SHORE OF SOUTH CAROLINA: GEOMORPHOLOGY AND COASTAL PROCESSES
Miles O. Hayes

ABSTRACT
The South Carolina Coast, owing to its location along a wide coastal plain on the trailing edge of the North American Plate, as well as to its moderate-sized waves (breaker heights that average 60 cm [2 ft]) and spring tides that approach 3 m (10 ft), is a depositional, mixed-energy coast with: a) short, drumstick-shaped barrier islands; b) numerous tidal flats and coastal wetlands; and c) abundant tidal inlets with large ebb-tidal deltas and small, to non-existent, flood-tidal deltas. The shoreline is composed of four distinct geomorphological compartments (from north to south) ― Grand Strand, Delta, Barrier Islands, and Low Country. The Grand Strand, which includes the highly populated Myrtle Beach area, is for the most part a slightly erosional shoreline arc that abuts the Pleistocene mainland. The Delta compartment
is composed of the seaward bulge of the largest river delta on the east coast of the United States, the Santee/Pee Dee Delta. The Barrier Islands compartment consists of a combination of relatively short, landward migrating (transgressive) barrier
islands and longer, prograding barrier islands that typically have a drumstick configuration, primarily because of the accretion on their northern ends of large swash bars of sand derived from the adjacent massive ebb-tidal deltas. Ebb-tidal deltas contain 77% of all the sand in the shore zone of the state. The Barrier
Islands compartment is also the site of a project carried out in 1983 (and repeated in 1996) that relocated a rapidly migrating tidal inlet, Captain Sams Inlet, a distance of 1,200 m (4,000 ft) updrift (northeast), which resulted in the accretion of 300
m (1000 ft) of sand on a highly erosional beach downdrift of the old inlet. The Low Country compartment contains massive estuarine systems with extensive intertidal flats and marshes and huge and diverse offshore sand shoals.

CONSTRUCTION AND PERFORMANCE OF SIX TEMPLATE GROINS AT HUNTING ISLAND, SOUTH CAROLINA
Steven B. Traynum, Timothy W. Kana, and David R. Simms

ABSTRACT
Hunting Island, South Carolina, a four-mile-long barrier-island state park, has one of the highest erosion rates in the United States, averaging over 20 ft/yr for the past ~50 years. After six federal and state nourishment projects (1968 to 2004) failed to keep pace with erosion, officials at the South Carolina Department of Parks, Recreation and Tourism (SCPRT) approved a beach stabilization project involving groins plus nourishment. The final plan called for construction of six groins in three clusters at strategic beach access locations along the largely undeveloped oceanfront. Nourishment was an integral and required part of the plan, because it provided a platform for land-based construction of the groins and a source of sand to accommodate sand trapping. In this mesotidal, moderate wave energy setting, the completed structures had to be ~450 ft long to provide a profile encompassing the design berm width and wet-sand beach to low water. Groin spacing in clusters was
~1,200 ft. The template profile followed design guidance by ASCE (1994) and is likely one of the first groin installations in the United States attempting this recommended configuration. The groins were constructed using ASTM A690 steel sheet pile with steel caps. Toe protection was limited to broad, armor-stone mats at the heads of each groin. The structures were designed for low reveal along their lengths. Post-project monitoring confirms that erosion rates have lessened within each groin cluster. However, excess nourishment sand has been lost mainly to the north spit (the principal transport direction in this setting). Downcoast areas have continued to receive sand during the first two years following construction. The quantities
of sand retained by the structures are dwarfed by the volumes of sand in the adjacent ebb-tidal deltas.

SAN PEDRO BAY DELTA IN SOUTHERN CALIFORNIA: SHORE AND SHORE USE CHANGES DURING THE PAST 1½ CENTURIES FROM A COASTAL ENGINEERING PERSPECTIVE
Robert L. Wiegel

ABSTRACT
The flood plain formed by detritus deposited by the Los Angeles, San Gabriel, and Santa Ana Rivers (and several streams) is a multi-river delta at the coast and shelf of San Pedro Bay, a hook-shaped bight in southern California. It is between Point
Fermin (southeastern tip of Palos Verdes Hills) on the northwest and Newport Bay/Corona del Mar bluffs at the southeast. The 30-mile-long shore has been extensively modified by anthropogenic activities and by natural events; construction of dams for flood control (which also traps sediments), river mouth structures, ground subsidence owing to oil, gas, and water withdrawal; structures and dredging at the entrances of landlocked bays; development and operation of marinas and navigation channels; and encroachment by buildings and infrastructure. Sand beaches are along almost the entire shore: Long Beach Municipal Beach, Belmont Shore Beach, Seal Beach, Surfside Beach, Sunset County Beach, Bolsa Chica State Beach, Huntington Cliffs, Huntington City Beach, Huntington State Beach, Santa Ana River Mouth County Beach, West Newport Beach, Balboa Beach. The sand is light in color, and is mostly silicate. The beaches and surf are easily accessible and extensively used by residents and visitors. The natural supply of sediment to the coast became severely restricted, and beach erosion studies have been made since the 1930s. There have been extensive beach nourishment (replenishment) projects for many decades that have successfully mitigated negative effects of sediment trapping, coastal structures, and ground subsidence. Beach profile surveys and “Clancy beach width” measurements made during many decades were used to evaluate the effectiveness of the Surfside-Sunset beach project (including West Newport
Beach). The wave climate in the Southern California Bight is complex. Six different meteorological patterns are the sources of the waves; they include North Pacific storms, local seas, and southern swell that have traveled thousands of miles from
storms in the south 40 to 50 deg. latitudes. The waves are affected (refraction, diffraction, reflection, shoaling) by the islands, banks, submarine canyons, and local bathymetry of the California Continental Borderland. Sources of wave measurements, analysis, storage, and retrieval are given. The region is subject to storm waves, floods, droughts, seawater intrusion, earthquakes, and tsunamis; some details of which are given. Damages caused by several severe wave events are described. A coastal lowland/wetland that was substantially impacted in the past century was restored recently, the Bolsa Chica Lowlands Restoration Project. Its history and restoration (a modification of the original) is described. The largest U.S. seaport complex, by volume, is in the northwest part of San Pedro Bay, the contiguous Los Angeles and Long Beach Ports/Harbors; with 9.2 miles of breakwaters (in three sections with two navigation entrances). The region has become extensively urbanized; it is part of the Los Angeles (coastal) megacity.