Hogrefe, K.R., Wright, D.J., and Hochberg, E.J., Derivation and integration of shallow-water bathymetry: Implications for coastal terrain modeling and subsequent analyses, Marine Geodesy, 31(4): 299-317, 2008.Online Links:
This is a Raster data set. It contains the following raster data types:
Planar coordinates are encoded using row and column
Abscissae (x-coordinates) are specified to the nearest 5.000000
Ordinates (y-coordinates) are specified to the nearest 5.000000
Planar coordinates are specified in meters
The horizontal datum used is D_WGS_1984.
The ellipsoid used is WGS_1984.
The semi-major axis of the ellipsoid used is 6378137.000000.
The flattening of the ellipsoid used is 1/298.257224.
hogrefek@geo.oregonstate.edu
This is a compilation of terrestrial and bathymetric datasets, a USGS DEM, nearshore bathymetry derived from Ikonos sattelite imagery and gridded multibeam sonar data, into a coastal terrain model (CTM). The CTM was created to support terrain analyses that cross the land-sea interface to study the impact of human settlement density to the health of coral reefs.Abstract of the thesis for which this dataset was created: The analysis of material and energy exchange between the marine and terrestrial components of island ecosystems enables research into the impact of human population and land use on the health of coral reef habitat. Satellite and acoustic remote sensing technologies enable the collection of data to produce high resolution bathymetry for integration with terrestrial digital elevation models (DEMs) into coastal terrain models. An integrated terrain surface that incorporates the land-sea interface, grounded by a geographic information system, is a powerful analytical tool for geomorphic studies of watersheds and coastal processes. The island of Tutuila, American Samoa is an ideal case study due to its high relief terrain, data availability and local interest in impacts to coral reef resources. The Tutuila model integrates a USGS DEM, multibeam bathymetry from 15 to 500 m and near shore bathymetric data from 0 to 15 m derived from IKONOS satellite imagery. The high spatial resolution of IKONOS imagery is suitable for detection of features with subtle relief and intricate structure. Shallow water bathymetry is derived by quantifying the relative attenuation of blue and green spectral band radiance as a function of depth. The procedure used to derive bathymetry, Lyzenga (1985), is identified as the most effective of several proposed in the recent literature. The product is error-checked using control points extracted from multibeam sonar data and collected during recent field surveys, as well as terrain profiles. The coastal terrain model provides morphological detail of fine resolution and high accuracy for terrain and land use analysis to enhance the study of ecosystem interconnectivity and the effects of anthropogenic inputs to coral reef habitats. Subsequent topographic analyses of the Tutuila model use drainage patterns to identify contiguous marine/terrestrial basins within which the marine environment is most directly impacted by land use through freshwater inputs from affiliated catchments. Human population density serves as an indicator of intensified land use and urbanization, which has been shown to increase pathogen and sediment loads in runoff, while percent coral cover, coral colony density and coral genera diversity are used as indicators of reef health. Spatiotemporal correlation analyses of population density against the three reef health indices within each of the marine/terrestrial basins reveal a decline in reef health associated with increased population density. This paper integrates and builds upon established methods of satellite imagery analysis and terrain modeling to create the Tutuila coastal terrain model and uses it to refine the scale of other studies linking human terrestrial activities to the physical condition of coral reefs.
Many thanks to NOAA’s Pacific Island Fisheries Science Center, Coral Reef Ecosystem Division and the Pacific Islands Benthic Habitat Mapping Center for collecting field control points and for providing the multi-beam sonar data.
Thanks also to NOAA’s Center for Coastal Monitoring and Assessment, Biogeography Team for providing at-sensor Ikonos satellite data.
For a detailed description of processing: <Cookbook_042108.pdf>
Person who carried out this activity:
hogrefek@geo.oregonstate.edu
File conversion Data conversion from digital number to radiance values Corrected for atmosphere and water surface reflection (deglinting) Linearization of spectral decay as a function of depth Georectification of spectral data with multibeam sonar data Derivation of bathymetry data from linearized spectral values Integration with other datasets
For a detailed description of processing: <Cookbook_042108.pdf>
Person who carried out this activity:
hogrefek@geo.oregonstate.edu
For a detailed description of processing: <Cookbook_042108.pdf>
Person who carried out this activity:
hogrefek@geo.oregonstate.edu
The elevation data are accurate to within the 10 meter contour interval of the original USGS 1:24000 topographic map. The gridded multibeam bathymetry is corrected for platform and tidal parameters and are presumed to be accurate to within a few meters. The derived bathymetry shows a consistant 5 m or greater overestimation of depth in the shallow range (< 5 m) and underestimation of depth the deep range (> 15 m).
There is a potential offset of 10-15 meters in the derived bathymetry due to the same offset in original IKONOS imagery.
Potential offset between DEM and multibeam sonar bathymetry of < .3 meters due to a vertical datum conflict.
There were gaps in the original multibeam data where sonar swaths did not overlap. There were gaps in the derived bathymetry data as a result of cloud cover, surf zones and emergent reefs. For the purpose of creating a constant surface for the CTM, these data gaps where filled using a moving window algorithm through the ArcGrid command line window that assigned values to NoData cells based on the values of a defined range of nearby cells.
All internally, logically consistent. Arc-node topology not applicable for this raster grid.
Are there legal restrictions on access or use of the data?
- Access_Constraints: None
- Use_Constraints:
- Not for navigational purposes. Please cite authors when using the data for your own work in print or on the web.
<dusk.geo.orst.edu/djl/samoa>
Downloadable Data
None
| Data format: | ArcGIS grid, ASCII |
|---|---|
| Network links: | dusk.geo.orst.edu/djl/samoa |
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