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5. Technical Report

Title:	Littoral processes study, vicinity of Santa Ana River mouth from Anaheim Bay to Newport Bay, California
Authors:	United States. Army. Corps of Engineers. Los Angeles District. Hales, Lyndell Z.
Keywords:	Beach erosion Tidal effects Beach nourishment Tidal marshes Littoral deposits Littoral drift Santa Ana River Shore protection Sediment transport Sedimentation Deposition California
Publisher:	Hydraulics Laboratory (U.S.) Engineer Research and Development Center (U.S.)
Series/Report no.:	Technical report (U.S. Army Engineer Waterways Experiment Station) ; HL-80-9.
Description:	Technical Report Abstract: Two separate but interrelated problems exist along the section of southern California coastline between Anaheim Bay and Newport Bay. These include: (a) erosion of the beach immediately east of Anaheim Bay (Surfside-Sunset Beach), and (b) determination of the optimum location and temporal distribution of one million (1,000,000) cu yd of material suitable for beach nourishment that will be excavated during the deepening and widening of the Santa Ana River flood-control channel. Two additional closely aligned tasks were investigated. They include: (a) the hydraulic design of a tidal flow system to allow for flooding and emptying of a marsh habitat development area immediately north of the Pacific Coast Highway (on the east side of the Santa Ana River), and (b) the development of potential alternative feasibility concepts for maintaining an opening at the mouth of the Santa Ana River to allow passage of tidal flow up the river to the habitat area. Complete closure of the exit of the river now occurs as littoral material is trapped between the jetties, particularly during the summer months when riverflow is minimal. The habitat development area is being proposed to mitigate the loss of wildlife habitat resulting from the planned widening of the Santa Ana River (8 acres), and for preservation in response to the mandate of the Endangered Species Act (84 acres). The utilization of as much of this excavation material as possible for beach nourishment purposes is highly desirable. It was determined that because of the sheltering effects of the offshore islands, the general orientation of the coastline, the large shoal region in front of San Pedro Bay, and the nearness of the Newport Submarine Canyon to the shoreline, significant variations in littoral drift occur with distance along the coast in this region. The Surfside-Sunset Beach region is experiencing a net southerly drift of approximately 276,000 cu yd per year; Huntington Beach region (including the vicinity of the Santa Ana River mouth) is losing approximately 112,000 cu yd net per year in a southerly direction; that region south of the Newport Submarine Canyon is experiencing a net southerly movement of approximately 127,000 cu yd per year. The Huntington Beach region will continue to be nourished naturally as long as the feeder beach at Surfside-Sunset Beach is maintained. Feasibility conceptual alternatives for providing unrestricted tidal exchange through the mouth of the Santa Ana River were considered, their probability of success was qualitatively deduced, and an order-of-magnitude estimate of their installation cost was approximated. These concepts included river jetty extensions, floodgates, pipelines, jet pump sand bypassing systems, and hydraulic structures. It was determined by Keulegan's approximation, and confirmed by one-dimensional numerical techniques, that a variety of concrete gated pipes and culverts could be installed that would effectively transmit approximately 98 percent of the tidal prism necessary to induce maximum bay water-surface elevation, a requirement dictated by the necessity to ensure a precise bay water-surface rise and fall with the lunar ocean tide of the region. The wide beach immediately to the west of the Santa Ana River should not be adversely affected by the extensions of impermeable river jetties into the surf zone for the purpose of preventing the accumulation of littoral drift material in the mouth of the river. The potential jetty extensions would also provide a cell for the placement of a large portion of the material to be excavated from the flood channel (between the east jetty extension and the westernmost groin of the Newport Beach groin field). Significant amounts of material could also be placed inside the groin field itself. NOTE: This file is large. Allow your browser several minutes to download the file.
Rights:	Approved for public release; distribution is unlimited.
URI:	http://hdl.handle.net/11681/13640
Appears in Collections:	Technical Report