Top Banner
Denise Reed Pontchartrain Institute University of New
24
Welcome message from author
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
Page 1: Denise Reed Pontchartrain Institute University of New Orleans.

Denise ReedPontchartrain InstituteUniversity of New Orleans

Page 2: Denise Reed Pontchartrain Institute University of New Orleans.

Projected Coastal Louisiana Trends: 1956-2050

LandWater

Land Loss 1956-2000Projected Land Loss 2000-2050

Land Gain 1956-2000Projected Land Gain 2000-2050

1956 – 2000 1525 sq. mi. of coastal landscape lost average rate 35 sq.mi./yr. for 44 years

2000 – 2050 Projected loss - another 513 square miles

Page 3: Denise Reed Pontchartrain Institute University of New Orleans.

The Past

Page 4: Denise Reed Pontchartrain Institute University of New Orleans.

Land

Are

a

Time

Natural cycles

Rapid land loss

Limited land building

20th century

Delta building- River deposition

Delta loss- subsidence, storms

Page 5: Denise Reed Pontchartrain Institute University of New Orleans.

Existing marshes must build up to survive

NaturalSubsidence

Sea-Level Rise

+

= Higher relative water levels

Page 6: Denise Reed Pontchartrain Institute University of New Orleans.

Can marshes keep pace with subsidence and sea-level rise?

Page 7: Denise Reed Pontchartrain Institute University of New Orleans.

Marsh Building ProcessesPEAT PLUS TRAPPED SEDIMENT

MINERAL SUBSTRATE

SLNET ACCRETION

NA + S = AA

SEDIMENT

SUBSIDENCE

T1 TIME T2

ORGANICMATTER ACCUMULATION

CO2

CH4

PRIMARY PRODUCTION

SEALEVEL

ORGANICCARBON EXPORT

DE

CO

MP

OS

ITIO

NO

R

OX

IDA

TIO

N

AB

SO

LU

TE

EL

EV

AT

ION

DETRITUS

ROOTS

PEAT PLUS TRAPPED SEDIMENT

MINERAL SUBSTRATE

PEAT PLUS TRAPPED SEDIMENT

MINERAL SUBSTRATE

SLNET ACCRETION

NA + S = AA

SEDIMENT

SUBSIDENCE

T1 TIME T2

ORGANICMATTERORGANICMATTER ACCUMULATION

CO2

CH4

PRIMARY PRODUCTION

SEALEVELSEALEVEL

ORGANICCARBON EXPORT

ORGANICCARBON EXPORT

DE

CO

MP

OS

ITIO

NO

R

OX

IDA

TIO

N

DE

CO

MP

OS

ITIO

NO

R

OX

IDA

TIO

N

AB

SO

LU

TE

EL

EV

AT

ION

DETRITUS

ROOTS

DeLaune et al. 1990

Page 8: Denise Reed Pontchartrain Institute University of New Orleans.

How do marshes build withoutsediments from the river?

Storms!Increase water levels and mobilize sediment

Page 9: Denise Reed Pontchartrain Institute University of New Orleans.

BB JL CC OOB BC LL TB0.000

0.005

0.010

0.015

0.020

Hurricane Andrew

Sed

imen

t D

epo

siti

on

(g

/cm

2/d

ay)

Sites

Pre-Storm Storm Post-Storm

Cahoon et al., 1995

Page 10: Denise Reed Pontchartrain Institute University of New Orleans.

Fourchon

Date

5/7

/96

5/2

1/9

6

6/4

/96

6/1

8/9

6

7/2

/96

7/1

6/9

6

7/3

0/9

6

8/1

3/9

6

8/2

7/9

6

0

0.0002

0.0004

0.0006

Sed

imen

t D

epo

siti

on

(g/c

m2 /

day

)

0.2

0.4

0.6

0.8

Tid

e (m

ab

ove

loca

l dat

um

)

Hurricane Dolly 22 August 1996

Page 11: Denise Reed Pontchartrain Institute University of New Orleans.

10/3

0/01

11/1

3/01

11/2

7/01

12/1

3/01

1/9/

02

1/23

/02

2/7/

02

2/21

/02

3/6/

02

3/21

/02

4/2/

02

4/16

/02

4/30

/02

5/17

/02

6/3/

02

6/12

/02

6/28

/02

7/10

/02

7/30

/02

8/15

/02

9/3/

02

9/17

/02

10/1

/02

10/1

7/02

10/2

9/02

0.0000

0.0005

0.0010

0.0015

0.0020

0.020.030.04

S

edim

ent

Dep

osi

tio

n (

g/c

m2 /d

ay)

Collection Date

NaturalChannel Spoilbank Gaps

Reed et al., 2006

Hurricane Lilli 2002

Page 12: Denise Reed Pontchartrain Institute University of New Orleans.

How Much Sediment for Maintenance?

Katrina and Rita estimated to have delivered 130 million tonnes (Turner et al., 2006)

Page 13: Denise Reed Pontchartrain Institute University of New Orleans.

River levees stop restrict delta building to a few areas

Regular sediment supply from the river to existing marshes is eliminated. Storm reworking is their only source of sediment.

Page 14: Denise Reed Pontchartrain Institute University of New Orleans.

Houma Navigation Channel

“MRGO”

Navigation Channels

Page 15: Denise Reed Pontchartrain Institute University of New Orleans.

Pipeline Canals

Page 16: Denise Reed Pontchartrain Institute University of New Orleans.

Solutions?

Maintain what we haveRebuild what we’ve lost

Page 17: Denise Reed Pontchartrain Institute University of New Orleans.

Continuing Current Management

Page 18: Denise Reed Pontchartrain Institute University of New Orleans.

Achieving Sustainability

Page 19: Denise Reed Pontchartrain Institute University of New Orleans.

“Prevent loss of sediments into the deep Gulf”

Page 20: Denise Reed Pontchartrain Institute University of New Orleans.

Coast 2050 Coast 2050 Coast 2050 Coast 2050

Page 21: Denise Reed Pontchartrain Institute University of New Orleans.

“..large-scale concepts that could provide significant long-term ecosystem restoration benefits”

Page 22: Denise Reed Pontchartrain Institute University of New Orleans.

Photo taken by NASA April 29, 2008

Average annual loss to Gulf~120 million tons of sediment

Page 23: Denise Reed Pontchartrain Institute University of New Orleans.

21st Century• Sea level rise accelerates….• Storm impacts increase….• Using the River gives Coastal Louisiana a

fighting chance

Page 24: Denise Reed Pontchartrain Institute University of New Orleans.