Use GIS to study cover type changes

The Penn Pilot web site provides historical aerial photos for most of Pennsylvania. You can either view the photos on the site or download them to use with other applications. Recently, in GIS class we used ArcGIS 9.2 to position the old aerial photos from 1937 over a current map of the southern portion of the Waynesboro Watershed using a process called georeferencing. Much of the area that is now the reservoir and its watershed was actively farmed. Here is an image of the map layout showing the farm fields outlined in green. (Click on the image to see a full screen version.)


When we remove the overlaid aerial photo we can see what the land looks like today with just the bouhdaries of the old fields. It’s evident that when forestry students in the 1950’s started working in the watershed they put the pine plantations on the old fields. This makes a lot of sense considering that it is much harder to put a plantation in existing forest.
historic_watershed2.jpgFor instructions of how to perform this operation click here. To use Penn Pilot click here.

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