It was interesting to learn about the various hard and soft measures for erosion and flood control in coastal areas.  In Manatee County, FL, we can see many of those protection measures in action.  From dunes and beach re-nourishment to seawalls, jetties and beach groins, we have tried them all to protect our little community in the surf.  Let’s take a look at how Manatee County has gone about maintaining the land that is slowly slipping away.

Manatee County began beach re-nourishment projects along the Gulf Coast in 1992 and has continued to bring in truckloads of dredged sand since then about every 10 years.  In 2013, Tropical Storm Debby wiped out approximately 328,000 cubic yards of sand from Anna Maria Island and cost the state and Federal government an additional $37.5 million to restore the dunes and vegetation along with the beach sand.  It has been estimated that by the year 2040 the cost on these re-nourishment projects to increase to as much as $1.7 billion due to the rate of sea level rise, not taking into account severe weather that could cause greater increases.

One relatively large project that began in 2004-2005 was the reclamation of 487 acres of unused and disturbed old farmland turned into a beautiful salt marsh preserve.  Robinson Preserve is now home to mangrove forest, nature trails, emergent islands, and a slew of wildlife including Roseate Spoonbills, Bald Eagles, White Pelicans, and Wood Storks.  A waterway system was reconstructed to allow the natural tidal flows to be restored here as well.

Seawalls can likewise be seen spanning the entire county from residential properties to commercial areas.  Most residents on the barrier islands opt for concrete seawalls where the homes on the interior inter-coastal waterways and inner canal systems have chosen more natural shoreline that has been reinforced with black or white mangrove.  The City of Palmetto most recently chose the removal of an old concrete seawall to make way for a ‘living seawall’ that is the first of it’s kind.  This is a combination of concrete seawall and reef balls that work together to protect the area from flooding, erosion, wave energy and sediment displacement all the while creating a reef habitat for the marine ecosystem below.

Take a look at the difference in the south jetty between Coquina Beach and North Longboat Key.  The jetty was placed here in the late 1950’s for beach retention and to control the waterway in the channel.  The jetty is causing the natural sediment flow northward to be halted now rendering the channel nearly impassible at this point.

A set of three groins was also put into place in the same time period on Conquina Beach north to Cortez Beach.  These groins were added to help stop the erosion of this stretch of beaches.  The groins were originally meant to have a 30 year lifespan and now, 50+ plus years later are in a state of major deterioration.  Plans have been put in place for a new set of three higher tech groins that are adjustable and permeable to allow the county to be able to control the amount of sediment and water flow through them.

Cited:

http://www.islander.org/2014/01/beach-renourishment-on-track-almost/

http://www.floridatrend.com/print/article/15815

http://www.bradenton.com/news/local/article45151770.html

http://ufdc.ufl.edu/

http://www.mymanatee.org/home/government/departments/public-safety/marine-rescue/beaches/beach-safety-information/piers-jetties-and-rocks.html

High-tech groins planned for beach