East Garden Grove-Wintersburg Channel Hydraulic Physical Model

Orange County, CA


PACE designed and constructed a hydraulic physical model of the East Garden Grove-Wintersburg Channel (Facility No. C05) to evaluate potential channel modifications and investigate alternative construction features. The channel at Interstate 405 is a complex flood control system composed of an array of culverts and tributary channels. Located in the Cities of Westminster and Huntington Beach, the channel system consists of a unique geometric configuration with multiple confluences and a storage basin, such that this particular reach of channel is difficult to analyze by mathematical and computer modeling alone. To address the issue of possible flooding in the upstream vicinity of the freeway and tributary channels during the 100-year storm event, an estimated $30 million in planned flood control improvements were dependent upon the accuracy of the hydraulic analyses at the Interstate 405 crossing. A hydraulic physical model would provide the most accurate understanding of the existing and proposed channel improvements for this reach of the channel system because of the complexity of the hydraulic processes.


The design met the following criteria:

  • A geometric scale of 1:15
  • Minimum reach length of 800 feet, replicated based on application of the Froude Law for hydraulic similitude
  • Existing mainstem channel of rectangular concrete with a 60-foot width
  • 100-year expected value design discharge
  • A customized 4-foot-wide hydraulic flume


There was uncertainty about the impact the proposed channel improvements at Newland Storm Channel and Edinger Storm Channel would have on the undercrossing and upstream water surface. Thus, the proposed channel improvements were modeled to evaluate discharge volumes and efficiently maximize the performance of both channels. The culverts and tributaries were scrutinized in the physical model to fully understand the channel hydraulics.


Key Features:

  • Hydraulic physical model
  • Complex hydraulic analysis
  • Detailed and specialized hydraulic experiments / measurements
  • Alternative design evaluations
  • Customized fabrication and specialized construction techniques

Orange County Flood Control Division

Flood Control Systems, Stormwater Management / Flood Control