Transcript Barrier Island Restoration, Marsh Creation, and River Diversion, Barataria Basin Feasibility Study

Louisiana Coastal Area,
Louisiana—
Ecosystem Restoration
Barrier Island Restoration, Marsh
Creation, and River Diversion,
Barataria Basin Feasibility Study
Importance of Coastal Louisiana to Nation
• The Mississippi River is the lifeblood of coastal
Louisiana’s industries, infrastructure, ecosystem,
and culture
• The Louisiana coastal area and the river greatly
contribute to the Nation’s economic development
• Billion dollar/yr coastal fishery industry
– 30% of nation’s production
– More than all of Atlantic seaboard production
– More than any other Gulf state
• Infrastructure for 17% of oil and 25% of natural
gas produced in nation
Importance of Coastal Louisiana to Nation
• Navigation projects for No. 1 Port complex in Nation
– 400 million tons/yr
– 155 miles of waterways threatened by coastal erosion
• Hurricane protection for 2 million people
• Coastal habitat for millions of birds and animals
• 70% of Nation’s migratory waterfowl of Mississippi
Flyway overwinter in Louisiana coastal area
• World renowned for recreation – fishing, hunting,
and boating
Importance of Coastal Louisiana to Nation
• The entire Mississippi River drainage basin drains
through south Louisiana
– Strategic national location for the regulation of basin
floodwaters using Old River Control Complex, locks, flood
gates, and levee systems
– Supports existence, economic growth, and prosperity of
businesses located along the floodplains of the entire
Mississippi River and its tributaries
– With the Nation’s necessary continued use of river controls
in south Louisiana, river water that is life giving to coastal
areas is channeled directly to the Gulf of Mexico
– This represents a continual loss of natural wetland
sustenance
Louisiana Land and Water Changes 1956-1990
Will Be Lost Forever...
1956
2050 ???
2050 projection adapted from LSU Natural
Systems Engineering Laboratory, 1998
LOUISIANA COASTAL PLAIN
Land Loss 1930's to 1990* and 2050 Projection
Land Remaining (thousand of acres)
6,000
1,500 square miles
1,000 square miles
5,500
5,000
4,500
4,000
3,500
1930
1956-58 1974 1983 1990
2050
* after Dunbar et al. 1992
Causes of Loss:
160 million tons of sediment are delivered to the
continental shelf each year. Most of this material is
unavailable for marsh building processes because
levees prevent overbank sedimentation.
Causes of Loss:
(continued)
Canal and Channel Dredging
Causes of Loss:
(continued)
Herbivory
Causes of Loss:
(continued)
Subsidence (ft/century)
Low 0-1
Intermediate 1.1 - 2
High 2.1 - 3.5
after Gagliano, 1999
Causes of Loss:
(continued)
Relative Sea Level Rise
Level Rise
(Inches)
20
10
8
0
1990
2010
2030
Year
2050
after Wigley and Raper, 1992
Will Be Lost Forever...
By 2050 nearly 1,000 square miles of
Louisiana’s wetlands, an area nearly the
size of Rhode Island, will become open
water.
Will be lost forever...
Impending Ecosystem Collapse
• Funded projects will have addressed 22% of projected
future marsh loss through 2050.
• Even with these in place, 408,000 acres of marsh and
233,500 acres of swamp will be lost.
• This will have major social, economic, and environmental
consequences. At risk are:
~ Communities
~ Infrastructure
~ Fisheries
~ Migratory Birds
~ A Unique Culture
• The Coast 2050/LCA Feasibility Study would address the
remaining 641,500 acres of projected wetland loss.
Available Options
• Abandon the coast — relocate.
• Put the coast on life support — rock,
ring, and pump.
• Status quo — small-scale solutions.
• One comprehensive plan that addresses
the causes of the problem — required
to sustain our coast.
Coast 2050:
Toward a Sustainable
Coastal Louisiana
Vision:
“…to sustain a coastal ecosystem that
supports the environment, economy and
culture of southern Louisiana, and that
contributes greatly to the economy and wellbeing of the nation.”
Coast 2050 Ecosystem Goals
• Assure vertical accretion to achieve sustainability
of greatest wetland acreage practicable
• Maintain estuarine gradient to achieve habitat
diversity
• Maintain exchange and interface to achieve
system linkages
Acceptable
to the
Public
Ecosystem
Needs
Federal State Local
PARTNERSHIP
Common
Ground
COAST 2050
Consensus Building
Strategic
Coastal
Plan
Results of Coast 2050 Initiative
• Consensus-based, grass roots planning initiative for
ecosystem restoration
• Comprehensive plan for restoration of Louisiana’s
coastal landscape by Federal, state, and parish
governments
• Identification of perceived and predicted problems
facing coastal Louisiana
• Broad-scale restoration strategies
• Basis for Louisiana Coastal Area Feasibility Study
The Consensus...
