Adding up Resources

This page explains the process of adding up resources that was used to assign scores to each parcel.

The first step is to assign a point value for each of the resources. A list of these resources, and the point values that were assigned to them for different runs of the scoring system is available on this site.

To accomplish this, a GIS coverage with all of the resources in it is created. Each polygon is coded with the resources that exist within its boundaries. Polygons are discreet areas shown on the map on the right, each with its own type of resources. These resources are then given weights and the total number of points for polygon is assigned. The map on the right is an example of this. Each polygon is coded for the resources that it contains. A value is assigned to each resource and the total for the polygon is added up. Click on the map to see the totals for each polygon.

For example, the area in green contains both wetlands and rare species habitat. This area receives the points allocated for rare species (10) added to the points allocated for wetlands (7). The total therefore is 17, which is the sum between wetlands and rare species habitat. This task is repeated for all the other polygons.

Selecting the Parcel

The next step is to take the values for each polygon and code them into the parcel. This is done by first determining the percentage of the parcel each resource occupies. The example map shows the same resource polygons as above, only with the percentage of the polygon's area relative to the parcel area coded. These areas are then multiplied by the points given to each polygon, and added up to get the total number of points for the parcel. To see the result of this process, click on the map.

The green polygon in the middle labeled 25% is the same polygon discussed in the example above. This polygon contains both rare species habitat and wetlands and was scored 17. This polygon makes up 25% of the total area of the parcel. Therefore the total number of points that is contributes to the parcel is 25% of 17, or 4.25. The same task was repeated for all the polygons and the points are totaled up.

There are some resources that are included in the analysis that were already organized at the parcel level. This includes the size of the parcel, the development capacity of the parcel, and the cultural significance of the parcel. The points allocated for these resources are added to the total determined above to get the final number of points for the parcel.

This value is then divided by the cost of the parcel per acre. The final value that is given is the points per dollars per acre. This gives a representation of the cost per resource protected, weighted by the relative importance of that resource.

A detailed discussion of the GIS methods that were used to achieve this.