Mississippi/Atchafalaya River and Delta Management for the Future

1. Mississippi/Atchafalaya River and Delta Management for the Future G. Paul Kemp Ph.D. Vice-President National Audubon Society Governor's Advisory Commission on Coastal Protection, Restoration and Conservation August 19, 2010 McNeese University

2. Current Management is seen as Unreliable and Destructive…But What Will Replace it?

3. 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…

4. 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)

5. 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

6. 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? Head of Passes Pass a Loutre West Bay Diversion Southwest Pass Jettied Navigation Outlet Bowman Bayou Crevasse South Pass

7. 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

8. Shelf Edge Delta is Geologically Unstable – Sinking and Slumping at 2 meters/century Without Considering Sea Level Rise Loading by River Mouth Sands Shelf edge slumping triggered by gas vents, seismic activity, tsunami or storm waves Low-Angle Slumps and Slides Upthrust of Mud Lump Diapirs 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.

9. 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

11. West Bay Diversion - Sediment is increasingly deposited upstream of traditionally dredged reaches

12. 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

13. Effect of Sea Level Rise Effect of Subsidence

14. Cumulative Deposition in Undredged Reaches = 8.6 Million yd3/y RSLR Sediment Accomodation in Dredged and Undredged Reaches = 3.0 Million yd3/y

15. Baptiste Collette Grand Pass West Bay Diversion Discharge and Sediment is also going around Bird’s Foot as Discharge through Upstream Passes Increases - Grand Pass/Tiger Pass - Baptiste Collette Pass

16. 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

17. 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!

19. 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

20. 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?

21. 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

22. 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

23. 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

24. 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

25. 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

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

27. 15-Day Water Particle Trajectories660K cfs Discharge

28. 15-Day Water Particle Trajectories800K cfs Discharge

29. 15-Day Water Particle Trajectories1,000K cfs Discharge

30. 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

31. 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

32. River Discharge Drops Quickly in Early June

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

34. 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

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

36. 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)

37. 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…

38. Thank You!sorry no birds this time… Questions?