Author(s): Tae Sung Cheong; S. Geoffrey Schladow; Il Won Seo
Linked Author(s): Il Won Seo
Keywords: Levee breach design; Sediment transport; Particle tracking method; Numerical modeling
Abstract: The controlled breaching of existing levees has received considerable attention as a means of reconnecting formerly farmed lands to natural riverine and estuarine processes. The goal of such breaches is not only to establish hydraulic connection to these lands, but to provide a means of sediment accrual. However, little attention has been directed to the design and placement of such breaches from the perspective of sediment accrual. A two dimensional flow model in which fluid and suspended particles are tracked using statistical concepts was developed to design levee breaches on the lower Mokelumne River, California, U. S. A. The model has been run for a hypothetical sinuous channel, in which the radius of curvature and the breach width were varied. Various flow velocities and breach/channel area ratios were also tested for verifications of model. The results show that total concentration passing through a levee breach increases as stream velocity increases, and decreases as the radius of curvature of channel increases. While larger breaches will allow more sediment to pass, a breach width of three times the channel width was the point at which increases became negligible. The results on the lower Mokelumne River show that the largest total concentration passing through a levee breach is presented in the levee breach placed in 155. 6 m downstream of the injection site in which breach width is three times of the channel width.