energy attenuation & hybrid living shorelines: a viable ... · mhw feature (i.e. land, sand...
TRANSCRIPT
Energy Attenuation & Hybrid Living Shorelines: A Viable Tool
for Coastal ResilienceHot Topic Session
Delaware Estuary Science & Environmental Summit“Balancing Progress & Protection – 10 Years of Science in Action”
January 25-28, 2015Cape May, New Jersey
Douglas JaniecNatural Resources Program Manager & Senior Restoration EcologistSovereign Consulting, Inc.
Photograph provided by Living Shoreline Solutions, Inc.
Page 2
What does a Hybrid Living Shoreline do?
A Hybrid Living Shoreline creates a multi-step wave energy attenuation system by mimicking natural processes.
•Supports LS Projects in Moderate to High Energy Systems
•Sediment Conservation
•Cost Saving for Dune and Nourishment Projects
• Infrastructure Protects
•Resilience (50+ years)
•Barrier Reefs
•Oyster Habitat
•Stabilizes Beaches for Horseshoe Crab and Migratory Birds
•EFH Uplift
•Sea grass/SAV Restoration
They provide the following benefits:
Natural Energy Attenuation System (concept cross section)
MLW
MHW
Feature (i.e. land, sand bar, reef, wide shallows, structure)
Arrows Represent Wave Energy
Natural Accretion Zone (may be beach, marsh, intertidal
bars, and/or SAV)
Dune, high marsh edge, forest, or other supratidal
feature
Existing Beach
Bottom w/o Irregular Feature
(mixed dune/beach/marsh/flat system)
Step 3(severe storm)
Attenuation
Step 1(higher energy)
Attenuation
Step 2(lower energy)
Attenuation
30000 100 200 400 500 600 700
Example of Spacing (ft)
800 900
Hybrid Energy Attenuation System (concept cross section)
MLW
MHW
Step 1 is goneExisting supratidal feature
gets hammered
Existing Beach
Existing Bottom
Targeted Resilient Shoreline (mixed dune/beach/marsh/flat system)
Step 3(severe storm)
Attenuation
Step 1(higher energy)
Attenuation
Step 2(lower energy)
Attenuation
30000 100 200 400 500 600 700
Example of Spacing (ft)
800 900
Most or all of Step 2 is absent
Hybrid Energy Attenuation System (concept cross section)
MLW
MHW
Hybrid Structure (n.t.s.)
Passive accretion and/or optional nourishment (may be beach, intertidal
bars, and/or some SAV)
Created or existing supratidal feature
Existing Beach
Existing Bottom
Targeted Resilient Shoreline (mixed dune/beach/marsh/flat system)
Step 3(severe storm)
Attenuation
Step 1(higher energy)
Attenuation
Step 2(lower energy)
Attenuation
30000 100 200 400 500 600 700
Example of Spacing (ft)
800 900
Page 6
Wave Constructive (in phase) Conditions & Destructive Wave (out of phase) Conditions
In Phase Out of Phase
Page 7
The longer the wind blows - the bigger the waves
The stronger the winds – the higher the waves
The longer the fetch - the bigger the waves
Substrate depth and slope affect wave type and break
Relative to the Delaware Bay, these factor limit wave size and energy.
Some Wave Basics
Page 8
How Wave Energy Interacts with Objects (BBW)
Refraction (bending)
Diffraction (wrapping)
Reflection (bouncing)
Apollo Bay, AU
Wave Diffraction
Constructive Wave
Destructive Wave Condition
Energy Redirectioningand Focusing
An Example
Shoreline Erosion Area
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Breakwaters & Hybrid Living Shorelines Are Functionally Different
Breakwaters provide a complete or partial linear barrier to redirect (manipulate) concentrated wave energy.
New hybrid living shorelines allow the wave to pass through the structural array as the wave attenuates (breaks up) and creates a destructive wave environment.
Erosion Patterns (not accretion patterns).
Although some attenuation occurs, much of the energy is still concentrated.
Fights with nature.
Examples of Breakwaters
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Example of Energy Attenuation:Cupped Wave Spreader – Loop Canal, Bethany Beach, DE
Log Cups Gap Logs
Red is refractions over logsPurple is diffraction around logsCumulatively, the combined wave manipulations result in energy cancellation and attenuation
Thank you, Delaware Center for the Inland Bays for sharing
Unconcentrated energy; suspended particuates
drop out of column
Concentrated energy
Page 13
Other Structural Energy Manipulations
Energy Focusing/Defocusing Baffled opening in structures Strategic constrictions and enlargements Strategic placement of structures
Energy Redirectioning X-Y Planar energy deflections (horizontal vector
alterations) Z Planar energy deflections (vertical vector
alterations)
Microturbulence
Page 14
• Energy Focusing/Defocusing• Energy Redirectioning• Microturbulence
Figures provided by Living Shoreline Solutions, Inc.
Example of Other Manipulations
Energy Attenuation Technology at Work
Video provided by Living Shoreline Solutions, Inc.
Energy Attenuation Offers a New Options for Shoreline Resilience Wayfarers®
(low to moderate energy)
Oyster Castles® (low to moderate energy)
WADs™(moderate to high energy)
Douglas Janiec
Natural Resource Program Manager
Sovereign Consulting, Inc.
973-433-6480
A typical summer evening at the point
Thank You