Archive for Science


What can the 1927 flood teach us about coastal restoration?

February 2, 2016 | Posted by Delta Dispatches in Coastal Protection and Restoration Authority (CPRA), coastal restoration, Community Resiliency, Diversions, Mid-Barataria Sediment Diversion, Restoration Projects, Science

By Natalie Peyronnin, Director of Science Policy, Mississippi River Delta Restoration, Environmental Defense Fund

During the historic 1927 flood, a portion of the Mississippi River levee south of New Orleans was dynamited to lower the water level and prevent catastrophic flooding – seen in much of the Mississippi River Basin – from occurring in the city. This explosion created a 2-kilometer wide crevasse, which redirected water into nearby Breton Sound.

Nearly 90 years later, scientists have completed measurements in the upper Breton Sound basin to quantify the sediment deposition in the 50-square-mile crevasse splay created by the levee break.

In the study, “Sediment Deposition at the Caernarvon Crevasse during the Great Mississippi Flood of 1927: Implications for Coastal Restoration,” John W. Day et al. state that “The 1927 crevasse deposition shows how pulsed flooding can enhance sediment capture efficiency and deposition and serves as an example for large planned diversions for Mississippi delta restoration.”

Figure 2. The Breton Sound Estuary. Dots indicate where core samples were taken and the approximate area of the crevasse splay deposit based on researchers measurements. Blue dots indicate cores that has additional analysis carried out. Upper right inset: aerial photo showing Mississippi River flowing through the 1927 Caernarvon levee breach. Dark black line at hte site of the crevasse is the estimated width of the levee breach.

Figure 2. The Breton Sound Estuary. Dots indicate where core samples were taken and the approximate area of the crevasse splay deposit based on researchers' measurements. Blue dots indicate cores that had additional analysis carried out. Upper right inset: aerial photo showing Mississippi River flowing through the 1927 Caernarvon levee breach. Dark black line at the site of the crevasse is the estimated width of the levee breach. John W. Day et al.

Researchers found a distinct layer of sediment from the 1927 crevasse, ranging from 0.8-16.5 inches thick, at 23 of the sites they sampled, with the thickest layer closest to the river. The investigators estimated that more than 40 million tons of sediment flowed from the Mississippi River into Breton Sound during the 108 days the crevasse was open.

The marshes in the splay captured approximately 55-75 percent of the suspended sediments that poured through the crevasse, which resulted in the deposition of roughly 30 million tons of sediment within the 50-square-mile crevasse splay. In one core, the sediment deposition rate in 1927 was at least 0.8 inches per month – that’s 10 times more than the annual post-1927 average. The results of this study could have important implications for future coastal restoration projects, specifically sediment diversions.

Lessons learned for restoration

The flood of 1927 was an unprecedented, fatal flood that caused massive and widespread economic and structural damages. Louisiana, as well as all the other communities along the Mississippi River, are now largely protected by a federal system of levees and spillways, as evidenced during this year’s winter flood.

But the 1927 flood also provided a major land-building opportunity, as wetlands help provide protection from future flooding and loss of life. Large, episodic flood events, like the 1927 flood and this winter’s high-water event, can be used to build vast land in relatively short periods of time, while balancing the needs of the ecosystem and the people and wildlife that depend on it.

The state of Louisiana is currently working to engineer and design controlled river diversions, which would harness the power of the river to build land. This past fall, the Coastal Protection and Restoration Authority voted to advance the Mid-Barataria and Mid-Breton sediment diversions. Controlled sediment diversions like these are vital components of any large-scale restoration plans.

Possible effects on fisheries

Despite their land-building potential, there currently exist some questions and concerns about how sediment diversions will affect fisheries. The researchers determined that the periodic opening of flood control structures, such as the Bonnet Carré Spillway and the 1927 crevasse, during high-water events, demonstrate the balance that can be achieved between inflows of fresh water and fishery concerns.

“The periodic opening of the Bonnet Carré Spillway and the 1927 crevasse at Caernarvon serve as good models for understanding the significance of this fishery concern. The periodic openings have minimized algal blooms to short periods and resulted in larger fisheries catches in years following openings,” the study says.

“Given predictions of accelerated sea level rise, increasing human impacts, and growing energy scarcity, delta restoration should be aggressive and large-scale. We believe that restoration of the Mississippi delta will require diversions similar in scale to historical crevasses if they are to be most effective.”

How was the research conducted? 

The scientists collected 23 sediment cores that extended down 1 meter throughout the 50-square-mile crevasse outfall area. The core sediments were analyzed for sediment type, properties and age. Deposition of sediment from the crevasse extended over seven miles from the break in the levee.

The 1927 sediment deposits were found at an average depth of 13.8 inches below the marsh surface, suggesting a post-1927 deposition rate of 0.2 inches per year. Deposition rates ranged from 0.2 to 4.6 inches per month over the 3.6 months that the crevasse was open.

