SLEUTH (Slope, Land Cover, Exclusions, Urban Areas, Transportation, Hydrologic)

While advances in space technology continue and visionaries predict the spread of human colonies into space, it appears many are more than happy to ‘spread out’ right here on Earth, potentially creating environmental concerns.

 Image Right: Forecast of development patterns in 2030 for current trends scenario. Click on image to enlarge. Credit: Claire Jantz, University of Maryland, College Park

Understanding that urban and suburban development can increase storm water runoff and threaten water quality, research scientists Claire Jantz and Scott Goetz of the University of Maryland, College Park, and others aimed to simulate policies affecting land use.

Computer Models and Satellites Give the ‘Big Picture’

The study relied on observations from NASA and commercial Earth observation satellites used in a United States Geological Survey computer model called SLEUTH (Slope, Land Cover, Exclusions, Urban Areas, Transportation, Hydrologic) to create a modeling system that could assess future planning by exploring the impact of different regional management scenarios. Growth was projected to 2030 for the Washington-Baltimore area using different scenarios.

Under current policies, development would increase by 80 percent by 2030, but with stronger protection of forests and agriculture, growth would be reduced to only 20 percent. The study also found that the region experienced a 39 percent increase in developed land between 1986 and 2000, with some of the most striking changes in northern Virginia, near Dulles Airport.

Such development has been at least partly responsible for a decline in water quality in the Chesapeake Bay estuary system. This research will give decision-makers more detailed information about the environmental impacts of development, such as the effects of greater storm water runoff or poor drainage.

Image Left: Forecast of development patterns in 2030 for ecologically sustainable scenario. Click on image to enlarge. Credit: Claire Jantz, University of Maryland, College Park

Beyond SLEUTH, other tools, such as Space Imaging’s IKONOS satellite can be used to complement NASA’s imagery from Landsat satellites. For this research, IKONOS images, with resolutions up to one meter (3.28 feet), were used with county-level air photos to link to 30-meter Landsat observations, which cover vast areas and offer a longer time frame for assessing urban change.

“The satellite observations provided us with an unprecedented ability to monitor the urbanization process and capture the patterns of urban sprawl,” said Goetz.

Putting Improved Technology to Use

SLEUTH is applicable to land use studies and can help local leaders assess the configuration of landscapes in forests and urban areas. The Maryland Department of Natural Resources is considering use of the model to target forest resources, restoration and conservation activities.

“The model is a tool that can be used for land use planning and resource management, it offers the ability to explore and visualize alternative futures,” Jantz said.

In recent years, other states have begun relying on satellite data, rather than the more expensive and time-consuming aerial photography, to evaluate how different urban planning programs effect population growth and land use. In 2002, researchers at NASA and the University Connecticut started the NAUTILUS project to provide city planners satellite data quickly in a form that non-scientists can understand.

The project lets city planners envision a hypothetical future of their city, assuming that it grows according to current zoning patterns. They can view simple maps, color-coded for environmental impacts, or they can choose to “fly through” a photo-realistic 3-D map of their future city to get a more visceral sense of things to come. It also lets them make changes and view the likely outcome of different growth scenarios