Impacts of Climate Changes on Coastal Urban Flooding

Coastal conurbations are at risk of flooding during extreme sea water levels caused by a combination of astronomical, meteorological and climatic factors. It is envisaged that urban flood risk will become more frequent as a consequence of several factors including population growth in flood prone areas, climate change, sea level rise and decaying or poorly engineered flood control infrastructure. The aim of this research is to demonstrate how numerical model of future hydrological conditions combined with understanding of current flood drivers can be used to simulate extent of future flood inundation in coastal urban floodplains and to evaluate flood risk and impact on people safety. Coastal City of Cork on the south of Ireland is a study case. In this research, the model was initially run for a variety of scenarios under present climatic conditions to provide a baseline for the quantification of impacts of climate change on coastal floods. Model runs were performed for mid-range and high-end future climate scenarios in order to consider changes to the coastal flood mechanisms. The maximum aerial extent of inundation and volume of floodwater generated for each scenario are intercompared between combinations of coastal drivers such as tides, storm surges and mean sea lever rise. Spatial patterns of water depths and velocities are utilized in instability curves to define danger zones associated with a particular flood event. Such danger zones provide some measure of the degree of hazard associated with a particular event. The results show that in current climate, climate-driven changes in both mean sea level and surges could result in a significant increase in coastal inundation when compared to current climate. These increases in coastal inundation under future climate scenarios will results in increases in risk to people safety in flood waters.