Effect of Macrorough Sidewalls on Flow Resistance in Steep Rough Channels

Previous studies showed that macrorough sidewalls increase the stability of step-pool sequences in steep narrow channels due to grain-sidewall interactions (i.e., jamming) and bed shear stress reduction sidewall friction. The main goal this study was quantify for six types using physical model tests. Experiments were conducted a tilting flume with initial slopes 4%–10% fixed rough beds without mobile containing sequences. A hydraulic geometry relation predict mean flow velocity extended relative roughness account friction effects sidewalls, resulting prediction errors below 8% experiments. Furthermore, presents method estimate resistance caused by applying modified correction. For bed, accounted 10%–70% total stress. In experiments, freely adjusted leading formation Consequently, 5%–40% because structures induced larger compared Overall, results allow determine thereby enabling future better mechanisms responsible sidewalls.