What is GAM?

The GAM Program is a major focus of

the U.S. Geological Survey (USGS), the

scientific research agency of the

Department of the Interior (DOI). The

GAM Program is a component of The

National Map, a framework for geographic knowledge needed by the Nation.

The National Map, a source of highquality geospatial data and information

from multiple partners, is accessible to

resource managers and the public. The

GAM Program contributes to The

National Map and other DOI programs

by using geographic analysis and monitoring to provide national and global perspectives on land surface change. In so

doing, it yields insights into many urgent

environmental, natural resource, and economic issues. GAM also provides essential data about the consequences of land

surface change needed by decisionmakers

in land use planning, management, and

resource conservation.

A Changing Planet

The Earth’s surface is changing rapidly.

Some changes have natural causes, such

as earthquakes, floods, or drought. Other

changes, such as urban expansion, deforestation, and agriculture, are brought

about by people.

Whatever their cause, land surface

changes can have profound environmental and economic impacts. They can

affect human health and the health of

ecosystems, influence vulnerability to

floods and fires, interfere with biogeochemical cycles, threaten biodiversity,

alter water and energy budgets, and affect

air quality. Cumulatively, changes at the

local level have the potential to adversely

affect global climate and threaten the sustainability of natural systems worldwide.

Focus of GAM Research

The GAM Program focuses on providing

the comprehensive information needed to

understand the rates, causes, and consequences of land surface change due to

both natural and human-induced processes. The Program’s research activities seek

answers to four fundamental questions:

What kinds of changes are occurring and

why? What are the impacts of these

changes? How do these impacts, in turn,

affect the land surface? And how can

GAM Program findings best be used?

Program Goals

To answer these important questions, the

GAM Program has several key research

goals: 

In 1913, Miami, Florida, was a small settlement

along the banks of the Miami River. Eighty-four

years later, the city and its surrounding landscape

had been utterly transformed. Buildings stood

where woodlands once grew. Networks of streets

and highways had replaced wetlands. And the

city’s population had burgeoned from a few

thousand to some 350,000 (Figure 1). Today,

Miami and its neighboring municipalities make

up the Nation’s 11th largest metropolitan area.

How significant are such changes to the landscape? What impact do they have on natural

ecosystems, resources, climate, and human

health? How do changes in one location affect

other parts of a region, an entire country, or the

rest of the world? What can we learn from past

land surface changes that will enable us to better

predict and handle changes in the future?

The Geographic Analysis and Monitoring (GAM)

Program is designed to answer these and other

vital questions about land surface change.

Figure 1. These two photographs of the same location in Miami, taken in 1913

and 1997, exemplify how dramatically urban expansion can alter the landscape, ecosystems, and the human environment over time. (photos courtesy

of: Historical Museum of Southern Florida, top; South Florida Water

Management District, bottom)

Geographic Analysis and Monitoring Program

U.S. Department of the Interior

U.S. Geological Survey

Fact Sheet 049-03

May 2003

1913

1997
• Analyze, model, and predict the consequences of land surface change on

ecosystems at regional, national, and

global scales.

• Determine how changes in land use

and land cover affect Earth’s climate

and its biochemical and geochemical

processes.

• Analyze land use practices to better

understand how they contribute to

land surface change.

• Investigate how changes in land use

and land cover affect the spread of

infectious diseases.

• Develop more versatile techniques to

monitor land surface change and

ecosystem structure and function.

• Devise better ways to communicate

research results and assist decisionmakers in developing strategies for

enhancing ecosystem sustainability.

Achieving these goals requires innovative investigations into many aspects of

land surface change. Research projects

being carried out under the GAM

Program take an integrated approach,

capitalizing on biologic, hydrologic, and

geologic resources to analyze change and

its impacts both spatially (by location)

and temporally (over time).

Working throughout the United States

and at selected overseas sites, GAM

Program researchers are studying land

use and land cover patterns, structure and

function of ecosystems, sustainability of

natural resources, biogeochemistry, natural hazards, and the effects of change on

human health and lifestyle. They are

quantifying rates of change, identifying

key forces that drive it, and forecasting

future trends. In their research, they combine satellite imagery and other remotely

sensed data with computer modeling and

field observations.

A Sampling of GAM Projects

GAM research projects focus on topics

ranging from the effects of land use

change on the Chesapeake Bay ecosystem to wildland fires and the global carbon cycle. A few GAM Program projects

are highlighted below. For a complete

project listing, visit the web site

gam.usgs.gov/gamcurrentstudies.shtml.

