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. |
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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). |
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 high-quality 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.
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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.
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?
To answer these important questions, the GAM Program has several key research goals:
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.
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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/jspapps/jsp/gam/highlight.jsp.
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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. |
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.
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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. |
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).
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.
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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. |
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.
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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. |
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.
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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.) |
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) 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.
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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. |
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).
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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. |
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.
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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.
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 information on these and other USGS products and services, call 1-888-ASK-USGS, or visit the general interest publications Web site on mapping, geography, and related topics at erg.usgs.gov/isb/pubs/pubslists/.
For additional information, visit the ask.usgs.gov Web site or the USGS home page at www.usgs.gov.
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.
Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government. This document has undergone official review and approval for publications established byThe National Mapping Discipline, U.S. Geological Survey. Some figures have been modified or added to improve the scientific visualization of information.
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