Geographic Analysis

One of the primary roles of GIS is to use the Geographic Information System to perform analyses for the various County Service Groups, and to teach them how to perform such analyses themselves.

 

Spatial relationships

The term spatial relationship can be best explained through an example. Consider the question “How many wells are in Volusia County?” This query is nonspatial in nature. The answer does not require knowledge of the physical location of the wells nor does it describe where the wells are in relation to one another. On the other hand, a question that asks “How many wells are in the County that are 10 inches in diameter and are 1000 feet apart?” is spatial in nature. To answer this question, one must have the ability to determine the location of each well, measure the distance between the wells and examine their attributes (e.g., diameter). A GIS can readily provide such information.

 

A GIS can do this because it has the ability to link spatial data with information (facts and figures) about a particular feature on a map. The information is stored as attributes, or characteristics, of the graphically represented feature. For example, without a GIS, a street network might be represented by simple street centerlines, in which case the actual visual representation of the road would not yield much information. To obtain the information about the road, such as type (paved, gravel, etc.), you would have to take the street name from the map and use it to query a separate database. As shown below, the GIS allows you illustrate the database on the map by using different symbols to draw the roads; such as by drawing heavy line, a regular line, or a dotted line to show whether the road is paved, surface-treated, or unpaved. The result of such a display is that the user can determine information about features on the map simply by looking at them.