Effects of Low Drop Grade Control Structure on Bed and Bank Stability

The channel response upstream of a low drop grade control structure was documented using field investigations, analysis of the engineering properties of bank materials, and repeat cross section and thalweg surveys. The data indicate that the structure successfully drowned out an advancing knickzone and rendered it inactive. Additionally, the structure enhanced the bank stability by reducing the bank heights through sediment deposition and by limiting the ability of the stream to remove the failed material at the bank toe. This case study clearly demonstrates that low drop grade control structures are appropriate stabilization techniques in channel systems where both bed and bank instability problems exist.