Observations of event‐based streambed deformation in a gravel bed channel

Abstract

The streambed is the major source of bed load sediment in gravel bed channels and is necessarily deformed during floods that mobilize sediment. This study uses observations of scour and fill from Carnation Creek, Canada, to articulate at‐a‐point relations of the occurrence and magnitude of bed deformation and the resulting adjustments in bed configuration over a series of flood events. The likelihood of local bed deformation by scour, fill, or both depends on flow magnitude. At most locations, there is an imbalance of scour and fill that leads to adjustments in bed elevation, and these imbalances increase with flow. Persistent deformation of locations in lower portions of the bed topography tend to produce larger total exchanges between bed and mobile sediment over the flood series but locations that experience similar frequencies of bed deformation do not produce unique depth distributions. These results underscore the importance of understanding the coupling of scour and fill that produces streambed adjustment when modeling streambed evolution and managing river habitat.