USGS - science for a changing world

Geographic Analysis and Monitoring Program

Miami, FL - 1913 and 1997
These two photographs of the same location in Miami, taken in 1913 and 1997, demonstrate how dramatically urban expansion can alter the landscape, ecosystems, and the human environment over time. (Photos courtesy of Historical Museum of Southern Florida)

A Changing Planet

The surface of the Earth is changing rapidly, at local, regional, national, and global scales, with significant repercussions for people, the economy, and the environment. Some changes have natural causes, such as wildland fires or hurricanes, while other changes on the land, such as resource extraction, agricultural practices, and urban growth, are human-induced processes. There are other types of changes that are a combination of natural and human-induced factors; landslides and floods, for example, are fundamentally natural processes that are often intensified or accelerated by human land use practices. Whatever their cause, land-surface changes can have profound environmental and economic impacts.

The goal of the USGS Geographic Analysis and Monitoring (GAM) Program is to contribute to an understanding of the changes occurring and the consequences of these changes. It assesses the Earth's land cover at a range of spatial and temporal scales to better understand the causes and consequences of land cover change.

Innovative applications of GAM research encompass many fields, including climatic and hydrologic variability, biogeochemical cycling, ecosystem health, natural hazards analyses (including disaster prediction, mitigation, and response), and wildfire science. These applications provide a basis for resource managers and the public to understand the dynamic nature of our landscape and to anticipate the consequences of the interplay between natural processes and human actions.

The GAM Program is responsible for two national-scale projects: the National Land Cover Database (NLCD) and the Land Cover Status and Trends Reports. These long-term compilations of land cover conditions provide the foundation of USGS land-surface monitoring efforts, as well as those of numerous governmental and nongovernmental organizations. The results of these projects are necessary components of any regional or national environmental assessments.

Analytical approaches to the geographic relationship of natural hazards and society enable GAM researchers to develop methods and processes, such as decision-support systems and economic models that can facilitate the use of USGS science in public policy. By understanding the vulnerability and resilience of human and environmental systems in the context of place, geographic science can link assessments of potential hazards with the development of risk-reduction measures.

Featured Science Tsunami exposure estimation with land-cover data

A Cascadia subduction-zone earthquake has the potential to generate tsunami waves which would impact more than 1000 km of coastline on the west coast of the United States and Canada. Although the predicted extent of tsunami inundation is similar for low-lying land along the Oregon coast, use of tsunami-prone land varies, creating variations in community exposure and potential impacts. An article in Applied Geography by USGS research geographer Nathan Wood summarizes the use of midresolution land-cover data to (1) describe tsunami-prone land, (2) approximate city-level estimates of community assets, (3) assess variations in city exposure to tsunamis, and (4) compare city-level exposure estimates based on land-cover and socioeconomic data. The ability to compare community exposure to natural hazards using land-cover data derived from midresolution remotely-sensed imagery could serve as one element in a national vulnerability monitoring effort to identify at-risk areas.

More Information


GAM Fact Sheet
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