project background

This project is based on the Columbia River Estuary, which forms the border between Oregon and Washington States in NW USA. An ~80 km2 study reach upstream of Tongue Point is the focus of detailed measurements and the channels between Port Westward (formerly Beaver Army Terminal) and downstream of Astoria are being surveyed to provide additional bathymetry and boundary conditions for the numerical modelling. The Columbia is the:

  • 2nd largest river in the USA
  • drainage area of 660 480 km2
  • mean discharge of 7280 m3 s-1
  • sand-bedded in the TIFZ with negligible clay

The Columbia River is tidally-influenced for 160 km upstream of Portland but tidal energy is only significant in the lower 40-50 km downstream of Wauna. Tides in the Columbia River Estuary are of mixed diurnal and semidiurnal type with the semidiurnal wave being 1.5 to 2.1 times larger in amplitude than the diurnal wave. The semidiurnal predominance increases in the upriver direction and the spring tidal range is 3.6 m with a large freshwater discharge. Peak river discharge occurs through spring snowmelt and from major winter subtropical storms. The Columbia River is regulated upstream of Portland and dredging occurs in the main navigation channel in the north of the estuary but this is outside the zone of interest of this project. The Columbia River Estuary is one of the National Estuary Programs (NEP).

Image Courtesy: USDA NAIP, 2009