Archive for Hurricanes


Louisiana’s Coastal Master Plan moves on to state legislature for approval

March 29, 2012 | Posted by Delta Dispatches in 2012 Coastal Master Plan, Community Resiliency, Diversions, Hurricanes, Restoration Projects

By David Muth, National Wildlife Federation

On March 21, Louisiana’s Coastal Protection and Restoration Authority (CPRA) unanimously adopted the revised Comprehensive Master Plan for a Sustainable Coast, which lays out a 50-year restoration plan for Louisiana’s coast. The Mississippi River Delta Restoration Campaign has worked closely with the state in the development of the plan, and many of our recommendations for improving and strengthening the draft were adopted in the final version.

Map depicting sediment starved wetlands and areas of wasted sediment in southeast Louisiana. Credit: CPRA 2012 Coastal Master Plan final draft

One such recommendation made by our campaign was to create clear paths forward for implementation of the nonstructural hurricane protection program and the design of a lower Mississippi River realignment. The final version of the plan also includes revisions supported by coastal stakeholders during the public review process, including relocating marsh creation or shoreline protection projects to locations that would help buffer vulnerable coastal communities. While these revised projects were not necessarily the best projects for optimizing land creation, they were justified because of the synergies they could provide with nearby protection projects. Even with these changes, 85% of the projects in the final plan were chosen by the Planning Tool to optimize land building in the face of less optimistic sea level rise scenarios.

Proposed Mississippi River diversions. Credit: CPRA 2012 Coastal Master Plan final draft

The final Coastal Master Plan revolutionizes the way Louisiana intends to move toward a sustainable coast. It proposes to spend $3.8 billion to reintroduce 50% of the peak flow of the Mississippi River into the most sediment-starved and deteriorating parts of the delta — a key goal of our campaign. This reintroduction could build up to 300 square miles of new delta over the next 50 years in the face of moderate subsidence and sea level rise. The plan also recommends designing a new navigation system to free up most of the remaining 50% of peak river flow for a new lower river alignment that will build additional new deltaic land. It also dedicates $20 billion toward the creation of over 200 square miles of marsh through sediment pipeline delivery to areas that cannot be reached by riverine reintroduction of sediment.

Credit: CPRA 2012 Coastal Master Plan final draft

Additionally, the plan provides for increased hurricane risk reduction for every coastal resident, by building resiliency for coastal communities through nonstructural measures such as elevating buildings, strengthening infrastructure and facilitating voluntary relocation. This fundamental shift away from the old standard of total reliance on levees, floodwalls and floodgates ratifies another fundamental goal of our campaign.

The Coastal Master Plan now goes to the Louisiana Legislature for adoption during the current session, which began on Monday and continues through June 4, 2012. If adopted, we move an important step closer towards implementing the goals of our campaign. Louisiana could become a world leader among vulnerable coastal areas in learning to live with the realities of future climate change and in learning to start living with water and natural processes rather than conducting a futile fight to the death against them.

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Predictive models form scientific backbone of Louisiana Coastal Master Plan

February 8, 2012 | Posted by Delta Dispatches in 2012 Coastal Master Plan, Hurricanes, Meetings/Events, Restoration Projects, Science

By Alisha A. Renfro, Ph.D., National Wildlife Federation

Louisiana’s Draft 2012 Coastal Master Plan is a bold, ecosystem-scale restoration strategy that outlines a 50-year plan to combat the land loss epidemic in the Mississippi River Delta. The plan puts forth solutions to addressing the destructive impacts of sea-level rise, subsidence, increased storm intensity, marsh collapse and other factors on Louisiana’s disappearing coastline. The plan is a science-based approach that, at its core, uses a suite of linked models to predict the future of Louisiana’s coastal landscape and the potential damage to communities over the next 50 years, both with and without implementation of the plan’s restoration and risk reduction projects.

The Louisiana Coastal Protection and Restoration Authority is hosting a series of seminars at universities throughout the state to give residents an overview of the plan’s predictive modeling efforts. These seminars go hand-in-hand with the master plan public meetings held in January. At each seminar, one or two of the individual models is explained by a leading researcher in his/her related fields. A full list of seminars is available online.

This pioneering modeling effort began 18 months ago, when a group of scientists and engineers were gathered to carry out and serve as a technical advisory team for the effort. The challenge was to use existing models, or create new models if none existed, to better replicate complex coastal processes and allow for the analysis of various future environmental condition scenarios as well as over 400 different restoration and protection projects.

Seven calibrated and interconnected models — each developed and refined by a team of scientists — were used to characterize different aspects and functions of the coastal Louisiana landscape:

  • Eco-Hydrology: Predicts changes in the flow of water, salinity, water level, sediment, nutrients and other aspects of water quality within the estuaries.
  • Wetland Morphology: Predicts losses and changes to wetlands by analyzing factors that affect wetland elevation (e.g., subsidence, sea-level rise) and factors that affect the configuration of the landscape (e.g., storms/hurricanes, saltwater intrusion, sediment transport).
  • Barrier Shoreline Morphology: Predicts changes in the barrier island shorelines and inlets due to processes such as relative sea-level rise, subsidence, erosion, storms and loss of interior wetlands.
  • Vegetation: Predicts changes in the types and location of vegetation based on changes in wetland area and the movement and characteristics of water in the estuaries.
  • Ecosystem Services: A group of models that predicts changes in habitat for commercially and recreationally important species as well as other key services. The individual species models included those for brown shrimp, white shrimp, American alligator, green-winged teal, eastern oyster, rosette spoonbill and others.
  •  Storm/Surge Waves: Predicts the storm surge and waves that result from various hurricane-level wind speeds and directions. This model is important for understanding the effect that structural protection such as levees and floodgates could have on reducing the effects of storms and waves on coastal communities, infrastructure and ecosystems.
  • Risk Assessment: Predicts the damage to assets in the coastal area caused by waves and storm surge by estimating the flooding that would result from levees being overtopped and flooding in areas without structural protection.

