Mississippi/Atchafalaya River and Delta Management for the

Future G. Paul Kemp Ph.D.

Vice-PresidentNational Audubon Society

Governor's Advisory Commission on Coastal Protection, Restoration and Conservation

August 19, 2010McNeese University

Current Management is seen as Unreliable and Destructive…

But What Will Replace it?

Diamond’s Dilemma

• Some cultures that failed to survive knew that they were destroying the environment they depended on…

• But were unable to change behavior fast enough to avert disaster…

Examples for the Commission to Consider

• Wetland Loss and Expansion of Marsh Channels Increase Cost and Decrease Feasibility of 100 Year+ Hurricane Protection– MRGO Case Study (Took 40 years & 2 disasters)

• Mississippi River Mouth is Retreating from ‘Bird’s Foot’ Shelf Edge Position – West Bay Diversion Case Study (Proposed cure does

not address real issue)• Apparent Incapacity to Respond to New

Information or Situations– Oil Spill Case Study (Exposed unaddressed problems

at Old River)

A TREASURE TROVE OF NEW INFORMATION ABOUT THE MOUTH OF THE MISSISSIPPI RIVER COMING OUTOF WEST BAY DIVERSION STATE-FEDERAL CWPPRA DISPUTE

-Great Compilation of Data from Tarbert Landing Downstream: 1962 – Present

-50 Years of River Surveys on CommonNAVD88 Datum

-Preliminary 1D, 2D, and 3D Model Results

-Focus on West Bay Diversion

Nowhere is collapse more evident than at the mouth of the Mississippi• The Deltaic Paradox: Why is land loss highest where the sediment

supply is theoretically greatest?

Southwest Pass Jettied Navigation Outlet South Pass

Pass a Loutre

West Bay Diversion

Head of Passes

Bowman Bayou Crevasse

New field data and modeling confirms results from LDNR/LSU

Small-Scale Physical Model

Sail-Through Lock Operates as Closure When Sand is Moving to Increase Diversion Efficiently

Shelf Edge Delta is Geologically Unstable – Sinking and Slumping at 2 meters/century Without Considering Sea

Level Rise

Shelf edge slumping triggered by gas vents, seismic activity, tsunami or storm waves

Loading by River Mouth Sands

Coleman et al. 1980. Subaqueous Sediment Instabilities in the Offshore Mississippi River Delta IN L.R. Handley (ed.) Environmental Information on Hurricanes, Deep Water Technology and Mississippi Delta Mudslides in the Gulf of Mexico. BLM Open-File Rept. No. 80-02.

Upthrust of Mud Lump Diapirs

Low-Angle Slumps and Slides

So what is happening at the mouth of the river??

Dredging Reduced 50 Percent Since 1998 from 19.4 to 11.5 Million CYD/y

Mississippi River Thalweg Elevation Downstream of Belle Chase (2004 USACE Hydro Survey) With ERDC 2009 Reach Numbers (R1-R15)

-200

-180

-160

-140

-120

-100

-80

-60

-40

-20

0

-20 -10 0 10 20 30 40 50 60 70 80

River Mile Above Head of Passes

Min

imu

m T

hal

weg

Ele

vati

on

(f

t, N

AV

D88

) Bolivar Point

The Jump

West Bay Diversion

Southwest Pass

R1R2

R3R4

R5

R6

R7R8

R9R10

R11

R12R13

R14

R15

Erosion or Deposition (red) and Relative Sea Level Rise (yellow): 1992-2004

-200,000

-100,000

0

100,000

200,000

300,000

400,000

500,000

600,000

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

ERDC Mississippi River Reach Number

Dep

ositi

on o

r Ero

sion

from

199

2 to

200

4 Su

rvey

(y

d3/y

/mile

)Reaches 10 - 12 Dredged Annually

806,452 yd3/y/mile

Reach 9 Dredged

Once (PAA)44,444

yd3/y/mile

- Sediment is increasingly deposited upstream of traditionally dredged reaches

West Bay Diversion

Why is dredging volume reduced in last decade?

• Less sediment coming into Lower Mississippi past Atchafalaya Diversion (Tarbert Landing)?– NOT REALLY

• More sediment depositing upstream of dredged reaches? YES

• More sediment depositing below dredge template?

