Analysis of Bank Stabilization in Steep Complex Streams Using A Two-Dimensional Model

by Raymond Walton,
Wilfredo A. Moneda,
Jeffrey B. Bradley,

Document Type: Proceeding Paper

Part of: North American Water and Environment Congress & Destructive Water


In cases where the channel is fairly uniform, and not divided, one-dimensional hydraulic models, such as HEC-2, generally give adequate results for scour evaluations and bank protection assessments. However, in more complex systems, including secondary flow channels, one-dimensional analyses may fail to give the level of lateral detail necessary for reliable assessments. Once considered to be too complex and too expensive, two-dimensional models today can be developed quickly, and give more complete details of the cross-sectional distribution of velocities for use in design. On the Sauk River in Washington State, flow in a secondary channel is attacking the left bank immediately upstream of a major highway crossing, endangering the bridge and requiring quick implementation of protective measures. The two-dimensional finite-element hydrodynamic model, RMA-2, in the modeling system, FastTABS, was used to model flows at the bridge for the 100-year flow. The FastTABS system was used to quickly (a few days) develop a hydrodynamic model of the reach containing the bridge and secondary flow channel. The model was then used to simulate the circulation patterns and near-bank velocities for a number of bank stabilization options, including spurs, groins, and bank guides. The entire analysis was performed within one week.

Subject Headings: Two-dimensional models | River bank stabilization | Channel flow | Hydraulic models | Hydrologic models | Finite element method | Secondary flow | Washington | United States

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