Frequency analysis of extreme precipitation based on climate change projections

In recent years, as a result of climate change and global warming, there have been great increases in the number and severity of extreme climate events. The primary reason for these increases is the increase in the water-holding capacity of the atmosphere caused by the increase in temperature. Climate change, along with other factors such as changes in land use, has a major role in floods becoming more frequent and severe around the world. In this regard, it is important to investigate and model the effects of changes that will occur in the coming years on extreme precipitation. In this study, the outputs of 5 new General Circulation Models (GCM) used within the scope of the Intergovernmental Panel on Climate Change (IPCC) Assessment Report published in 2021 are used to analyze future extreme precipitation events under two new socio-economic scenarios (SSP2-4.5 and SSP5-8.5). The names of these models are as follows: BCC-CSM2-MR (China), CMCC-ESM2 (Italy), and GFDL-ESM4 (America). HadGEM3-GC31-LL (UK) MPI-ESM1-2-LR (Germany). Virginia State of the United States was chosen as the region of the study. In addition to model outputs, daily data measured at five observation stations were also used in the analyses. Uncertainties in the models were corrected by comparing the simulations in the reference period with the measured values. For this, the linear scaling method was used. Frequency analyses were handled with two different methods known as annual maximums and peaks-over-threshold. Using these two methods, partial duration time series were produced and these series were fitted to appropriate distribution functions. Then, the intensity of extreme precipitation events with 2, 5, 10, 20, 50, 100, 500, and 1000 years return period was calculated for 1985-2014 (reference period), 2015-2040 (near future), 2041-2070 (med-term future) and 2071-2100 (late future) periods. According to the results of the research, it is estimated that there will be a decrease in the intensity of extreme precipitation in the region in the near future compared to the reference period. This difference will close in the mid-term future and change negatively in the late future. Namely, serious increases in the intensity of extreme precipitation have been modeled at the end of the century, especially under the SSP5-8.5 scenario. These results highlight the importance of low-emission scenarios in reducing natural disasters.