Protect The Natural Dune Seawall, Our First Line of Defense Against Hurricanes Richard L. Watson,...
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Transcript of Protect The Natural Dune Seawall, Our First Line of Defense Against Hurricanes Richard L. Watson,...
Protect The Natural Dune
Seawall, Our First Line of
Defense Against
Hurricanes
Richard L. Watson, Ph.D.
TexasCoastGeology.com
(361) 749-4152
TexasCoastGeology.com
A River of Sand,A River of Sand,Sand Movement in the Surf ZoneSand Movement in the Surf Zone
• 700,000 to 800,000 cuyd/yr
• 250 Dump Trucks Per Day
• One Dump Truck Every 6 Minutes
TexasCoastGeology.com
Sabine
TexasCoastGeology.com
Central Padre Convergence, AccretionCentral Padre Convergence, Accretion
con
verg
ence
From GLO
MANSFIELDMANSFIELD PASSPASS
TexasCoastGeology.com
San Luis Pass Ebb DeltaTexasCoastGeology.com
Packery Channel, 11/27/2005Packery Channel, 11/27/2005
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Galveston East JettyGalveston East Jetty
TexasCoastGeology.com
TexasCoastGeology.com
Dredging Rates
From Bales and Holley, 1989
The Breakers,1906
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The Breakers, 1994
The Breakers, 1995
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The Breakers, 1998
TexasCoastGeology.com
Freeport Jetties, Surfside
Old Delta
Location
New Delta
Freeport Channel
TexasCoastGeology.com
Brazos River Delta
1935
1954
NEW OLD
New Brazos River Delta
San Bernard River
TexasCoastGeology.com
Old
Del
ta
The Octagon, 1969
From Surfriders website
The Octagon, 2000From Surfriders website
From Surfriders website
Surfside before H. Rita
TexasCoastGeology.com
Surfside Village, TX after RitaSurfside Village, TX after Rita
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Surfside Village after RitaSurfside Village after Rita
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Holly Beach before RitaHolly Beach before Rita
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Holly Beach After RitaHolly Beach After Rita
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Holly Beach, LA after RitaHolly Beach, LA after Rita
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Dauphin I., AL after KatrinaDauphin I., AL after Katrina
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1912 to 1978 Hurricanes1912 to 1978 Hurricanes
USACE Texas Coast Hurricane Study, Corpus
Christi Bay Study Segment, 1979
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All Storms Since 1851All Storms Since 1851
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Hurricane Carla Wind Field, 1961Hurricane Carla Wind Field, 1961
Miles O. Hayes, 1967
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Hurricane Carla Surge, 1961Hurricane Carla Surge, 1961
Miles O. Hayes, 1967
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Celia Surge Flood, Port Aransas USACE, GALVESTON DIST.
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Port Aransas, Early 60sPort Aransas, Early 60s
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Pre-Jetty Foredune RidgePre-Jetty Foredune Ridge
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Beach and Dune SystemBeach and Dune System
Texas General Land Office (GLO)
TexasCoastGeology.com
Private land boundarySeaward limit structures
Weak Area Natural Dune SeawallWeak Area Natural Dune Seawall
Texas General Land Office (GLO)
TexasCoastGeology.com
Natural Dune Seawall BreachedNatural Dune Seawall Breached
Texas General Land Office (GLO)
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Beulah Opens Corpus Christi Pass, 1967Beulah Opens Corpus Christi Pass, 1967
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Temporary Bridge after Celia, 1970Temporary Bridge after Celia, 1970
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Island Road after Allen, 1980Island Road after Allen, 1980
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Storm Erosion of DunesStorm Erosion of Dunes
Texas General Land Office (GLO)
TexasCoastGeology.com
Dune Erosion by Carla, 1961Dune Erosion by Carla, 1961
Miles O. Hayes, 1967
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Multiple Buggy Cuts, 1970Multiple Buggy Cuts, 1970
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Protect the Dune Seawall, 1970Protect the Dune Seawall, 1970
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Poor Beach Management, 2005Poor Beach Management, 2005
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Pure Sand Graded from RoadPure Sand Graded from Road
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Removing Dune SandRemoving Dune Sand
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Lost to the Natural Dune SeawallLost to the Natural Dune Seawall
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Port Aransas Beach Regulations
Port Aransas Beach Regulations
The City of Port Aransas shall prohibit The City of Port Aransas shall prohibit beach maintenance activities which will beach maintenance activities which will
result in the SIGNIFICANT result in the SIGNIFICANT REDISTRIBUTION of sand or which will REDISTRIBUTION of sand or which will
SIGNIFICANTLY ALTER THE BEACH SIGNIFICANTLY ALTER THE BEACH PROFILE.PROFILE.