The estimated sediment load entering through the crevasse from the river during the 1927 event was 40 to 54 million tons, and roughly 30 million tons of that sediment was deposited and retained within the 50-square-mile crevasse splay. Based on the varying thickness of the 1927 deposit over the splay, the volume of the 1927 deposit could cover 11.5 square miles with about 3 feet of sediment.

The lessons learned from researching previous high-water events can help planners design the best, most effective restoration solutions to help rebuild wetlands vital to our future.

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Mississippi River’s High Water Brings (Literally) Tons of Needed Sediment to Louisiana

January 20, 2016 | Posted by jhebert in 2011 Mississippi River Flood, Army Corps of Engineers, Coastal Protection and Restoration Authority (CPRA), coastal restoration, Diversions, Mid-Barataria Sediment Diversion, Science

By Alisha Renfro, Staff Scientist, Restore the Mississippi River Delta Coalition, National Wildlife Federation

This is the second in a series of blog posts focusing on the recent opening of the Bonnet Carré Spillway in response to the Mississippi River high-water event. See the first post on the history of the Mississippi River and Tributaries (MR&T) system here

The current high-water event on the Mississippi River is sending more than one million cubic feet of water per second down the lower Mississippi River, carrying with it sediment that is an essential ingredient to restoring Louisiana’s wetlands. The unfortunate irony is that a great deal of this sediment is passing right through Louisiana and off the outer continental shelf, beyond where it can be of any immediate restorative benefit to the state’s vanishing wetlands.

Historically, flood events like this helped to build and maintain the once vast wetlands of the Mississippi River Delta. Today, without sediment diversion projects in place, much of that turbid brown water completely bypasses our sediment-starved wetlands and is lost. Once in place, sediment diversions, integrated with the flood protection system, will capture this opportunity and put the river back to work rebuilding our wetlands.

SedimentGraphJan2016

On average, the Mississippi River carries about 2.5 tons of sediment per second past the Belle Chasse river gage south of New Orleans. However, during high discharge events, sediment load in the river can increase considerably. When river discharge reaches one million cubic feet per second, roughly 6.5 tons of sediment is carried past the Belle Chasse station every second – that’s more than double the average.

Over the last two years, an estimated 184 million tons of sediment has passed Belle Chasse. Some of this sediment is deposited in the river channel, in wetlands and in shallow water around the Bird’s Foot Delta. However, most of this sediment is lost to deeper waters off the continental shelf, as seen in the above MODIS satellite image.

As Louisiana’s land loss crisis has worsened, the need to capture and use this sediment is greater than ever. But while our sediment counter continues to tick away, some progress has been made. Since 2012, projects in the vicinity of Lake Hermitage, Bayou Dupont and Grand Liard have used sediment dredged from the river to create land. Even more significant, last October, the Coastal Protection and Restoration Authority recommended the advancement of two sediment diversion projects at Mid Barataria and Mid Breton into engineering and design. Together, marsh creation and sediment diversion projects will better leverage the precious resource that is constantly flowing through our state to help restore Louisiana’s coast.

Hopefully the next time we have a high-water event like this one, we’ll have sediment diversions in place to make the most out of the situation: to both reduce potential flooding AND capture sediment for restoration. Now that’s a win-win.

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New study: Cost of not pursuing significant coastal restoration could reach $133 billion

December 21, 2015 | Posted by jhebert in 2012 Coastal Master Plan, Army Corps of Engineers, Coastal Protection and Restoration Authority (CPRA), coastal restoration, Community Resiliency, Economics, Federal Policy, Hurricanes, Reports, Restore the Coast, Science

By Elizabeth Van Cleve, Communications Manager, Environmental Defense Fund

Louisiana has lost nearly 1,900 squares miles of land since the 1930s. Without future action to restore the coast and reverse this trend, the state stands to lose another 1,750 square miles of land by 2060.

This land loss crisis not only impacts the communities, wildlife and ecology of south Louisiana, but it also puts cities, homes, infrastructure and industries at risk. Coastal wetlands serve as a buffer against the effects of waves, storms and sea level rise. The continued loss of wetlands jeopardizes Louisiana’s diverse economy as well as the entire nation that depends on the Mississippi River Delta for shipping, oil and gas, fisheries, tourism and other industries.

A recent study conducted by the Louisiana State University (LSU) and the RAND Corporation aims to measure the future economic impacts of continued coastal land loss. Commissioned by the Louisiana Coastal Protection and Restoration Authority (CPRA), “Economic Evaluation of Coastal Land Loss in Louisiana” provides a quantitative understanding of the economic damages caused by wetlands loss if we don’t take action now to restore the coast.

