GIS5100 Module 6, Part 1: Suitability & Least-Cost Analysis

In this lab, we were tasked to determine the suitability of an area for housing development. For this, we must consider: land cover, soils, slopes, distance to streams, distance to roads of the area. These five considerations will determine which areas in the location are suitable for development.

Analysis

First, I use the Reclassify tool to convert the values within the “landcover” raster into values of suitability. With the Polygon to Raster tool, I converted the “soils” polygon feature class into a raster. I then reclassified using the Reclassify tool turning soil class into suitability ratings. I used the Slope tool to create a slope of the “elevation” raster in degrees, and the Reclassify tool to class slope (in degrees) into suitability rating. I used the Euclidean Distance tool to create a distance to rivers, and the Reclassify tool to class distance to rivers into suitability rating.

I repeated the above steps for the “road” line feature class (creating a distance to roads raster, then reclassified into suitability ratings).

I combined the (5) rasters we got from the above steps (roads, soils, slope, streams, and land cover) using the Weighted Overlay tool using equal percentages (20%) for each raster.

I then tried the Weighted Overlay tool again with different percentages per raster to explore an alternative scenario:

  • Land cover – 20%
  • Soils – 20%
  • Slope – 40%
  • Distance to Streams – 10%
  • Distance to Roads – 10%

 

Results

The map on the left, “Equal Weighted Suitability”, depicts what equally weighted percentage amount across our five criteria points (20%) looks like. The map on the right, “Alternative Weighted Suitability”, depicts what the outcome is when different criteria are given different percentage amounts (indicated on map). The dark green is equal to a suitability rating of 5 (highest suitability rating), and dark red is equal to a rating of 2 (in this case, the lowest suitability rating).

From the resulting map and table, we can see the difference that placing weight evenly or unevenly can cause the outcome to change. This comparison can help the developer make a more informed decision.

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