Columbia River Estuary Hybrid Model Studies. Report 4: Entrance Channel Tests

Abstract : A hybrid modeling approach using a fixed-bed physical model, numerical models, and analytical techniques was used to study investigation channel shoaling at the mouth of the Columbia River. Sixteen plans for reducing channel maintenance dredging at the existing 48-ft depth and at 55- and 60-ft depths were tested. Effects of the plans on tides and currents were found to be subtle. Nondeepening plans had minor effects on salinity intrusion while channel deepening increased salinities by 1 to 6 ppt up to about mile 18. Only one structural plan reduced shoaling below base conditions for the 48-ft channel. Channel deepening increased shoaling considerably. (Author)