storms, floods, waves and debris: observations and inferences for protection-, risk-, and...

8/10/2019 Storms, Floods, Waves and Debris: Observations and Inferences for Protection-, Risk-, and Marsh-Management Decisions

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DEC 3 rd Fact Finding Meeting:What do we know about storm protection and the role of Piermont Marsh?

Piermont, Wed Jan 7, 2015

Storms, Floods, Waves & Debris:Observations and Inferences for

Protection- , Risk- andMarsh-ManagementDecisions

Klaus H. JacobLamont-Doherty Earth Observatory &School of International and Public Affairs, Columbia University

[email protected]


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This presentations has three parts:

I. Relationships between Marsh andStorms/Floods

II. How these Relationships could change ifsome of the Marsh was going to bemodified.

III. My personal Comments &Recommendations based on (1) and (2)for pending development of aMarsh Management Plan


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Key Points Re I.) Marsh Effects during Storms

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3.5 NAVDx

3.5 NAVDx

and applies to ordinaryhigh-tide flooding

1. Marsh does not diminish the (still-water) flood elevation

9.7 .1x

8.9I

V

This applies to extreme surgesi.e. Sandy

USGS SandyHigh-Water

Marks

My own.

9.7x


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Key Points Re I) Marsh Effects during Storms2. Marsh reduces wave action substantially.

In Bogertown, neither during Irene nor Sandy any perceptible waves wereobserved In contrast, north of the pier, wave heights were estimated to be at least 2

to 3 feet during Sandy These findings are supported by theoretical and experimental studies,

e.g.: USGS study in San Francisco Bay Area:


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Key Points Re I) Marsh Effects during Storms2. Marsh reduces wave action substantially.


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Key Points Re I) Marsh Effects during Storms3. Marsh catches debris & reduces risk of impact to houses


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Key Points Re I) Marsh Effects during Storms

4. High & dense phragmites works better than lesser plants


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4. High & dense phragmites works better than lesser plants

5. This is especially true for very high storm surges. Why?

Phragmites exceeds height of Flood Crests(even for Sandy)

The entire water column and wind boundary layerexperiences friction


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6. The Marsh (even with phragmites) needs to be sufficiently wide

to catch debris and attenuate wave action.


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Key Points Re I) Marsh Effects during Storms6. The Marsh (even with phragmites) needs to be sufficiently wide

to catch debris and attenuate wave action.7. Where it was not, Sandy damaged retaining wall of Condos


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8.Debris and breaking waves seem to flatten the phragmites

in distinct patterns (but heavy wet snow can too).

Winter 1969/70


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Key Points ReII) Potential Flood Effects and Risks from Phrag Removal

1. Marsh looses much of its capacity for wave attenuationand debris protection, probably for a decade or more

2. The Risk for Marsh Erosion is increased


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3. If Herbicides were used, high tides could flood them intosome gardens several times a year, and during storms intolow-lying houses , the ball field & 2 childrens playgrounds ,although less often.


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Key Points ReII) Potential Flood Effects and Risks from Phrag Removal4. If Herbicides were used, risks to amphibians and fish(*)

are likely, and because of transport during floods, risks toflood-exposed residents cannot be ruled out. Recentresearch hints that the risk is highest when e.g. Glypho-sates enter the food chain(**) . This may jeopardize homegardening & fishing (and perhaps usage of play grounds & thevillage ball field ?). Risk not known, but Safety not proven either!!

* http://www.esajournals.org/doi/abs/10.1890/04-1291http://scholar.google.com/scholar?q=glyphosate+amphibian&btnG=&hl=en&as_sdt=0%2C33http://scholar.google.com/scholar?hl=en&q=glyphosate+fish&btnG=&as_sdt=1%2C33&as_sdtp=

** Swanson N.L. et al. 2014. J. Organic Systems 9 (2), 6-37, 2014 KHJ: Correlation ! Causation. => Hint!Samsel, A. & S. Seneff 2013. Entropy 2013, 15, 1416-1463. KHJ: Causation through the guts microbiome and other references on request to KHJ.


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- 1 0 1 2 3 4 5 6 7

8 9 1 0

F e e

t a b o v e

M H H W


5. Sea Level Rise accelerates & amplifies all of the above.

My Garden Floods

Sandy

IreneDonna 1962Noreaster

Monthly Flood Extremesat Battery,

1884-2014


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III. Inferences for Management Plan from I) Marsh Effects during Storms; and II) Phrag Removal

1. Removal of Phragmites, if at allcontemplated, should be limitedto a small diversity garden in anear-central part of the Marsh. Isuggest the area surrounded bythe oxbow (after infilling theshort-cut channel).

2. Reason: preserve maximumwave attenuation, debriscatchment, sedimentation, andnutrient cleanup, and avoiderosion. Lesser plants performpoorer protection especiallyduring severe storms. =>Liabilityre home damage & home values.


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III. Inferences for Management Plan

3. Use freed up resources to consideroyster reefs on E side (outboard) ofthe marsh as breakwaters ==>

and/or off N Piermont / Marinas.

Source: Scape / RBD


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5 . No herbicides in Marsh => Flooding => for Public Health& Liability Issues alone.

6. Use the Cautionary Principle : if you dont understand theprocesses that relate causes to effects, and effects tocauses, or actions to outcomes, then desist acting there-by minimizing possible risks (to marsh, people, life & NYS).

Also: Justifying actions by Benefit Cost Analyses is ethically/morallyquestionable if potential costs are unacceptable, whatever the benefits.

Recent Example of Applying the Cautionary Principle :Governors Decision to Sustain Fracking Ban for New York State

because of Uncertainty in Environmental Risks & Health Hazards

III. Inferences for Management Plan fromI) Marsh Effects during Storms; and II) Phrag Removal

=> =>-


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Thank you


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2010 (pre-Irene)

2013

Post-Sandy

&Post-Snow

of Nov 7

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