Table 4.4 (continued)
Case
study Predictors
Method
Reference
Phosphorus content in soil C horizon, mg/kg
Rubidium content in soil C horizon, mg/kg
Total clay content in soil C horizon, weight
percent
Lead content in soil C horizon, mg/kg
Nickel content in soil C horizon, mg/kg
Top bedrock unit
Stream order number of the closest stream
to well
Distance to nearest stream indicated by a
stream order number, meters
Calculated distance from screened interval
to clay layer, meters
Land surface elevation, meters (point data
used for initial model development)
Land surface elevation, meters (point data
used for predictive map development)
Completed well depth, meters
Casing depth, meters
Length of the screened interval, meters
Eastward-measured distance
Northward-measured distance
Calculated elevation at the bottom well,
meters
Area- and depth-weighted average percent
of sand
Area- and depth-weighted average percent
of silt
Area- and depth-weighted average percent
of clay
Percent of soil classified as hydrologic
group A
Land use code
Distance to the nearest major river, meters
Bismuth content in soil C horizon, mg/kg
Calcium content in soil C horizon, weight
percent
Iron content in soil C horizon, weight
percent
Potassium content in soil C horizon, weight
percent
Lithium content in soil C horizon, mg/kg
(continued)
90
S. K. Singh et al.