Scour around Double-Winged Log Frames under Clear Water Condition

Abstract

In-stream low-head hydraulic structures are eco-friendly solutions to maintain the natural aquatic ecosystems. This study focused on scour characteristics around double-winged log -frames under different hydraulic conditions and structure configurations, including stone-reinforced structures. Three types of equilibrium scour morphologies were distinguished for each tested configuration. Generally, two scour formations occur upstream and downstream of the structure, depending on its configuration. Empirical equations are proposed to predict maximum depth and other characteristic lengths of the scour hole and dune. A new equivalent densimetric Froude number was derived by dimensional analysis. The equations were validated with data pertaining to similar structures. Overall, this study shows that double-winged log frames are suitable for creating resting pools for fish species, and can contribute to enhance bank stability. Although the analysis was limited to straight channels, the proposed design equations represent the first quantitative tool to assess scour features for this structure typology.