Whittier Narrows Dam Overtopping Embankment Sectional Model

 Project Duration:  October 2025 – Present

 Study Area: Hazard reduction and failure prevention, Hydraulic design and optimization, and Hydraulic Strucutres

 Location: Whittier Narrows Recreation Area in Los Angeles County, California

 Principal Investigator(s): Dr. Chris Thornton

 Graduate Student: Rory Alspaugh

 Project Partner(s): Barnard Inc.

 Project Contact(s): Rory Alspaugh (rory.alspaugh@colostate.edu) and Jeff Ellis (jeff.ellis@colostate.edu)

Project Description

Whittier Narrows Dam is a 3-mile-long earthen embankment located in Los Angeles County, California. The dam and reservoir facility, constructed and operated by the US Army Corps of Engineers (USACE), serves as a major component of the flood control system for the Los Angeles County Drainage Area (LACDA). Due to the probability of the dam overtopping during a large flood event, an overtopping protection structure is being designed for the dam, including a stepped section and hydraulic jump stilling basin. 

The Colorado State Hydraulics Laboratory was contracted by Barnard to construct, test, and analyze a 1:4 scale model of a 16ft wide section of the dam. The purpose of the testing was to determine the end sill configuration required to contain the hydraulic jump within the stilling basin. Tests were performed for three variations of the stepped section, representing various construction and erosion conditions.

Key Highlights

  • Hydraulic analysis of an overtoppping embankment
  • Creating a constructable hydraulic model
  • Hydraulic jump performance based on step geometry and end sill configuration