South Carolina and Landsat: Forests, Watersheds and Salt Marshes

South Carolina, the eighth state admitted to the Union, is bigger than its size in history, natural beauty, natural resources and cultural diversity. The Upstate, which takes in part of the Blue Ridge Mountains of the Central Appalachians, has more than 100 waterfalls; the Lowcountry faces the Atlantic with 187 miles of coastline and 35 barrier islands. Forests cover two-thirds of the state, and forestry and agriculture together — agribusiness — are its leading industry. Cotton and tobacco, the historic crops, are still among the top 10 commodities, though corn and soybeans now rank higher, and poultry, cattle, peanuts and flowers make the list too.

More than five million people live there, alongside black bears (Ursus americanus), American alligators (Alligator mississippiensis), bottlenose dolphins (Tursiops truncatus) and many other birds, reptiles and fish. More than 100 kinds of tree grow in the state, and one of them gives it its nickname, "The Palmetto State."

A subtropical climate, a long coast and low elevations leave South Carolina highly exposed to tornadoes, hurricanes and coastal flooding, and projected sea level rise is a growing worry. Landsat, the satellite series run jointly by the U.S. Geological Survey (USGS) and NASA, helps manage resources on land and in rivers, marshes and the coast — showing not only what a place looks like now but what it looked like decades ago. A USGS fact sheet gives three examples.

Managing the forests

South Carolina's woodlands range from the common loblolly pine to many kinds of oak. Several state and national forests lie within its borders, but most forest land is privately owned. Forests add $21 billion to the state's economy, from pulp and paper to logging and recreation. The South Carolina Forestry Commission is one of 13 state forest agencies in the South in the Southern Forest Area Change Tools (SouthFACT) project, which uses Landsat images to show where forests are changing and by how much.

Congaree National Park holds some of South Carolina's forest land, with an old-growth bottomland hardwood forest and an upland pine forest. Credit: Victoria Stauffenberg, National Park Service.

Watching the watersheds

Landsat imagery is the basis of the National Land Cover Database (NLCD), whose maps show land cover and how it changes over time, helping managers analyse, model and decide how land is used. The South Carolina Department of Health and Environmental Control includes NLCD data in its Watershed Atlas, an interactive map with layers of data for understanding and responding to water quality problems.

Assessing the salt marshes

Landsat's wide coverage and archive of more than 50 years make it valuable for many purposes. In 2020, the South Carolina Department of Natural Resources, the Department of Health and Environmental Control and the USGS worked with a NASA DEVELOP project team to judge how vulnerable the productive salt marshes near Charleston are to rising seas and to changes in land use upstream, so as to see which areas might need more resources. The team used the UnVegetated-Vegetated Ratio (UVVR), a method based partly on Landsat data, to map changes in vulnerability back to 1984.

In Charleston, too, the National Oceanic and Atmospheric Administration's (NOAA) Office for Coastal Management uses Landsat for its Coastal Change Analysis Program (C-CAP), which produces land cover and change products and feeds tools such as the Sea Level Rise Viewer.

A marsh on Bulls Island off the coast of South Carolina. Credit: Steve Hillebrand, U.S. Fish and Wildlife Service.

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. Its information feeds everyday decisions on land, water and resources — protecting lives and property, safeguarding the environment, advancing science and education, and growing the economy. Businesses build customer applications on it, and commercial imaging companies use it to refine their products. A 2024 study put the total annual economic benefit of Landsat data at $25.6 billion, far more than it costs to build and run.

Landsat 8 and Landsat 9 together image Earth's land surface every 8 days. NASA and the USGS are working towards a 2031 launch of Landsat 10, with significant improvements, to extend a record of more than 50 years — the world's longest of Earth's land surface. Because the data are consistent, accurate and free, users can study large areas and long-term change, 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 "South Carolina and Landsat," U.S. Geological Survey Fact Sheet 2022–3005, published by the U.S. Geological Survey; rewritten in hubnx's own words.

• Sources the fact sheet cites: South Carolina Department of Agriculture (2022), South Carolina Forestry Commission (2022), Southern Forest Area Change Tools (2022), South Carolina Department of Health and Environmental Control (2019), Stidd and others (2020), NOAA Office for Coastal Management (2022), and Loomis and others (2024).
• The fact sheet's opening sentence reads "deep, and Landsat rich history," evidently a slip for a deep and rich history.
• The fact sheet's image of the state's Watershed Atlas is credited to the South Carolina Department of Health and Environmental Control and is not reproduced.