Post on 18-Aug-2020
SCIENCE TO SUPPORT COASTAL RESILIENCE:
THE ROLE OF NATURAL SYSTEMS
Denise Reed, Chief Scientist Restore America’s Estuaries November 2014
COASTAL RESILIENCE IN 2014
Business as usual isn’t working
THE ROLE OF SCIENCE
What can we really provide?
THE ROLE OF SCIENCE
How much better can we be?
Lightbody & Nepf, 2006
THE ROLE OF SCIENCE
Concepts based on sound science • What might work where?
Site specific analyses • What should work here?
CONCEPTS BASED ON SOUND SCIENCE
Concepts based on sound science • What might work where?
Site specific analyses • What should work here?
WHY are we using/expecting performance from ‘natural’ features? HOW do ‘natural’ features compare to ‘traditional’ approaches?
Geomorphology
Low High Resistance to change
Low
High E
nerg
y R
egim
e Reducing Erosion by Waves
Seagrass
Salt marshes
Oyster Reefs
Barrier islands
Beaches
Coral Reefs
Freshwater wetlands
Seawalls/ revetments
Groins Breakwaters
Example Conceptualization
SLR/Durability
Urb
aniza
tion
Low
High
Low High
Current Future
Storm Impact
Salt marshes
Barrier islands
Beaches
Coral Reefs
Dunes
Maritime forests
Surge Barriers
Nonstructural
Seawalls/ revetments
Breakwaters
Storm Damage Risk Reduction
Example Conceptualization
Mangroves
Different Species With mangroves
Without mangroves
Without mangroves
With mangroves
Increasing age of trees
Brinkman, 1997
Mazda
Mazda et al., 2006
Quartel et al., 2007
Suzuki et al., 2012
Cyclone waves Varying factors for roots, stems and canopies
Mangroves
Coral Reefs Gelfenbaum et al. 2011
High tide - low tide Roughness
Marshes
Loder et al. 2009. Idealized marsh simulations: Sensitivity of storm surge elevation to seabed elevation. ERDC/CHL CHETN-I-78.
0
100
200
300
Janu
ary
Mar
ch
May
July
Sept
embe
r
Nov
embe
r
Man
grov
e bi
omas
s (t
ons
hect
are
-1)
0
5
10
15N
umbe
r of t
ypho
ons
2001
to 2
005
mangroves
typhoons
0
200
400
600
800
1000
Janu
ary
Mar
ch
May
July
Sept
embe
r
Nov
embe
rSeag
rass
bio
mas
s (g
m-2)
2
3
4
5
Max
imum
ave
rage
win
d (m
s-1)
seagrasswind
Koch et al., 2009
When do the events occur? When does the ecosystem act to reduce the effect?
Examination of the effect of landscape character/restoration on storm surge & waves
Cobell et al, 2013
Cobell et al, in press Distance (Km)
300m flume experiment Real marsh sods
‘The higher than expected rates of storm wave dissipation and the fact that marsh surfaces are able to withstand larger wave forces without substantial erosion effects increase their reliability as part of coastal defence schemes and shifts debates about marsh stability and resilience to those locations where the marsh profile is exposed. In such settings, lateral retreat (for example, cliff undercutting/collapse on marsh fronts and channel widening) may be enhanced by the presence of vegetation, for example, when roots become exposed to wave impact. The long-term balance between vertical and lateral marsh dynamics thus becomes a key area for further study’.
Moeller et al., 2014.
W H A T D O W E N E E D , W H E R E ?
Weinstein & Reed, 2005
What do we want our coasts to do for us? Where can we apply different measures? How can they work together?
Role of coastal marshes in response to increases in relative sea level. (A) Contemporary natural
shoreline. (B) Natural shoreline w/SLR. (C) “Holding the line” (D) Hybrid interventions
where space is allowed for the maintenance of natural coastal defenses
Spalding et al., 2013
C O M M U N I T I E S A N D L I V E L I H O O D S AT R I S K
Predicted Future Flooding from a 100 Year Flood Event Future Without Action
Potential for damages to reach $23.4 billion annually
Increasing threats to lives, jobs, communities and the economy
2 0 1 2 C O A S TA L M A S T E R P L A N
CONCLUDING THOUGHTS
The stakes are high • Coastal systems are changing, risk of erosion and storm damage is
increasing
There is a lot of useful scientific information on the role of natural features in risk reduction • More for erosion control/wave attenuation than for storm surge damage
reduction
We need to capture the information we have and use it to guide coastal managers • Where/when do natural features make sense • Where/when do natural features NOT contribute to risk reduction
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