Projected flood extent polygons and flood depth points based on 10-, 50-, 100-, and 500-year wave-energy return periods, with and without coral reefs, for the Commonwealth of the Northern Mariana Islands (the islands of Saipan and Tinian)

Flood water depths were extracted from a grid of modeled total water levels for 4 modeled storm return periods (10, 50, 100, or 500 years) with and without the influence of coral reefs. Points were extracted every 4 meters along shore normal profiles with a 100 m alongshore spacing and saved as an ESRI point shapefile in the following format: [Sublocation]_rp[#]_[REEFSTATUS]_floodpoints, where [Sublocation] = one of 22 sublocations within the 7 main geographic areas of the States of Hawaii and Florida, the Territories of Guam, American Samoa, Puerto Rico, and U.S. Virgin Islands, and the Commonwealth of the Northern Mariana Islands, [#] = wave energy return period (10, 50, 100, or 500 years), and [REEFSTATUS] = with reef (wrf) or without reef (wofr). See Storlazzi and others (2019) for a detailed description of model development and methodologies.

Flood water depth shapefiles were merged to create a single shapefile for each of the 7 main geographic areas of the States of Hawaii and Florida, the Territories of Guam, American Samoa, Puerto Rico, and U.S. Virgin Islands, and the Commonwealth of the Northern Mariana Islands. A Scenario attribute was added to identify the wave-energy return period and reef status combination used to derive the flood depth based on the original shapefile.

The merged flood water depth shapefiles were exported as a text file in a comma separated value (.csv) format.

Flood extent polygons were built by creating a minimum-bounding polygon between flood points along adjacent shore normal profiles for 4 modeled storm return periods (10, 50, 100, or 500 years) with and without the influence of coral reefs. The resulting 8 polygons for each geographic sublocation area were clipped and/or extended to a simplified coastline based on the 0-m contour used in the elevation model and edited to remove spurious results. The edited polygons were merged into a single shapefile (flood mask) and are identified by a unique MaskName attribute in the following format: [Sublocation]_rp[#]_[REEFSTATUS]_floodmask, where [Sublocation] = one of 22 sublocations within the 7 main geographic areas of the States of Hawaii and Florida, the Territories of Guam, American Samoa, Puerto Rico, and U.S. Virgin Islands, and the Commonwealth of the Northern Mariana Islands, [#] = wave energy return period (10, 50, 100, or 500 years), and [REEFSTATUS] = with reef (wrf) or without reef (wofr).

Edited metadata to add keywords section with USGS persistent identifier as theme keyword. No data were changed.

Performed minor edits to the metadata to correct typos. No data were changed.