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Many natural phenomena that occur along the coast are considered to be hazardous. These phenomena include tsunamis, large waves, rip currents, storms, earthquakes, erosion, bluff collapse, liquefaction, fires and others. Many of these events can be characterized through geographic components, areas of flooding and inundation, zones of liquefaction and subsidence, areas of rip currents, hot spots for beach erosion, tsunami run-up zones, bluff collapse areas and focused storm tracks. Some events have a temporal or seasonal component, such as El Niño storms or fires. The main approaches to hazards, regardless of timing or location, are monitoring, land use planning, engineering and response.

Santa Monica Bay in Los Angeles, California, was a pilot region for evaluating potential responses to geographically linked and temporally linked hazards. Hazard timelines were compiled to establish some of the temporal characteristics, showing El Niño and La Niño events, fires, storms and other disasters, as well as changes in population and rainfall. This combination of temporal and geographic information provides tools to develop hazard histories and provide scenarios for future risk. It also allows examination of the use and utility of various approaches to addressing hazards.

Anthropogenic activities primarily impact coasts by reducing sediment inputs, altering sediment transport processes, and accelerating sediment losses to the offshore. These activities include: sand and gravel extraction, navigation and shore protection works; non-structural shoreline management strategies such as beach nourishment, sand by-passing and beach scraping, dams and flood control works; channel and inlet dredging; subsidence caused by fluid extraction and reduction of carbonate beach material. Although many of these activities have improved the quality of life, they also have had unintended effects on the coast. The issues that arise from human alterations of the coast are common to many coastal regions around the world; this paper draws from several areas of the United States to present an overview and provisional assessment of the economic consequences of anthropogenic activities along the Pacific coast.

Outfalls, after detailed consideration of alternatives, have proven to be cost-effective means of safely disposing treated wastewater by dispersing it in water bodies at locations that are relatively deep and/or far from shore. Among the major coastal cities employing ocean outfalls as essential elements of their wastewater systems are Athens, Sydney, Hong Kong, San Francisco, Shanghai, San Diego, Mumbai, Los Angeles, Taipei, Boston, and Singapore. Factors important to the design, construction, operation, maintenance, and monitoring of large coastal wastewater outfalls are discussed herein.

Tourism revenues are critically important to the economic health of many coastal regions, including Santa Pola, an historic Mediterranean port city on the Costa Blanca of Spain. Santa Pola has developed and is implementing plans to improve the beach experience by seasonally augmenting existing coastal structures with cost-effective facilities that allow visitors and residents better access to the shore and sea.

Performance observations strongly indicate that all concrete armor units for coastal structures should be reinforced. It is proposed that reinforcement be required in concrete armor units for coastal structures unless conclusively demonstrated to be unnecessary by the responsible design engineer and agreed to by the owner and/or the responsible government agency.

Shores and beaches are important sources of recreation opportunities and are especially vital in crowded urban areas. In these areas, there are clear economic and political incentives to restore long forgotten or impacted shores and beaches and even to create new ones. In response to the need for open space, many cities have developed and preserved green belts; “blue belts” along urban shorelines are equally important for maintaining and enhancing quality of life. In order to have sustainable beaches on our coasts, we must use our finite sand resources wisely and not squander potential beach material.

Tomales Bay is situated along the California coast and is approximately 65 kilometers north of San Francisco. It was formed by the interaction of the San Andreas Fault and the northern California coastline. Tomales Bay has been experiencing ongoing sedimentation, which is controlled by the fluvial processes of the creeks flowing into the bay, the coastal processes outside of the bay, the geologic activity of the San Andreas Fault, and the human activities. The objective of this study is to (1) access the sedimentation rate and locations within Tomales Bay, (2) investigate the causes of sedimentation, and (3) evaluate the current and future impact of sedimentation on the use of the Bay.

Major coastal structures are generally intended to be planned, designed, built, operated, and maintained to last a long time. However, many such structures fail long before their time, some catastrophically. Critical elements of the planning, design, construction, operation, and maintenance of major coastal structures are discussed herein.

This paper presents a history of the repeated attempts to construct a single jetty at the mouth of the Russian River near Jenner, California, USA. This "lost jetty" at Jenner provides a useful example of the futility of designing, building, and maintaining a coastal project in ignorance and/or disregard of the powerful forces of nature.

Completed in 1977, the Reef Runway embankment at Honolulu International Airport was created by placing and compacting millions of cubic meters of dredged coral fill material over an existing coral reef. The wave protection structure on the deeper portion of the ocean side of the embankment included the placement of more than 18,000 6-ton and 4-ton unreinforced concrete dolos armor units. The wave protection structure has been in place for more than 30 years and, although to date it has fulfilled its essential performance objectives, has experienced ongoing maintenance, repair, and replacement challenges associated with the dolos armor units. This paper builds upon surveys, maintenance, and repairs conducted by and for the Hawaii Airport Authority.

The general increase of human activities, including the exploitation of the hydraulic and sediment resources of rivers, has caused extensive coastal erosion throughout the world, especially during the last 150 years or so. The true costs and impacts of this erosion have not been reflected in the price of providing commodities such as sand and gravel. These impacts and their estimated costs are presented using information from the states of Washington, Oregon, and California on the Pacific Coast of the United States of America.