Shallow-water (generally, less than 30 meters) bank areas in the Northwestern Hawaiian Islands were identified using semi-automated image analysis of Landsat 7 ETM+ satellite imagery. An area of approximately 10,000 sq. km was mapped using the moderate-resolution satellite imagery and shallow-water bank maps were generated for the French Frigate Shoals, Gardner Pinnacles, Lisianski Island, Laysan Island, Maro Reef, Necker Island, Nihoa Island, Pioneer Bank, Raita Bank, St. Rogatien Bank, the Brooks Banks, and the bank west of Nihoa. This project is a cooperative effort among the National Oceanic and Atmospheric Administration, State of Hawaii Department of Land and Natural Resources, and the U.S. Fish and Wildlife Service to produce benthic habitat maps and georeferenced imagery for the Northwestern Hawaiian Islands. This project was conducted in support of the U.S. Coral Reef Task Force.
The National Ocean Service is conducting research to digitally map biotic resources and coordinate a long-term monitoring program that can detect and predict change in U.S. coral reefs, and their associated habitats and biological communities. This project was conducted in support of the U.S. Coral Reef Task Force (https://www.coris.noaa.gov).
ground condition
These maps are NOT to be used for navigation. These maps of shallow-water bank areas in the Northwestern Hawaiian Islands have been reviewed by numerous decision makers and scientists familiar with the Northwestern Hawaiian Islands region.
1305 East West Highway, N/SCI-1
NOAA, University of Hawaii, U.S. Fish and Wildlife Service
Multispectral Landsat satellite imagery was positioned using National Geodetic Survey ground control data or Landsat satelite ephemeris data for French Frigate Shoals, Gardner Pinnacles, Lisianski Island, Laysan Island, Maro Reef, Necker Island, Nihoa Island, Pioneer Bank, Raita Bank, St. Rogatien Bank, the Brooks Banks, and the bank west of Nihoa.Where available (French Frigate Shoals, Gardner Pinnacles, Lisianski Island, Laysan Island, Maro Reef, Necker Island, Nihoa Island), IKONOS satellite imagery was used to verify the positioning of the Landsat satellite imagery. For the remaining areas, at least two Landsat satellite images were used to perform a least-squares positioning adjustment of the imagery.
In order to improve the contrast, the bank maps of several locations were converted from a blue color scheme to a panchromatic color scheme. Those maps using the blue color scheme are French Frigate Shoals, Lisianski Island, and Laysan Island. Those maps using the panchromatic color scheme are Gardner Pinnacles, Maro Reef, Necker Island, Nihoa Island, Pioneer Bank, Raita Bank, St. Rogatien Bank, the Brooks Banks, and the bank west of Nihoa. No satellite imagery was available for the Gambia shoal, therefore the location of shallow-water banks was estimated from nautical charts of the region using the 10 fathom isobath as a proxy.
All of the imagery is horizontally positioned to less than one Landsat multispectral pixel (28.5 meters). Spatial data meets or exceeds national map accuracy standards for fixed features positioned to less than one Landsat multispectral pixel (28.5 meters). Spatial data meets or exceeds national map accuracy standards for fixed features.
none reported
Moderate-resolution Landsat satellite imagery was analyzed to produce maps of shallow-water banks in the Northwestern Hawaiian Islands
A map of the shallow-water bank visible in Landsat 7 ETM+ satellite imagery for French Frigate Shoals, Gardner Pinnacles, Lisianski Island, Laysan Island, Maro Reef, Necker Island, Nihoa Island, Pioneer Bank, Raita Bank, St. Rogatien Bank, the Brooks Banks, and the bank west of Nihoa was produced by generating a water reflectance transformation of the satellite blue band. The procedure converts DNs to at-satellite reflectance, then transforms at-satellite reflectance to water reflectance using the technique described by Neckel and Labs. The blue band is stretched using image analysis software to depict the extent of the shallow-water (to a water depth of ~30 meters) bank.
1305 East West Highway, N/MB7
not to be used for navigation
