Geometry of Local Scour Holes at Boulder-like Obstacles during Unsteady Flow Conditions and Varying Submergence

Local scour holes are erosional bed structures that related to different scientific disciplines in Earth science and hydraulic engineering. scouring at naturally placed boulders is ubiquitous, but many competing factors make it difficult isolate the effects of a given variable. This especially true for local natural instream obstacles exposed unsteady flow conditions course flood hydrograph experiments. Experimental investigations laboratory flumes offer advantage boundary can be systematically varied. We present novel experimental data on impact submergence ratio, skewness, intensity boulder-like during evaluate effect discharge chronologies. In total, 48 flume experiments subcritical clear-water channel degradation were performed. The results reveal dominantly occurred rising limb when depth was comparable obstacle size, so unsubmerged. steeper limb, quicker hole matured. relevant interpretation found field. They may utilized as proxy minimum duration beginning stage flood.