Page - 454 - in Book of Full Papers - Symposium Hydro Engineering

downstream along the channel than other beds. In fact, bed forms like small dunes were present in cases with pure sand, which were not discerned in other sediment beds. This has important implications for the evaluation of the scour hole evolution, echoing that the sediment bed composition has significant and complicated effects on the scour dimensions below sills, as identified in previous studies. Fig. 1. Cross section averaged final bed elevation in relation to different inflow discharges for (a) uniform 100% gravel bed, (b) uniform 100% sand bed, (c) 53% gravel and 47% sand bed, and (d) 22% gravel and 78% sand bed. 454