The Great Salt Lake shrank between 1985 and 2010

Great Salt Lake 1985 [left], 2010 [right]. Landsat satellite imagery shows the dramatic changes in the area of the Great Salt Lake over the last 25 years

Aug 21, 2014 • [By Jon Campbell, USGS] A recent White House-led assessment found that Landsat is among the Nation’s most critical Earth observing systems, second only to GPS and weather. A new USGS study, Landsat and Water — Case Studies of the Uses and Benefits of Landsat Imagery in Water Resources, provides examples of why Landsat is so valuable.

Landsat supports many types of resource management

The Landsat satellites have been a central data source for Earth science since the launch of Landsat 1 in 1972. In 2008 the use of Landsat data expanded dramatically when the USGS adopted a free and open data policy. Since then, the amount of Landsat data used, the number of users, and the variety of applications of the data have increased exponentially. Landsat is now used for both research and decision support by users ranging from government agencies and large corporations to individual scientists and entrepreneurs.

Landsat continues to shape our scientific understanding of how the Earth has changed with modern society. Furthermore, Landsat provides decision makers with critical operational information about the Nation’s – and the world’s – crops, forests, and water. For example, Landsat data helps forest managers design restoration after a wildfire and respond to insect infestations or disease. It helps states and counties identify land use practices that affect water quality and helps agricultural agencies forecast crop production both nationally and globally.

Landsat for water resources

Water is managed by many levels of federal, state, local, and tribal governments; by the private sector; through the courts; and through international and interstate treaties and compacts. At all these levels, water users and managers rely more and more on Landsat data about water conditions both ­at the moment and in the context of four decades of Landsat record.

The Nation’s largest wholesaler of water, the U.S. Bureau of Reclamation, uses Landsat data for mapping and monitoring on the lower Colorado River, including:

• monitoring agricultural water use

• annual estimates of evapotranspiration from riparian vegetation

• estimates of evaporation from the surface waters of the lower Colorado River

• identification of types, locations, and acreages of crops, irrigated lands, and riparian vegetation.

Landsat imagery makes it possible to generate this information at a level of accuracy that would otherwise not be feasible.

At the state level, Landsat’s unique combination of thermal and optical data makes for an efficient tool for fair enforcement of the Upper Colorado River Compact, which spans Wyoming, Utah, New Mexico, and Colorado. The member parties of the compact all rely on Landsat data to offer consistency and transparency in measurements taken across the multi-state area and to provide cost savings compared to other measurement and monitoring approaches.

The Colorado Water Conservation Board has used Landsat data for 20–25 years to assist in water planning activities. Currently, Landsat is used in almost every basin to delineate between irrigated and non-irrigated land and to help estimate actual consumptive use of water. Landsat has special benefit in areas where there are no ground-based diversion or pumping records available.

Water justice through Landsat

In dry environments and times of drought, state water courts hear disputes regarding use, timing, and location of water resources. These decisions increasingly rely on data from Landsat.

In Idaho, two recent water rights cases used Landsat data as evidence. In one case, water restrictions were lifted from a group of users based on Landsat data used with the state’s METRIC model (a computer simulation; Mapping EvapoTranspiration at high Resolution with Internalized Calibration). In another case, water use was curtailed based on Landsat and METRIC evidence showing that the status quo had caused harm to a group of water rights holders. Landsat is similarly used by the Wyoming State Engineer’s office to monitor the Green River Basin and administer the state’s obligations under the Colorado River Compact and by the Nevada State Engineer’s office to verify agricultural water use and adjudicate water rights applications and protests. Further examples in California, Colorado, Nevada, and Oregon are described in the report.

Additionally, Landsat’s unique combination of thermal and optical band data allows for identification of irrigated and non-irrigated lands and is routinely used for this purpose by the State of Nevada and others.

Private companies increasingly use Landsat

Agricultural producers also face challenges with water shortages. The wine business offers an example of the use of Landsat data to conserve water and sustain — or improve — crop productivity during a period of drought.

E. and J. Gallo is the largest winemaker in the world and the first known company in the U.S. beverage industry to use Landsat data in viticulture practices. A pioneer of efficient water management through remote sensing, Gallo downloads all available Landsat data for approximately 20,000 acres of California vineyards during the grape-growing season. Gallo uses the data to decrease the amount of water applied by 20–30 percent, develop more efficient seasonal irrigation schedules, and improve grape quality — measures that factor into increased profitability.

Landsat’s global coverage creates the potential to adopt similar practices in vineyards in other parts of the world. The report includes examples of Landsat applications for Chilean and Australian viticulture.

Advancing water monitoring and resource management worldwide

In Chile, Landsat has been instrumental in helping estimate water demand under frequent droughts. Because agricultural production is such a large enterprise in Chile, water shortages can affect overall economic growth. In Australia, Landsat imagery, in conjunction with images from NASA’s MODIS and commercial satellites, has been used to map flood extent to provide situational-awareness information to emergency services in order to save lives and mitigate economic impact. Water explorations have been successfully conducted in the Darfur conflict region as well as in Venezuela.

As a powerful source of continuous, trusted data about the Earth’s land surfaces, Landsat has contributed tremendously to crisis prevention, crisis mitigation, and improved management of natural resources worldwide.

Further Reading:
+ Landsat’s Role in Water Resource Management
+ USGS press release
+ USGS Landsat & Water report