2015 Kiawah Island Beach Monitoring Steven Traynum
April 5, 2016
Influence of Ebb Tidal Deltas
• Ebb deltas contain significant sand
reserves
• Waves push sand landward in
discrete shoals
• Shoals attach to beach
Historical Shoal Bypassing at Kiawah
1998 and 2005 Events
• Created new barrier island ~1,500 ft seaward of old
shoreline. Will continue to evolve over next decades.
1998 2005
2006 Restoration Project
• Moved ~550,000 cy
• Inlet realignment
plus beach
restoration
• Used land-based
equipment
2015 Channel Realignment Project
• Moved 100,000 cy
• Limited beach restoration
• Focus on habitat
conservation
Monitoring Stations and Reaches
Key Events
• October 2014 – Monitoring Survey
• May-June 2015 – East End Channel Realignment and
Captain Sams Inlet Relocation Projects
• October 2015 – Hurricane Joaquin
• November 2015 – Monitoring Survey
• February 2016 – Monitoring Report
Post-Project Changes
Present Condition (Jan 2016)
Channel Migration
2015 Captain Sams Inlet
Relocation
• Relocated CSI ~3,000 ft east to the
~1960 position
• 3rd time project has been
completed
• Inlet will migrate towards Seabrook
up to 300 ft/yr
Monitoring Results
Reach Name
2014-2015 Unit
Volume Change
(cy/ft)
2014-2015 Total
Volume Change
(cy)
2007-2015
Average Unit
Change (cy/ft)
1 Kiawah Spit -84.3 -743,597 -8.4
2 West Beach -0.6 -7,346 2.2
3 Turtle Point 5.9 80,032 4.8
4 Ocean Course 13.6 122,528 8.9
5 Lagoon -33.8 -270,196 4.9
6 Stono Inlet -13.7 -82,454 -4.3
1-6 All -15.7 -901,033 1.9
Stono Inlet Reach
• Erosional along the
south end
• Net loss of 82,500
cy last year
• Total loss of 215,000
cy since 2007
• Overwash during
Hurricane Joaquin
Lagoon Reach
• Long-term processes
masked by short-term
changes
• Shoal-bypassing
• Reach lost 270,200 cy
over past year
• Net gain of 320,000 cy
since 2007
Lagoon Reach
Migration of offshore shoal Erosion of outer berm
Lagoon Reach
Overwash
beach
Note lack of dune
Ocean Course Reach
• Gained 122,500 cy 2014-2015
• Western end eroded, eastern
accreted
• Net gain of 660,000 cy since 2007
16th Hole - Erosion 18th Hole - Accretion
Western Reaches
Turtle Point Reach
• Gained 80,000 cy over past year
• Minor dune erosion
• +532,800 cy since 2007
Line 30
Line 35
Turtle Point Reach Hurricane Joaquin Dune Breach
West Beach
• Net loss of 7,350 cy last year
• Erosion of western end
• Accretion at eastern end
• Gained 211,300 cy since 2007
Kiawah Spit (Captain Sams)
Kiawah Spit
• Inlet relocated ~3,000 ft to the east in spring 2015
– Previous project in 1996
• Net loss of 743,600 cy over past year
• Reach lost 33,700 from 2012-2014
• Despite loss, reach holds 158,000 more sand than in 1999
Kiawah Spit
Summary
• Island lost a total of 901,000 cy
• Majority was due to Captain Sams relocation
• Additional losses due to evolution of lagoon
• Developed central portion of island gained sand or was
stable
• Hurricane Joaquin produced “storm beach” conditions
Next Steps
• Additional monitoring scheduled for 2016 and 2017
• Project-specific monitoring is ongoing (birds, channel
boundary)
• Habitat monitoring needs to be conducted under a new
scope
• Next project can be completed in 2018
• Should monitoring suggest action needed earlier, permit
modification should be sought