SPARROW modeling: Great Lakes, Mississippi River, Ohio River, and Red River Basins

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SPARROW models for the Great Lakes, Ohio River, Upper Mississippi River, and Red River Basins predict long-term mean annual loads, yields, concentrations, and source contributions of water, nitrogen, phosphorus, and sediment throughout the Midwest.

SPARROW (SPAtially Referenced Regression On Watershed attributes) models track the transport of water, nutrients (particularly nitrogen and phosphorus), and sediment from local inland watersheds to regional, coastal waters by explaining spatial patterns in
stream water-quality conditions in relation to human activities and natural processes.

 

Ongoing 2012 Midwest SPARROW Models

Figure showing phosphorus delivered from throughout the MRB3 basin

(a) Total phosphorus delivered to each of the Great Lakes, (b) total phosphorus deliveries to the Great Lakes, subdivided by each contributing source, and (c) total phosphous delivered from the entire MRB3 basin.

As part of Cycle 3 in the National Water-Quality Assessment Program, the capabilities of SPARROW were expanded to include streamflow and suspended sediment. Updated SPARROW models were developed using nutrient input data from management practices similar to 2012. These models were being developed using smaller catchments (average of 2 square kilometer catchments delineated using NHD Plus version 2) to enable improved spatial descriptions of nutrient and sediment sources. The models were calibrated using water, total phosphorus, total nitrogen, and suspended sediment loads from sites throughout the Midwest.

 

2002 MRB3 SPARROW Models 

The Great Lakes, Ohio, Upper Mississippi and Red River Basins (MRB3; Upper Midwest) SPARROW models were based on 2002 nutrient-input data and included watersheds that deliver nitrogen and phosphorus to the Great Lakes (published in the Journal of the American Water Resources Association in 2011) and Upper Mississippi and Ohio River Basins.
 The 2002 MRB3 models indicated:

  • 2002 U.S. nutrient loadings to Lakes Michigan and Ontario were similar to those in the 1980s, whereas loadings to Lakes Superior, Huron, and Erie had decreased.
  • Highest loads were from tributaries with the largest watersheds, but the highest yields were from areas with intense agriculture and large point sources of nutrients.
  • Input from agricultural areas was a dominant source of nutrients, contributing 33-44% of the phosphorus and 33-58% of the nitrogen to each of the Great Lakes, except for areas around Superior with little agriculture.
  • Point sources were also important in some areas, contributing 14-44% of the phosphorus and 13-34% of the nitrogen to each of the Great Lakes.
  • Watersheds around Lake Erie contributed nutrients at the highest rate (similar to intensively farmed areas in the Midwest) because they have the largest nutrient inputs and highest amount delivered downstream, while those around Lake Superior contributed the least nutrients.
  • Nutrient deposition in lakes and reservoirs intersecting the tributaries to the Great Lakes was important in reducing nutrient delivery to the lakes.

Read the full press release on the 2002 MRB3 SPARROW model results.

Binational (Canada and U.S.) SPARROW Models

SPARROW models have been developed for the entire binational Great Lakes, Lake of the Woods basin.  See the Binational SPARROW modeling page.