Originally Posted By: Carcassman
I worked on a couple of creeks where we had fish traps/racks that were permanently installed. We walked the streams weekly, the whole anadromous zone. The racks stopped bedload movement. Every year we had to dredge about 100 cubic yards of gravel from above the rack. But the word thing is that the configuration of the creek stayed the same. Riffles were in the same place, pools were in the same place. How the gravel moved through system but left the bed intact always amazed me.


Qualifier: "I'm not a hydrologist," but I think the operative word or term is "hydraulic control." I took the "Instream Flow Incremental Method" courses from CSU in 1980-82. I remember that term hydraulic control referring to either the larger substrate at pool tailouts or the underlying geography-geology below the streambed that controls the water surface elevation. The result is the pools and riffles in some reaches or some streams stay in the same place even though bedload is continuously moving downstream with higher flow events. Conversely, it also explains why riffles and pools are always moving around in less stable stream valleys like the Quinault, Queets, and Hoh. It's all part of the when, where, and why redd scour occurs.