T180 From the Abyss to the Beach: In Honor of Orrin H. Pilkey

Tuesday, 4 November 2003
1:30 PM - 5:30 PM

SOME BEACHES ARE MOVING; OTHERS ARE SIMPLY FADING AWAY

Paper number: T180-16
Program: Technical Sessions
Time: 5:15 PM – 5:30 PM

Authors

Abstract

Wallace Kaufman and Orrin Pilkey’s 1979 seminal book "The Beaches Are Moving" generated a wave of interest by the informed public. Building upon the pioneering works of Dolan and others, the authors popularized the concept that barrier islands—the typical coastal shoreline of much of the US Atlantic and Gulf coasts—constantly shift to and fro, in many locations with a shoreward trend. The overall pattern is thus one of shoreward migration, and today’s dune line is destined to become tomorrow’s swash zone. Their pioneering efforts resulted in a generation of research, scientific (and not-so-scientific) debate, public education, and ultimately, vastly improved coastal management policies.

But there is more to the story than shifting and landward-moving barrier islands. Many coastal areas of the U.S.—particularly the west coast and Hawaii—are backed by steep terrain. Sandy beaches, where present, tend to be trapped in embayments or pinned against sea cliffs. They cannot move. Without a clear retreat pathway (vis-à-vis low-lying coastal plain settings) there exist only three options: beaches grow, remain stable, or diminish (fade away.) Analyses from California and Hawaii—two markedly different shoreline types --show that significant beach loss is common. Without significant counter-balancing sources, many beaches have been reduced to thin veneers as grains are lost to near-shore rocky or to deepwater areas. Beaches appear to be stable, or in few cases accreting, only where significant local sources are present, including cannibalism of adjacent beaches. With diminished sources and migration routes blocked, many beaches will fade to a minimum presence.