The impacts of climate change on the flood risk for Cork city: A case study

Cork city is considered to be in a vulnerable region to flooding and is expected to face significant economic and social damage due to the effects of climate change in the upcoming future. An increasing trend in the precipitation and temperature coupled with a rise in severity and frequency of storm events leads to a higher frequency of expected flooding for Cork city in the upcoming decades. More floods and severe heatwaves during the summer months will hugely impact Cork’s large agricultural sector and property in the urban, suburban and rural areas surrounding the city. In 2009, Cork city experienced a severe flood event that devastated property resulting in €90 million worth of damages only to the city centre.

This study focuses on the identification of the most vulnerable regions in Cork city based on the historically observed flood-related data. Furthermore, the changes in flood vulnerability and risk for the city in the future corresponding to different climate change scenarios have been explored. Three regional climate models (RCMs) and two Representative Concentration Pathways (RCPs) has been considered to obtain future projected meteorological variables, which were used to simulate future projected streamflow using Soil Water Assessment Tool (SWAT) model for each RCM and RCP. The daily simulated streamflow in the future was used to first extract the annual maximum flow, and then to obtain flood quantiles corresponding to different return periods using generalized extreme value distribution. The flood quantiles were then fed into the HEC-RAS model to generate flood inundation maps for Cork city. Comparison of flood inundation maps for a chosen return period for the historical and future period corresponding to different climate change scenarios revealed that the flood depth and flood extend is expected to increase in the future for the majority of the climate change scenarios.

A detailed risk assessment based on those developed flood inundation maps were then performed will then be performed for Cork to identify the most vulnerable areas. Subsequently, the social and economic impact of flooding has been quantified in this study. It has been noted that due to climate change, the expected damage from future flood events will ellipse the damage seen in the 2009 flood at Cork city.