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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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