Virtual field trip - channelization and mass wasting along the Keystone trail in Omaha.
This is a short virtual field trip showing characteristic sites of mass wasting and accelerated erosion in Omaha, starting with some features found along the Keystone trail , a popular walking and biking path along the channelized Papillion creek. This site is in the Irvington, U.S.G.S. quad just south of Blondo on the outside bend and consists of an active slump (photo taken 10/16), which has had similar activity in the past. Large aggregate is placed on these features to stabilize them, and you see the remains of previous slumps and mitigation in the two white patches below.
This is a close-up of the slump, which is in reworked alluvial material and fill. It is about 12 by 14 meters. The sidewalk for the trail is immediately above. Portions of this feature were active at the time this photo was taken. Note the toe material diverting flow in the channel below, compromising the engineering of this channel.
The sidewalk directly above is depicted here and shows a nice crown crack. This had been repaired before and had opened almost an inch in the weeks prior to this photo. Various sections of the trail have had to be repaired because of this activity.
Just downstream is a small dam of large limestone aggregate that has deflected flow and is causing channel bank erosion. One can predict that in the future this will develop further (with large discharge events) and this back will become unstable. Note the stabilization efforts to the left.
Similar features can be found sporadically along the trail.