2015 Kiawah Island Beach Monitoring - Amazon S3...Monitoring Results Reach Name 2014-2015 Unit Volume Change (cy/ft) 2014-2015 Total Volume Change (cy) 2007-2015 Average Unit Change

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