Landsat Helps Bolster Food Security

“A vision to 

observe Earth 

for the benefit 

of all... ”

Interior Secretary 

Stewart Udall, 1966

One of the cruelest, most complex narratives in the 

world today (2016) is written in the hunger of subSaharan Africa. When famine is the only yield from the 

scorched Earth, survival often depends on a heart-rending 

calculation—how far is the distant feeding center; how 

close is the nearest well.

In many ways, the ability of remote-sensing satellite 

imagery to capture the unforgiving side of Nature has 

become a valuable asset to decision makers facing 

troubling food insecurities in their homelands. Turning 

satellite imaging on to Earth’s natural resources—as 

former Interior Secretary Stewart Udall first proposed 

doing in 1966—became a crucial component of the Famine 

Early Warning Systems Network (FEWS NET) project 

started in 1985 by the U.S. Agency for International 

Development (USAID). The FEWS NET effort relies 

extensively on the U.S. Geological Survey (USGS) 

and other Federal agencies to provide timely, 

accurate data to participating countries to 

assist with the early detection of agricultural 

drought and to mitigate famine.

Today, Landsat satellites are poised to 

take an even greater role in that mission.

U.S. Department of the Interior

U.S. Geological Survey

Fact Sheet 2016–3060

August 2016
0 5 10 MILES

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Figure 1. Landsat data are useful in creating evapotranspiration maps, which detail 

water usage and availability in a region. This map shows where water is transpiring 

from plants or evaporating from the ground in an irrigation district of South Africa from 

October 2013 to February 2014. The blue and green areas indicate greater water usage, 

whereas the yellow and orange areas indicate less water use. The circular blue areas 

denote center-pivot irrigation systems where water use is highest. Such maps are useful 

in providing early detection of agricultural drought to mitigate famine.

Although coarse-resolution remote 

sensing by weather satellites has been 

part of FEWS NET from virtually the 

beginning, Landsat’s involvement has 

evolved in recent years, according to 

Michael Budde, a USGS geographer at 

the Earth Resources Observation and 

Science (EROS) Center in Sioux Falls, 

South Dakota. The evolution of largescale data processing by Google Earth 

Engine and others now makes analyzing 

massive global datasets much easier in 

2016, Budde noted. Extensive computing 

capabilities, made possible by the USGS 

decision in 2008 to make Landsat satellite 

data free to the public, opened the door 

to numerous products that could prove 

useful to FEWS NET projects in Africa, 

Central America, and Central Asia.

Combining Landsat data with 

precipitation and runoff data, USGS 

scientists have created computer models 

that accurately predict water availability 

and usage in a region. These models 

work well in the western United States, 

where researchers are producing maps 

of evapotranspiration (ET)—water that 

transpires from plants and evaporates 

from the ground. Landsat-derived ET 

indices are useful globally, at local scales, 

in identifying water shortages for crops, 

and the impact of such shortages on low 

food production.

Landsat also plays an important role in 

monitoring crop growth. Satellite sensors 

measure wavelengths of light absorbed 

and reflected by green plants. Raw data 

from the plants are then transformed 

into vegetation indices that describe 

the relative density and health of the 

vegetation. These vegetation indices give 

rough measures of vegetation quantities 

and condition. Using 30-meter resolution 

imagery from Landsat, vegetation 

evaluations are nearly 70 times more 

detailed than vegetation condition 

measurements from moderate-resolution 

satellites.

The compatibility of the European Space 

Agency’s new Sentinel-2 satellite with 

Landsat satellites 7 and 8 means revisit 

times are more frequent. Greater satellite 

frequency over an area is useful in places 

where fields are large enough to study 

crop management practices, Budde noted. 

Increased revisit times also have proven 

valuable in validating coarser-resolution 

products that look at snowmelt, flooding 

concerns, even the operational mapping 

of irrigation.

Landsat provides decision makers with 

crucial information needed on crop, 

natural vegetation, and water availability 

data. Accessibility to Landsat data can 

help agencies in prioritizing where to 

direct food assistance by identifying 

where one area may be in worse 

condition than another area because of 

flooding or drought. When they need 

information, USAID officials have 

indicated that data and evidence-based 

information provided by FEWS NET 

are important in the organization’s 

decision-making process.

For the sake of those individuals living 

in places where famine is the Earth’s 

only yield, the decisions made by 

organizations such as USAID are critical 

for their survival. As remote-sensing 

technology continues to evolve, Landsat 

and FEWS NET will help provide those 

much-needed answers.

For additional information, contact:

Michael Budde 

Earth Resources Observation and Science 

(EROS) Center

U.S. Geological Survey

47914 252nd Street

Sioux Falls, SD 57198 

605-594-6511 

http://eros.usgs.gov

ISSN 2327-6916 (print) 

ISSN 2327-6932 (online) http://dx.doi.org/10.3133/fs20163060