Impact of Hurricane Irene on Pivers Island Shorelines Carolyn Currin, NOAA NOS Objective: Provide data on resiliency of ‘living shorelines’ to storm impacts.

PIE

PIW

PIN

Impact of Hurricane Irene on Pivers Island ShorelinesCarolyn Currin, NOAA NOS

Objective: Provide data on resiliency of ‘living shorelines’ to storm impacts

•Installed 6 horizon makers at each PI site, at lower, middle and upper edge

•Read SETS at PIW (Sill) and PIN (NAT) post –storm

•Examined hardened structures for evidence of erosion

PIE marsh-oyster restorationPIW marsh-sill

NOAA NWLON station 8656483

Win

d sp

eed

(mph

)

Sediment deposition layer (mm)

Elevation Plot PIE PIW PIN

Lower 1 2.65 4.19 1.97

4 0 . NA

Mid 2 4.78 . .

5 5.49 0.55 .

High 3 13.82 . .

6 . 3.73 .

Sediment accretion in Pivers Island Marshes

Hurricane Irene resulted in net sediment deposition to PI sites

Erosion behind west-facing bulkhead(consistent with R. Gittman assessment of stabilization structures in Bogue Sound)

Erosion of bank behind riprap

Minimal erosion of unvegetated sediment bank

Intact upland border adjacent to marsh

20 yr old Oyster reef – marsh project‘Dredge Island’

October 2011 post-Irene

Conclusion: Marsh – oyster reefs provide an effective shoreline stabilization alternative

Additional data on Hurricane Irene impacts to estuarine shorelines

South shore of Dredge Island restoration site

Dredge Island wave exposure setting

Salt marsh

Carteret Co. marsh width vs. wave energy

Two other assessments :

J. Fear NERRS: marsh sill projects -little damage, wrack deposition -ome adjacent erosion of shoreline

R. Gittman UNC: bulkheads, sills, marshes in Bogue & APES

-bulkhead erosion more prevalent than marsh erosion

Sill structures showed no damage with marsh intactSome accumulation and sediment trapping by larger structures. Design matters.

Bulkheads and upland revetments showed some damage and scour – often overtopped.

Slope is important. Unvegetated sediment banks eroded

Intact marsh-upland boundaries showed no upland erosion or marsh loss.

Oyster reef-marsh shorelines showed no erosion.

We documented net sediment gain in Pivers Island shoreline marshes.

Summary of observations on Irene impact on shoreline stabilization projects

Pivers Island transplanted marshOyster cultch addition DMF