ASCENSION
VERMILION
ASSUMPTION
CALCASIEU
CAMERON
Coast 2050 Plan
JEFFERSON
IBERIA
TERREBONNE
LAFOURCHE
TANGIPAHOA
LIVINGSTON
ST. TAMMANY
ORLEANS
ST. MARY
ST. MARTIN
Approved by all
Coastal Parishes
ST. JOHN
THE BAPTIST
ST. JAMES
ST. CHARLES
PLAQUEMINES
ST. BERNARD
LCA Feasibility Study
• USACE Reconnaissance Report:
– Supports the Coast 2050 Plan
– Approved for feasibility study start in May 99
• LCA General Investigations study authorization
– Used existing 1967 authority
– Broad latitude for study purposes
– Current purpose: ecosystem restoration
• Project funding vehicle: Water Resources
Development Act (WRDA)
Barataria Basin Study Methodology
for Ecosystem Restoration
• No dollar-based benefit-cost ratio criteria
– Primary Criteria: $/Habitat Unit
– Additional Selection Criteria: Economic Impact
• estimation of economic impact as ancillary
benefits
• hurricane, flood control, navigation
• economic analysis qualified for intended use
– Existing information updated
– Ranges of costs stated
• Cost Effectiveness/Incremental Cost Analysis used to
optimize plans
Louisiana’s Coast 2050 Regions:
Coastal Louisiana
Hydrologic Basin Area
Louisiana’s Coastal Basins:
LOUISIANA COASTAL AREA, LOUISIANA -- ECOSYSTEM RESTORATION
REGION AND BASIN MAPS FOR
LOUISIANA COASTAL AREA AUTHORITY
U.S. ARMY ENGINEER DISTRICT, NEW ORLEANS, LA
CORPS OF ENGINEERS
August 1999
COAST 2050 REGION 2 REGIONAL
ECOSYSTEM STRATEGIES
Divert through Existing Locks
Manage Outfall of Existing Diversions
Enrich Existing Diversions with Sediment
Restore Swamps
Small River Diversions
Manage Diversion Outfall
Flood Protection
Restore Natural Drainage Patterns
Protect Bay Fringe Marshes
Interior Breakwaters
Reef Zones
Preserve Land Bridge
River Diversions
Maintain Shoreline Integrity
Dedicated Dredging
LEGEND
Sediment Trap
for Marsh Creation
Rebuild Little Lake
Marshes
Conveyance Channel
and Delta Lobe
Restore/Maintain
Barrier Shoreline
Improve Drainage
Mississippi River Diversions
with Outfall Management
Marsh creation with dredged
material
Marsh Creation
along Hwy 1 and
Caminada Bay
Extend Barrier
Shoreline
Build and Maintain
Delta Splays
Prevent loss of
sediments off of
the Continental Shelf
Approach for Barataria Study
18-mo. interim report
• Focus -- critical, fragile gulf
perimeter:
– Marsh creation
– Barrier island
restoration
– River diversion
• Objectives:
– Rebuild and protect
unique gulf fringe, bays,
and shoreline ecosystem
– Provide support to basin
interior for restoration
Preparation for envisioned
3-yr study during 18-mo.
interim report:
• Hydrologic and Hydraulic
modeling developed for
basin
• Objective:
– Prepare to evaluate
interior basin strategies
related to movement
and circulation of water,
sediment, and nutrients
Land Loss
1930’S to 1956-58
1956-8 to 1974
1974 to 1983
1983 to 1990
R2-17. Dedicated Delivery of
Sediment for Marsh Building
in Caminada Bay
R2-16. Dedicated Dredging
for Marsh Creation along Hwy. 1
Marsh Creation
Barrier Island Restoration
R2-22. Restore/maintain
Barrier Shoreline,
Port Fourchon to Sandy Point
R2-11. Delta Building
Diversion at Bastian Bay
LOUISIANA COASTAL AREA, LOUISIANA -- ECOSYSTEM RESTORATION
Barrier Island Restoration, Marsh Creation, River Diversion,
and Ecosystem Restoration, Barataria Basin
MARSH CREATION, BARRIER ISLAND, & RIVER
DIVERSION RESTORATION AREA MAP
U.S. ARMY ENGINEER DISTRICT, NEW ORLEANS, LA
CORPS OF ENGINEERS
August 1999
Considerations for Investigation
Marsh Creation
• Target areas (Hwy. 1 and Caminada Bay):
• Alternatives for investigation:
– Dredge and fill
– Terracing
– Vegetative Plantings
• Three scales of analysis — each alternative
Considerations for Investigation
Marsh Creation
• Cut-to-fill volume of available material
• Supply of dredging resources
• Coordination with Gulf Region dredging events
• Environmental impact to borrow areas
• Slope stability of borrow areas, relocations
• Potential dredge material sources:
– Bayou Lafourche
– Interior Barataria Basin lakes
– Offshore
Strategies to Meet Design Challenges:
Marsh Creation
• Research historical estuarine features of area.
• Develop conceptual designs to emulate
historically open water in areas.
• Use combination of dredge-and-fill, terracing,
and vegetative plantings.
• Conserve available borrow resources.
Considerations for Investigation
Barrier Island Restoration
• Volume and characteristics of available material
• Ship Shoal
• Barataria basin ebb-tide shoals
• Mississippi River
• Types of dredging systems to efficiently and
effectively perform work
• Availability of dredging equipment
• Coordination with regional dredging events
• Environmental impact to borrow areas
Considerations for Investigation
Barrier Island Restoration
Adaptive Management Concept:
• New sand in system thru dredge-and-fill
• Sand will re-arrange itself over time – littoral drift
• Some sand will be lost to gulf
• Minimal Operation and Maintenance costs over
project life (30-50 yrs)
Strategies to Meet Design Challenges:
Barrier Island Restoration —
Port Fourchon to Sandy Point
• Comprehensive offshore seismic and boring program
– Wide swath gulfward of islands
– Ship Shoal
• Sediment suitability analysis
• Three alternatives combining measures such as:
– Dredge and place
– Coastal structures (e.g., breakwaters, revetments,
geotubes)
• Three scales for each alternative
Coast 2050 Strategy
Delta Building Diversion at Bastian Bay
WHAT IS THE COAST 2050
PARTNERSHIP ?
Coast 2050 is about
planning a better future
for coastal Louisiana.
The public and federal,
state, and parish
representatives have
developed a single
strategic plan to sustain
our estuaries, using the
best science available.