TREND ANALYSIS ON HEAVY RAINFALL LEADING TO FLOOD DAMAGE AT 58 CLASS A RIVER BASINS

Abstract

 In recent years, there has been concern about the increase in flood risks due to climate change, and the revision of flood control plans towards climate change has become a severe challenge. In this study, in order to understand the changes in the risk that have already occurred, we quantitatively analyzed the trends of changes in heavy rainfall leading to flood damage at 58 class A river basins for which rainfall data have been continuously maintained for more than 30 years. Specifically, using rainfall observation data from the 58 basins, we conducted trend analysis on rainfall intensity and frequency by Mann-Kendall test for 1, 24, and 48-hour time units, both nationally and for each class A river system. The results showed an increasing trend both in the intensity and frequency of rainfall nationwide and in maximum annual rainfall with approximately 70% of class A river systems. In addition, there have already been rainfall more than the design rainfall at the 20 of the 45 class A river systems for which design rainfall are set, and the total frequency of the exceedances for the 45 river systems has also increased significantly.