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Garden State Greenways Methods Summary


The Garden State Greenways GIS data showcased on this site is the outcome of a complex process of data synthesis, analysis and assessment. This summary is intended to provide users with a basic outline of the process, sufficient for those using the interactive mapping or the prepared county maps. However, those interested in using the data for their own GIS analyses should familiarize themselves with the more detailed methodology available in the New Jersey Green Infrastructure Assessment Report (PDF, 2.2 MB).

Garden State Greenways identifies and assesses the value of ‘greenway hubs’ and ‘greenway connectors’. Hubs are contiguous patches of undeveloped land containing or protecting important resources, while connectors are potential routes that can be used to link hubs. The identification of Garden State Greenways hubs followed a three-step process:
  • Identify undeveloped land (as of 2000).
  • Define contiguous tracts of undeveloped land (potential hubs) using roads as edges.
  • Select hubs from contiguous tracts using the following critieria: contiguous forest, unmodified wetlands, buffers of environmentally sensitive water bodies, critical plant or wildlife habitat, currently preserved land, contiguous agriculture or grassland, and vegetated dunes plus areas identified as important in regional workshops.

Once selected, the hubs were subjected to an assessment based on the following categories: hub size, extent preserved/unpreserved, estimated groundwater recharge, buffers around environmentally sensitive waterbodies, floodplains, prime soils, and concentrations of rare, threatened and endangered species.

After the values for each of these assessment categories were determined for each hub, the values were used to rank the hubs. This ranking was used to reduce the number of hubs in the final mapping and data products. In order for a hub to be included in the interactive mapping, printable maps or GIS data, it must have scored within the top 10% in at least one assessment category. To reduce the impact of geographical variation, the ranking was performed on regional subsets of the hubs (the regions were based loosely on the state's physiographic regions).

The Garden State Greenways connectors were routed between these top scoring hubs in the following manner. First, a number of landscape features were combined into a "suitability" layer. These features were weighted by their contribution of beneficial or negative conditions to a greenway connector. This suitability layer was then used to route optimal riparian/wetland and upland connectors between hubs. The path chosen for each greenway was the shortest path possible that minimized the negative conditions while maximizing the positive conditions in the suitability layer.

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