Climate Change Impacts on Catchment-Scale Extreme Rainfall Variability: Case Study of Rize Province, Turkey

This paper conducts a catchment-scale analysis of extreme rainfall events of the reference (1961-1990) and three future climate periods (2013-2039, 2040-2070, and 2071-2100) for Rize Province, Turkey. The extreme value theory (EVT) is applied to analyze observational and projected extreme rainfall data including regional climate model (RCM) outputs guided by two general circulation models (GCM) under SRES-A2 and RCP8.5 greenhouse gas scenarios. A new rapid and effective bias correction method is also developed and applied to adjust the climate models simulations. The EVT analysis results demonstrated significant differences between the model runs for both the reference and future periods with considerable spatial variability in rainfall extremes. Based upon the assembled mean results, approximately a 30% decrease in the median value of extreme rainfall events is projected over the study region for the near future, 2013-2039, and middle of the century. This change dramatically decreases to 15% of its historic value at the end of the century. The results from the implemented GCM-RCM combinations revealed that more intense rainfalls are produced by the combination forced by the RCP8.5 scenario. In addition, the results from goodness-of-fit tests among different distribution models showed that general extreme value distribution can be used appropriately to characterize the behavior of projected extreme rainfalls over the study region.