Transcript Living Shorelines Panel Part 1

Living Shorelines:
The origins of a practice, the sudden rise of interest
within the stormwater community,
and the debate
Jana Davis
Chesapeake Bay Trust
Definition of Living Shorelines
"Living shorelines" are defined as shoreline stabilization
techniques that use as many natural habitat elements as
possible to protect shorelines from erosion while also
providing critical habitat for Bay wildlife.
The “Problem:” Eroding Shorelines
33% of all Chesapeake Bay shorelines are actively eroding.
The “Problem:” Eroding Shorelines
Erosion is a natural process
7,000 years ago
present
10,000 years from now
Maps courtesy of UDel
The “Problem:” Eroding Shorelines
Erosion is a natural process.
Human processes play a role.
Sea Level Rise: > 1 foot (40 cm) last century
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Hardening of Shorelines
We’re hardening our shorelines to protect against erosion
28-32% Maryland is armored
11-19% Virginia is armored
Hardening of Shorelines
But armor doesn’t always work,
and people starting thinking it might not be so good for critters
History of “Living Shorelines”
● 1970s
Environmental Concern begins using purely non-structural
approaches. Failures abound
● 1980s
“Hybrid” projects introduced
● 1980s
“Living shorelines” term coined in Maryland
● 1990s-2000s Implementation of projects in MD, VA, NC takes off
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Types of Living Shoreline Projects/Designs
Living Shorelines
Structural practices
low structure
high structure
Non-structural living
shorelines:
natural habitat elements
only: vegetation, oyster
reef, coarse woody
debris, sand.
Hybrid living
shorelines:
include natural
habitat elements,
as well as some
hard structures
such as stone sills
or breakwaters
practices without a natural
habitat component:
Bulkheads/Seawalls
Revetments
Breakwaters
Groins/jetties
Structural erosion control
practice
Non-structural living shoreline
Low-structure hybrid
living shoreline
Medium-structure
hybrid living
shoreline
Non-Structural
BEFORE
Hidden Pond,
Crownsville, MD
AFTER
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Low Structural
BEFORE
St. Johns College,
Annapolis, MD
AFTER
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Hybrid Living Shorelines
Segmented Sill Design
Continuous Sill With Windows
window/tidal gate
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Hybrid Living Shorelines
BEFORE
AFTER
Chesapeake
Maritime Museum,
Miles River
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High Energy/High Structure
Chesapeake Bay Ecology Center, Grasonville, MD
Asbury Retirement Home, Calvert County
Breakwaters
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History of “Living Shorelines”
● 1970s
Environmental Concern begins using purely non-structural
approaches. Failures abound
● 1980s
“Hybrid” projects introduced
● 1980s
“Living shorelines” term coined in Maryland
● 1990s-2000s Implementation expands
● 2003
● early 2000s
● 2007-8
● 2008
North Carolina passes Living Shoreline Law (HB 1028)
Delaware puts “no bulkhead” policy in place
Florida state gov’t begins Living Shoreline Initiative
Maryland passes Living Shoreline Protection Act
History of “Living Shorelines”
● 1970s
Environmental Concern begins using purely non-structural
approaches. Failures abound
● 1980s
“Hybrid” projects introduced
● 1980s
“Living shorelines” term coined in Maryland
● 1990s-2000s Implementation expands
● 2003
● early 2000s
● 2007-8
● 2008
North Carolina passes Living Shoreline Law (HB 1028)
Delaware puts “no bulkhead” policy in place
Florida state gov’t begins Living Shoreline Initiative
Maryland passes Living Shoreline Protection Act
Connection to other issues: Climate Change and Bay Pollution
● 2008
MD Climate Action Plan - LS as climate change defense
● 2015
Bay Program gives LS N, P, and S credit –
Expert Panel on Shoreline Management Practices
The Debate:
Living Shorelines as
Solutions for multiple ills:
Deserved, or overstated?
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Sources of Sediment “Pollution?” in the Chesapeake
• Watershed – Ag and SW
• Oceanic Input
• Shoreline
5.2 million tons/year
Oceanic
Watershed
Shoreline
Sources of Sediment “Pollution?” in the Chesapeake
• Watershed – Ag and SW
• Oceanic Input
• Shoreline
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Sources of Sediment “Pollution?” in the Chesapeake
• Watershed– Ag and SW
• Oceanic Input
• Shoreline
Is sediment all bad?
1,600,000
Types of sediment loads
1,400,000
1,200,000
MT/year load
MD
1,000,000
800,000
600,000
400,000
200,000
0
Fines
Coarse
Sediment type
Organic
VA
Expert Panel “Protocols” to give reduction
credits for shoreline erosion control practices
• Tidal Marsh Denitrification
• 85 lbs/acre of revegetation
• Sediment Trapping through Accretion
• 5.289 lbs P/acre, 6,959 lbs sediment/acre of revegetation
• Marsh Redfield Ratio – Standing Crop of Vegetation
• 6.83 lbs N/acre of revegation, 0.3 lbs/acre – 1 time credit (not annual)
• Prevented Sediment
• In MD – assumes 2.43 kg/m/d reduction x 0.551 (because 44% is coarse)
• In VA – assumes 1.01 kg/m/d x 0.337 (because 66% is coarse)
• As of July 2015, WTWG recommended to eliminate the nutrient credit for
prevented sediment pending further study.
• Concerns that the cumulative BMP loading reductions could possibly
exceed available simulated loadings.
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Baltimore County Essex Skypark Example
2,610 linear feet
Before: erosion rate 1-1.5 ft/yr
bank height 4-7 ft
After: 1.8 acres vegetation
Total pollutant load:
- 165.3 lb TN first year, 153 lb/yr future
- 10.6 lb TP first year, 9.52 lb/yr future
- 462,596 lb TSS/yr
Folks start asking: Are we sure these things
“work?”
Nekton: several species increased at LS; none decreased
Blue Crab
living shoreline
control
0.06
After-Before (change in density; #/sq m)
0.05
0.04
0.03
0.02
0.01
0
-0.01
bulkhead to LS
Striped Bass
0.07
eroding to LS
Species density
living shoreline
control
0.02
0.06
0.05
0.015
0.04
0.01
0.03
0.02
0.01
0.005
0
0
-0.005
-0.01
-0.01
-0.02
bulkhead to LS
eroding to LS
bulkhead to LS
eroding to LS
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