Storm Protection & Coastal Restoration: Moving in to the 21 st Century Denise J. Reed University of New Orleans Restore or Retreat March 2009

Master Plan Objectives Objective #1: Reduce economic losses from storm based flooding Objective #2: Promote a sustainable coastal ecosystem by harnessing the processes of the natural system Objective #3: Provide habitats suitable to support an array of commercial and recreational activities coastwide Objective #4: Sustain the unique heritage of coastal Louisiana

Main Points It’s an ever changing system What does it take to achieve sustainability? – Maximize the use of our resources – Capitalize on natural processes What do we need to do now? – Establish leadership and engage national stakeholders and technical experts

Larose GIWW Cocodrie B. Terrebonne B. Grand Caillou B. Lafourche GIWW Presquile Boudreaux B. Petit Caillou Lafourche Parish Lafourche Parish Terrebonne Parish Terrebonne Parish N N Bourg Ashland 56 Chauvin Dulac Morganza to the Gulf of Mexico Project Morganza to the Gulf of Mexico Project REACH A REACH B Houma Navigation Canal Lock Sector Gates Work in Kind (WIK) Levees Federal Levee Alignment Montegut REACH E REACH F REACH H REACH G REACH I REACH J REACH K REACH L REACH J-1 Houma

MINORS CANAL REACH A REACH B REACH E REACH F REACH H-1 REACH H REACH I REACH JREACH K REACH L REACH G Wetlands Behind Levees = Opportunities?

More tidal exchange = more opportunity for sediment input Existing levees Existing levees Roads

MORGANZA-TO-THE-GULF TECHNICAL PANEL REVIEW Robert Twilley (Chair), Ph.D. Mead Allison, Ph.D. Louis Capozzoli, Sc.D., P.E. Retired Shirley Laska, Ph.D. Larry McKee, P.E. Ehab Meselhe, Ph.D., P.E. Denise Reed, Ph.D. Tim Ryan, Ph.D.

Basic Assessment Continue work on levees, floodgates and environmental structures on the current authorized levee alignment with the goal of providing a minimum system-level of protection (e.g., equivalent to that currently provided by the J1 reach) to the planning area (Phase 1 construction). Continue work on the HNC lock-floodgate structure given its vital role in the protection system and its potential to be used to benefit the ecosystem.

Basic Assessment Integrate proactive wetland restoration approaches (funded under other authorities) into the ongoing design and operation of the Morganza project. Routinely (e.g., every 5 years), revisit the project to reassess risk to communities and the economy, evaluate ecological impacts and benefits, and revise future construction and operation plans and schedules as appropriate.

Planning for Flood Risk Reduction Initiate a comprehensive, community-based planning process to identify the elements that need to be protected for the Terrebonne communities to thrive. Increase efforts to inform the business community and the general public of the level of protection and risk reduction provided. Implement a comprehensive flood management approach for the area that leverages existing programs for non-structural flood risk reduction, provides incentives to businesses and the general public, and provides for the safe location of future development.

USACE Slide courtesy of Pete Rabbon

Planning for Flood Risk Reduction Develop conservation easements, land-use plans and zoning ordinances to protect existing wetlands in the planning area from loss to development. Initiate a public education program to communicate scientifically based assessments economic benefits of improved construction standards on residual risk in the context of future storm frequency, sea level rise and subsidence, oil and gas activities.

Improved Tools and Analyses for Assessment of Integrated Risk Reduction Outcomes Continue to develop a system-wide model and use it, as well as conceptual models and monitoring, to design and operate environmental structures within the levee system; and convene an independent expert panel to guide this adaptive management process. Hold a workshop and/or convene a panel to consider the effects of flooding and salinity changes on wetland plant communities and soil development processes to inform evaluation of project effects on wetlands. Apply planning tools that allow integrated, spatially explicit assessments of structural and non-structural measures in risk reduction and that consider a range of possible future economic, social and environment scenarios.