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Port Aransas Beach Regulations
Port Aransas Beach Regulations
The City of Port Aransas shall prohibit The City of Port Aransas shall prohibit beach maintenance activities unless beach maintenance activities unless
maintenance activities will not maintenance activities will not materially weaken dunes or dune materially weaken dunes or dune
vegetation or reduce the protective vegetation or reduce the protective functions of the dunes.functions of the dunes.
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State Beach Regulations Add Further LimitationsState Beach Regulations Add Further Limitations
All sand moved or redistributed due to All sand moved or redistributed due to beach maintenance activities shall be beach maintenance activities shall be
returned to the area between the line of returned to the area between the line of vegetation and mean high tide.vegetation and mean high tide.
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State Beach Regulations Add Further LimitationsState Beach Regulations Add Further Limitations
The General Land Office encourages The General Land Office encourages the removal of litter and other debris the removal of litter and other debris by handpicking or raking and strongly by handpicking or raking and strongly discourages the use of machines discourages the use of machines (except during peak visitation periods) (except during peak visitation periods) which disturb the natural balance of which disturb the natural balance of gains and losses in the sand budget gains and losses in the sand budget and the natural cycle of nutrients.and the natural cycle of nutrients.
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Violation of Federal Regulations
Violation of Federal Regulations
The U.S. Army Corps of Engineers has The U.S. Army Corps of Engineers has requested that the City of Port Aransas requested that the City of Port Aransas cease dumping sand below the Mean cease dumping sand below the Mean High Water line. To do so, the City High Water line. To do so, the City needs a federal permit or it is in needs a federal permit or it is in violation of the Clean Water Act (CWA).violation of the Clean Water Act (CWA).
TexasCoastGeology.com
New Dune Ridge in 8 Years, 2005New Dune Ridge in 8 Years, 2005
High Dune, Wide Beach Best?High Dune, Wide Beach Best?High Dune, Wide Beach Best?High Dune, Wide Beach Best?
• Is a high dune and a wide beach the best protection?
• The most important part is the maximum volume, height and width of dunes.
• Hurricane surge will quickly cross any width beach and begin eroding the dunes.
• We MUST have the largest possible vegetated dune system to buy time for the storm to pass.
• Is a high dune and a wide beach the best protection?
• The most important part is the maximum volume, height and width of dunes.
• Hurricane surge will quickly cross any width beach and begin eroding the dunes.
• We MUST have the largest possible vegetated dune system to buy time for the storm to pass.
How Should We Manage the Beach?
How Should We Manage the Beach?
• Put a row of bollards in the center of the present road where the trash cans are now.
• Narrow the driving lane or move the present bollards seaward.
• This will maintain a pedestrian beach, a driving roadway, parking, and allow the dunes to grow.
• There is no downside. We maintain the full utility of the beach and get additional hurricane protection at no cost to the City
• Put a row of bollards in the center of the present road where the trash cans are now.
• Narrow the driving lane or move the present bollards seaward.
• This will maintain a pedestrian beach, a driving roadway, parking, and allow the dunes to grow.
• There is no downside. We maintain the full utility of the beach and get additional hurricane protection at no cost to the City
TexasCoastGeology.com
What about the future?What about the future?• Create a procedure to evaluate future needs,
including after a hurricane as well as after further dune growth.
• Require that the dunes be allowed to grow.• Create a permanent beach and dune
protection board staffed by local citizens and local scientists.
• Recognize that our beach is our most important tourist attraction and our dunes are our most important hurricane protection.
• Create a procedure to evaluate future needs, including after a hurricane as well as after further dune growth.
• Require that the dunes be allowed to grow.• Create a permanent beach and dune
protection board staffed by local citizens and local scientists.
• Recognize that our beach is our most important tourist attraction and our dunes are our most important hurricane protection.
TexasCoastGeology.com
Vegetated Coppice DuneVegetated Coppice Dune
TexasCoastGeology.com
Protect The Natural Dune Seawall, Our First Line of
Defense Against
Hurricanes
Richard L. Watson, Ph.D.
TexasCoastGeology.com
(361) 749-4152
•Our best storm Our best storm protection is a protection is a high and wide high and wide natural dune natural dune system.system.
•Let nature build it Let nature build it for us, it is free.for us, it is free.
•Our best storm Our best storm protection is a protection is a high and wide high and wide natural dune natural dune system.system.
•Let nature build it Let nature build it for us, it is free.for us, it is free.