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 |