Wk3_Rivers_JFreeman

Rogue River, Oregon. [PHOTO: visitingashlandoregon.com]

 This week I decided to re-visit the Rogue River here in Southwestern Oregon. I came here years ago on a family vacation to enjoy the beautiful scenery and whitewater rafting offered by the Rogue. 

Things I was able to note from a new geological viewpoint were of interest. The Rogue River has a dendritic drainage pattern for instance, something I never would have been able to consider before. This means that the underlying materials are relatively uniform in resistance to erosion so there’s no clear control of pattern or streamflow. This results in a tree branch like pattern in its offshoots or drainage from the basin.

 The flow of the Rogue river is more evidently turbulent than others, this is due largely in part to the velocity of the streamflow. Turbulence contributes to the stream’s aptitude to erode the channel. The Rogue River is a meandering channel, this means that it frequently bends or follows an ‘S’ like pattern as it moves towards its mouth at the Pacific Ocean. The clearer color of the water leads me to believe that the Rogue River has a significantly lower suspended load opposed to its dissolved or bed load.

The Rogue River has flooded over a dozen recorded times in the last 160 years according to the Flood Management of Grants Pass, OR. Heavy rain events are frequent in Oregon and Grants Pass which leads to a higher likelihood of flooding. Add to that the event of snowing and the eventual melting and runoff of the snow and the Rogue River can quickly turn from the normally peaceful river into a raging current that can cause massive flood plains. The completion of the 1977 Lost Creek Dam, 55 miles upstream of the Rogue River completely changed the river’s floodplains forever. The dam cannot prevent floods, but has since lessened the severity of them when and if they do occur.