RAE 2012 | Tampa, FL
Decision Support Tools for the Design of Structures in Living Shorelines
Poster #STP-14
1
Webb ,
B. M., S. L.
1
Douglass ,
S.
1,2
Powers ,
S.
3
Scyphers ,
R. J.
1
Allen ,
and T.
1
Buhring
Abstract
Goals & Objectives
Living Shorelines Database
A key component of many living shoreline projects is a wave attenuating
structure, or breakwater. While energy dissipation is the primary goal of a
breakwater, research has shown that they provide ecological habitat and
enhance ecosystem services. The functional design of breakwaters for
living shorelines projects has not received detailed treatment. Existing
resources do not specifically address the implementation of structures in
living shorelines where specific requirements on wave attenuation for
vegetation and habitat viability may exist. A decision support toolkit
currently under development will improve the function and efficiency of
living shorelines through a refined treatment of the role of structures in
attenuating wave energy when wetland protection and habitat creation
are express goals. The toolkit will allow end-users to identify and describe
impacts of the structures on the study area; the viability of coastal
wetland habitat in the lee of structures; expected ecological benefits of the
structures; and the socioeconomic impacts of the living shoreline project.
Anticipated benefits to society include functional, more resilient, and
more impactful living shorelines, with an ultimate goal of providing the
framework for an alternative to bulkheads, seawalls, and revetments
which eliminate or impair intertidal habitat.
The goal of this project is to develop a framework for an alternative to
bulkheads, seawalls, and revetments which eliminate or impair intertidal
habitat. Specific objectives are to:
" Synthesize existing literature
" Document living shorelines
" Perform physical experiments
" Develop a suite of tools
One objective of this project is to
develop a comprehensive database
of existing living shorelines projects
around the country. The database is
being developed in cooperation with
the American Society of Civil
Engineers’ Coasts, Oceans, Ports &
Rivers Institute (COPRI). For more information about the database, and
to learn more about how you can add your own project, please visit
Poster #PP-1 (Douglass, Scott L.).
Natural, sheltered shorelines are vanishing in many parts of the country
as property owners elect to armor, or bulkhead, their shoreline to protect
upland property. In some cases, property owners armor their shorelines,
and consequently eliminate or impair intertidal habitat, due to a lack of
knowledge regarding suitable alternatives, and in some cases based on
state coastal zone management doctrine (i.e., the ability to permit an
alternative to a bulkhead, revetment, or seawall).
Did You Know?
!  Gulf of Mexico accounts for
>50% of U.S. coastal wetlands
!  Mobile Bay has >14,000
acres of coastal marshland
!  Mobile Bay has lost over 35%
of emergent marsh habitat in
recent years
1University
of South Alabama;
!  Alabama’s shoreline erosion
rate is ~2 m/yr
2Dauphin
Island Sea Lab;
3Northeastern
Timeline & Implementation
The Toolkit
The decision support toolkit will allow the end-user to generate a
structure design that is optimized for desired levels of:
" Shoreline stabilization
" Coastal wetlands habitat
" Ecological benefits
Motivation
Figure 1. Shoreline armoring and
population trends around Mobile
Bay, Alabama (Douglass & Pickel).
Figure
2
(left).
Wave
diffraction
coefficients at a wave fence. Figure 3 (top).
Physical testing of bagged oyster shell.
Figure 4 (right). A conceptual flowchart
for the structure and organization of the
decision support toolkit.
Wave Attenuation Experiments
Physical
experiments are
being conducted in
the USA wave basin
to determine the
wave attenuating
capabilities of
structural
technologies used
in living shorelines.
University
Figure 5. Physical testing of (a) concrete wave
attenuating devices, and (b) bagged oyster shell
breakwater.
Figure 6. A living shoreline using a wave fence and Spartina alterniflora along a
sheltered shoreline (Dog River, AL) where boat wakes constitute the design wave
height.
This two-year research project is currently underway, with an expected
completion date of Summer 2014. A synthesis of living shorelines
research has been conducted; development of a living shorelines database
is ongoing with the help of ASCE COPRI; and physical testing of
structural technologies is underway. Integration of ecological and
ecosystem service indicators will occur in early 2013.
Acknowledgments
This poster was made possible through support
provided by the U.S. Department of Commerce
through the National Oceanic and Atmospheric
Administration through The University of
Southern Mississippi under terms of Agreement
No. NA10OAR4170078. The opinions expressed
herein are those of the authors and do not necessarily reflect the views of the
U.S. Department of Commerce, the National Oceanic and Atmospheric
Administration or The University of Southern Mississippi.
Background photo courtesy of Carl Ferraro, ADCNR: EDRP Habitat
Restoration Project at Little Bay, Alabama.
Bret M. Webb – Phone: (251) 460-7507; Twitter: @dr_bw
Email: [email protected]; Web: www.usacoe.org/bwebb