Sustainability? Master Plan Planning Objective 2 Promote a sustainable coastal ecosystem by harnessing the processes of the natural system. – providing for daily, seasonal, and episodic fluctuations in water levels and salinities, and/or reestablishing natural pathways of sediment movement and nutrient uptake. – Appreciation of the dynamic nature of the coastal system must be integral to the planning and selection of preferred alternatives – route riverine waters through estuarine basins

The Past

Continuing Current Management

Achieving Sustainability

Coast 2050

Is it achievable? There’s not as much sediment in the river as there used to be…… It’s futile to try and build new land in the face of sea-level rise and subsidence……

ECOGEOMORPHOLOGY of Deltaic Coast Wax Lake Delta – An analogue to study the processes of a growing delta; In contrast to Terrebonne & Lafourche that represent degrading stages of delta

. SUMMARY: The Delta Mass Balance The Dynamic Delta Top = competition between sea-level rise + subsidence and deposition of sediment and organic matter: A top the area of the delta top where H is eustatic sea level, σ spatially averaged subsidence rate, Q s total volumetric sediment supply, f r the fraction retained in the delta top, and r org the rate of storage of organic matter in the sediment column, Wonsuck Kim, Gary Parker, David Mohrig, Robert Twilley, submitted 1990

. SUMMARY: The Delta Mass Balance The Dynamic Delta Top = competition between sea-level rise + subsidence and deposition of sediment and organic matter: A top the area of the delta top where H is eustatic sea level, σ spatially averaged subsidence rate, Q s total volumetric sediment supply, f r the fraction retained in the delta top, and r org the rate of storage of organic matter in the sediment column, Wonsuck Kim, Gary Parker, David Mohrig, Robert Twilley, submitted 2000

. SUMMARY: The Delta Mass Balance The Dynamic Delta Top = competition between sea-level rise + subsidence and deposition of sediment and organic matter: A top the area of the delta top where H is eustatic sea level, σ spatially averaged subsidence rate, Q s total volumetric sediment supply, f r the fraction retained in the delta top, and r org the rate of storage of organic matter in the sediment column, Wonsuck Kim, Gary Parker, David Mohrig, Robert Twilley, submitted 2002

. SUMMARY: The Delta Mass Balance The Dynamic Delta Top = competition between sea-level rise + subsidence and deposition of sediment and organic matter: A top the area of the delta top where H is eustatic sea level, σ spatially averaged subsidence rate, Q s total volumetric sediment supply, f r the fraction retained in the delta top, and r org the rate of storage of organic matter in the sediment column, Wonsuck Kim, Gary Parker, David Mohrig, Robert Twilley, submitted 2005

MIGRATION OF THE MODEL FROM WAX LAKE TO THE MISSISSIPPI RIVER BELOW NEW ORLEANS: Two diversions: Barataria Bay and Breton Sound (Envisioning the Coast)

BASE CASE: SEA-LEVEL RISE = 2 mm/yr, SUBSIDENCE = 5 mm/yr = 918 km 2 Solid line: variant case Dotted line: base case “Worst case”: still 701 km 2 of new land And extra land-building due to organics is not yet included Developing a Self-Maintaining Coast is Possible VARIANT CASE: SEA-LEVEL RISE = 4 mm/yr, SUBSIDENCE = 10 mm/yr = 701 km 2

A New Approach to River Management for the 21 st Century

Captain A. A. Humphreys Lieutenant H. L. Abbot Delta Report 19 th Century River Management

Tributary Basin Improvements Levees Floodways Channel Stabilization 20 th Century River Management Mississippi River & Tributaries Project 20 th Century River Management Mississippi River & Tributaries Project

21 st Century Protection, Restoration AND Navigation

Main Points Morganza can balance protection and restoration – we have to make sure it does Levees are not the only thing we need to do to protect ourselves Sustainable restoration takes bold action and will mean change 20 th century - change for the worst 21 st century – change for the better?