This is the first week of Applications in GIS. For just starting out we have a pretty rigorous initial project - land suitability analysis. Land suitability analysis is where certain factors are taken into account, such as slope or land cover type, and assigned values corresponding to their qualities and the desired usage of the land. These different attributes are combined with the weighted overlay tool to find the areas that most fit the desired properties.
This particular map was designed with land development in mind. If a developer wanted to buy up empty lots in an undeveloped area there are several things they would want to take into account before making their purchase. This spatial analysis takes into account slope (lower the better), land cover (which ones are easier to develop), soil type (certain types are more conducive to easy construction), distance from rivers (don't want to be on top of a stream in case it floods), and distance from roads (closer is better). Using spatial analysis it is possible to assign all these traits certain values and combine them together to identify the best regions.
The map on the left treats all the properties with equal weight while the map of the right puts greater emphasis on slope and less on distance from rivers and roads. Using alternative weights can be useful as building on a steep slope could be much costlier and more undesirable to live on than living further away from a road. The resulting areas are slightly different, especially for the equal weight areas by the river which are mostly excluded from the prime valuation. Comparing different methods is useful in judging what decision is best for the project.
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| This map shows how weighting all the different traits equally versus giving them different weights produces a different final result. |
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