Impacts of climate change on intensity–duration–frequency curves in the rainiest city (Rize) of Turkey

Changes in precipitation events due to climate change might have significant influences on the characteristics of most hydrological events as well as its own related variables such as intensity, duration, and frequency. Since the intensity–duration–frequency (IDF) curve is an important tool to design infrastructures in water resources management, updating IDF curves under future climate projections nowadays becomes a necessary practice. Therefore, we intended to investigate potential changes in the IDF curves due to climate change using the equidistance quantile matching method in the wettest region of Turkey. We aimed to examine two critical issues: (i) the estimation of changes in IDF curves for three future periods (namely, 2013–2039, 2040–2069, and 2070–2099) and (ii) a comparison analysis between the outcomes based on the two worst-case climate change scenarios (namely, SRES A2 and RCP 8.5) released for the fourth and fifth assessment reports by the IPCC. Our analysis results showed that the outcomes based on SRES A2 revealed an increase in intensities during all the future periods for recurrence intervals under 50 years. According to the outcomes of recurrence interval above 50 years, there is an increase in intensities at the beginning period of the century; however, a decrease in intensities prevails at the ending period of the century. On the contrary, the results based on RCP 8.5 showed that there is a decrease in intensities at the beginning of the century while there is an increase in intensities at the end of the century for all return periods. Our results were discussed according to the indications of the IPCC 5th assessment report. Although conflicting indications were noted between the two worst-case scenarios, our study results may be an inspiration to call a need to update all former design storms based on IDF in any region all over the globe.