Land Cover Trends

The Land Cover Trends project is a joint

effort between the USGS and the U.S.

Environmental Protection Agency (EPA)

to study land cover

change in the conterminous United States

from 1972 to 2000.

The project divides

the United States into

84 ecoregions. Each

ecoregion is a geographically distinct

assemblage of environmental conditions,

soil type, terrain, natural communities of

living things, and

human activities.

Historical Landsat

satellite images and

aerial photographs are

used to determine the

land cover in each

ecoregion for five

periods, typically

1973, 1980, 1986,

1992, and 2000.

These data are then

combined with on-site

observations to determine trends in how,

and to what degree,

each ecoregion has

changed over time, as

well as the primary driving forces behind the

changes (Figure 2).

Results from the Land

Cover Trends project will reveal a

detailed story of land cover change in the

lower 48 States over the past three

decades.

Geographic Analysis of Disease

Health problems caused by infectious

diseases are a growing concern worldwide. Certain diseases are shared by people and wildlife. Invertebrates, such as

mosquitoes, can be carriers of infection

between the two. Since outbreaks of

viruses and other disease-causing agents

are often evident in wildlife populations

before people are affected, understanding

environmental health is essential to protecting human health (Figure 3).

Figure 2. In this figure, ecoregion color (see scale, lower left) represents the

average amount of land cover change per analysis period (1973-80, 1980-86,

1986-92, and 1992-2000). Pie charts depict the major types of transformations

within each ecoregion. The inset graph (top left) shows overall rates of

change for each analysis period.

Figure 3. In the United States, the first cases of

West Nile virus, which is transmitted by mosquitoes

to birds and certain mammals, including people,

occurred in New England. GAM researchers are

using geographic analysis and monitoring techniques to better understand how geography and

other factors affect the spread of the virus. This

map shows in red all counties in the United States

in which West Nile virus was discovered to be

present (in humans, horses, wild birds, chickens, or

mosquitoes) in 1999, 2000, 2001, and most of 2002.

West Nile Virus

Activity

1999-2002
The recent spread of West Nile virus

across the United States highlights the

importance of understanding the complex geographies of such diseases. As

part of the GAM Program, researchers

from the USGS and the Centers for

Disease Control and Prevention (CDC)

are working collaboratively to monitor

and model environmental changes, such

as altered land use patterns and urban

growth, that increase the rate of human

exposure to West Nile virus. They are

also developing forecasting techniques to

help predict the spread of the disease.

Post-Fire Mapping and Analysis

Wildland fires can seriously disrupt

ecosystems and nearby urban areas.

Assessing fire hazards and identifying

ways to reduce them are key aspects of

the Nation’s fire management policy.

Researchers with the GAM Program’s

Post-Fire Mapping and Analysis project,

working with the National Park Service

and the USGS Biological Resources

Division, are using Landsat satellite data

to create burn severity maps (Figure 4).

Burn severity is an overall index of fire

effects and ecosystem response. These

maps are used by land managers to

assess the impact of major fires, monitor

ecosystem restoration, and identify

opportunities for fire-risk reduction.

Urban Dynamics

Metropolitan areas in the United States

are growing at unprecedented rates, creating extensive urban landscapes where

farmland, wetlands, forests, and other

natural ecosystems once existed. GAM’s

Urban Dynamics research project analyzes landscape transformations resulting

from the growth of metropolitan areas

over time (Figure 5).

Using historical maps, aerial photographs, and Landsat satellite data,

researchers assemble retrospective urban

land use databases to reflect several

decades of change. These are then used

to analyze the impact of urbanization on

the landscape and model future urban

growth under alternative scenarios.

Armed with a clear understanding of past

change and its impacts, communities and

regions are better equipped to plan and

prepare for environmentally sustainable

future growth.

Early Warning and Environmental

Monitoring

The U.S. Government extends economic,

development, and humanitarian assistance to friends and allies in the developing world. Many of these countries are

threatened with resource depletion, land

degradation, floods, droughts, and other

natural hazards. The Early Warning and

Environmental Monitoring project,

through its Famine Early Warning

System Network (FEWS NET) activity,

strives to reduce the incidence of

drought-induced famine in 17 African

countries by (1) providing timely and

accurate information regarding potential

famine conditions (Figure 6), and (2)

Figure 4. This burn severity map of Mesa Verde

National Park in southwestern Colorado shows several fire scars (in various shades of red) from major

wildland fires that occurred on this juniper and

sagebrush landscape between the 1950s and the

present. Bright green indicates healthy vegetation.

