Bed Forms in a Sand-Gravel Stream with Unsteady Flows

An acoustic distance measuring device was used to automatically collect bed elevation records in the Goodwin Creek Experimental Watershed. The bed material at the study site is composed of a mixture of sand and gravel with a median diameter of 8.3 mm. Bed forms were found for all flows in which a significant portion of the bed sediment was in motion. For the runoff events for which data was collected, bed form periods and spacings were found not to be a function of boundary shear stress. This was attributed to the fact that the coarser grain sizes were not in motion over most of these flows. The height of the bed forms was found to increase while the friction factor was found to decrease with increasing boundary shear stress.