Impacts of climate change on IDF curves for urban stormwater management systems design: the case of Dodola Town, Ethiopia.

Climate change impacts are one of the global challenges that change the intensity and frequency of rainfall. The Dodola town has previously experienced rainfall-induced flooding effects, and future floods may be more frequent and severe due to possible variations in rainfall intensity due to climate change. In this study, the rainfall intensity-duration-frequency (IDF) curves are updated for the design of urban stormwater drainage infrastructures under climate change to reduce flooding risks. To assess the variations in the rainfall intensity, the future IDF curves for the periods (2020-2100) and two GCMs (CanESM2 and HadGEM2-ES) were derived and compared to the current IDF curves. It was found that rainfall intensities for future climate conditions will differ from the current period for all durations and return periods. The comparison results show that the relative change between future rainfall intensities and historic rainfall ranges from 1.5 to 30.6%, 2.48 to 42.6%, and 3.7 to 23.24% for 2020-2040, 2041-2070, and 2071-2100, respectively. The IDF relationships revealed that as a result of climate change, urban flooding will increase in the future. This study will help to better understand the impacts of climate change on rainfall IDF relationships, as well as have implications for the design of current and future stormwater management systems in Dodola, Ethiopia.