• More sediment bypassing dredged reach?– Upstream Diversions or More Efficient Conveyance

Downstream

Effect of Sea Level Rise

Effect of Subsidence

Erosion or Deposition (red) and Relative Sea Level Rise (yellow): 1992-2004

-200,000

-100,000

0

100,000

200,000

300,000

400,000

500,000

600,000

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

ERDC Mississippi River Reach Number

Dep

osi

tio

n o

r E

rosi

on

fro

m 1

992

to 2

004

Su

rvey

(yd3

/y/m

ile)

Reaches 10 - 12 Dredged Annually

806,452 yd3/y/mile

Reach 9 Dredged

Once (PAA)44,444

yd3/y/mile

Cumulative Deposition in Undredged Reaches = 8.6 Million yd3/y

RSLR Sediment Accomodation in Dredged and Undredged Reaches = 3.0 Million yd3/y

Discharge and Sediment is also going around Bird’s Foot as Discharge through Upstream Passes Increases

- Grand Pass/Tiger Pass

- Baptiste Collette Pass

West Bay Diversion

Percent Mississippi River Discharge Through Upstream Passes

0

5

10

15

20

25

1960-1970 1970-1980 1980-1990 1990-2000 2000-2010

Decade

Pe

rce

nt

Dis

ch

arg

e a

t T

arb

ert

La

nd

ing

(%

)Baptiste Collette Grand Pass Upstream Pass Total

Baptiste Collette

Grand Pass

Relative Sea Level Rise

• Favors upstream diversions over those closer to sea level– Grand/Tiger Pass mean discharge has risen

from 4 % up to 10 % of Tarbert Q since 1960s– Baptiste Collette Pass discharge has also

risen from 4 % up to 10 % of Tarbert Q since 1960s

– Pass a Loutre mean discharge has decreased from 30 % to 12 % of Tarbert Q since 1960s

Why is dredging volume reduced in last decade?

• Less sediment coming into Lower Mississippi past Atchafalaya Diversion (Tarbert Landing)?– No, not for sand.

• More sediment depositing upstream of dredged reaches?– Yes!

• More sediment depositing below dredge template?– Yes!

• More sediment bypassing dredged reach?– Yes, more goes around every year!

What does this mean for river mouth evolution?

• With relative sea level rising at 0.5 ft/decade, river is abandoning its ‘low-stand’ bird-foot mouth

• 20th Century river management including revetments and jettying has slowed this abandonment but at great cost to adjacent deltaic wetlands

• Opportunities exist to manage a shorter river for improved navigability (deeper draft) and a more sustainable delta

River Mouth Case StudyHow long can we pretend not to

see what is happening?

Diamond’s Choice Keep patching existing system until it breaks catastrophically OR prepare a

fall-back plan?

Examples for the Commission to Consider

• Wetland Loss and Expansion of Marsh Channels Increase Cost and Decrease Feasibility of 100 Year+ Hurricane Protection– MRGO Case Study

• Mississippi River Mouth is Retreating from ‘Bird’s Foot’ Shelf Edge Position– West Bay Diversion Case Study

• Apparent Incapacity to Respond to New Information or Situations– Oil Spill Case Study

Deepwater Horizon BlowoutApril 22, 2010 – July 15, 2010

• Blowout in federal waters on OCS 50 miles from Louisiana

• Louisiana requests concurrence from USACE to open Davis Pond and Caernarvon Diversions to full capacity

• USACE asked to consider using Old River Structures to shift Mississippi River discharge between Bird-Foot and Atchafalaya outlets to protect coast

• ERDC CHL (Vicksburg) makes AdH model runs

Deepwater Horizon BlowoutApril 22, 2010 – July 15, 2010

• Louisiana NGOs asked by EPA Administrator Jackson to make recommendations (June 5)– Top recommendation is to optimize use of the River including

adjusting Old River percentage as appropriate

• White House contacts Kemp and asks him to confer ERDC CHL Director Martin about emergency measures as Mississippi discharge drops precipitously

• Kemp (Audubon) makes recommendations to the White House, while State pursues berm projects

• • River rises fortuitously, NO EMERGENCY DECLARED

Deepwater Horizon BlowoutApril 22, 2010 – July 15, 2010

• Blowout in federal waters on OCS 50 miles from Louisiana

• Louisiana requests concurrence from USACE to open Davis Pond and Caernarvon Diversions to full capacity

