Methodology and Interpretation
The percentage of urban land cover is calculated by dividing the number of urban land cover cells in
the reporting unit by the total number of land cover cells in the reporting unit minus those cells
classified as water (i.e., total land area). High amounts of urban land indicate substantial
modification of natural vegetation cover and may have profound effects on wildlife habitat, soil erosion,
and water quality.
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 Census 2000 (c2k) - Metadata
- United States Roads (Wessex / GDT) - Metadata