This project uses Spatial Analyst to look at the question of how many people would be affected in Florida, and where, if the sea level were to rise just two meters. This download contains a 17-minute ScreenCam movie showing the entire exploration in operation. It also contains special files used in the project. (Anyone using Windows can watch the movie using just the Lotus ScreenCam player, available as free download from www.lotus.com/screencam.)
If global warming is a real phenomenon and sea-level rise does occur, would people be affected? This is a problem that calls for ArcView and Spatial Analyst. By exploring elevation data and integrating this information with the location and population of cities in Florida, we can begin to see some of the possible impact.
This package of files includes a ScreenCam video showing ArcView and Spatial Analyst in operation. The movie contains a series of captions, showing groups of steps. The steps are listed below. You should be able to follow the basic operation and duplicate the procedure on your computer, if you have ArcView and Spatial Analyst. The video shows accessing some data that had been copied to the hard drive from the Spatial Analyst CD and from the ArcUSA CD. The data file of Florida cities (from the 1990 Census) and the elevation legend shown in the video are included in this package of files.
Use the ScreenCam player (freely available from http://www.lotus.com/screencam/) to display the video. Use the video control panel buttons to rewind, pause, play, and fast forward as needed.
To complete this activity get the data files from the attached zipped file: "lsn_safl.zip".
Now that you have seen the operation at work, see if you can duplicate the process. You may want to move the North America DEM data from the Spatial Analyst CD to your hard drive, as well as the ArcUSA decimal degree 1:2,000,000 scale county data, to speed up the data display process. Then, be sure to navigate to where you have the data stored, at the appropriate steps.
The original exercise shows one way to accomplish the task. There is another way, starting at Step#14. See if you can follow these directions to accomplish a similar result.
(Finally, if you want to try this and don't have access to the source data from the Spatial Analyst CD, included in the "lsn_safl" directory is the Florida elevation subset, as a grid called "fl_elev." This will let you shortcut the original steps 3-8.)
DISCUSSION: The Spatial Analyst extension to ArcView allows you to conduct some very powerful analyses. You might find other ways to explore similar information in other parts of the U.S., or the world. It is important to recognize that the data being used will affect the quality of decisions that can be made. This specific example uses fairly coarse elevation data Â-- 1 kilometer resolution. Finer scale data is available for local areas, and is vastly preferable if decisions actually affecting lives are being made. Similarly, the cities are shown here only by "internal center," rather than extent of populated area. The query was set to identify city centers within 3 miles of the flooded zone, which might miss some important areas of impact. Still, the process shows, quickly and roughly, that a large number of people would be directly affected by such flooding. This should be sufficient to inspire further analysis, using more detailed data, if more exact implications are needed.
The activity easily could be replicated to provide a look at localized flooding in river valleys. Similar procedures might permit the exploration of numbers of people affected by dispersion of various contaminants, or exploring the impact of airport noise on different neighborhoods. There are many opportunities to expand these concepts and skills!
TECHNICAL NOTE: The movie demonstrates a technique that can speed up procedures in ArcView. When the user is comfortable with the tasks and data, many operations can be performed without having to display all the changes. The movie doesn't actually show the display of data until Step#9. This saved a number of "display changes," which can mean a significant time saving when using large data sets. This is only a savings, though, when the user knows for sure what would be displayed.
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