“The rate of coastal land loss in Louisiana has reached catastrophic proportions. Within
the last 50 years, land loss rates have exceeded 40 square miles per year, and in the
1990’s the rate has been estimated to be between 25 and 35 square miles each year. This
loss represents 80% of the coastal wetland loss in the entire continental Unites States”
Coast 2050: Toward a Sustainable Coastal Louisiana
Louisiana Coastal Restoration
The Problem
The Mississippi River is one of the world’s great rivers. It is the longest and
largest in North America and ranks 3rd in terms of length, 2nd in terms of area worldwide.
It impacts 31 states and 2 Canadian Provinces, about 40% of the total area of the United
States and 1/8 of North America. It is also a mature river in that it has been, for the most
part, fully developed. The upper river has been dammed to allow commercial navigation
and the lower river has been chanalized and dredged. Levees have been built to protect
both agriculture and local communities from devastating flooding. The city of New
Orleans has received much of this protective effort and over the years has developed an
extensive array of flood control structures. Unfortunately, as the recent hurricanes have
shown, these structures were not adequate to protect the city, much of which lies below
sea level.
As a result of this significant development, the natural course and functions of the
river have been altered. Some experts content that the Mississippi, if left unregulated,
would divert to the Atchafalaya basin. This, of course, would leave New Orleans without
a port and significantly alter one of the nation’s busiest commercial waterways.
Consequently, the government has constructed a massive control structure to prevent this
from happening.
A collateral problem with this development that has not received the same
attention as the flooding of New Orleans has been the significant erosion of the coastal
area drained by the river. Policies and structures designed to promote navigation and
prevent flooding have altered sediment flows and considerably changing the coastal
geography. It is estimated that the degradation of the Louisiana Coast over that past
century has resulted in 1900 square miles of lost wetlands, an area the size of Delaware.
If left unchecked, by 2050, another 900 square miles could be lost.
The Causes of Wetland Loss
Scientists have been studying this problem for sometime and the causes of this
degradation are both manmade and natural. The problems can be categorized as follows:
NATURAL CAUSES
Barrier Island Degradation. Barrier islands form natural protection for coastal
areas. As a result of storm activity, barrier islands naturally erode, and unless replaced,
lose their protective functions.
Storms. Tropical storms and hurricanes contribute to erosion in many ways. Wave
and wind action eat away at coastal areas. Vegetative cover is lost, increasing losses.
Louisiana has averaged over one significant storm per year since1871.
Sea Level Rises. Sea levels have been increasing for some time. EPA estimates
that global levels will rise by 5.9 inches by 2050.
Subsidence. Land elevations in the La coastal area have been decreasing due to
compaction of sediments, faulting and groundwater depletion.
HUMAN CAUSES
Flood Control. As explained earlier, the entire river basin has been undergoing
significant flood control efforts. Approximately 2250 miles of levees have been built in
coastal Louisiana. These levees provide two functions, to contain river flows and to
protect against storm surges.
Sediment Reduction. As a result of the channelization of the river and upstream
reservoirs, sediment is both reduced and diverted from normal deltaic functions. It is
estimated that the lower river has approximately 67% less sediment loads and these
sediments are funneled into a very narrow area rather than distributed broadly across the
entire coastal area.
Navigation. Navigation channels and policies have altered sediment flows and
hastened saltwater intrusion on the one hand, and created barriers to natural sediment
distribution on the other hand.
Oil and Gas Development. Since the discovery of extensive oil and gas deposits in
the gulf, the area has been significantly altered by canals and pipelines
Hypoxia. While hypoxia is not an erosion problem, it is an increasing
environmental issued associated with the restoration effort. Hypoxia is caused by excess
nitrogen that creates oxygen depletion zones in gulf waters.
THE CHALLENGES
It is certainly a national challenge to deal with these issues. The government has
taken some initial steps, most notably the Breau Bill , which devoted $50 Million
annually to study and take beginning steps. Two separately funded projects, the
Caernarvon and Davis Pond diversions, costing in excess of $130 Million, when
combined with Breau Bill provisions, are estimated to prevent up to 22% of the projected
losses by 2050. Clearly, much more will need to be done. There are three significant
challenges
Funding. Marshalling the needed resources to tackle this problem will be an issue
in a tight state and federal budget environment. Early estimates of restoration efforts
exceed $14 billion. An early plan presented to OMB called for an initial investment of
over $1 billion. The true costs are difficult to know, given the many variables of the
issue.
Science. The science of environmental restoration is still evolving. While we
know more and more about ecosystems, applying this science to a massive project such
as Louisiana Coastal restoration has never been attempted. Perhaps the only known
example is the Everglades restoration, however, this project is still in its initial stages and
controversy has been extensive.
National Will. Perhaps most importantly, the issue of Louisiana Coastal
restoration has not yet reached a critical mass for a project of this size, scope and
complexity.
REFERENCES
Required Reading
a.
Coastal 2050: Toward a Sustainable Coastal Louisiana.
http://www.lacoast.gov/Programs/2050/MainReport/report1.pdf Read, pages
1-6, skim rest of report.
b.
Mississippi River. http://biology.usgs.gov/s+t/SNT/noframe/ms137.htm. skim
document for a good overview of hydrology and environmental issues.
ISSUES
1. Given the visibility that Hurricane Katrina and Rita have provided for the
issues of watershed management, how do you see the national debate
changing?
2. With regard to the City of New Orleans, how have past policies made the city
more vulnerable? How can we structure a debate to proceed with rational and
perhaps cost effective policies toward reconstruction?
3. Given the huge challenges regarding coastal restoration, both scientific and
budgetary, at what pace ought we to proceed? Is there time to develop more
rational policies and better science, or does the situation dictate that we
proceed as quickly as possible.
4. How can we better balance the traditional uses of our rivers, navigation, water
supply, industrial development, agriculture, with the newer claimants such as
ecosystem restoration and recreation? What does this say about how we
should think about the way ahead?