기후변화에 따른 하수관거시설의 계획우수량 산정을 위한 일반극치분포 분석

Abstract

Climate change has brought precipitation events that exceed the capacity of the sewer system frequently occur and then urban sewer system often fails to cope with the excessive waters, resulting in more damages due to flooding in the cities. Therefore, the uncertainty of climate change should be predicted and the currently applied design criteria for storm sewers need to be re-evaluated as well. In this research, statistical analysis on both stationary and non-stationary climate were implemented using past rainfall data measured in Seoul with generalized extreme value (GEV) distribution and Gumbel distribution. In the non-stationary climate, the characteristics of rainfall were estimated considering the location parameter (ξ) including the variable of time (t). When the probable rainfall depth estimated in non-stationary climate was compared with that of the stationary climate, it increased by 1.1mm to 6.2mm for GEV distribution and by 1.0mm to 4.6mm for Gumbel distribution during the same return periods used in each computation. As the rate of change in annual maximum rainfall (ξ1·t) was applied to the estimated location parameter, the temporal change of the return period could be predicted,thus making it possible to evaluate the design return period. Therefore, the life expectancy and design return period of the sewer assets could be re-evaluated and the design criteria for sewer system should be newly suggested, considering the temporal change in sewer service capabilities under climate change.