The two-year study measures the projected economic costs associated with continued land loss under future-with-no-action scenario, including projected damages to capital stock, such as buildings, homes and roads; disruption of economic activity, including employment and trade flows; and changes in ecosystem services and related industries, such as fisheries, tourism and recreation.

Key findings from the report include:

  • $2.1-$3.5 billion: Total replacement cost associated with capital stock at risk from land loss
  • $5.8-$7.4 billion: Total annual output (economic activity) at risk from land loss
  • $10-$133 billion: Increase in storm damage to capital stock
  • $5-$51 billion: Total output lost to increased storm damage

“Every dollar we spend today on coastal restoration and protection will save us many, many more dollars in the future,” said CPRA Board Chairman Chip Kline in a press release. “But beyond being cost-feasible, we’re talking about saving lives, families, homes, business and our way of life. This study by LSU and RAND is important in making our case to Congress and the nation that it is better for many reasons to spend now rather than later.”

Read the full report on CPRA’s website here.

The Times-Picayune (video): Coastal erosion, hurricane could cost Louisiana $133 billion

Learn more about how coastal restoration is important to the economy at OurCoastOurEconomy.org.

RANDLSUCoastalEconomicsStudy

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Help Count Birds for Science during Audubon’s Annual Christmas Bird Count

December 11, 2015 | Posted by lbourg in Birds, Climate, Science, Wildlife

The National Audubon Society invites birdwatchers to participate in the longest-running citizen science survey, the annual Audubon Christmas Bird Count (CBC). From December 14 through January 5, birders and nature enthusiasts in Louisiana will take part in this tradition, many rising before dawn to participate.

BUFH  - wing feathers

Buff-bellied Hummingbird wintering in Louisiana swamp. Photo: John Hartgerink

“Louisiana is home to millions of birds each winter, including waterfowl, shorebirds, and songbirds. Understanding how the populations of these birds are changing is revealed through CBC efforts, which is critical for knowing how to best ensure their survival,” says Dr. Erik Johnson, Director of Bird Conservation for Audubon Louisiana.

Each year, the Audubon Christmas Bird Count mobilizes over 72,000 volunteer bird counters in more than 2,400 locations across the Western Hemisphere. The Audubon Christmas Bird Count utilizes the power of volunteers to track the health of bird populations at a scale that scientists could never accomplish alone. Data compiled in Louisiana will record every individual bird and bird species seen in a specified area, contributing to a vast citizen science network that continues a tradition stretching back more than 100 years.

To date over 200 peer-reviewed articles have resulted from analysis done with Christmas Bird Count data. Bird-related citizen science efforts are also critical to understand how birds are responding to a changing climate. This documentation is what enabled Audubon scientists to discover that 314 species of North American birds are threatened by global warming as reported in Audubon’s groundbreaking Birds and Climate Change Study. The tradition of counting birds combined with modern technology and mapping is enabling researchers to make discoveries that were not possible in earlier decades.

In addition to counting up some of our more common birds, Louisiana CBC participants also look for vagrants – birds that normally spend the winter elsewhere, but made a wrong turn somewhere along the way. Last winter, Louisiana CBC volunteers found a total 254 species of birds, including amazing vagrants like Lucy’s Warbler, Ferrugineous Hawk, and Brown Boobies. What unusual birds will be found this winter?

Birders of all ages are welcome to contribute to this fun, nationwide citizen science project, which provides ornithologists with a crucial snapshot of our native bird populations during the winter months. Each individual count is performed in a count circle with a diameter of 15 miles. At least ten volunteers, including a compiler to coordinate the process, count in each circle. The volunteers break up into small parties and follow assigned routes, counting every bird they see. In most count circles, some people also watch feeders instead of following routes.

Want to get involved?

 

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New sediment counter shows amount of uncaptured sediment passing through LA every second

December 2, 2015 | Posted by lbourg in coastal restoration, Restoration Projects, Science

By Alisha Renfro, Staff Scientist, Restore the Mississippi River Delta Coalition, National Wildlife Federation

There’s less sediment moving down the Mississippi River than there used to be. Much of that missing material is trapped behind dams built upriver of Louisiana. Despite the reduction in sediment it carries, the Mississippi is still mighty with approximately 90 million tons of sediment passing the city of Belle Chasse, La. each year1. Tragically, much of that mud and sand will be carried past the sediment-starved wetlands and barrier islands of the delta – where it could have great benefits – and out into the Gulf, leaving us with a missed opportunity to restore health and resiliency to our coast.

sediment counter

Photo: CPRA

The new sediment counter, published on the homepage of our website, shows the tons of sand and mud in the water that moves pass the USGS gage in Belle Chasse, La every second. For this counter, the sediment is estimated using the relationship between sediment and the flow of the Mississippi River at Belle Chasse for years 2008 to 2010, as described by Mead Allison, Ph.D. and others in the appendix of their 2012 paper, “A water and sediment budget for the lower Mississippi–Atchafalaya River in flood years 2008–2010: Implications for sediment discharge to the oceans and coastal restoration in Louisiana.” For more specific details, see “How we calculated uncaptured sediment.”

