Water Resources Professional Project Reports

Document Type

Technical Report

Publication Date

4-2018

Abstract

Bank failure can occur from multiple reasons including geotechnical failure, failure from hydraulic forces, or a combination of both. Hydraulic failure is driven by a lack of vegetation, high boundary velocities, and toe scour. Erosion from hydraulic forces is often related to flow velocities or direction (Baird, 2005). Large-scale bank erosion is initiated by failure of bank materials at the base or toe of the outer bank (Sclafani, 2011). The Taos Pueblo are concerned with channel migration which has caused bank failure of the Rio Pueblo along Pueblo Canyon Road leading to the sacred Blue Lake. The objective of this project is to evaluate the potential for bendway weirs to serve as a practical bank stabilization method for Pueblo Canyon Road. Methods used for this project included a mix of field methods and one-dimension hydrodynamic modeling. The field component included channel cross section measurements and a Wolman pebble count. Data collected from the field were coupled with the hydrodynamic model. The hydrodynamic modeling was completed using the U.S. Army Corp of Engineers Hydrologic Engineering Center River Analysis System (HEC-RAS) and used to calculate maximum velocity, flow area, and water depth (USACE, 2008). The modeling approached used for this project combined field-measured cross sections and a 1-meter Digital Elevation Model (DEM) to generate the cross sections needed to model a 1.16-mile continuous reach. Various flow scenarios were modeled which included 2, 5, and 10-year flood frequency intervals. The modeled results were used to calculate bendway weir geometry. In addition, a physics-based analysis was conducted to determine the rock size needed to ensure the weirs would remain stable throughout various flow periods. Lastly calculations were conducted to ensure the height of the weir was sufficient to cause a hydraulic jump. Results indicated that a rock diameter of 0.5 ft is sufficient for the selected design flows.

Language (ISO)

English

Keywords

geotechnical failure, hydraulic forces, erosion, Taos Pueblo, Rio Pueblo, Pueblo Canyon Road, Blue bendway, bank stabilization

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