Posted by: reefrescue | April 1, 2010

Why beach renourishment projects haven’t worked

Over the last several decades the southeast coast of Florida has witnessed an endless stream of taxpayer dollars literally being washed to sea in the name of beach renourishment. In a recent paper published by The Geological Society of America, Dr. Harold R. Wanless examines the performance of the southeast Florida beach projects and concludes projects built with the wrong materials are doomed to failure.

Dr. Wanless, head of the Department of Geological Sciences, University of Miami was an expert witness for the Surfrider’s successful challenge of the Town of Palm Beach Reach 8 beach renourishment permit (Click to read: NY Times Reach 8 article;  Read: the administrative law judge’s Reach 8 ruling).

ABSTRACT: A history of poor economic and environmental renourishment decisions in Broward County, Florida

Southeast Florida’s beaches, which are heavily developed and imperiled by rising sea level, continue to be seriously mismanaged and uneconomically maintained and generate increasing environmental stress for adjacent marine habitats. Broward County heads the list of counties that stretch from St. Lucie southward to Miami- Dade. Five serious problems plague the stability of these barrier-island shorelines: inlet disruption of littoral drift; beach management that enhances shore erosion (lack of shore vegetation, inappropriate vehicular traffic, and structural protections that enhance erosion); historically very poor-quality renourishment sediment (in size and durability); strong resistance by coastal engineering and dredging firms and counties to embrace an understanding of sandy shore dynamics; and a philosophy that renourishment projects are a solve-all management approach to maintaining beaches and protecting infrastructure. This has led to seriously destabilized beaches, overly aggressive beachfront development, major economic waste, and severe environmental degradation to adjacent marine waters and associated valuable sandy bottom and hard-bottom communities. Many of these sandy shorelines may well not survive this global warming century of rapidly rising sea level. It is economically and environmentally critical for both the future risks to be understood and for lessons from the repeated failed history of beach management to be learned. Continued mismanagement will shorten the inhabitable lifetime of this developed sandy coast by decades and at great economic and environmental cost.

The paper lays out seven principles that must guide the selection of appropriate sand for beach renourishment projects to succeed:

(1) characterize the natural sand from the historically stable beach as a standard;

(2) avoid sand particles that will tend to transport in suspension;

(3) document the entrainment and transport behavior of skeletal carbonate sands in proposed fill;

(4) establish through testing that the sand to be used is durable in the beach environment;

(5) do not use “overfill”;

(6) analyze proposed fill sand wet; and

(7) recognize the responsibility to meet the highest standards in beach fill material.

Click to read A history of poor economic and environmental renourishment decisions in Broward County, Florida

(Editors note: Truck-haul projects using quartz sand from inland sources have been gaining popularity for restoring dunes and providing beach protection. While initial costs may be much higher than dredging sand from offshore; inland sand has an increased potential to remain on the beach because grain size, density, durability and low silt content more closely resemble native beach sand.)    

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