Module 6: Part1-Land Suitability Raster Analysis

The scenario for this task was to create a raster showing suitable land for development within a set study area. Criteria to consider for suitable land included the categories below: 

1. Land cover (Agricultural areas were rated the highest suitability, while water/wetland were rated as the least suitable)
2. Soils
3. Slopes (gentle slopes were rated higher than steep slopes)
4. Rivers/Streams (areas greater than 1000ft  were rated higher than areas within 1000ft of a river)
5. Roads (areas within a close distance to existing roads received a higher rating)

In order to complete this analysis, a land cover raster, soils data (polygons), and elevation DEM, and a rivers polyline dataset was required. The soils and rivers data were converted to rasters using the Euclidean Distance tool or the Polygon to Raster tool. The Euclidean Distance tool created a raster that contained data for the distance from the river polyline. The Slope tool was used to create a slope raster from the elevation DEM. The rasters were then reclassified using the Reclassify tool to create set class ranges that best fit this scenario. For example, the slope raster was reclassified to have 5 categories. The first class included all slope values that fell between 0 and 2, followed by 2-5, 5-8, 8-12, and >12. The rivers distance raster was classified into two categories, <1000ft and >1000ft of the river. The roads was processed in a similar way, with 5 distance range classes. After running the Reclassify tool, a new column was added to the attribute table of each output raster to include a rating value from 1 to 5 for each class. In order to find the best areas that met all five criteria, all the rasters needed to be combined using the Weighted Overlay tool. This tool combines all five rasters based on a common scale (rating column) and gives the option to "weigh" each according to their importance. Two analyses were completed, one output where all rasters were weighed equally at 20%, and a second analysis where the slope was weighed at 40%, land cover 20%, soils 20%, distance to rivers 10% and distance to roads 10%. A map comparing the two outputs is shown below: 

The areas with the least rating are showing as red and the areas with the highest rating is shown as green. Both scenarios show the river/canyon as not good for development. However, the alternative scenario has more options because it weighs land cover categories with higher importance.