Table 3

The environmental variables selected for this study. Study unit: census block groups.

Variable

Description

Mean for all 658 census blockgroups in Indianapolis, Indiana, USA.


Land use land cover (LULC)

Area percentage of each LULC category

Varied by seasons and years


Impervious surface

Average percentage of impervious surface

38.8%


Elevation

Elevation variation

12.9 m (42.3 ft)


Slope

Mean slope

1.6°


Stream

Total stream length and stream density

466.7 m (1531.2 ft)


Wetland

Total size of wetlands

51437.4 m2 (553 667.6 sq.ft)


Pollutant

Distance from centroid of each census blockgroup to the closest pollutant in National Pollutant Discharge Elimination System (NPDES)

3,201.8 m (10 504.6 ft)


Pipe

Distance from centroid of each census blockgroup to the closest pipe in NPDES

7,831.3 m (25,693.2 ft)


Waste industry

Distance from centroid of each census blockgroup to the closest waste industry site

804.9 m (2,640.7 ft)


Population density

Human population density

1,587 per sq. km


Liu et al. International Journal of Health Geographics 2008 7:66   doi:10.1186/1476-072X-7-66

Open Data