While there is no single solution for restoring our coast, it is vital that we treat sediment as the precious resource it is and maximize its capture and use for coastal restoration. The 2012 Coastal Master Plan identified two types of projects, marsh creation and sediment diversions, that use sediment to build and maintain land. Marsh creation projects dredge and pipeline sand from the river to strategically build new land. However, reliance on this project type alone means missing out on the mud that makes up at least 70 percent of the sediment that the river carries. Sediment diversion projects tap into both the sand the mud carried by the river to build new land and to help sustain the existing wetlands, that in the absence of sediment input, would continue to rapidly disappear.

Using these two types of restoration projects we can use the sand and mud – the foundation and lifeblood of the delta – to create a healthy and more resilient future for coastal Louisiana.

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What We Know Now About the BP Oil Disaster

November 16, 2015 | Posted by lbourg in 5 Years Later, BP Oil Disaster, Science, Seafood, Wildlife

By Ryan Fikes, Staff Scientist, National Wildlife Federation, Gulf Restoration Campaign

This post has been cross-posted from the National Wildlife Federation's Wildlife Promise blog.

It’s been more than five years since the Deepwater Horizon oil rig exploded. Since that time, a council of federal and state Trustees have been extensively investigating the impacts of the disaster on wildlife and habitats, but that information has been kept under wraps—for use in litigation against BP. Now that the case has settled, this research has finally been made public in a draft Programmatic Damage Assessment and Restoration Plan.

The impacts to wildlife and their habitats are shocking and far reaching. Despite clean-up efforts and the natural weathering processes over the five years since the spill, oil persists in some habitats where it continues to expose resources in the northern Gulf of Mexico. In many cases, the damage to wildlife and habitats was more severe than previously understood. The ecological linkages of these habitats and communities and their connectivity to the larger Gulf of Mexico ecosystem can result in cascading impacts, influencing the overall health and productivity of the Gulf of Mexico ecosystem.

Together, the National Wildlife Federation and Ocean Conservancy scientists have worked to dig in to the massive report and digest its findings. Here is a snapshot of the types and severity of impacts outlined in the draft report.

 BP_impacts_web_small

1. Birds

While the Trustees acknowledge that this is a very conservative estimate, the total number of birds killed by the BP oil disaster is from 56,100 to 102,400 birds. At least 93 species of birds across all five Gulf Coast states were exposed to oil.

2. Beach & Dune Habitat

BP oil covered at least 1,300 miles of the Gulf coastline, including 600 miles of beach, dune and barrier island habitat.

3. Lost Human Use

The public lost 16,857,116 days of boating, fishing and beach-going experiences. The total loss of recreational use of the Gulf due to the disaster is worth $528 million to $859 million.

4. Oysters

Between 4 and 8.3 billion oysters are estimated to have been lost. Over three generations (minimum recovery time), the dead oysters would have produced a total of 240 to 508 million pounds of fresh oyster meat.

5. Salt Marsh

Louisiana lost up to 53 percent of its salt marsh plants across 350-721 miles of shoreline. In Louisiana wetlands, erosion rates approximately doubled along at least 108 miles of shoreline. The effect lasted for at least 3 years.

6. Sargassum

Sargassum, a floating seaweed that provides habitat for young fish and sea turtles, was exposed to oil, which may have caused the loss of up to 23 percent of this important habitat.

7. Seagrass Habitat

Seagrass beds covering a total area roughly the size of 206 football fields (272 acres) were lost from the time of the disaster through 2012.

8. Larval Fish

The Trustees estimated that 2-5 trillion larval fish were killed. The loss of larval fish likely translated into millions to billions of fish that would have reached a year old had they not been killed by the BP oil disaster.

9. Sea Trout

Several of species of sea trout, including the spotted (or speckled) sea trout, were severely impacted by the disaster. An estimated 20-100 billion sea trout larvae were killed as a result of the disaster.

10. Shrimp

The growth of young white, pink and brown shrimp was dramatically affected by oil. The total loss of shrimp production over 2010 and 2011 due to oiling is estimated at more than 2,300 tons.

11. Red Drum

The growth of young red drum fell by up to 47 percent along marsh shorelines in Louisiana that were persistently oiled since 2010, and an estimated 700 tons of red drum were lost. Reduced red drum production persisted through 2013 and is expected to continue.

12. Whales

While nearly all of the species of whales in the footprint of the oil have demonstrable, quantifiable injuries, the most hard-hit was the Bryde’s whale. With only about 50 Bryde’s whales left in the Gulf, roughly half of these animals were exposed to oil—and nearly a quarter were killed. It is unclear if Bryde’s whales will be able to recover.

