Accuracy Assessment Field Data for Benthic Habitat Maps of Palau

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; IMSG; and Analytical Laboratories of Hawaii, LLC. The goal of the work was to incorporate previously developed mapping methods to produce coral reef habitat maps for The Republic of Palau. GPS field observations were used to establish the thematic accuracy of this thematic product. 623 benthic habitat characterizations were completed in UTM Zone 53N for this work.

The National Ocean Service is preparing digital map products of these biotic resources and coordinates a long-term monitoring program that can detect and predict change in U.S. coral reefs, and their associated habitats and biological communities. The goal of the work was to implement previously developed coral reef mapping methods to produce GIS map products of benthic habitats by photo interpreting ortho-rectified remotely sensed imagery. These Accuracy Assessment point data were generated to assess the thematic accuracy of these habitat maps.

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The National Oceanic and Atmospheric Administration (NOAA) National Centers for Coastal Ocean Science (NCCOS) will publish this data on CD-ROM. NCCOS Biogeography Program does not guarantee the accuracy of the geographic features or attributes. Please see the metadata records for each data set for complete information on the source, limitations, and proper use.

Contact NOAA for distribution options (see Distributor).;

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The geographic coordinate positions of the points in this thematic data were acquired by GPS using a Trimble GeoExplorer 3 with a customized data dictionary designed to reflect the NOAA Coral Classification Scheme for Benthic Habitats of the Pacific. All habitat determinations were made in the field, recorded in the GPS data logger and seamlessly transferred to ArcView GIS using Trimble Path Finder Office Software.

Point positional accuracy is determined by two tests producing circular RMS statistics. First, point GPS data were acquired by repeated occupation of a registered survey monument that has been recently recovered and positioned using survey grade GPS buy the National Geodetic Survey. Second, replicate GPS positions were collected after navigating to a way point by boat to estimate the positional error generated from variables due to environmental conditions offshore. The 95% sigma RMS accuracy error was calculated to be 0.97 meters and the precision calculated to be 0.84 meters on 141 measurements on registered monuments. The navigation accuracy error was calculated to be 1.36 meters with precision calculated to be 1.11 meters. Each GPS measurement was the average of 100 GPS positions. Thus, all point features in these accuracy assessment data meet the NOAA contract standard of 95% sigma of 5 meters.

Data are complete for the entire main archipelago of Palau. Habitat attributes are determined by direct observation in the field. These data are considered truth at the time of collection. Habitat types are subject to change over time due to population dynamics of the dominant biological communities.

These data were objectively managed. They were with held from the photo interpreter during map making. The Coral Reef Assessment and Monitoring Program (CRAMP) of the Hawaii Institute of Marine Biology (HIMB) maintained these data at facilities other than ALH. Ultimately, these data were used to prepare the error matrix upon when the statistical report of the thematic accuracy of the maps was generated.Transfer of the habitat assessment data is seamless from the field determination to the final GIS product. The data is not transcribed or rewritten by hand. Errors in processing are not expected.