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Overview of Methodology

This page describes the process that was used to rank parcels in Charlestown. For general information about point systems and openspace protection see the background pages.

Additional Pages

Adding Up Resources
Detailed Methods
Parcel Level Methodology
Point System Background
Openspace Background

This methodology creates a map of every parcel in town with a score reflecting how valuable the parcel is to protect as openspace. This map is used for planning purposes to assess the results of the ranking system and to advise specific acquisitions. This page outlines the methodology used to apply the ranking system to the entire town.

The point system finds areas of co-occurring resources. This is built on the premise that the more resources on a parcel, the better. For example, a parcel that has both wetlands and is in a community wellhead protection area is better to protect then a parcel that just has wetlands.

These resources are weighted by their relative importance. This weighting is different in the two scoring systems presented in this study. The weightings that are used come from the web survey, and a planning workshop in January. More information about the development of the scoring system is available on this site. These weightings assign relative values to the resources. For example, if community wellhead protection areas are worth 50 points, and wetlands are worth 25 points, a parcel with community wellhead protection areas will be protected before the parcel with wetlands.

A GIS system is used to add the resources up and code them into parcels. A discussion of this portion of the methodology in more detail is in the adding up resources page. This system determines the number and type of resources in each parcel, and added up their respective weights to give the parcel an overall score. Analyzing each parcel individually is an important part of this analysis. More discussion on parcel level analysis is available on this site.

Finally, the cost of protecting the land is taken into account. More information on incorporating cost into this process is available. This was accomplished by relating the assessed value of the land to the amount of resources that would be protected by purchasing it. The cost of the land per acre is divided by the total number of points given to the parcel. Therefore, the final mode of evaluation for the parcel is the number of resource divided by the amount of money it would cost, per acre to protect that land.

Resources Considered

Groundwater and Surface Water Protection
Community Wellhead Protection Areas
Non-Community Wellhead Areas
Ground Water Recharge Areas
Ground Water Reservoirs
300 ft. Surface Water Buffers

Habitat Protection
300 ft Protected Land Buffers
300 ft River Buffers
300 ft Wetland Buffers
Wetland
Forests and Brush Lands
Rare Species Habitat

Cultural Resources
Greenways
Historic Districts
Scenic Areas

Farmland
Agricultural Lands
Prime and Important Agricultural Soils

Growth Management
The number of houses that can potentially be built on the parcel

Size of the Parcel
Larger parcels get more points

This increases the efficiency of openspace acquisition, by creating a system that evaluates the cost of resource protection, and will identify parcels where more resources can be protected per dollar spent.
6.01 Matthew Amengual