How Landsat Serves Nevada

This USGS fact sheet describes Landsat and its plans as they stood when it was written.

Landsat satellites have recorded the Earth's land surface for 50 years, the world's longest such record, and the data are free. This U.S. Geological Survey (USGS) fact sheet describes how Nevada uses them.

Watching the water

The Colorado River Basin supplies water to seven U.S. states and to Mexico, and it has been in drought of varying severity since 2000. In August 2021 Lake Mead fell to a record low of about 35 percent of capacity, and the Bureau of Reclamation declared a water shortage for the lake, one of the river's two key reservoirs, for the first time. That cut water supplies for Nevada, Arizona and Mexico starting in 2022.

Lake Mead, behind Hoover Dam on the Colorado River, supplies 90 percent of southern Nevada's water. The white "bathtub ring" around the lake marks the old high-water line and shows more as the water drops. Photo by Michael R. Rosen, U.S. Geological Survey.

Landsat images show the lake growing and shrinking over the years, and the data help measure water use on land to improve water budgets and models. Measuring evapotranspiration (ET), the movement of water into the air through evaporation and plant transpiration, with Landsat can show how much water goes to irrigation, which accounts for more than two-thirds of fresh water used in Nevada. The Nevada Department of Water Resources has used Landsat-based data to help monitor farm water use.

Threats to sagebrush

Sagebrush survives drought and grows where other plants cannot, and some species live as long as 150 years. Some wildlife, such as the greater sage-grouse, live only in sagebrush country. But sagebrush cannot survive wildfire and can take decades to recover from fire or other disturbance. It is also threatened by invasive plants such as cheatgrass, which raise the risk of fire. Landsat's wide coverage and long archive help map cheatgrass and other invaders over time and use those patterns to model where the land will be vulnerable next.

USGS cheatgrass and exotic annual grass maps built from Landsat data feed maps like this one for Fuelcast, which estimates plant biomass across the western United States. Map by Matt Reeves, U.S. Department of Agriculture.

Cities

Landsat images show decades of the Las Vegas area's remarkable growth. The data can also reveal urban heat islands, areas with more pavement and buildings and less natural cover, where temperatures day and night run higher than in the surroundings and put vulnerable residents at greater risk of heat illness or death. A NASA project to help the Washoe County Health District reduce heat in the Reno–Sparks area used Landsat land-cover and land-surface-temperature data to find places with high heat and vulnerability.

Landsat can show how cities and landscapes change, as in these maps of where the Las Vegas metropolitan area grew. U.S. Geological Survey.

Landsat nationally

• Access: the USGS National Land Imaging Program provides satellite and other geospatial data to government, business, universities and the public, and funds the USGS Earth Resources Observation and Science (EROS) Center, which gives worldwide access to Landsat data.
• Use: Landsat is the most widely used land remote sensing data source in federal civilian agencies.
• Value: a 2017 USGS study put its total annual economic benefit to the United States at $2.06 billion, far more than it costs to build and run.
• Coverage: Landsat 8 and Landsat 9 image the Earth's land every 8 days.
• What is next: NASA and the USGS were reviewing findings from a joint Architecture Study Team to shape Landsat Next, the mission to follow Landsat 9.

Sources

• U.S. Geological Survey, "Nevada and Landsat," Fact Sheet 2022–3026. https://pubs.usgs.gov/publication/fs20223026/full
• The fact sheet cites Serbina and Miller (2014) on agricultural water use, Pastick and others (2021) on invasive grasses, Heslin and others (2018) on urban heat, and Straub and others (2019) on Landsat's economic value.