The purpose of the 2012 Coastal Master Plan is to identify restoration and protection projects that will create a more resilient and sustainable Louisiana coastline. The suite of predictive models developed for the plan was used to predict the future of Louisiana landscape without any action, as well as the future of the coast with individual restoration and protection projects under different environmental scenarios. The glimpse into our possible future if no large-scale restoration projects are implemented is bleak, with a potential loss of 800 to 1800 square miles of land. To avoid this future, large-scale coastal restoration projects, like diversions, are required to maximize natural land-building processes and build a more sustainable future in the face of uncertain environmental conditions.

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Study Analyzes Damaging Impacts of Hurricanes on Louisiana’s Coastal Wetlands

November 15, 2011 | Posted by Elizabeth Skree in Hurricanes, Reports

By Alisha Renfro, Ph.D., National Wildlife Federation

Hurricanes are powerful storms that have the ability to alter coastal landscapes in a few hours. The wetlands of coastal Louisiana are similar to wetlands elsewhere, but they are often more susceptible to storm impacts due to their low elevation and the thick, organic-rich soil (and the lack of mineral sediment) that dominates much of the region.

In a new study, “Hurricane Impacts on Coastal Wetlands: A Half-Century Record of Storm-Generated Features from Southern Louisiana,” Robert Morton and John Barras of the U.S. Geological Society (USGS) use aerial photographs and satellite images to identify the patterns of land loss and types of features that develop as a result of hurricanes in coastal Louisiana. The study examines how a storm’s path, duration, magnitude and resulting impact to wetlands to differentiate wetland loss attributed to storms from wetland loss associated with sea level rise, subsidence, decreased sediment input and other longer-term processes that affect Louisiana’s coastal landscape.

Hurricane Katrina in the Gulf of Mexico (Credit: GOES 12 Satellite, NASA, NOAA)

The study determines that a storm’s speed, intensity, direction, the shape and topography of the coastline, and the timing between the maximum storm surge and the maximum wind speed all affect the magnitude of impact that a storm event has on a coastal region. The erosional features from the hurricanes studied in coastal Louisiana were typically found to be long-lasting, with some impacts that could still be identified nearly a half-century later.

The most substantive storm impact is newly-formed ponds and expanded ponds, which convert hundreds of square miles of wetland into open water. Back-to-back storms are particularly damaging to the region’s wetlands, with the combined impacts of Hurricanes Katrina and Rita (2005) expanding the open water area in coastal Louisiana by more than 300 square miles, and Hurricanes Gustav and Ike (2008) increasing open water by another nearly 200 square miles.

Prior to the 1930s, topographic maps show that ponds generated from storms were confined to the marshes closest to the shore. However, since that time, storm-impact features have migrated farther inland due to the cumulative impact of storm events coupled with high subsidence rates, sea-level rise and the absence of mineral sediment from the river that once fueled natural marsh-building processes.

Before the 20th century, the Mississippi River provided enough sediment, nutrients, and freshwater to repair some of the extreme-storm impacts to the coastal wetlands, but that capability no longer exists. If the natural land-building processes of the Mississippi River are not restored, the wetlands will continue to become more vulnerable and storm effects will continue to move inland, destroying ecologically and economically vital habitat.

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Hurricane Season Starts Today: A Renewed Call for Restoration

June 1, 2011 | Posted by Elizabeth Skree in 2011 Mississippi River Flood, BP Oil Disaster, Congress, Hurricanes

Hurricane Katrina in the Gulf of Mexico. August 29, 2005. Credit: GOES 12 Satellite, NASA, NOAA

By Elizabeth Skree, Environmental Defense Fund

The National Oceanic and Atmospheric Association (NOAA) is predicting an above-average hurricane season, which starts today, so communities along Louisiana’s coast are bracing for yet another possible disaster.  The historic Mississippi River floodwaters have barely begun to recede.  Additionally, the Gulf is still recovering from last summer’s devastating BP oil disaster.  These tragic events, in addition to the ongoing rapid land loss along Louisiana’s coast during the last eight decades, continue making the state’s coastal communities and cities vulnerable to disaster.

Every hour, more than a football field’s worth of Louisiana’s wetlands disappear.  These wetlands act as a natural storm surge barrier, protecting Louisiana’s coast.  As land loss caused by sinking land increases, these vital wetlands disappear, leaving people and infrastructure exposed and vulnerable.  Numerous industries, communities, and wildlife depend on the Mississippi River Delta for survival, and it is imperative that the region be revitalized and restored for the future of the region and the nation.

One way to bring Louisiana’s coast and the Gulf back to health is for Congress to dedicate at least 80 percent of Clean Water Act penalties from the BP oil spill to Gulf restoration.  The states that were devastated by last summer’s disaster deserve compensation, especially in Louisiana, where the ecological damage was greatest.  This money can be used to replant damaged wetlands, which will in turn help protect the state from future disasters.  Directing BP’s fines to Gulf restoration will make the region safer and better than it was before the oil spill.  And with the six-month hurricane season starting today, we have no time to lose.

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