Methodology and Interpretation

Rainfall-derived erosivity [R factor] (unitless)
This metric is a RUSLE weighted-average rainfall-derived erosivity metric, which is derived from a PRISM 2-km grid, and is computed on a cell-by-cell area basis. An increase in soil erosivity may indicate an increase in the amount of runoff of sediment and chemical constituents associated with sediment (e.g., phosphorus) to streams and lakes.

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

• United States STATSGO Soils - Metadata