06 June 2008

Satellite Imagery Drives U.S. Global Food Security Effort

International system links remote sensing, crop models to warn of famine

A farmer tends his crop of Chinese cabbages at Simpha village in Malawi.

By Cheryl Pellerin
Staff Writer

This article is the second in a two-part series on the U.S. Agency for International Development Famine Early Warning System network.

Washington -- Food security -- a state in which everyone has all the food they need for a healthy life -- is a simple concept with many variables. These variables include crop planting and yield, local livelihoods and markets and trade.

Measuring such elements is the increasingly technical job of the U.S. Agency for International Development (USAID), which in 1985, with four other U.S. agencies, established the Famine Early Warning System (FEWS) and in 2000 made it FEWS NET -- an extended network of international, regional and national partners.

Remote sensing of the Earth’s surface from satellites revolutionized the study of the natural environment and made FEWS NET possible. The program combines continent-scale satellite imagery of rainfall and vegetation in Africa and other regions with socioeconomic data about food markets and local income sources. The information is used to warn nations and regions months in advance of impending food shortages.

“Production is one of the fundamental elements of food security,” Gary Eilerts, USAID program manager for FEWS NET, told America.gov, “and we have an ability to monitor the growth of a plant from space.”

U.S. partners include NASA, the National Oceanic and Atmospheric Administration (NOAA), the U.S. Geological Survey (USGS) and the U.S. Department of Agriculture. Chemonics International, a global development firm, implements the program for USAID. (See “Famine Early Warning System Can Predict Food Shortages.”)

USAID established the system to help prevent or respond to famine conditions in sub-Saharan Africa. Now, FEWS NET has offices in 17 African nations; regional offices in Burkina Faso, Kenya and South Africa; and country offices in Afghanistan, Haiti and Guatemala.

EYES IN THE SKY

Satellite sensors acquire images of Earth and transmit the data to ground receiving stations worldwide. Once the raw images are processed and analyzed, scientists can document changing environmental conditions like pollution, global climate change, natural resource distribution, urban growth and more.

For FEWS NET, geographer Molly Brown, who works for the Biospherics Sciences Branch at NASA’s Goddard Space Flight Center in Maryland, told America.gov, “satellite remote sensing is where it all begins.”

In this work, NASA and NOAA contribute satellite imaging data, and USGS processes imagery for distribution to FEWS NET analysts.

Data about vegetation and rainfall come daily from sensors on NOAA’s advanced very high resolution radiometer (AVHRR) satellite. One sensor produces the integrated spectral vegetation index, which measures reflected sunlight, or energy, directly from the plants. Another sensor measures rainfall.

An African child eats banana leaves as his daily meal.

Rainfall measurements also come from the Tropical Rainfall Measuring Mission satellite -- a joint mission between NASA and the Japan Aerospace Exploration Agency -- and the Defense Meteorological Satellite Program Special Sensor Microwave/Imager.

Rainfall estimates are combined with ground measurements so analysts can “figure out how much rainfall has happened,” Brown says, “and then FEWS NET takes those estimates and puts them through a model” that allows analysts to estimate a plant’s ultimate yield based on factors like when it was planted during the growth season and how much rain it received.

“What we’re trying to do now, Brown said, “is to multiply that yield effect due to rainfall by the actual amount of land in crop to get an estimate of how much food was either produced or is in deficit.”

TECHNICAL DIPLOMACY

Over time, FEWS NET has employed an increasing number of country or regional residents to work in its offices as analysts. Today, all the employees are from the region where the office is located.

“There has been a progressive handing over of a lot of the remote sensing work,” Eilerts said, “so our field people look at it as part of a product delivered to them from a local source. It’s a NASA-NOAA product processed and sent out by USGS to local partners who have been trained to do this.”

At Chemonics International, the global development firm that implements the program for USAID, Chief of Party Charles Chopak told America.gov that FEWS NET teaches local staff how to do assessments, use geographic information systems and deal with a range of technical issues required for early warnings.

“In a lot of ways, we don’t have the resources to collect primary data,” said Chopak, an agricultural economist, “so we go to the governments and say, ‘Can we have your production data, your price data, what’s going on with this,’ and we’re pulling from that. But what we give back is capacity building and stronger networks.”

In some countries, FEWS NET has developed national vulnerability assessment committees chaired by a government official, which assess the country’s vulnerability and food security situation after harvests.

“In countries where we don’t have solid networks, we don’t get to consensus as quickly and there tends to be an argument about how to proceed,” he added.

“In [one country] with a complex political environment, this year we were able to organize and help complete a harvest assessment that included government,” Chopak said. “Even though it’s a very difficult government” that did not want its land policies to appear to be failing, “the consensus production estimate showed that less than 30 percent of their needs were being met.”

By keeping the work on a technical level, he added, “We’re able as a group to leverage resources and expertise to get good work out.”

FEWS NET, Eilerts said, “is working with people, working with the agencies around us, and that includes repressive governments, incapable governments, good governments, U.N. agencies and private voluntary organizations. We have a reputation for being open, transparent and collaborative.”

More information about FEWS NET is available at the USAID Web site.

For more about remote sensing systems, see "U.S. Agencies Moving Forward in Planning Landsat 7 Successor."