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Jonathan A. Warrick

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This portion of the USGS data release presents topography data collected during surveys performed on the Elwha River delta, Washington, in May 2011 (USGS Field Activity Number W-04-11-PS). Topography data were collected on foot with global navigation satellite system (GNSS) equipment mounted on backpacks operating in Real-Time Kinematic (RTK) mode. A total of 3 GNSS backpacks, each equipped with a dual-frequency GNSS receiver and handheld data collector, were used during the survey. Differential corrections were transmitted at 1-Hz intervals by a VHF radio to the backpack GNSS receivers from a GNSS base station placed on a benchmark with known horizontal and vertical coordinates relative to the North American Datum...
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This portion of the USGS data release presents bathymetry data collected during surveys performed on the Elwha River delta, Washington in September 2010 (USGS Field Activity Number W-03-10-PS). Bathymetry data were collected using a small boat and a personal watercraft (PWC), each equipped with single-beam sonar systems and global navigation satellite system (GNSS) receivers. The sonar systems on the survey vessels consisted of an Odom Echotrac CV-100 single-beam echosounder and 200 kHz transducer with a 9° beam angle. Raw acoustic backscatter returns were digitized by the echosounder with a vertical resolution of 1.25 cm. Depths from the echosounders were computed using sound velocity profiles measured using a...
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We characterized seafloor sediment conditions near the mouth of the Elwha River from underwater photographs taken every four hours from September 2011 to December 2013. A digital camera was affixed to a tripod that was deployed in approximately 10 meters of water (Tripod location from September 2011 to April 2013: 48.15333, -123.55931; tripod location from April 2013 to December 2013: 48.15407, -123.55444). Each photograph was qualitatively characterized as one of six categories: (1) base, or no sediment; (2) low sediment; (3) medium sediment; (4) high sediment; (5) turbid; or (6) kelp. For base conditions, no sediment was present on the seafloor. Low sediment conditions were characterized by a light dusting of...
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This portion of the USGS data release presents bathymetry data collected during surveys performed on the Elwha River delta, Washington in July 2015 (USGS Field Activity Number 2015-648-FA). Bathymetry data were collected using two personal watercraft (PWCs), each equipped with single-beam sonar systems and global navigation satellite system (GNSS) receivers. The PWC sonar systems consisted of an Odom Echotrac CV-100 single-beam echosounder and 200 kHz transducer with a 9° beam angle. Raw acoustic backscatter returns were digitized by the echosounder with a vertical resolution of 1.25 cm. Depths from the echosounders were computed using sound velocity profiles measured using a YSI CastAway CTD during the survey....
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This portion of the USGS data release presents sediment grain-size data from on the Elwha River delta, Washington in July and August, 2015 (USGS Field Activities 2015-648-FA and 2015-652-FA). Bed sediment was sampled using a small ponar, or 'grab', sampler on July 28, 2016 from the R/V Frontier at a total of 70 locations in water depths between approximately 1 and 17 m around the delta. An additional 17 samples were obtained by SCUBA divers between July 22 and August 23, 2015 using a 15 cm diameter push corer inserted into the seabed as far as possible to a maximum depth of 15 cm. Forty-eight samples were collected at low tide at intertidal locations on the delta. The locations of grab samples and intertidal samples...
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