Port of Hood RiverWaterfront Recreation Committee

Hood River Delta•Historical Overview•Existing Conditions•Future Changes

Historic Perspective

• Sand Bar was present before Bonneville• Speed of Hood River is faster than

Columbia• Delta is caused by Hood River meeting

Columbia• Several sand moving forces exist

1930

1935

1967

Wind River 35

Cascade Locks 1935

Rock Creek 1930

Patterns

• Changes to river system caused by:– Railroad construction– Bonneville Dam– Control dikes– Freeway construction– Dam Pool management

• Similar patterns exist along river

Current Conditions

• Sand bar has existed for many years• Bar slowing increasing in size• Major Hood River flow events cause

significant change– Flood of ’96– Flood of ’06

• High Columbia flows erode/change bar

2005

2007

Comparison 2005-2007

Current Conditions

Animation

Process Details

Friction-dominated deltas are associated with high bed friction and shear stress. These stresses cause the flow to slow down rapidly and deposit sediment with a wider lateral extent than the inertia-dominated deltas. The river/basin setting for this type of situation is more common. It consists of a shallow water level where the river flow and basin meet. This shallow area is a major factor in producing a friction-dominated delta. Features associated with this type of delta include subaqueous levees, middle ground bars (fining seaward), and bifurcated channels.

Friction-Dominated Delta

Future

• Delta is searching for Equilibrium• Equilibrium is not static• Public impact is possible with

“equilibrium”• Meteorological event frequency hard

to predict

Quantities

• Additional Sand on existing bar– Estimated at 8 ft average = 750,000cy

• Additional Sand Bar area 26 acres– Additional sand volume = 750,000 cy

• Removal cost/yard varies by method

Hood River Profile

Sand Bar/Delta

Additional Elevation

Hood River Summer Pool

Typical

Additional Sand

Extended into

River

Additional

Sand on Bar

Issues

• Recreation – Opportunities– Separation– Uses– Safety

• Commerce– Tour boat dock access– Event Site impact