Defining nationally consistent coastal flood severity thresholds

The exposure to coastal flooding is increasing due to sea level rise, population growth, and the ever-increasing land intensification in the low-lying coastal regions. Hence, a monitoring system that helps planners and managers understand the spatio-temporal patterns of flooding to design flood mitigation plans is essential. NOAA’s National Weather Service (NWS) has minor, moderate and major flood height severity thresholds established for dozens of NOAA tide gauges along the U.S. coastline used in public communications. Despite the importance of flooding thresholds in spatio-temporal monitoring of coastal floods, such information is available only in places where installed tide gauges are accompanied with long enough monitoring systems. There are numerous instances of the same flood category (e.g. ‘minor’) with very different impacts that range from inconsequential/no flooding to widespread and damaging flooding. To avoid under- or over-estimating impacts in public weather communications and to contextualize changes in current risk profiles due to sea level rise, a more consistent definition of minor, moderate and major coastal flooding and associated impacts is needed. Approaches such as those based upon Machine Learning should explore cause and effect relationships between various physical data (like local elevation profiles, rainfall, water level, and wave data time series) with chronologies of archived NWS advisory/warning guidance, available damage reports and other quantifiable impacts to produce spatially relevant and consistent flood threshold metrics for U.S. coastlines. In this project we propose a machine learning-based framework for determining nationally consistent coastal flood severity thresholds beyond unevenly distributed tide gauges. The developed framework, considering different physically-relevant features as input data, will go through a comprehensive validation process at all three levels of minor, moderate and major flood levels to produce spatially relevant and consistent flood threshold metrics for U.S. coastlines.