US Army Corps of Engineers
Portland District

Overview of controlling factor: Currents

color graphCurrents are the rates and patterns of water movement, which in turn influence the erosion and deposition of sediments.

The figure at bottom left shows surface velocity (m/s) in the estuary during June 2002 (Baptista et al. 2003).

The figure at bottom right shows "virgin flow" (what would have occurred without dams and irrigation) and observed flow measured by USGS at the Dalles from 1878-1999 (Jay 2003).

Stressors that affect currents:

  • Dredging
  • Extreme climatic events
  • Filling
  • Visual color comparison from 1900-1975Flow regulation
  • Logging
  • Marinas and overwater structures
  • Shoreline armoring
  • Volcanic activity
  • Water diversion

Ecosystem structures that are affected by currents:

  • Plankton
  • Emergent marsh
  • Mud / sand flats
  • Submerged aquatic vegetation
  • Shallow slope
  • Deep channel

Interactions and equations:

 

Contact information

Ronald Thom, Ph.D
360-681-3657

Marine Research Operations, PNNL
1529 W. Sequim Bay Rd.
Sequim, WA 98382