Compound Flooding

Flooding is a vast and widely recognized problem throughout coastal South Carolina. Our coastal communities suffer flooding from intense rainfall, tropical storm surge, and “sunny day” tidal flooding. These processes are challenging, but they are generally well-understood and predictable. In the last decade, however, coastal South Carolina has been confounded by unpredictable compound flooding--where multiple flooding sources occur at the same time. Sea level rise, intense rainfall, and landscape change associated with development have lead to a new type of flooding in this “compound flooding zone” where floodwaters from stormwater runoff collide with tidal floodwaters moving inland. The spatial extent and timing or this flooding zone is difficult to predict, and very few tools exist for planners or managers struggling to mitigate flooding in these areas. 

In light of this issue, scientists and engineers with Robinson Design Engineers, the College of Charleston, SC Sea Grant, and various other stakeholders are working to develop a series of methods and tools to analyze the behaviors of and estimate the effects of compound flooding in Coastal South Carolina. Supported by funding from SC Sea Grant, a Compound Flooding Risk (CFR) tool will be a GIS-based application that will enable users to estimate the magnitude and likelihood of compound flooding for a given location based on a range of publicly available geospatial datasets. These data will help stakeholders better understand and predict compound flooding, especially in areas where conventional flood modeling methods have fallen short.