Summary Information for Field Activity 2000-030-FA

Area of Operations: John Day Reservoir, Columbia River, Washington, Oregon, United States, North America

Dates: September 13, 2000 to September 28, 2000

Chief scientist: Dave Twichell

   Guy Gelfenbaum (Coastal and Marine program, Western Region); Mike Parsley (BRD, Cook, WA)

Objectives: High-resolution seismic reflection, sidescan mapping, and sediment sampling of reservoir floor to determine the amount, distribution and types of sediment being trapped. These data are important to understanding changes in salmon spawning grounds and to quantifying changes in sediment supply to the coast.

Type of Activity: Sampling; Seismic profiling; Sea floor mapping; Photography;Sea floor mapping

Information to be derived:

Summary: The work was done in cooperation with researchers in the Biological Resources Division in Cook, WA. Sidescan sonar imagery and chirp seismic profiles were collected during the first 8 days and video and sediment sampling was collected during the last 3 days. Most of the lake floor was imaged with the SIS-1000 which was set to scan 750-m to each side. Sub-bottom profiles were collected simultaneously with the sidescan imagery, and also along tie lines in one 10-km stretch of the reservoir. Windy conditions, and the fact that the post-impoundment sediment was usually too thin to resolve seismically, did not warrant extending the length of the cruise to collect more seismic data. Video images were collected at 48 stations in the reservoir, and sediment samples were recovered at 41 stations. Sidescan sonar: 287.7 km; Sub-bottom: 287.7 km; Video transects: 48; Sediment samples: 41; Bottom photos: 130.

Contact: Dave Twichell (dtwichell@usgs.gov)

InfoBank: uses the identifier E-30-00-WA. Visit this site for more information.

Related Links: http://walrus.wr.usgs.gov/infobank/e/e3000wa/html/e-30-00-wa.meta.html