Coastal Hazards: Geological Perspectives from the U.S...

Coastal Hazards: Geological Perspectives

from the U.S. Atlantic Coast

Ilya Buynevich Temple University, USA

N. Asp, P. Souza Filho

R. Angulo

W. Cleary

D. FitzGerald A. Bitinas

D. Pupienis

R. McBride

R. Goble

R. Ballard

S. van Heteren

M. Fenster

Collaborators

Hurricane

Katrina

(2005)

July 2001

Aug 2005

Chandeleur Islands, LA

USGS Coastal and Marine Geology Program

- Erosion

- Flooding

- Submergence

U.S. Atlantic

& Gulf Coasts

>$3 trillion

Hurricane

Sandy

(2012)

Seaside Heights, NJ

USACOE

Seaside Heights, NJ

USACOE

Beach NourishmentBeach Nourishment

1414

•• enough sandenough sand•• same or coarsersame or coarser•• after stormsafter storms

U.S. Army Corps of Engineers

(USACOE) Offshore breakwatersOffshore breakwaters

1313

tombolo tombolo effecteffect

U.S. Atlantic

& Gulf Coasts

>$3 trillion

Deposition

(sand invasion)

Ingleses, Brazil

Desert dunes, Mauritania

Baltic Sea coast Dune Village, Silver Lake, Michigan

1. What are the stability thresholds for sandy coasts?

- signatures of erosion – timing and hindcasting

- quantitative analysis of wave climate and storm-surge parameters

- response to accelerated sea-level rise and increased storminess

2. How do old channels affect coastal behavior?

- subsurface anomalies within coastal sequences

- vulnerability of barrier segments to breaching

- tidal prism reconstruction and sea-level change

3. Dune reactivation phases: causes and timing

- climatic vs. internal triggering mechanisms

- paleo-wind reconstruction (102-103 yr)

- human-landscape interaction

NEW FRONTIERS

Recognition and Dating of Erosion in Sand-Dominated Systems

Questions and Challenges

SEVERE SEA FLOODSNorth Sea and English Channel

Medieval Warm

Period

RELIABLE HISTORICAL ACCOUNTS

Europe

North America

1000 1400 1800 800AD 1200 1600 2000AD

Little Ice Age

from Lamb (1995)

Temperature( C)

Numberof

floods

15

10

5

0

11

10

9

8

ANNUAL TEMPERATURECentral England

South America from S. de Champlain (1605)

60-95%

vertical resolution

0

1 mm

1 cm

10 cm

1 m

10 m

1 km

10 km

100 m

1 mm 1 cm 10 cm 1 m 10 m 100 m 1 km 10 km

deepseismic

shallowseismic

reflection

GPR(120 MHz)

vibracoringscope of

coastal-stratigraphicresearch

pulse-augercoring

wash-borecoring

high-resolutionstratigraphy

Field Techniques

GPR

200 MHz

resolution

pe

ne

tra

tio

n d

ep

th

High-Resolution Geophysics

Groundtruth

Field Techniques

Research Sites

Active projects

Outside collaborator

Ukraine

Lithuania

Kuwait

India

Alaska

New England

VA,NC,SC

Pará, Brazil

Santa Catarina,

Brazil

New Mexico NJ,PA,MD Israel

Turkey

Texas Bahamas

Part 1

Erosion: Signatures and Chronology

Progradation: Deposition - Erosion

photo by P. Brown (Rocky Mountain Tree-Ring Research)

tree rings

From Ebernards et al (2006)

Ground-Penetrating Radar (GPR)

Revolutionized coastal geological research: Continuous high-resolution imaging

- physical structures

- textural contrast

- composition

(+ iron oxides,

clays, organics)

- moisture content

- bulk density

- porosity

Layer 1

Layer 2

200 MHz antenna

control unit

electromagnetic waves

Causes of reflection:

Signal loss: - saltwater, thick clay, metal

South Waihi Beach, New Zealand

HMC

buried HMCs

Heavy-Mineral Concentrations (HMCs) proxies for high-energy events

photos by T. Hume

HMC

Superstorm Sandy

(2012)

Erosion: Events and Signatures

Hurricanes/Typhoons Cyclones Extra-tropical storms

Beach/dune scarps HMC Surge channels

Tsunamis

NASA/Digital Globe images

2004 tsunami (photo by Rob Evans)

