The utilization of seawalls in response to shoreline erosion: consequences, socio-economic, political and legal forces, and alternatives

Abstract

When coastal buildings or roads are threatened, the typical response is to harden the coast with a seawall. Seawalls run parallel to the beach and can be built of concrete, wood, steel, or boulders. Seawalls are also called bulkheads or revetments; the distinction is mainly a matter of purpose. They are designed to halt shoreline erosion caused primarily by wave action. If seawalls are maintained, they may temporarily hold back the ocean from encroaching on shoreline development. In spite of their ability to hold back the ocean, when waves hit a seawall, the waves are reflected back out to sea, taking beach sand with them and eventually causing the beach to disappear. Moreover, seawalls can cause increased erosion at the ends of the seawall on an adjacent beach that is not walled. Alternatives to seawalls exist, such as beach nourishment and managed retreat. Making coastal land use decisions that ensure a seawall will not be needed in the future to protect structures, however, is the most prudent coastal management solution. This can be accomplished by establishing setback lines and conducting managed retreat of structures that are threatened by shoreline erosion before the situation worsens, or structures that have the potential for being threatened in the future. Regional case studies are presented to illustrate.