Figure 5. This series of maps compares changes in urban (red), agricultural (gold), and forested (green) lands

in the Patuxent River watershed near Washington, D.C., over the past 140 years. Since about 1900, the

amount of agricultural land has declined as urban areas and forested lands have increased.

Figure 6. Crop water balance calculations, derived from remotely sensed data, are used to map the extent

and severity of drought in Africa. This type of geographic analysis guides ground data collection to determine the number of people affected and the scope of the required response by the international community.

This image shows Southern Africa in 2002, where 1.2 million metric tons of food aid are needed by over 12

million people in 6 countries. (Red, pink, and white areas are the most seriously affected.)
helping to establish more effective food

security and response planning networks.

With support from the U.S. Agency for

International Development (USAID),

GAM Program researchers assist FEWS

NET by providing access to satellite data

and other remote sensing and geographic

information system (GIS) technologies to

identify threats to food security from

drought and flood hazards.

Sustainable Tree Crops

The Sustainable Tree Crops project focuses on enhancing sustainable development

among small landholders in Africa, Latin

America, and the Caribbean. GAM

Program researchers work with local

cooperators to develop GIS-based systems

that document production methods for

tree crops such as coffee, cacao, and

cashews, provide data for improving crop

management strategies, and promote environmentally sound agricultural practices.

Distributors and consumers can access

these databases through the Internet. The

project emphasizes increased productivity,

enhanced market efficiency, and improved

socioeconomic return for farmers, while

at the same time promoting biodiversity,

resource conservation, and restoration of

degraded land (Figure 7).

Communication of Risk

Translating scientific data into information that is accessible, easily understood,

and socially relevant is a challenge faced

by many research agencies. The GAM

Program’s Communication of Risk project

addresses this challenge. The project is

working to develop innovative methods

for better communicating USGS scientific

research results—including spatially oriented land use, land cover, and earth science data—to land managers and other

decisionmakers who are wrestling with

complex economic, social, and environmental issues. Many of these issues stem

from the need to mitigate risks posed by

natural or human-made hazards, such as

earthquakes, floods, and pollution.

An initial outcome of the project is the

Land Use Portfolio Model (LUPM). This

technological tool combines hazard information with economic theory and data to

help decisionmakers weigh the economic

and environmental pros and cons of various risk-reduction strategies (Figure 8).

To put the LUPM into practice,

researchers are developing customized,

interactive GIS-based extensions that can

be used to quickly compare various

approaches to risk reduction and determine which options best suit the needs of

a particular community or region.

Program Outcomes

Although the GAM Program is new, it

builds upon the long tradition of land

cover mapping activities within the

USGS. By conducting assessments to

understand the rates, causes, and consequences of land surface change, the

Program will provide information critical

to addressing national agenda issues,

understanding global change, and supporting foreign policy initiatives, especially in

developing countries.

Cooperators and Customers

The GAM Program collaborates with and

provides information to a broad assortment of Federal, State, and public organizations that make land management decisions and shape policy. Primary partners

are Department of Interior Bureaus and

regulatory agencies working with the

USGS, and other Government agencies,

including the U.S. EPA, U.S. Forest

Service, USAID, and National Weather

Service.

The GAM Program maintains and

strengthens existing ties to academic

institutions through grants, cooperative

projects, onsite faculty, and graduate

students. GAM is also aligned with the

research objectives of the U.S. Climate

Change Science Program and is an active

participant in international global science

initiatives.

For More Information

For more information on the Geographic

Analysis and Monitoring Program,

please contact:

Dr. Doug Muchoney, GAM Program

Coordinator

U.S. Geological Survey

12201 Sunrise Valley Drive, MS 519

Reston, VA 20192, USA

Phone: 703/648-6883

E-mail: dmuchoney@usgs.gov

Please also visit the GAM Program web

site at gam.usgs.gov.

Figure 7. By combining satellite imagery, GPS coordinates, and a digital elevation model, researchers with

the USAID-funded Sustainable Tree Crops project in Africa created these images showing the coffee production area (outlined in yellow, left, and green, right) on the slopes of Mt. Elgon in Uganda. Mt. Elgon

National Park lies directly above this area. Shade-grown coffee farms can act as ecological buffer zones

around national parks and other protected lands.

Figure 8. Communication of Risk project

researchers combine land use data, such as those

used to create this image of Watsonville,

California, with hazard information, economic

theory, and other datasets to compare different

approaches to risk reduction in communities.