Modelling the impact of sea-level rise on urban flood probability in SE China

Urban drainage systems in coastal cities in SE China are characterized by often complex canal and sluice-gate systems that are designed to safely drain pluvial flooding whilst preventing tidal inundation. However, the risk of coastal flooding in the region is expected to increase over the next 50–100 years, as urban areas continue to expand and sea-levels are expected to rise. To assess the impact of projected sea-level rise on this type of urban drainage system, a one-dimensional model and decision support tool was developed. The model indicated that although sea-level rise represents a significant challenge, flood probability will continue to be most influenced by rainfall. Events that are significant enough to cause flooding will most likely be minimally impacted by changes to the tidal frame. However, it was found that a sea-level rise of up to 1.2 m by 2010 would result in increased drainage times and higher volumes of over-topping when flooding occurs.