Service Description: The presence or absence of eelgrass and widgeon grass was delineated for coastal Rhode Island using tidally-coordinated orthophotography, GPS, and underwater video recordings. These 2021 data utilize consistent mapping methodology with previous mapping efforts in 2016, 2012, and 2006. Therefore , these data may support SAV dynamics (see accompanying report by Bradley et.al), conservation, marine spatial planning, coastal resource management.
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Description: Zostera marina and Ruppia maritima (submerged aquatic vegetation) beds were delineated (polygons) using ortho-imagery collected in June, 2021. In order to maximize the identification of photo-signatures of SAV, the imagery was acquired using specifications from the NOAA Coastal Change Analysis Program including low tide, slight winds, low sun angle, full sun, and minimal humidity or haze. During the ortho creation process, solar glint was minimized by selecting flight lines with minimal glint. The delineation process was supplemented by geo-referenced underwater video recordings. To identify field survey locations, GPS enabled tablets were loaded with draft versions of the 2021 ortho-imagery and preliminary SAV delineations. After processing of field data, 999 acres of SAV were identified and delineated in coastal Rhode Island waters. To test the accuracy of the delineations, a user's and producer's matrix was developed (Story and Congalton, 1986). The overall user's accuracy for the 2021 SAV surveys was 83%.
Copyright Text: RI CRMC, URI-EDC, Narragansett Bay National Estuarine Research Reserve
Spatial Reference: 102100 (3857)
Initial Extent:
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Spatial Reference: 102100 (3857)
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Spatial Reference: 102100 (3857)
Units: esriMeters
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