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| Geologic Studies of Coral Reef Habitats: Remote Sensing Applications to Coral Reefs
Hawaiian Islands: Moloka'i |
Introduction | Data | Applications | Resources | Coral Reefs Main Page
![[View Hawai'i Map]](images/HawaiiMap_s.gif)
Map of the Hawai'ian Islands showing location of the Hawai'ian Islands and Moloka'i. (170 kilobytes) |
Moloka'i, one of the islands of Hawai'i, has the largest continuous fringing coral reef in Hawai'ian waters, extending approximately 30 miles (50 kilometers) along the southern and eastern coasts of the island. Studies under the USGS Coastal and Marine Geology coral reef project at this site include exploring the impact of land use on reef health and mapping various coral reef features. The investigation into the types of information that can be extracted from remotely sensed images to help study, map, and monitor coral reef environments is part of the USGS project. Digital image maps, as well as various cover type coral reef maps, are being generated using the remotely sensed images and used where ever applicable within the project.
Among the various remotely sensed data sets being used digitized aerial photography and digital airborne SHOALS (Scanning Hydrographic Operational Airborne Lidar Survey) bathymetry data covering the southern and eastern shores of the island of Moloka'i have been the two main data sets at this stage. The aerial photographs contain spectral/color information about the various cover types in the area, while the SHOALS Lidar bathymetry contains topographic information (i.e., depth and slope).
The digital image maps covering approximately 30 miles of near-shore coastal waters have been processed to enhance information in both shallow and deeper water areas using spatial filtering and 3-D stereoscopic procedures. The georeferenced digital image maps are being used for various applications, including to navigate directly to features seen in the images during field mapping and interpretation studies. One of the studies deals with identifying areas affected by deposition of terrigenous mud from coastal stream discharge, an impact locally important along the southern shore of Moloka'i. One result of the remote sensing component will be georeferenced high-resolution image maps of critical coral reef habitats suitable for state and federal managers to use in providing guidance for planning and ecosystem management. These high resolution image maps will also be useful as a baseline for future monitoring efforts.
Aerial Photomosaics & Bathymetry: access to digital image maps generated using aerial photography and airborne SHOALS Lidar bathymetry | 
Change Detection: an example using multitemporal aerial image maps to detect and map changes over time | 
Depth Corrections: an example using image processing techniques and modeling to correct for depth effects in digitized aerial photography with and without the use of SHOALS bathymetry data | 
Digital Camera Stations: using digital cameras to record and monitor water conditions along the shoreline |
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