Data Management Plan

This project is a cooperative effort among the National Ocean Service, National Centers for Coastal Ocean Science, Center for Coastal Monitoring and Assessment; the University of Hawaii; and Analytical Laboratories of Hawaii, LLC. The goal of the work was to develop coral reef mapping methods and compare benthic habitat maps generated by photointerpreting georeferenced color aerial photography, hyperspectral and IKONOS satellite imagery. Twenty-seven distinct benthic habitat types within eleven zones were mapped directly into a GIS system using visual interpretation of orthorectified aerial photographs and hyperspectral imagery. Benthic features were mapped that covered an area of 790 km^2. In all, 204 km^2 of unconsolidated sediment, 171 km^2 of submerged vegetation, and 415 km^2 of coral reef and colonized hardbottom were mapped.

Process Steps:

• 2001-10-10 00:00:00 - Benthic habitat maps were digitized by delineating habitat boundaries from georeferenced imagery loaded into ArcView 3.2 GIS software with the Image Analysis and NOAA Coral Reef Habitat Digitizing extensions both activated. Digitizing was conducted using heads-up computer screen methods with the minimum mapping unit (MMU) set to 1 acre and the image scale at 1:6,000. All three types of remotely sensed imagery were processed by NOS prior to map production. Individual color aerial photographs were georeferenced and mosaicked. The hyperspectral data composed of 72 ten nm wide bands were subsetted to three band composites that enhanced deep and shallow water features. IKONOS satellite imagery was corrected for atmospheric and water column effects. During the digitizing process, image stretched and manipulating image contrast, brightness and color balance were performed in the ArcView Image Analysis Extension to enhance features in the processed imagery. A first draft map was completed and features in the imagery where uncertainties existed, due to confusing or difficult to interpret signatures, were identified for future ground validation effort. An ArcView GIS point theme was generated with points positioned on the features of uncertain habitat type or along transects though gradients between habitat types. The GIS points were converted to GPS waypoints using Trimble Pathfinder Software and were navigated to in the field using a Trimble GeoExplorer 3 GPS data logger. A benthic habitat characterization was conducted at each site by snorkeling, free diving, or via observations from the surface where water depth and clarity permitted. GPS data were collected at each location and site ID, depth, habitat type, zone and the method used to make the assessment were recorded. The ground validation data were incorporated into the second draft of each map.