Sediment transport on a high-energy ebb-tidal delta

By: , and 

Links

Abstract

Six tripods were deployed at shallow (~14-m) and deep (~24-m) sites on the northern, middle, and southern flanks of the Grays Harbor, Washington, U.S.A. ebb-tidal delta from early October through December, 1999 to measure waves, currents, temperature, and suspended-sediment concentrations as part of a wave-refraction and sediment-transport experiment. Directional wave spectra show that the general direction of wave approach shifted from WNW to WSW as the North Pacific weather pattern shifted from summer to winter, and we were fortunate enough to capture a large storm (offshore significant wave heights of ~8 m) in late October and a sequence of about 8 smaller events with ~4 to 6-m waves in November and December. As expected, wave directions indicated refraction around the ebb-tidal delta, and varied with incident wave period and direction. Direct estimates of sediment flux about 0.4–0.6 m above the bottom, and modeled estimates of depth-integrated suspended sediment flux indicate net offshore and northward transport. By comparison, estimated net bedload flux was onshore, but at much lower rates. These results indicate that sand on the ebb-tidal delta can be mobilized frequently under winter conditions, and can bypass the inlet at depths of at least 24 m. The data also suggest that significant offshore transport occurs at these depths and that offshore suspended-sediment transport during winter is so great that it might not be balanced by onshore bedload transport.

Study Area

Publication type Conference Paper
Publication Subtype Conference Paper
Title Sediment transport on a high-energy ebb-tidal delta
DOI 10.1061/40566(260)48
Year Published 2001
Language English
Publisher American Society of Civil Engineers
Contributing office(s) Pacific Coastal and Marine Science Center, Woods Hole Coastal and Marine Science Center
Description 10 p.
Larger Work Type Book
Larger Work Subtype Conference publication
Larger Work Title Coastal dynamics '01
First page 473
Last page 482
Conference Title Fourth Conference on Coastal Dynamics
Conference Location Lund, Sweden
Conference Date June 11-15, 2001
Country United States
State Washington
Other Geospatial Grays Harbor
Google Analytic Metrics Metrics page
Additional publication details