Methodology and Interpretation

Percent Agriculture / Grassland on Slopes greater than 3%
The proportion of each reporting unit that has agriculture / grassland land-cover on slopes greater then 3 percent is calculated using an overlay. The area where agriculture / grassland and slopes over 3 percent are coincident is summed and divided by total reporting unit area.

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. For continuity of the browser content, and consistency among maps, legend gradients are from higher values (red) to lower values (green).

Metric input GIS data:

• 244 Subwatersheds - Metadata

• 2003 Land-Cover - Metadata

• National Elevation Dataset (NED) - Metadata