Methodology and Interpretation

Net Sediment Delivery [SEDMOD] (kg / ha / yr)
SEDMOD weighted-average net sediment delivery computed iteratively from several intermediate input parameters on a cell-by-cell area basis, expressed as kilograms/hectare/year of sediment. Because net sediment delivery is correlated with the amount of phosphorus in runoff to streams and lakes, the modeled erosion of soil in a watershed may be an indicator of eutrophication or the diminution of water clarity in surface water. These models are responsive to soil characterization precision, thus computed and actual sediment delivery values may vary.

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

• National Elevation Dataset (NED) - Metadata

• National Land-Cover Dataset (NLCD) - Metadata

• Stream Network - Metadata

• STATSGO - Metadata