Tracking Creatures of Bavarian Folklore Using a Least-Cost Path Model

Table of Contents

  1. Tracking Creatures of Bavarian Folklore Using a Least-Cost Path Model
  2. Setting up Your Workspace
  3. Preparing the Data
  4. Skill Drill: Geocoding an Address and Creating a CSV Table to Import As XY Data
  5. Skill Drill: Defining the Study Area
  6. Skill Drill: Acquire Elevation Data from the USGS National Map Viewer
  7. Skill Drill: Acquire Land Cover Data from the USGS National Map Viewer
  8. Skill Drill: Acquire Hydrography Data from the USGS National Map Viewer
  9. Changing Global Environment Settings for Raster Processing
  10. Creating Cost Surface Models Using a Relative Cost Scale
  11. Creating a Remap Table to Reclassify Elevation
  12. Skill Drill: Creating a Remap Table to Reclassify Slope
  13. Skill Drill: Creating a Remap Table to Reclassify Tree Canopy Density
  14. Converting the Hydrography Features to Cost Surface Models
  15. Creating a Total Cost Surface Model
  16. Creating a Cost-Distance Surface Model
  17. Creating a Migration Corridor
  18. Determining the Least-Cost Path
  19. Skill Drill: Creating a Map of the Results

Creating a Migration Corridor

Corridors are useful in the early stages for many projects when you want to define a general location rather than a specific path or when you need to delineate a path wider than a single cell. To create a corridor for the wolpertinger, you will combine the two cost-distance surface models by adding them together. You will then symbolize the cells to observe patterns and delineate a corridor. There are a couple of ways to create a migration corridor in ArcMap. You could use the Raster Calculator to add the two layers together. The Distance toolbox also comes with a tool, called Corridor, that does the same thing. In this example, you will use the Corridor tool. For the Input cost distance raster 1, choose the Orick cost-distance surface. Choose the den cost-distance surface for Input cost distance raster 2. Save the output to your working folder and click OK.

An image of the corridor tool

The initial result may seem unremarkable. To observe patterns and delineate a corridor, you will have to change the symbology in the layer properties. There are many options to chose from in the symbology tab. I have found using a histogram equalization stretch type with the Temperature color ramp works well for observing patterns created by the Corridor tool. You may choose a different method if you find one that works better for you. Open the layer properties for the corridor layer and navigate to the Symbology tab. On the left, choose Stretched as the symbology method. For the Stretch Type, choose Histogram Equalize. For the Color Ramp choose the Temperature color scheme. You can view the color ramp labels by right-clicking on the color ramp and un-checking Graphic View. When you are ready, click OK.

An image of the symbology tab

As you can see the highest values fall east of the Klamath River because crossing the river generated a very high cost. Areas in white and very light pink represent areas of low relative costs. These are the areas this species will likely move through based on the given cost factors. In the next step, you will narrow the path even further by determining the least-cost path from each den location to the town of Orick.

An image of the migration corridor
In this image, the two cost-distance layers were added together to create a migration corridor. Overlapping areas of high-cost and low-cost are exaggerated to create the corridors.