Using Buildout to Analyze Resource Protection

One of the goals of acquiring openspace in residential areas is to prevent rural land from being developed. Openspace acquisition effectively prevents parcels from being converted from undeveloped land to residentially developed land. Therefore, one of the main goals of acquisition is to prevent houses from being built in certain areas.

Using buildout, it is possible to analyze the different levels of protection of a resource by the number of houses that are prevented from being built in the areas where that resource exists. This is accomplished by overlaying the resource maps with the parcel maps, and determining the percentage of unconstrained land that overlaps with the resource for each parcel. A simplifying assumption is made that the housing units in the parcel will be evenly spread throughout the land without constraints in the parcel.

The graph on the right shows the percentage of houses in each resource group that will be prevented from being built because of openspace acquisition as a function of the amount of money spent purchasing openspace using assessed value. Please see the background section for more information about the model used to make this graph. The characteristics of the graph are very similar to the graph evaluating the protection of resources by area. Namely, the shape of the curve, and the cluster of resources together. This is to be expected, because the size of a parcel is somewhat related to the number of houses that can be built on it. There are some differences between the rate of protection of specific resources when analyzed by area as opposed to when they are analyzed by prevention of housing units. It is apparent that agricultural resources do not get protected at the highest rate of all resources as they do when analyzing the protection of resources by area. Another difference is that the slope of the curve is not as steep in the graph of the amount of units prevented as the slope in the graph of the area protected. This is most likely because the highest scoring parcels tend to be in areas of the town that are zoned at low densities.

Number of Housing Units Prevented From Being Built in Each Resource Area The Web Survey's Scoring System Click on graph to enlarge Number of Housing Units Prevented From Being Built in Each Resource Area The Conservation and Planning Commissions' Scoring System Click on graph to enlarge

This method of analyzing the scoring systems can be used when analyzing resources that will be greatly affected by residential development, and when the amount of development is more important then the area that it takes up. If a scoring system is designed specifically with keeping houses from being built, it might give preference to areas that are zoned at a high density. This may be important for resources such as groundwater protection, where the number of potential septic systems in the area is very important, possibly more so then the total area of the land.

The graphs are extremely similar despite the different scoring systems that are used. Further analysis of the difference is in the comparing the two scoring systems section.