Applications in GIS - M6 Suitability Analysis

Suitability analysis for development in the Applegate. More suitable areas are ranked higher (green), and less suitable areas are ranked lower (red).

In the first section of this lab, we learned the principles of combining several reclassified rasters with the Cost Distance, Cost Path, and Corridor tools to determine suitability and least-cost paths. 

For this development scenario we were given rasters for landcover, elevation, and soil types as well as shapefiles for roads and rivers, then asked to help a developer determine sites for potential development based on suitability. The hypothetical developer preferred certain soil types that were good for building and wanted to be close to roads but further from rivers and wetlands, as well as avoid construction on steep slopes. 

The first step was using the Euclidean distance tool to create rasters of the rivers and roads where cell values would be representative of the distance to those features. This would allow them to be reclassified later with areas further from rivers ranked higher, and far from road access ranked low. I also used the Slope tool on the elevation digital elevation model, so that cells in the new elevation-related raster were representative of the land slope, rather than height. 

With 5 comparable rasters, I ran the Reclassify tool on each with a scale of 1-5, ranking desirable factors like grassland landcover high and undesirable factors like sandy soil low. Once all the rasters were reclassified I used the Weighted Overlay tool to combine them, first with all suitability rasters having an equal weighting, then again with slope having a higher weighting and distance to roads and streams having less weighting. This makes some sense for development, as the trade-offs of being closer to a river or further from main roads are more easily addressed than the trade-offs for trying to build on steep slopes. 

With the weighting adjusted more land was available as suitable for development, particularly land in the valley area, closer to rivers and streams.