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Geographer Ron Eastman develops geographic information software that helps urban and rural planners make informed decisions about how to allocate land for different purposes. |
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Risky business: allocating land using GIS
Professor Ron Eastman's research
Urban and rural planners make decisions that have profound effects on people's lives. Where should scarce food resources be allocated during a famine? What is the best evacuation route in the event of a flood? Where should a day-care center be located? Which site for a new manufacturing plant will be most cost-effective and least damaging to the environment?
Geographer Ron Eastman,
creator of the award-winning IDRISI
geographic information system (GIS) software, designs software tools that help planners
think logically about the locational decisions they make. These tools also allow planners
to keep a record of the steps, choices, and assumptions that went into a particular decision.
The IDRISI software allows planners to
- Create a map of each criterion that figures in the location decision.
- Combine multiple criteria into a single map of suitability for the intended use or action.
Making locational choices is not an exact process. The data used in making a decision is not always complete, or for the desired point in time, or of high quality. Often money is not available for the collection of higher quality or more up-to-date data. IDRISI allows planners to take into account their assessments of data quality and
- Consider how risk-averse or risk-taking they are willing to be when choosing a location site.
The scenario below illustrates a locational case study. Decisions being made at each stage of the process are summarized in blue.
An example: choosing land for an industrial park in Kenya
Establishing criteria
In this scenario, the objective is to determine the best location for a new industrial park in a growing urban region of Nakuru, Kenya. Planners require a site that will be
- close to roads,
- close to the center of population,
- away from a wildlife reserve,
- and fairly flat (less than 10 degrees of slope).
Using the IDRISI GIS software, they create one map for each of these criteria. Each map is structured as a grid, and each cell in the grid is assigned a numerical value that represents, according to the criterion:
- The distance of that grid cell from the nearest road (see examples)
- distance of that grid cell from the urban center
- distance of that grid cell from the wildlife reserve
- the slope of the land at that grid cell location
At this point in the process, the p
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Additional Resources
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 Computer mapping: representing a geographical area as a grid. If any of the computer generated maps below were enlarged sufficiently, you would see that they are composed of pixels, each of which has a numerical value. More information. |
 Map showing distance from nearest road. The whiter the pixel, the closer to a road and the more suitable the location for the industrial park. Roads are superimposed in red. |
 Map showing distance from park. The whiter the pixel, the further from the park and the more suitable the location.The wildlife preserve is superimposed in red. |
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