This week's lab focused on determining the least-cost paths and creating corridors using cost distance surfaces. The map layout below shows the result of a corridor analysis of black bear movement between two green zones, in this case Coronado National Forest.
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| View of possible bear routes between forested areas. |
To run the analysis a cost surface was created - first by converting all vector data to raster, then by reclassifying the values of the input data. The cost surface inputs included the distances from roads, ranges of elevation, and types of land cover. Each cost surface was classified, and all cost surfaces were then added together using the Weighted Overlay tool. The weighted overlay results were then inverted using the Minus tool, since in our model the higher values actually represent the more desirable areas for black bears to travel within. Once complete the Cost Distance tool was run twice - one for each 'source' location. These results were then used as the input values for the Corridor tool.
Other Thoughts
This lab was actually very difficult for me - I kept hitting all kinds metaphorical walls until I finally realized what small random misstep I had taken. And the missteps were small - for example I had trouble getting my weighted overlay results to show something other than linear-like features. It wasn't until I really thought about what the data was meant to represent before it clicked what the problem was (in my case, the roads needed to show a range of distances... and to do that one needed to run the Euclidean Distance tool
before running the Weighted Overlay!). Overall it was a learning experience as I believe I've gained some very useful knowledge on what it takes to complete a corridor analysis.
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