1978 storm scarp ocean

Punctuated Progradation Hunnewell Beach, Maine

Silver Lake MAINE

70

45

47

68 67

44

43

47

4646

71

45

44

1983

1978 scarp

photo by D.M. FitzGerald

Relict erosional scarps (no geomorphic evidence)

5 mm

Optically-Stimulated Luminescence (OSL) Dating

Buynevich et al. (2007)

recent

scarp

dunes:

167±13

1,545±170 391±36 287±27

153±17 years BP (1635)

(1815)

45±15

5,600-5,000 BP

3,580-3,380 BP

cal 14C ages

Storm Chronology and Climate Links ocean

photo by K. Fink

5 m

3

0

depth

(m

)

391±36 287±27 yBP

(1635 Hurricane)

S1

S4

S3

S2

Paleo-scarp interval vs. time

Visbeck et al (2001)

Atlantic Hurricane Tracks (1980-2005)

(HRC/NASA)

post-storm sandbars

paleo-scarp interval (dS)

Part 2

Paleo-Channels: Geological Legacy

Transgressive Coastlines

Long Island, NY (photo by Covello & Terchunian)

Landward transfer of sand during storms:

integral to barrier migration

with sea-level rise

(modified after John Norton)

flood-tidal delta

washovers

breach

LANDWARD SAND TRANSFER

GEOHAZRD

Superstorm Sandy

(2012)

20031977193818861846

GPR only

20031977193818861846

GPR only

Erosion is NOT uniform

N

1 km

Average shoreline retreat (m/yr) over 150 years (MCZM data)

0.5

1.0

0

Channel fill:

>60%

longshore transport

Inlet History

Falmouth, MA

Cape Cod, Massachusetts

-3.5

-3.0

-2.5

-2.0

-1.5

-1.0

-0.5

0.0

0 20 40 60 80 100 120 140 160

Channel Dimensions

Minimum bank-full width (m)

mean tidal

range

N=21

dredged

annually

GPR only

historic

present (stabilized)

w

d

Falmouth south shore

-3.5

-3.0

-2.5

-2.0

-1.5

-1.0

-0.5

0.0

0 20 40 60 80 100 120 140 160

Channel Dimensions

Minimum bank-full width (m)

mean tidal

range

N=21

dredged

annually

GPR only

historic

present (stabilized)

w

d

Falmouth south shore

Vineyard Sound

stabilized

channel

sand plug

Paleo-channel Research

1846

1997

Hurricane Bob

washover

(1991)

Buynevich (2003)

relict channel

Menauhant Beach, Cape Cod, MA

relict

feature

Providence, RI – 23 September 1815

The Great September Gale of 1815

Reconstructed damage – Fujita Scale (courtesy E. Boose – Harvard Forest)

New Currituck Inlet

(1713-1828)

storm breach

Old Currituck Inlet

(<1585 -1731)

20 mchannel-bottom reflection

~10 m

dune sands

CHANNEL

MIGRATION

N S

last position

VA

NC

Roanoke, NC (1584)

Old Currituck Inlet Paleo-channel

Tidal Prism

Reconstruction

Oceanic Inlets (Jarrett, 1976)

Ac = 6.954x10-6Ω1.14

20 mchannel-bottom reflection

~10 m

dune sands

CHANNEL

MIGRATION

N S

Ω Ac

Paleo-tidal prism:

Ω=9.6x106m3

Ω=1.5x106m3

last position

VA

NC

New Currituck Inlet

(1713-1828)

storm breach

Old Currituck Inlet

(<1585 -1731)

Part 3

Dunes as Archives of Climate Change and Human-Landscape Interaction

Coastal Dune Research

- Activity through Holocene

- Global distribution

- Sensitivity to environmental changes

Record of:

- wind patterns (GCM groundtruth)

- wind velocity

- sea-level change

- sediment supply

- precipitation/water table elevation

- vegetation dynamics

- recent human activities

Major Dunefields

Reactivated Dunes

buried

forest

OSL

~1m

5m

Atlantic Ocean

dune migration

Basin-Scale Links Baltic Sea

Cape Cod, Massachusetts

- NAO-sensitive regions

- similar SL history, climate, vegetation

- different history of human activities

Ongoing research: - Landscape change (6,000 – present)

- N. Atlantic climate: 102-103-yr shifts - Synchroneity of aeolian phases?