• USACE asked to consider using Old River Structures to shift Mississippi River discharge between Bird-Foot and Atchafalaya outlets to protect coast

• ERDC CHL (Vicksburg) makes AdH model runs

Domain of AdH model used by CHL in early May to test concept of changing operation at Old River to reduce oil

impacts (Ebersole 2010)

Ebersole, B. 2010. Effects of Increased MS River Discharge on Potential for Spill Movement Into Breton Sound and Adjacent Wetlands. Powerpoint Presentation dated May 7, 2010, from Chief, Flood and Storm Protection Division, ERDC Coastal and Hydraulics Laboratory. Vicksburg, MS

Simulation begins on May 6 when tide range is decreasing. Onshore winds a week later occur during spring tides.

15-Day Water Particle Trajectories660K cfs Discharge

15-Day Water Particle Trajectories800K cfs Discharge

15-Day Water Particle Trajectories1,000K cfs Discharge

Results Indicate Potential for River Flow to Protect Marsh

(Ebersole 2010)• 200,000 cfs increase from 800K to 1000K cfs is

comparable in magnitude to large deviation in flow at Old River

• Particles released in Breton sound tend to remain in Breton Sound, same as 660K and 8080K cases, but move closer to the barrier islands and away from the interior marshes

• There are more beneficial effects at 1,000K discharge level in terms of spill movement into Breton Sound

Deepwater Horizon BlowoutApril 22, 2010 – July 15, 2010

• Louisiana NGOs asked by EPA Administrator Jackson to make recommendations (June 5)– Top recommendation is to optimize use of the River including

adjusting Old River percentage as appropriate• White House contacts Kemp and asks him to confer

ERDC CHL Director Martin about emergency measures as Mississippi discharge drops precipitously

• Kemp (Audubon) makes recommendations to the White House to use river to keep oil out of marsh, while State pursues berm projects

• River rises fortuitously, NO EMERGENCY DECLARED

River Discharge Drops Quickly in Early JuneMississippi and Atchafalaya Discharge During Deepwater Horizon Release

0

100,000

200,000

300,000

400,000

500,000

600,000

700,000

800,000

900,000

1,000,000

12-Apr-10

2-May-10

22-May-10

11-Jun-10

1-Jul-10 21-Jul-10

10-Aug-10

30-Aug-10

Date

Dis

ch

arg

e (

cfs

)

Miss Q Atch Q

May 2

BlowoutApril 22

May 30

June 18

July 1Well CappedJuly 15

TS Alex

As Latitudinal Discharge Dropped 71,000 cfs in 1 day (June 7), Discharge past New Orleans was reduced by 59,000 cfs

Options Recommended to White House

• The President could declare a Mississippi River Emergency that would allow actions outside of standard operating procedures at ORCS or on tributary dams

• Convene external advisory group to guide Corps on spill response similar to DOE group overseeing BP well ops

• Put investigators and instruments in field to validate model results and provide feedback

• Develop strategy to work around Low Sill Structure deficiencies

USACE were unable to respond to Oil Emergency primarily because of unaddressed issues related to safety of Low Sill

StructureHead Across Low Sill Structure at Old River During Deepwater Horizon Release

0

5

10

15

20

25

30

35

12-Apr-10 2-May-10 22-May-10 11-Jun-10 1-Jul-10 21-Jul-10 10-Aug-10 30-Aug-10

Date

Hea

d D

iffe

ren

ce (

ft)

Head Redline 10%Deviation

Maximum Head Difference Currently Allowed Across Low Sill Structure

Maximum Head Required to Put 10 Percent More Flow Past New Orleans

Examples for the Commission to Consider

• Wetland Loss and Expansion of Marsh Channels Increase Cost and Decrease Feasibility of 100 Year+ Hurricane Protection– MRGO Case Study (Took 40 years & 2 disasters)

• Mississippi River Mouth is Retreating from ‘Bird’s Foot’ Shelf Edge Position – West Bay Diversion Case Study (Proposed cure does

not address real issue)• Apparent Incapacity to Respond to New

Information or Situations– Oil Spill Case Study (Exposed unaddressed problems

at Old River)

Diamond’s Dilemma

• Some cultures that failed to survive knew that they were destroying the environment they depended on…

• But were unable to change behavior fast enough to avert disaster…

Thank You!sorry no birds this time…

Questions?