13. Bottlenose Dolphins

The number of bottlenose dolphins in Barataria Bay and Mississippi Sound—two areas particularly affected by the disaster—is projected to decline by half. The populations are expected to take 40-50 years to recover. In the 5 years after the oil disaster, more than 75 percent of pregnant dolphins observed within the oil footprint failed to give birth to a viable calf.

14. Coral Reefs

The footprint of injury to mid-depth coral reefs is just over 4 square miles. These areas along the continental shelf edge, known as the Pinnacles, showed extensive damage to both the coral colonies and the reef fish associated with them. The larger ecological functions of this habitat were very likely impaired.

15. Sea Turtles

All five of the Gulf’s sea turtles are either threatened or endangered. It is estimated that somewhere between 61,000 and 173,000 sea turtles—of all ages—were killed during the disaster. For the endangered Kemp’s ridley sea turtle, this equals 10-20 percent of the average number of nesting females each year, which would have laid approximately 65,000 – 95,000 additional hatchlings.

16. Deep Seafloor

The footprint of BP oil on the Gulf seafloor around the wellhead is an area more than 20 times the size of Manhattan (over 770 square miles). An additional 3,300 square miles may have been affected.

Click here to view the PDF of the graphics and impacts data.

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Groups Pleased As Key Sediment Diversions Advance, Coastal Restoration Funds Protected

October 21, 2015 | Posted by Elizabeth Van Cleve in 2012 Coastal Master Plan, Coastal Protection and Restoration Authority (CPRA), Media Resources, Meetings/Events, Mid-Barataria Sediment Diversion, Science

FOR IMMEDIATE RELEASE

Contact:
Emily Guidry Schatzel, National Wildlife Federation, 225.253.9781, schatzele@nwf.org
Jacques Hebert, National Audubon Society, 504.264.6849, jhebert@audubon.org
Elizabeth Van Cleve, Environmental Defense Fund, 202.553.2543, evancleve@edf.org
Jimmy Frederick, Coalition to Restore Coastal Louisiana, 225.767.4181, jimmy.frederick@crcl.org
John Lopez, Lake Pontchartrain Basin Foundation, 504.421.7348, jlopez@saveourlake.org

Groups Pleased As Key Sediment Diversions Advance, Coastal Restoration Funds Protected

CPRA Board Moves Forward on Two Diversion Projects, Proposes Using GOMESA Funds for Highway Elevation

(October 21, 2015 – Baton Rouge) Today, Louisiana’s Coastal Protection and Restoration Authority (CPRA) board announced two major developments. First, CPRA recommended advancing both the Mid Barataria and Mid Breton sediment diversion projects in the Coastal Master Plan, which will reintroduce fresh water and sediment from the Mississippi River into its surrounding, collapsing wetlands and rebuild land over time. Secondly, the CPRA board voted to approve a new proposal to use Gulf of Mexico Energy Security Act (GOMESA) money, rather than funds previously committed to projects in the state’s Coastal Master Plan, for elevating Louisiana Highway 1.

The Restore the Mississippi River Delta Coalition – which includes Lake Pontchartrain Basin Foundation, Coalition to Restore Coastal Louisiana, Environmental Defense Fund, National Audubon Society and National Wildlife Federation – issued the following statement in response:

“We are pleased to see CPRA leverage the most current and best-available science to move forward the Mid Barataria and Mid Breton sediment diversions projects into engineering and design. The urgency and severity of our collapsing delta requires that we use the most powerful tools at our disposal. Sediment diversions provide the best opportunity to restore the coast over time, preserving our communities, industries and entire way of life. We will continue to pursue and understand the science behind diversions, but there is no scientific uncertainty about our physical reality – we live in a landscape built by the river, disappearing because we have cut the delta off from the river.

“This announcement is an important step toward getting sediment diversions up and running. We’re in a race against the clock and forces of nature. We need to move forward at full speed while ensuring efficiency and transparency in the steps ahead.

“Louisiana Highway 1 is a critical corridor for our state and national economic vitality. We believe that the elevation of Highway 1 is eligible for GOMESA funding, and we join with the LA1 Coalition in pursuit of adequate funding for this and other coastal infrastructure projects. We support the development of a prioritization system that would allow for up to 10 percent of GOMESA revenues to be spent on coastal infrastructure projects, with a focus on projects that are directly impacted by coastal wetland loss. This system should reflect the significant role of coastal infrastructure projects such as Highway 1, which contribute to energy security, community resiliency, and the national, state and local economy. This is a long-standing and well-understood aspect of GOMESA and does not veer from any prior commitments to restoration.

“We are gratified that the state has made the right decision in considering an appropriate funding source for this coastal infrastructure improvement project and has not moved forward with using oil spill funds it previously committed to the Coastal Master Plan.”

