MODEL DESIGN

The New England SPARROW models are based on the premise that nutrient loads in a stream reach can be estimated from upstream nutrient sources and watershed characteristics. The models use a hydrologic network of 42,000 stream reaches and associated watersheds. Nutrient data from point sources are derived from the U.S. Environmental Protection Agency (USEPA) Permit Compliance System; information about nonpoint sources is derived from land use and atmospheric deposition data. Watershed and stream characteristics, tested in model calibrations, include streamflow, time-of-travel, stream density, percent wetlands, slope of the land surface, and soil permeability.

Hydrologic Network

• The New England SPARROW Model is the first major application of the National Hydrography Dataset (NHD) (1:100,000-scale)
• The network contains 42,000 stream reaches and watersheds
• Watersheds average 1.7 mi² in size, are hydrologically connected, and conform to the National Watershed Boundary Dataset (WBD) delineated to the 12-digit Hydrologic Unit Code (HUC) level
• Estimates of mean annual flow and velocity are assigned to each stream reach
• Surface area is assigned to each waterbody
• Tidal reaches are identified

About New England SPARROW

Model Input