Evaluating the Hydrologic Risk of n-Year Floods According to RCP Scenarios

Abstract

Recent climate change has brought about irregular rainfall patterns along with an increased frequency of heavy rainfall, and flood damage in Korea is increasing accordingly. The increased rainfall amount and intensity during the rainy season lead to flood damage on a massive scale every year in Korea. In order to reduce such flood damage and secure the stability of hydraulic structures, evaluation of hydrologic risk corresponding to design floods is necessary. As Korea’s current climate change scenarios are generally applied to mid-sized watersheds, there is no practical application method to calculate the hydrologic risk of local floods corresponding to various future climate change scenarios. Using the design flood prediction model, this study evaluated the hydrologic risks of n-year floods according to 13 climate change scenarios. The representative concentration pathway (RCP) 8.5 scenario resulted in the 100-year floods increasing 134.56% on average, and 132.30% in the Han River, 132.81% in the Nakdong River, 142.42% in the Gum River, and 135.47% in the Seomjin-Youngsan River basin, compared with the RCP 4.5. The 100-year floods at the end of the 21st century increased by +3% and +13% according to the RCP 4.5 and 8.5, respectively. The corresponding hydrologic flood risk increased by 0.53% and 8.68% on average according to the RCP 4.5 and RCP 8.5, respectively, compared with the current level of hydrologic risk of a 100-year flood.