A recent poll found tremendous statewide support for coastal restoration:

  • 94 percent indicate that a gubernatorial candidate’s commitment to protect and restore coastal Louisiana will be important to them when they vote.
  • 90 percent want the next governor to ensure funds currently dedicated to coastal restoration are not spent on anything but coastal restoration.
  • 87 percent want the next governor to work to identify and secure funding for future projects identified in the state’s Coastal Master Plan.
  • 85 percent believe restoration of coastal Louisiana should be a high priority for the new governor.
  • 95 percent want the new governor to commit to move quickly and get started building coastal restoration projects.
  • 78 percent believe protecting and restoring coastal Louisiana is as important as other issues facing the state.
  • Two-thirds (66 percent) indicate support for river diversions to build new land in Louisiana.

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The Restore the Mississippi River Delta Coalition is working to protect people, wildlife and jobs by reconnecting the river with its wetlands. As our region faces the crisis of threatening land loss, we offer science-based solutions through a comprehensive approach to restoration. Composed of conservation, policy, science and outreach experts from Environmental Defense Fund, National Audubon Society, National Wildlife Federation, Coalition to Restore Coastal Louisiana and Lake Pontchartrain Basin Foundation, we are located in New Orleans and Baton Rouge, Louisiana; Washington, D.C.; and around the United States. Learn more at MississippiRiverDelta.org and connect with us on Facebook and Twitter.

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Expert Diversion Panel: State has all information needed to make decision on advancing diversions

October 1, 2015 | Posted by lbourg in 2012 Coastal Master Plan, Coastal Protection and Restoration Authority (CPRA), coastal restoration, Diversions, Restoration Projects, Science

By: Alisha Renfro, Staff Scientist, Restore the Mississippi River Delta Coalition, National Wildlife Federation

Diversion Locations

Diversion locations

Sediment diversions are restoration projects that carry sediment and water from the river through a gated structure on the levee into nearby basins, mimicking the way the Mississippi River once built much of southeast Louisiana. This type of project was identified in the 2012 Coastal Master Plan as a vital tool for far-reaching and long-lasting restoration of our coastal wetlands. Four sediment diversion projects from the Coastal Master Plan –Mid-Barataria, Mid-Breton, Lower-Barataria and Lower Breton – are currently moving forward in either planning or engineering and design. This fall, the state is expected to announce which sediment diversion projects they will continue move forward into full engineering and design.

Data collection and modeling efforts allowed the state to study and understand the full benefits that a sediment diversion could provide to our coastal wetlands and to anticipate the influence of the project on water levels, fisheries and salinity distribution in the receiving basins compared to future conditions without sediment diversions. In addition to those studies, an Expert Diversion Panel on Planning and Implementation – an independent group from outside of Louisiana with expertise in natural science, social science and engineering – was convened by the Water Institute of the Gulf to provide advice and guidance to CPRA on plans for sediment diversion projects.

The fifth meeting of this panel, held in August, focused on the state’s approach to using the data and modeling information to decide which sediment diversion projects will move forward. On September 16th, the Expert Panel released its report from that meeting, agreeing that the state had the information it needed to decide which sediment diversion projects to advance. The panel also decided that the socio-economic analysis and the work being done to predict the effect of diversions on the basins are appropriate for this stage of the process.

In the panel’s opinion “no other environmental restoration project in the nation has come so far so quickly.” The state’s decision on which sediment diversion projects to focus its efforts on and move into engineering and design is important, as it is one step forward in a longer process towards full implementation. Using sediment diversions to put the sediment of the river back to work for us is crucial for restoration and one the best tools we have to create a sustainable future for Louisiana.

You can show your support for coastal restoration by taking the pledge to urge leaders to be a powerful voice for coastal restoration. Take the pledge at RestoretheCoast.org

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New report quantifies storm reduction benefits of natural infrastructure and nature-based measures

September 29, 2015 | Posted by lbourg in 2012 Coastal Master Plan, coastal restoration, Community Resiliency, Restoration Projects, Science

By Shannon Cunniff, Deputy Director for Water, Environmental Defense Fund

Coastal zones are the most densely populated areas in the world. In the U.S., they generate more than 42 percent of the nation’s total economic output. These coastal communities, cities and infrastructure are becoming increasingly vulnerable to the effects of climate change. Rising seas and increased storms, as well as ongoing coastal development, have stripped these natural environments of their innate resilience to storms and flooding, leaving coastlines and the people who live there especially exposed.

EDF photo beach dune

Beach dune

Protecting coastal areas requires a multipronged approach. Traditional hardened infrastructure, such as levees and floodwalls, should be combined with natural infrastructure, such as dunes and barrier islands, to optimize storm protection. By attenuating wave energy, natural infrastructure measures can enhance the performance of and complement traditional gray infrastructure. And in certain situations, natural coastal infrastructure measures can reverse coastal erosion, help rebuild shorelines and even keep pace with rising sea levels.

