Methodology and Interpretation
Roughness coefficient (unitless)
This metric is a SEDMOD weighted-average Mannings' n surface roughness coefficient. An increase in
surface roughness may indicate a decrease 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