Surface-sediment grain-size distributions from the Elwha River delta, Washington, July 2015
Dates
Publication Date
2016
Start Date
2015-07-22
End Date
2015-08-28
Citation
Stevens, A.W., Gelfenbaum, G., Warrick, J.A., Miller, I.M., and Weiner, H.M., 2016, Bathymetry, topography, and sediment grain-size data from the Elwha River delta, Washington, July 2015: U.S. Geological Survey data release, http://dx.doi.org/10.5066/F7S75DG9.
Summary
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 were determined [...]
Summary
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 were determined with a hand-held global navigation satellite system (GNSS). Samples obtained by divers were collected adjacent to fixed monuments on the seabed with previously determined coordinates.
The grain-size distributions of samples were determined in the USGS Pacific Coastal and Marine Science Center sediment lab. Approximately 20 g of sediment was sub-sampled and 10 mL of 35% hydrogen peroxide was added to remove organic material in the sample. The sample was heated at 250 °C to remove any remaining hydrogen peroxide and was placed in an ultrasonic bath to liberate the fine fraction. Subsequently the sample was centrifuged for 1.5 hours to remove soluble salts. Samples were funneled through 2 mm and 63 um sieves to separate the gravel (>2 mm), sand (63 um to 2 mm), and mud (<63 um). The sand and gravel fractions were dried in an 80 °C oven and weighed. Five mL of sodium hexametaphosphate was added to the mud fraction and a 20 mL aliquot was taken from a 1 L graduated cylinder to determine the weight of the mud. The particle-size distribution of the mud and sand fractions was analyzed separately using a Beckman Coulter LS 13 320, and the gravel, sand, and mud results were integrated into a single grain-size distribution for each sample. The final grain-size data are provided in comma-separated text format (.csv).
Data were obtained to assess the ecosystem response following the removal of two dams on the Elwha River. These data are intended for science researchers, students, policy makers, and the general public.
