USGS Multimedia Gallery: (Video)--Land Area Change in Coastal Louisiana (1932 to 2010)

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

its citizens.