Please use this identifier to cite or link to this item: https://hdl.handle.net/11681/13277
Title: Imperial Beach, California design of structures for beach erosion control : hydraulic model investigation
Authors: United States. Army. Corps of Engineers. Los Angeles District
Curren, Charles R.
Chatham, C. E. (Claude E.)
Keywords: Beach erosion
Shore protection
Hydraulic models
Breakwaters
Imperial Beach, California
Erosion control
Water wave experiments
Groins
Coastal structures
Design
Water waves
Sedimentation
Deposition
Shoaling
Sediment transport
Publisher: Hydraulics Laboratory (U.S.)
Engineer Research and Development Center (U.S.)
Series/Report no.: Technical report (U.S. Army Engineer Waterways Experiment Station) ; H-77-15.
Description: Technical Report
Abstract: A 1:75-scale (undistorted) hydraulic model, reproducing approximately 2.6 miles of shoreline and sufficient offshore area to permit generation of the required test waves, was used to investigate the arrangement and design of alternative proposed structures for prevention of erosion of the Imperial Beach shoreline. The proposed structures consisted of (a) continuous breakwaters at the -15 ft and -10 ft contours, (b) segmented breakwaters at the -15 ft and -5 ft contours, (c) stepped breakwaters at the -10 ft and -5 ft contours, (d) a system of five groins, and (e) a system of nine groins. A 115-ft-long wave generator, crushed coal tracer material, and an automated data acquisition and control system (ADACS) were used during model operation. It was concluded from model test results that : (1.) Existing conditions are characterized by strong rip currents and longshore currents for most wave conditions with considerable onshore-offshore movement of sand. (2.) The original improvement plan for Imperial Beach (i.e., the authorized five-groin plan) is ineffective in trapping tracer material and, in fact, contributes to the offshore movement. (3.) The originally proposed breakwater plan (Plan 1) is not adequate for full protection of the beach. Raising the crown elevation of the Plan 1 structure to a sufficient height will make this plan effective from a functional standpoint; however, a substantial cost increase results due to greatly increased volume of rock required. (4.) Of the plans tested, Plans 3A, 4A, 5A, 5B, and 7 provide adequate beach protection. Plans 4A and 5A require the least volume of rock but may pose some construction problems. Plan 5A would have the least impact on the longshore transport (due to its location at the -5.0 ft contour resulting in more natural sand bypassing around the structure) and therefore would be the most viable plan from the viewpoint of minimizing effect of the improvement on adjacent shores . The Plan 3A and 4A breakwaters would be submerged except for extremely low tide stages and, therefore, would probably be the most aesthetically pleasing. 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/11681/13277
Appears in Collections:Technical Report

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