Road flooding is a serious operational hazard in the low-lying areas of southern Louisiana. This hazard is especially acute for the region’s emergency evacuation routes, which must be accessible by coastal residents who plan evacuations ahead of an approaching hurricane. Numerous factors contribute to road flooding during a hurricane. These include road elevations, tidal ranges, winds, storm surge, and storm speed and direction. To enhance the situational awareness and mitigation of these inundation hazards for emergency and operational managers, a decision support tool was developed as a proof-of-concept for identifying the flood hazards of specific road segments vulnerable to hurricane flooding. Additional research was performed to analyse the risks of these hazards to civilian and military vehicles. Geographic information systems (GIS) software is used to estimate and display storm surge inundation over road surfaces that have flooded in the past. The data utilized for this project included road surface elevations (in feet, NAVD88) of previously flooded, state-maintained highways provided by the Louisiana Department of Transportation & Development (LADOTD), storm surge estimates (in feet, NAVD88) published by the National Weather Service (NWS), and the locations of tide and water gauges maintained by the U.S. Geological Survey (USGS) and the NWS. Attributes depicting worse case hurricane storm surge scenarios were subtracted from road elevations to estimate the water depth over a road surface. Inundation estimates and nearby gauge data were synthesized and accessible using a map interface. Finally, this report includes a summary of research that analysed the flood risk associated with vehicle type. The analysis addresses the relationship between flood characteristics (e.g., flowing versus standing water and wind driven water) and the configuration of both civilian and military vehicles (e.g., size, weight, and ground clearance). (Author/publisher)
Samenvatting