- Storminess – trigger of dune activity? - Natural vs. human-induced changes

Aquinnah Dunefield

Curonian Spit,

Lithuania Visbeck et al (2001)

Martha’s Vineyard

USA

GoogleEarth Image

Lithuania

Baltic

Sea

10 km

wind

Highest coastal dunes in Northern Europe

Russia

Curonian

Spit

STUDY

AREA

N

massive

(107-109 m3)

landward

sand

transfer

oversteepening

and collapse

dune migration

lagoon

lagoon

Baltic Sea

14 settlements buried by migrating dunes

Sand Invasion (14-19th centuries)

Advancing dunes(16-18th century)

Buried settlements ( relocation)

Modern townsGPR transect

(segment shown below)

North

Curonian Lagoon

Baltic Sea

Old Karvaičių II

(1740-1797)

Neolithic site

(~4.5 ka BP)

1 km

Buried settlements ( relocation)

Modern townsGPR transect

(segment shown below)

North

Curonian Lagoon

Baltic Sea

Old Karvaičių II

(1740-1797)

Neolithic site

(~4.5 ka BP)

1 km

Neringa

Outcrop/core studies – limited information

water

table

Paleosols – Chronology & Landscape Stability

16

0

Baltic Sea

water table

deflation surface (25 m above MSL)

Russia

Lithuania

deflation remnant

33o

Paleosol

P1 P2

0 5 10 m

De

pth

(m

)

20 km deflation surface

Naglių

Nature Reserve

Range: 300 ns Vertical Resolution: 16-18 cm

230

0

Tw

o-w

ay tra

vel tim

e (n

s)

P3

exposed paleosol P1

dune slipfaces

dune migration

GPR profileMS profile

Paleosols:exposedburied

P1P2P3

P4

P1

0 50 m 100

Baltic Sea(1700 m)

Curonian Lagoon(200 m)

GPR profile

P1

paleo-dunemigration

vegetateddune

ds

dr

drds

ds

deflationremnant

(dr)

CuronianLagoon

BalticSea

Nida

Juodkrante

5 km

N

Lithuania

Russia

C

wind

Radiocarbon and OSL Chronology (cal yBP)

3,355±115 1,255±8

5

5,690±80

700±40 Little Ice Age

begins

14C

OSL 5,243±33

0

3,893±21

0

1,283±80 163±20

Activity-Stability Phases

Phase 1: ~5,700 cal BP

Phases 2-4: 3,400-700 cal BP

Phase 5: post-700 cal BP

(Little Ice Age)

P4

P4 P3 P2

P1

deflation

buried paleosols

soil

soil

P4 P3 P2 P1 Similar evolution:

Łeba dunes, Poland (Borówka, 1975)

Cape Flattery dunes, Queensland, Australia (Pye, 1993)

Age of spit

> 6 ka

burial

with SL rise

Reactivation of aeolian activity: Triggers

charcoal

Storms, disease, deforestation

Fires (natural and man-made)

P1

P1

Buried Landscapes and Structures

7 m

0

water table

ground surface

hyperbolics

dune migration

200 MHz

buried structures?

tree root

buried utilities

Curonian Spit

0 5 10 m

5 m

lagoon

dune surface

dune migration

Human-Landscape Interaction

buried occupation

surface

GPR near Old Karvaičių II

(1700-1797)

Buried settlements ( relocation)

Modern townsGPR transect

(segment shown below)

North

Curonian Lagoon

Baltic Sea

Old Karvaičių II

(1740-1797)

Neolithic site

(~4.5 ka BP)

1 km

Buried settlements ( relocation)

Modern townsGPR transect

(segment shown below)

North

Curonian Lagoon

Baltic Sea

Old Karvaičių II

(1740-1797)

Neolithic site

(~4.5 ka BP)

1 km

~15 m

0

Summary Extreme Events – key mechanism of landward sand transfer

Integrated approach:

- onshore-offshore geophysics

- groundtruth: deep cores (5-10 m in sand)

- multi-dating techniques

New opportunities to reconstruct and quantify:

- Beach/shoreface gradients (texture/depth/wave energy)

- Extent and chronology of erosion (storm impact)

- Quantitative storm hindcasting based on geological indicators

- Shoreline retreat rates (vulnerability to SL rise)

- Channel distribution (onshore-offshore links, stability)

- Channel dimensions (tidal prism, longshore transport)

- Dune stratigraphy (regional climate, sediment supply, sand invasion)

Paldies ~ Thank You

Research Support