Authors: Sadaf Mahmoudikouhi – University of Alabama
Title: Future Tidal Level Exceeding the High Tide Flooding Threshold: A High Spatial Resolution Case Study of the US Coastlines
Abstract: Sea level rise, an impact of climate change and a worldwide happening, is anticipated to increase the frequency of recurrent nuisance flooding (a.k.a. high tide flooding), and easier reaching of local flooding thresholds during average high tides. Hence, more people and infrastructures are at risk of high tide flooding in coastal communities, which seeks the immediate attention of policymakers and governments to achieve coastal flood mitigation and adaptation strategies. However, having validated information and insight about the potential risks is essential for them to come up with these strategies. In this project, we aimed to provide the data needed for policymakers by combining future sea level rise rates and tidal levels in a bathtub method to achieve the future total tidal levels on a high-resolution scale (every 10 km) along the US coastlines. The high-resolution scale can be beneficial for coastal cities as they do not need to use the information available at their nearest gauge station, which might be hundreds of miles away and do not share the same physical characteristics with. For this aim, we first achieved high spatial SLR rates by developing a machine learning algorithm and then, projected them into the future by the multiple linear regression method. Afterward, we ran DFlow-FM as the hydrodynamic model to achieve the high spatial resolution of tidal levels for 18.6 years, which is an entire tidal cycle with the assumption of tidal levels being stationary, was added up to the future SLR rates in a bathtub method and provided the future tidal levels. Finally, these tidal levels were compared to the high tide flooding thresholds (also achieved by training a machine learning algorithm that provides these thresholds in a fine spatial resolution), and the number of hours and probability of occurrence of flooding in years 2030, 2050, and 2100 were regionally obtained along the US coastlines. This research is a helpful source for becoming aware of what is coming in the next decades and how to provide strategies for each region exclusively.