The University of the West Indies Organization of American States
PROFESSIONAL DEVELOPMENT PROGRAMME: COASTAL INFRASTRUCTURE DESIGN, CONSTRUCTION AND MAINTENANCE
A COURSE IN COASTAL ZONE/ISLAND SYSTEMS MANAGEMENT
CHAPTER 3
COASTAL PROCESSES 1 ADDITIONAL SLIDE PRESENATION
OLD DOMINION UNIVERSITY COASTAL HYDRAULIC LABORATORY NORFOLK, VIRGINIA, USA US ARMY CORPS OF ENGINEERS, VICKSBURG, MA, USA
Organized by Department of Civil Engineering, The University of the West Indies, in conjunction with Old Dominion University, Norfolk, VA, USA and Coastal Engineering Research Centre, US Army, Corps of Engineers, Vicksburg, MS , USA.
Antigua, West Indies, June 18-22, 2001
AA RIVERRIVER OFOF SANDSAND Video (20 minutes) by Professor Douglas Inman, Ph.D. Scripps Institute of Oceanography and, John S. Shelton, Ph.D. American Geological Institute available from Encyclopedia Britannica Educational Corp. Chicago, Illinois 1967 THE BEACH: A RIVER OF SAND (video) Summary
• Sand for beaches comes from upstream mountains • Beaches are formed by the seasonal variation of waves • Waves breaking at angle cause sand transport along the beach, like a river of sand • Man’s structures (harbors, breakwaters, upland dams, etc.) interrupt the sand movement
US Army Corps of Engineers THE BEACH: A RIVER OF SAND (video) Summary
• Conclusion “Whenever man interferes with such a system, he becomes involved in its operation. To the degree that man upsets the natural balance of the system, he and his machines must do the work that nature did before.”
Inman and Shepard, 1967
US Army Corps of Engineers
(c) Pocket beach (c) Pocket Narrow rocky shorelines Rocky headland
Reference Baseline Reference
W
H M
,
m
u
i stable Y, r
b i l i u q E Waves Dune, cliff, man's artifacts and vegetation cliff, Dune, Rocky headland
THE BEACH: A RESERVOIR OF SAND
• Naturally, stable shorelines include rocky headland/bay beaches and pocket beaches.
• The minimum dry beach width, Ymin (or volume) depends on storm wave energy. • Beaches are shaped by the seasonal variation of waves. • Storm waves drag sand offshore to build bars.
US Army Corps of Engineers THE BEACH: A RESERVOIR OF SAND
• Normal waves naturally rebuild beaches after storm events. • The beach is a reservoir of sand to mitigate coastal storm impacts. • Conclusion
The beach is INFRASTRUCTURE for coastal storm hazard mitigation and must be maintained if erosion, man’s interference or extreme hurricane events diminish the reservoir volume.
US Army Corps of Engineers