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Land Area Change in Coastal Louisiana (1932 to 2010)
Coastal Louisiana: A vast expanse of wetlands and fertile habitats vital to the ecology and
economy of the region and Nation. Coastal Louisiana wetlands contain over one-third of the
coastal marshes and support the largest commercial fishery in the lower 48 states. These
wetlands protect human populations and provide critical habitat to many threatened and
endangered species. However, these wetlands are in danger as Louisiana currently experiences
more coastal wetland loss than all other states in the contiguous United States combined.
Coastal Louisiana wetlands are critical to the economy, the security, and the well-being of the
entire North American Continent. One-third of the oil and gas production or transport in the
United States occurs in coastal Louisiana. Five of the Nation’s largest ports, which support
approximately 20% of the Nation’s waterborne commerce, are located here. More than 5 million
migratory birds traveling on the Mississippi and Central flyways make this coastline their home
during the winter. These wetlands truly are one of America’s greatest treasures.
Scientists at the United States Geological Survey’s National Wetlands Research Center have
been using many data sources to study Louisiana’s wetlands. In a recent study of land area
change, wetland change has been quantified over a 78-year period from 1932-2010.
The findings of this research have given scientists the ability, not only to quantify the amount of
wetland loss, but also to identify the time period in which it was lost. This temporal resolution, or
time sequence, helps scientists to understand what might have caused these losses. The new
dataset provides the ability to observe patterns such as gradual shoreline erosion, and distinguish
them from losses due to specific events, such as hurricanes. This time series of data shows the
gradual loss of wetland areas in the deltaic Plain of the Mississippi River. The red on the map
indicates land loss.
From 1932-2010, coastal Louisiana has experienced a net decrease in wetland area of 1,883
square miles. This net change in land area amounts to approximately 25% of the 1932 land area
or an area approximately equivalent to the entire state of Delaware.
In more recent analyses, the rate of wetland loss from 1985-2010 has averaged 16.6 square miles
each year. If this loss were to occur at a constant rate, it would equate to losing more than a
football field every hour.
Despite multiple stressors and high rates of sea level rise and subsidence, some land gain has
been observed in coastal areas that receive direct sediment delivery from the Atchafalaya and
Mississippi Rivers. Two examples of active land and delta formation occur in the Atchafalaya
River and Wax Lake Deltas. This time series of imagery shows the gradual building of these
deltas, which receive regular sediment. The new land is shown in green.
Deltas are dynamic and have the capacity to be resilient. Subsidence, sea level rise, hurricanes
and other stressors affected the Mississippi River Delta for centuries prior to alteration of the
system by humans, yet the delta built despite these stressors.
The staff of the U.S. Geological Survey National Wetlands Research Center continually strives
to improve methods, models, monitoring, and technical expertise needed by decision-makers to
remediate and save our rapidly disappearing coastal zone. Scientists and policymakers are
beginning to harmonize natural landscape functions with human needs to guide management of
healthy ecosystems and a sustainable delta. Only by understanding our natural resources, can we
ensure the vitality of the Nation’s economy, the health of its environment, and the well-being of
Title: Land Area Change in Coastal Louisiana (1932 to 2010)
Coastal Louisiana wetlands make up the seventh largest delta on Earth, contain about 37 percent of the estuarine herbaceous marshes in the conterminous United States, and support the largest commercial fishery in the lower 48 States. These wetlands are in peril because Louisiana currently undergoes about 90 percent of the total coastal wetland loss in the continental United States. Documenting and understanding the occurrence and rates of wetland loss are necessary for effective planning, protection, and restoration activities. USGS land change analyses show that coastal Louisiana has undergone a net change in land area of about -1,883 square miles (mi2) from 1932 to 2010, or an area equivalent to the size the of State of Delaware. This net change in land area amounts to a decrease of about 25 percent of the 1932 land area. Trend analyses from 1985 to 2010 show a wetland loss rate of 16.57 mi2 per year. If this loss were to occur at a constant rate, it would equate to Louisiana losing an area the size of one football field per hour, or an area greater than the size of the Island of Manhattan every year.
Location: LA, USA
Date Taken: 7/20/2011
Video Producer: Ryan M. Twilley , USGS National Wetlands Research Center
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