Natural coastal infrastructure measures also provide significant co-benefits to communities. In addition to reducing the effects of storm waves and surge, these wetlands and other plant-based means also improve water quality, enhance recreational and commercial fisheries, add to the coastal esthetic and attract tourists. Their installation or restoration can also buy time for communities as they develop long-term strategic plans to cope with sea level rise.

In Louisiana, coastal planners understand the importance of nature-based designs, such as sediment diversions and barrier beach nourishment, when developing coastal restoration and protection plans – the state’s Coastal Master Plan is a combination of restoration, protection and resiliency projects.

But with their myriad of benefits, why aren’t natural infrastructure measures being implemented to a greater degree in other parts of the nation?

In part, the reason is the lack of accepted engineering design guidance – a document that explains the engineering principles, issues, methods, and performance metrics for evaluating, siting and designing features. Lacking such, engineers cannot formally sign off on the designs and risk benefits that will be realized.

How can we quantify the storm risk reduction benefits of nature-based measures, so as to help decision-makers and planners choose the best methods for their needs and find financing to implement these projects? Can we accelerate development of engineering guidance?

Natural Infrastructure Workshop and Report

Mangroves public domain pix

Mangroves

Seeking to answer these questions, Environmental Defense Fund (EDF) convened a workshop of 19 coastal engineers, scientists, program managers, and financiers to discuss establishing storm risk reduction performance measures of various natural coastal infrastructure solutions.

After completion, EDF produced the report, “Performance of Natural Infrastructure and Nature-Based Measures as Coastal Risk Reduction Features,” which reviews the state of knowledge on the risk reduction performance of natural and nature-based infrastructure, compiled from existing literature as well as workshop participant input. The report includes findings on a host of nature-based measures, including beach nourishment, vegetated dunes, barrier island restoration, edging and sills (living shorelines), oyster reefs, coral reefs, mangroves, maritime forests and coastal wetlands (non-mangroves).

While the report is a bit technical, the authors hope that city planners, coastal engineers and other decision-makers find it useful when determining which storm protection measures to implement in their communities.

Grand Terre_Abita SOS 2

Grand Terre

For each of the measures, the report summarizes its storm risk reduction attributes (e.g., wave attenuation and storm surge protection); lists its strengths, known weaknesses and uncertainties about utility for risk reduction; and identifies suitable conditions for implementation. The report also indicates where engineering design guidelines already exist (e.g., for beach nourishment and dune building) and whether they can be created by modifying existing guidelines (e.g., oyster and coral reefs function like submerged breakwaters).

For the layperson, Table 1 is a one stop shop for information on how each storm risk reduction measure stacks up next to other methods. The table is a summary of the strategies – natural, nature-based, as well as structural – and how each compares regarding risk reduction performance, costs, climate change mitigation, and adaptability to seal level rise and changing community needs.

NI Performance Summary Table

To guide further research supporting adoption of natural infrastructure into coastal resilience plans, the report provides the most catalytic and pressing research needs and lists other survey needs gathered from the literature or raised during the workgroup discussion.

Workshop participants – and subsequent consultation with other engineering experts – confirm that there is sufficient confidence in the ability of natural coastal infrastructure measures to reduce impacts of storms and sea level rise to coastal communities, such that these approaches should be routinely considered as viable options by decision-makers.

With what we know now, implementation of these approaches can be facilitated by developing detailed engineering guidelines that provide functional and structural design guidance as well as address other design issues. As projects are built and monitored, we can further expand knowledge of the circumstances where these measures work best; learn more about how traditional structural, nonstructural, natural infrastructure and nature-based measures can optimally work together; understand how coastal processes are effected; and track the measures’ life expectancies in our increasingly dynamic coastal environments.

You can show your support for coastal restoration by taking the pledge to urge leaders to be a powerful voice for coastal restoration. Take the pledge at RestoretheCoast.org

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It's a Marathon, not a sprint: Small steps build lasting momentum for comprehensive restoration

September 23, 2015 | Posted by lbourg in 2012 Coastal Master Plan, coastal restoration, Community Resiliency, Louisiana Coastal Area (LCA), Restoration Projects, Science

By Estelle Robichaux, Restoration Project Analyst, Environmental Defense Fund and Gaby Garcia, Science Intern, Environmental Defense Fund

This post is part of a series on early restoration planning in Louisiana. Be sure to check out parts one and two for more information on previous plans.

By the early 1990s, Louisiana’s coastal land loss crisis had been studied and documented for more than two decades. Successful establishment of the state-level Office of Coastal Restoration and Management and the Wetlands Trust Fund in 1989 galvanized support and action for wetlands restoration at the federal-level as well. In 1990, Louisiana U.S. Senator John Breaux co-sponsored and helped pass the Coastal Wetlands Planning, Protection and RestorationCWPPRA Act (CWPPRA), sometimes called the “Breaux Act.”

