Data Management Plan

The Klawock River on Alaska's Prince of Wales Island drains a 29,061 acre watershed with 132 miles of streambed habitat supporting seven salmon and trout species. Traditionally the river and lagoon supported salmon harvests exceeding 30,000 fish annually. The salmon fishery is an important economic factor and food source in the Klawock area. It is also an important cultural resource to local inhabitants. In 1964 a causeway was constructed blocking access to the lagoon from adjacent Klawock Bay. This has resulted in dramatic decreases in salmon harvests. The Nature Conservancy has lead a broad partnership to construct a culvert through the causeway thus re-establishing free passage between the river and Klawock Bay which is expected to help restore a full use of the river as spawning habitat by salmon and generally improve the quality of the lagoon. Benthic habitats in the lagoon and adjacent Klawock Bay and Klawock Harbor were mapped in spring 2011 to establish a baseline of benthic communities in the area with emphasis on eelgrass beds which are essential to the early survival of salmon fry. The habitat map will guide ongoing monitoring activities in the lagoon and form the basis of future change detection efforts.

Aerial multi-spectral imagery was collected over the lagoon, bay, and harbor during the week of April 19, 2011. The mission was timed to coincide with the breaching of the causeway. The environmental considerations important to successful benthic mapping were incorporated into the mission planning. These included, imagery to be collected within 1.5 hours of a zero or negative tide, clear water conditions (no algal blooms, or sediment plumes from runoff), low winds to avoid surface waves, and sufficient solar illumination to image submerged areas. These collection parameters were defined by the Office for Coastal Management prior to collection of the imagery. Despite weather and water conditions which were not ideal, imagery adequate to map most of the habitats in the lagoon was successfully collected on April 19, 2011.

Eelgrass habitats in the Lagoon did not have sufficient biomass or illumination through the water column at the time of the aerial mission to be mapped from that source so eelgrass habitats were determined by two field-digitizing processes, one in August 2010 and one in September 2011. The final hybrid map captures habitats 10m x 10m or larger and has the same positional accuracy as the source imagery.

Field data to guide the mapping was supplied by several project partners. A comparison between the field data and the map shows high levels of agreement, although no traditional quantitative accuracy assessment was conducted.

Original contact information:

Contact Org: NOAA Office for Coastal Management

Phone: 843-740-1202

Email: coastal.info@noaa.gov

Process Steps:

• 2011-04-01 00:00:00 - The imagery was flown on 4/19/2011 between 9:35 and 10:24 A.M. by Geovantage Inc. The horizontal spatial accuracy of the imagery reported by the vendor is within +/- 3 meters CE95 of position on the ground. The radiometric resolution of the 4 band image composites is 12-bit. The imagery was processed to remove atmospheric effects such as haze and to highlight the spectral response of submerged areas. The imagery has some exposure variation between adjacent flight lines and between sunlit and cloud shaded areas. The 4 band imagery is provided in GeoTIFF format. The imagery was captured at a spatial resolution (pixel size) of 0.25m x 0.25m and was delivered in a Universal Transverse Mercator - Zone 8 projection using the NAD1983 datum.
• 2011-10-01 00:00:00 - The benthic habitat map was developed through image segmentation using the Trimble eCognition Developer software. Image segments representing spectrally homogenous area in the source imagery were generated using a scale factor 20-25. A draft map was generated by classifying the image segments into one of 5 habitat classes (coastal marsh, unconsolidated sediments, unconsolidated bottom, macroalgae, and eelgrass) using the Nearest Neighbor classifier in Trimble eCognition Developer. Training data was derived through photo interpretation using available provided field information as a reference. The resulting draft map was reviewed by the project team through visual inspection and comparison to ground photos. Additional edits were made through manual labeling of the segments. Due to poor water clarity in Klawock Lagoon eelgrass habitat boundaries in the lagoon were generated by staff kayaking along the perimeter of the beds with a GPS logging their position every second. Two of these kayak-digitized polygons (one collected in August 2010 and one in September 2011) were merged to create a maximum extent of eelgrass polygon which was incorporated into the final benthic habitat map.
• 2015-01-01 00:00:00 - The data were converted from a single ESRI polygon shapefile classified according to the System for Classifying Habitats in Estuarine and Marine Environments (SCHEME) to the Coastal and Marine Ecological Classification Standard (CMECS) 2012 format (which can be found at https://coast.noaa.gov/digitalcoast/tools/cmecs-crosswalk) which produces separate geoform, geoform, and geoform feature layers from the original input benthic habitat dataset. This geoform feature layer contains CMECS geoform component attributes where an "Equal" or "Nearly Equal" SCHEME value was present in the original data. Polygons for which no geoform information was present have been removed. No other changes to the original polygon boundaries or any other alterations of the original SCHEME data were made during this process.