of the steep gradient, coarse-grained and ephemeral Placer Creek channel through time, coupled with headcutting by knickpoint migration through the stream crossing, has created a challenge in upper Castle Valley for road maintenance. Compare and contrast the conditions that existed five years ago and today.
Placer Creek crossing on 1 May 2019. Note crushed culvert and concrete on downstream side of roadway. By attempting to maintain this knickpoint in the stream profile for the long term only exacerbated the erosion that eventually occurred here.
Placer Creek crossing on 30 June 2024. Significant scour has deepened the channel once again. The knickpoint has migrated upstream and behind the two large boulders on the left.
The road crossing is now graded to a more stable position in the short term, at the same elevation of the stream channel both upstream and downstream, now that the knickpoint has migrated upstream and no longer occurs right at the crossing as seen in the early image.
View upstream showing the knickpoint in the stream channel that will continually erode upstream with future events.