How Landsat Helps Ohio: Floods, Lake Erie Algal Blooms and Spongy Moths

The Landsat satellites have imaged Earth's land for 50 years — the longest continuous record of its kind — and their data are free. In Ohio, that record helps with three recurring problems.

Floods

Landsat's resolution and its huge archive make it useful for mapping floods along the Ohio River and the state's other waterways:

• before a flood, images show rivers at normal levels;
• during one, they help emergency managers estimate the flooded area — especially in cities, where flooding can be very concentrated;
• and the data feed flood models that assess floodplain topography, making disaster management more efficient.

Right: Landsat 8 view of the flooded Scioto River south of Columbus, February 26, 2018. Left: the same river at normal levels two years earlier. Image from the U.S. Geological Survey

Harmful algal blooms in Lake Erie

Western Lake Erie, near Toledo, has harmful algal blooms every year: calm winds, sunshine, heat and spring fertilizer runoff from farms in southeast Michigan, southern Ontario and northwest Ohio create ideal conditions. In 2014, a huge bloom fed by agricultural phosphorus choked the lake that supplies Toledo's water, and Toledo became the first large U.S. city whose tap water was made unsafe by cyanobacteria. Landsat has since been used to track the blooms, so Ohio's water managers know when and where they occur.

A large phytoplankton bloom in western Lake Erie near Toledo, September 2017, seen by Landsat 8. Image from the U.S. Geological Survey

Spongy moths

Satellites have long been used to spot large areas stripped of leaves by spongy moth caterpillars, which can badly damage forest health, ecosystem services and carbon storage. After Ohio drew up a plan in 1998 to slow the moths' spread west, researchers showed that Landsat could locate defoliated areas across the state for targeted treatment.

Landsat for the nation

• It is the most widely used land remote-sensing data source among federal civilian agencies, and local, state and tribal agencies rely on it too — for decisions on land, water and resources that protect life and property, safeguard the environment and support climate resilience.
• Businesses use it to improve logistics, allocate resources and guide investment; commercial imaging companies build products on it.
• A 2017 USGS study put its annual economic benefit to the United States at $2.06 billion — far more than it costs to build and run.
• Landsat 8 and 9 together image Earth's land every 8 days. NASA and the USGS are planning Landsat Next to continue the record.

The data are distributed worldwide through the USGS Earth Resources Observation and Science (EROS) Center, funded by the National Land Imaging Program.

Sources

Based on "Ohio and Landsat," U.S. Geological Survey Fact Sheet 2020–3065, U.S. Geological Survey; a work of the United States government in the public domain.