Louisiana and Landsat: Watching a Coast That Is Slipping Away

Louisiana holds a place of its own in American history, economy and culture. Its offshore oil operations help power the national economy. The Port of South Louisiana is the busiest in the country by cargo volume, and the nearby Port of New Orleans ranks sixth. Long before independence, the former French and Spanish colony was a key link to the Caribbean, and its mix of peoples produced a Creole culture that shaped America far beyond the state's borders.

That heritage draws more than 18 million visitors a year to New Orleans, to the 13 colourful blocks of the French Quarter with their flowers, beignets and crawfish, and to the city's jazz, rock, country and zydeco. But the same closeness to the Gulf Coast, and a city sitting just 6.5 feet above sea level, carry a warning. Hurricane Katrina struck New Orleans in 2005 and was tied to more than 1,800 deaths, one of the worst U.S. weather disasters of this century. Environmental change has made tropical storms more dangerous; with more frequent and stronger storms, rising seas threaten low-lying places such as Lake Charles, and unpredictable weather threatens cities and farms further north.

Landsat, the satellite series run jointly by the U.S. Geological Survey (USGS) and NASA, helps with early warning, disaster response and tracking recovery. Its 50-year archive of repeated images of the same places also guides resilience plans and feeds models that help states like Louisiana prepare for change on the coast and inland. A few examples follow.

A U.S. Department of Agriculture Wetlands Reserve Program site in Natchitoches Parish, Louisiana. Credit: Glenn Austin, Natural Resources Conservation Service.

Watching the coast

Louisiana's coastal wetlands blunt storm surges during tropical storms and shelter shorebirds and other wildlife, but they are disappearing fast. In 2017 the Geological Society of America estimated that Louisiana's coast was sinking by between 6 and 20 millimetres a year. Landsat can follow shoreline change over wide areas and long periods. One study that mined the record found that the shoreline of Bay Champagne retreated 292 metres from 1983 through 2018, and that at that pace the area would be entirely underwater in 40 years.

Water quality

From the Gulf to the Mississippi's upstream tributaries, clean water underpins both Louisiana's ecology and its economy. Landsat records light in bands the human eye cannot see; looking beyond red, green and blue into the infrared and near-infrared helps researchers spot dissolved organic matter and harmful algal blooms more clearly and over wider areas.

• One study combined Landsat with other satellite data to map water quality trends over time in the Barataria Basin.
• Another used Landsat to follow damage from the Deepwater Horizon oil spill, which released more than 200 million gallons of oil into the Gulf and fouled more than 1,300 miles of coastline in several states, Louisiana among them. It found that the worst harm to the health of above-ground vegetation in Louisiana's salt marshes came in the first 2 years after the spill.

Mapping disaster, tracking recovery

With 7,721 miles of coastline, Louisiana is one of the states most exposed to hurricanes. Immediately after a storm, Landsat imagery goes into the USGS Hazards Data Distribution System, which delivers satellite images to first responders and to researchers mapping floodwater. In the months and years that follow, repeated images build a long record of the storm's effects. Ten years after Katrina, for example, Landsat showed swollen lakes, new waterways and drowned marshes in some of the hardest-hit wetlands.

New Orleans after Hurricane Katrina, which struck in August 2005. Left, September 7, 2005, just over a week after the storm: dark areas are floodwater. Right, October 9, 2005: once-flooded areas show brown where vegetation was destroyed. Landsat 5 images. Credit: U.S. Geological Survey.

Landsat across the country

The USGS National Land Imaging Program supplies satellite imagery and other remotely sensed and geospatial data to government, business, universities and the public, who can reach the Landsat archive worldwide through the USGS Earth Resources Observation and Science (EROS) Center.

Landsat is the most widely used source of land remote sensing data among federal civilian agencies, and local, state, tribal and federal agencies use it to monitor and forecast what happens on the land surface. Its information feeds everyday decisions about land, water and resources — protecting lives and property, safeguarding the environment, advancing science and education, supporting climate resilience and growing the economy. Businesses build customer applications on it to improve logistics, resource allocation and investment, and commercial imaging companies use it to refine their products. A 2017 USGS study put the annual economic benefit of Landsat data in the United States at $2.06 billion, far more than the cost of building and running the satellites.

Landsat 8 and Landsat 9 together image Earth's land surface every 8 days. NASA and the USGS were reviewing the findings of a joint Architecture Study Team to shape Landsat Next, the mission to follow Landsat 9, so that the series — the world's longest record of Earth's land surface — can continue. Because the data are consistent, accurate and free, users can study large areas and long-term trends, and new cloud computing tools put Landsat into decision-support systems for government and industry. Like GPS and weather data, Landsat is used every day to understand a changing planet.

Sources

Based on "Louisiana and Landsat," U.S. Geological Survey Fact Sheet 2022–3059 (version 1.1, March 2025), published by the U.S. Geological Survey; rewritten in hubnx's own words.

• The wetland photograph comes from the fact sheet's PDF: https://pubs.usgs.gov/fs/2022/3059/fs20223059.pdf
• Studies the fact sheet cites: Nienhuis and others (2017) on subsidence; Dietz and others (2018) on Bay Champagne; Liu and others (2019) on the Barataria Basin; Mo and others (2017) on Deepwater Horizon; Barras (2006) and NASA (2022) on Katrina; Straub and others (2019) on Landsat's economic value.