices in the eastern part of the basin and nonsignificant trends (both increasing and decreasing) in the western part. On the other hand, for the future period, the results demonstrated that the amount of total precipitation will increase (a positive trend in PRCPTOT). However, the number of dry days will increase. This situation indicates that there will be no significant change in the total amount of precipitation, but there will be an increase in the intensity of precipitation and the number of dry days during the coming years that can cause flooding and drought, respectively. Therefore, suitable adaptive and mitigative actions have to be taken, especially in terms of urban planning and agriculture.