Bank Protection, Bass Location, Willamette River, Oregon: Hydraulic Model Investigation

Abstract : The Bass Location, Willamette River, is located between river miles 137 and 135, just southeast of Corvallis, Oregon. This area is subject to severe bank erosion during the high-water months of each year. The model study was conducted to look at the alternative of using stone groins as a method of bank protection instead of blanket stone revetment. This method was favored due to studies indicating that stone groins provide a more favorable habitat for river micro-organisms and fish than does blanket revetment. The model, built to a horizontal scale of 1 to 100 and a vertical scale of 1 to 50, had both a movable bed and bank line. The study considered two conditions: (a) Installation of eight groins in the right bank below the Bass Phase I revetment. (b) Installation of the groins plus closing of the right channel at river mile 136.7. Results of the study indicate that: (a) Installation of the eight groins below the Bass Phase I revetment will greatly reduce the erosion of the bank line and cause no significant increase of velocities in the channel; (b) Installation of the groins plus closing of the right channel at river mile 136.7 will reduce the erosion of the right bank, but not to the extent that groins without the right channel closure would. Velocities on the bank opposite the groins increased enough to cause concern for erosion of the left bank.