Coastal Hazard Assessment w/High-Res Data: A Pacific Island Case Study

Low-lying island environments are particularly vulnerable to impacts from coastal hazards, including inundation (coastal flooding), whether the increased water levels are from episodic events (storm surge, wave run-up, king tides) or from chronic conditions (long term sea-level rise). Elevation is the primary geophysical variable that determines exposure to inundation in coastal settings. Accordingly, coastal elevation data are a critical input for assessments of inundation exposure. High-resolution, high accuracy data from multiple remote sensing sources (unmanned aerial systems, sonar, lidar, satellite imagery) are used to construct seamless elevation models across the land-water interface, and these models are used in coastal assessments. A quantitative analysis of inundation exposure was conducted for Majuro Atoll in the central Pacific nation of Republic of the Marshall Islands. The resulting mapping products delineate areas subject to marine inundation and other low-lying lands at different inundation levels, and they demonstrate the substantial value of high-resolution, high-accuracy data for assessing inundation exposure and the enhanced information from accounting for vertical uncertainty. The integrated coastal elevation models are developed as a component of the USGS Coastal National Elevation Database (CoNED) project, and additional application examples along the U.S. coast are shown.