The Act was one of the first attempts to support a comprehensive approach to restoring Louisiana’s coastal wetlands by establishing a dependable, long-term funding stream for projects. A new federal interagency task force, made up of five federal agencies and the Louisiana state government, was also created by the Act to oversee coastal restoration activities, including the prioritization, planning and implementation of small- to medium-scale projects.

Three years after CWPPRA was enacted, in 1993, the Task Force published their Louisiana Coastal Wetlands Restoration Plan, which recommended changes in management of the lower Mississippi and Atchafalaya Rivers. The plan focused specifically on increasing the sediment and freshwater supply to coastal wetlands to reestablish natural land-building processes.

The CWPPRA plan only has a 20-year time horizon, as opposed the 50-year perspective taken in other contemporary plans published by the Louisiana Governor’s Office of Coastal Activities, the Louisiana Department of Natural Resources (LDNR), Louisiana State University or the 2012 Coastal Master Plan. Despite the shorter outlook of the CWPPRA plan, it relies on similar principles and strategies we see in these other plans. Namely, this plan calls for:

  • Shifting navigational use from the existing bird's foot delta to a new western delta in a neighboring estuary, possibly Breton Sound;
  • Multiple diversions to address land loss in Barataria Basin;
  • Reactivation of old distributary channels;
  • Seasonal changes in the Atchafalaya River’s flow distribution; and
  • Projects to facilitate hydrologic restoration, such as: Nourishing barrier island chains and Controlling tidal flows in large navigation channels.

Small scale tests, important success

Even before the passage of CWPPRA, the LDNR was implementing small-scale diversions by cutting crevasses into banks of the southernmost reach of the Mississippi River. Between 1986 and 1993, 20 crevasses were constructed with a mean discharge rate of less than 4,000 cubic feet per second (cfs). Despite the lower flow rates, these crevasses created nearly 1,400 acres of emergent marsh during this period, an impressive amount of land considering the scale of these projects.

The early results of these experimental projects encouraged the prioritization of sediment diversions in the CWPPRA planning process, many of which have also performed well. The Channel Armor Gap Crevasse, for instance, was constructed in 1997 in one of the most rapidly subsiding areas of the delta. This crevasse created nearly 200 acres of land over 10 years and increased overall sediment elevation by more than three feet.

The West Bay Sediment Diversion, on the other hand, was constructed in 2003 and had formed little subaerial land despite the creation of two small spoil islands in the bay in 2009. Due to this lack of land building, it was considered a complete failure and was in the process of being deauthorized. But after the historic flood of 2011, which delivered large quantities of sediment to coastal Louisiana, dry land had emerged in West Bay by that fall. This combination of spoil islands and pulsing floodwaters has proven successful in building land here and may be translated elsewhere across the coast.

WestBay

West Bay Sediment Diversion

Scaling up the vision for restoration

CWPPRA has played an important role in funding restoration projects, beyond diversions, across the coast. The program has also been critical in supporting long-term, large-scale undertakings, such as the Coast-wide Reference Monitoring System and planning efforts like the Barrier Island Shoreline Feasibility Study and Coast 2050.

The Barrier Island Shoreline Feasibility Study was the first large-scale feasibility study sponsored through CWPPRA. The technical analysis, completed in 1997, was designed to figure out the most effective barrier island configurations to protect inland areas from saltwater intrusion, wind and wave action, storm surge and other extreme events, such as oil spills. An estimate of the possible quantitative effects of different regional barrier island arrangements on Louisiana’s environmental and economic resources were produced through this work as well.

The scope of the study was limited to the shoreline from the Atchafalaya River east to the Mississippi River and provided two alternatives for restoration. These results ultimately informed the initial Barrier Shoreline Restoration studies conducted as part of the Army Corps’ Louisiana Coastal Area (LCA) Ecosystem Restoration Study, which in turn formed the basis for two of our priority projects, Barataria Pass to Sandy Point and Belle Pass to Caminada Pass Barrier Island Restoration.

While the CWPPRA Plan proposed some forward-thinking solutions at the basin-wide level to mimic natural processes, Coast 2050 took comprehensive planning even further. This initiative, finalized in 1998, was jointly developed by the Louisiana State Wetlands Authority and the CWPRRA Task Force and takes a regional perspective on restoration strategies for long-term ecosystem sustainability. The LCA Ecosystem Restoration Study was largely based on the recommendations and vision of Coast 2050, both of which played a significant part in shaping the 2012 Coastal Master Plan and the way we envision restoration in coastal Louisiana.

Be sure to check out our next post for more details on Coast 2050 and the Louisiana Coastal Area Study!

You can show your support for coastal restoration by taking the pledge to urge leaders to be a powerful voice for coastal restoration. Take the pledge at RestoretheCoast.org

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