Array: The Array module used to manipulate mathematically one, two, or a series of 2D or 3D grid files. Depending on the options selected, operations include addition, subtraction, multiplication, division, averaging, minimum, maximum, probability value within a range, reclassification, and basic statistics. These are basic grid tools used in Geographical Information Systems (GIS). This tool can be useful for data preparation, or for data and result analysis.

For example, by reclassifying a contaminant plume map and a geologic uncertainty map, it is possible to optimize future sampling to collect data in areas of greatest risk and uncertainty. Here, two "cost" grids are multiplied together:

The red areas represent areas where 1) the least is know about the geology, and 2) where the geology is most conducive to contaminant flow. The blue areas represent areas of 1) where the geology is believe to be well describe, and 2) non-conducive to contaminant flow. Click for full size image
The red areas represent areas near the EPA standard for this contaminant. The goal here is to define the boundary of the legally contaminated zone. The blue areas represent areas which are 1) unlikely to have any contamination, or are 2) highly contaminated. We know the highly contaminated areas will need to be remediated, and are more interested defining the boundary of actual contamination. Click for full size image
Given the two maps above, and assuming they are of equal importance (if this isn't true, array can use weights), these maps can be multiplied together. Click for full size image
The results of combining the above map identifies area of both high geologic and contaminant uncertainty or risk. By concentrating future exploration in the red and green areas, the risks associated with the assumptions defined here could be minimized. Click for full size image

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