This study uses the extensive multibeam bathymetry coverage around American Samoa to analyze and classify Bathymetric Position Index (BPI) zones, structures and rugosity for depths that can not
be efficiently reached by other surveying methods. The methods developed here and applied to American Samoa sites are the first to successfully create a benthic
classification for multibeam bathymetry beyond 30 meters depth that extends existing shallow water benthic classifications (The Development and Application of Benthic
Classifications for Coral Reef Ecosystems Below 30M Depth using Multibeam Bathynmetry: Tutuila, American Samoa, 2004, Appendix A). Spatial analysis was used to derive
slope and multiple scales of bathymetric position from the original bathymetry. The resulting derivative grids were combined with a new algorithm to develop final products:
BPI zones, structures and rugosity classification maps for each study site. The maps make use of a new classification scheme that may be extended to other coral reef systems.
The classification methods identify four BPI zones: crests, depressions, flats, and slopes.
if (nfb02_tpi250s >= 100) fb_zns = 1
else if (nfb02_tpi250s <= -100) fb_zns = 2
else if (nfb02_tpi250s > -100 and nfb02_tpi250s < 100 and nfb02_slp <= 5) fb_zns = 3
else if (nfb02_tpi250s > -100 and nfb02_tpi250s < 100 and nfb02_slp > 5) fb_zns = 4
For additional information see <ftp://ftp.soest.hawaii.edu/pibhmc/web/docs/Lundblad_Thesis.pdf>