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Environmental Score

The Environmental Score evaluates ecological and physical environmental quality in Philadelphia neighborhoods.
It uses three equally weighted indicators calculated at the census-tract level and then aggregated to neighborhoods:

  1. Vegetation Health (NDVI)
  2. Proximity to Parks & Green Space
  3. Urban Tree Canopy Coverage

All indicators are normalized to a 0–1 scale, where higher values represent more favorable environmental conditions.

Indicators

1. Vegetation Health (NDVI)

Calculated from Landsat 8 Surface Reflectance imagery:

\[ \text{NDVI} = \frac{(\text{NIR} - \text{Red})}{(\text{NIR} + \text{Red})} \]

Min–Max normalization:

\[ \text{NDVIScore} = \frac{\text{NDVI}_{\text{tract}} - \text{NDVI}_{\min}} {\text{NDVI}_{\max} - \text{NDVI}_{\min}} \]

2. Proximity to Parks

Distances from tract centroids to nearest park are computed using a KD-Tree.

\[ \text{ProximityScore} = 1 - \frac{d_{\text{tract}} - d_{\min}} {d_{\max} - d_{\min}} \]

3. Urban Tree Canopy

Tree canopy coverage is estimated using PPR’s 2015 tree canopy points.
Tree density is calculated per tract as:

\[ \text{TreeDensity} = \frac{\text{TreeArea}}{\text{TractArea}} \]

and normalized as:

\[ \text{TreeScore} = \frac{ \text{TreeDensity}_{\text{tract}} - \text{Density}_{\min} }{ \text{Density}_{\max} - \text{Density}_{\min} } \]

Composite Environmental Score

The final environmental domain score is the equal-weighted average of NDVI, park proximity, and tree canopy:

\[ \text{EnvironmentalScore} = \frac{ \text{NDVIScore} + \text{ProximityScore} + \text{TreeScore} }{3} \]

Neighborhood values are computed by averaging tract-level environmental scores within each neighborhood boundary.

Visualizations

Neighborhood Environmental Score Map

Environmental Score Map

NDVI: Passyunk Square ranks low on the citywide NDVI distribution, indicating limited vegetation health relative to other neighborhoods.
Proximity to Parks: The neighborhood has moderate access to parks, with several reachable on foot but fewer large green spaces nearby.
Tree Canopy: Tree coverage is sparse in Passyunk Square, lowering its overall environmental domain score.