A National View of Storm Surge Risk and Inundation

Abstract

The National Oceanic and Atmospheric Administration (NOAA), specifically the National Weather Service’s (NWS) National Hurricane Center (NHC), utilizes the hydrodynamic Sea, Lake, and Overland Surges from Hurricanes (SLOSH) model to simulate storm surge in 27 basins along the U.S East and Gulf Coasts. This information is provided to federal, state, and local partners to assist in a range of planning processes, risk assessment studies, and decision making. Based on climatology, tens of thousands of hypothetical hurricanes are simulated in each basin, and the potential storm surges are calculated. Storm surge composites—maximum envelopes of water (MEOWs) and maximum of maximums (MOMs)—are created to assess and visualize storm surge risk under varying conditions. While MEOWs and MOMs provide a local assessment of storm surge risk, they do not provide a national perspective owing to the 27 discrete grids. National assessments must therefore merge the grids together, which is a laborious task requiring considerable SLOSH and hydrodynamic modeling expertise. This paper describes the technique used to create national inundation maps for category 1–5 hurricanes using the SLOSH MOM product, and it provides a simple quantitative assessment of the potential societal impacts. Approximately 22 million people along the U.S East and Gulf Coasts are vulnerable to storm surge. For all hurricane categories, a substantial portion of the coastal population and housing units are at risk, and many evacuation routes become inundated. Florida is the most vulnerable state with 40% of its population at risk. These maps and analyses provide a new way to view, analyze, and communicate national storm surge risk and inundation.

The combined risk of extreme tropical cyclone winds and storm surges along the U.S. Gulf of Mexico Coast

“…From 1950 to 2000, the population in the five states surrounding the Gulf of Mexico increased by 164% [ U.S. Department of Commerce Bureau of Economic Analysis , ], and according to United States Geological Survey [], over 50% of U.S. citizens live within 80 km of a coastline. Twenty‐two million people along the U.S. East and Gulf Coasts are vulnerable to storm surge, with Florida being the most vulnerable state [ Zachry et al , ]. Of all the deaths occurring in the United States attributed to Atlantic tropical cyclones from 1963 to 2012, 49% are caused by storm surge and 8% by wind [ Rappaport , ].…”

The role of tidal modulation in coastal flooding on a micro-tidal coast during Central American Cold Surge events

“…5 Figure 16 shows the maps of maximum flood (TSSE) corresponding the the four tide scenarios done for Event A (reminding that TS3 corresponds to the actual tidal phase that occurred during Event A). It is important to note that the time at which the maximum flood ocurred is not the same in the sea side and inside the lagoon, and is not the same for each simulation, similar to the criteria used with flood risk analysis in other studies (Zachry et al, 2015). It can be seen that the flood worst case scenarios were for TS1 10 (high tide during the peak of the storm) and TS4 (rising tide near mean sea level during the peak of the storm), and significantly lower with tide scenarios TS2 and TS3 (see summary in Table 1).…”

Assessment of coastal flooding and associated hydrodynamic processes on the south-eastern coast of Mexico, during Central American cold surge events

“…Figure 12 shows the maps of maximum flood (TSSE) corresponding to the four tide scenarios carried out for Event A (TS3 corresponds to the actual tidal phase that occurred during Event A). It is important to note that the time at which the maximum flood occurred is not the same on the sea side as inside the lagoon, nor is it the same for each simulation, similar to the criteria used with the inundation threat analysis in other studies (Zachry et al, 2015). The worst-case flood scenarios were for TS1 (high tide during the peak of the storm) and TS4 (rising tide near mean sea level during the peak of the storm), and TSSE were significantly lower with scenarios TS2 and TS3 (see summary in Table 2).…”

“…The latter depends on several factors, such as the maximum water level reached, the flow velocity, the flood duration, the speed of sea-level rise, and the flood frequency. Flood hazard assessments are normally performed based on historic or synthetic flood data (Lin et al, 2010;Zachry et al, 2015). However, since wind reanalysis data sets have become available, such as the North American Regional Reanalysis (Mesinger et al, 2006) and the Climate Forecast System Reanalysis (CFSR; Saha et al, 2010), they have been used to force hydrodynamic models to generate sea-level reanalysis.…”