Methodology and Interpretation
Permeability (in / hr)
This metric is derived from STATSGO weighted-average soil permeability rate, measured in inches of
water flow through soil layers, per hour. An increase in soil permeability (i.e., a decrease in soil
impermeability) may indicate a decrease in the amount of runoff to streams and lakes, which may contain
sediment, road salts, or other compounds.
Quantile: Each class contains an approximately equal number (count) of features. A quantile
classification is well-suited to linearly distributed data. Because features are grouped by the number
within each class, the resulting map can be misleading, in that similar features can be separated into
adjacent classes, or features with widely different values can be lumped into the same class. This
distortion can be minimized by increasing the number of classes.
Metric input GIS data:
- United States Hydrologic Units (8-digit HUCs) - Metadata
- United States Coastal Change Analysis Program (CCAP) - Metadata
- United States National Elevation Dataset (NED) - Metadata