Modeling Phosphorus and Nitrogen Loading throughout the Entire Great Lakes Basin using SPARROW

Session: 35. - Watershed Modeling across all Scales from Small to Large

Dale Robertson, U.S. Geological Survey, [email protected]
David Saad, U.S. Geological Survey, [email protected]
Glenn Benoy, International Joint Commission, [email protected]
Ivana Vouk, [email protected]
Richard Burcher, National Research Council of Canada, [email protected]

Abstract

Eutrophication problems in the Great Lakes are caused by excessive nutrient inputs (primarily phosphorus, P, and nitrogen, N) from various sources throughout its basin. In order to develop nutrient protection and restoration plans, it is important to understand where and from what sources the nutrients originate. As part of a binational effort, new SPARROW (SPAtially Referenced Regression On Watershed attributes) watershed models were developed to simulate P and N loading in streams throughout the entire Great Lakes Basin; previous SPARROW models only simulated U.S. contributions. The new models cover the entire Basin at higher resolution (~2 km² catchments) enabling improved descriptions of where nutrients originate and what are the dominant sources of P and N at various spatial scales. The new models were developed using harmonized geospatial datasets describing the stream network, nutrient sources (location and quantity), and the environmental characteristics affecting nutrient delivery. The models were calibrated using loads estimated from sites monitored by U.S. and Canadian organizations. Model results are being used to estimate the P and N input to each Great Lake, compare loading and yields from various tributaries and governances, and estimate the relative importance of each nutrient source, including the upstream lakes.

1. Keyword
modeling

2. Keyword
Great Lakes basin

3. Keyword
nutrients

4. Additional Keyword
SPARROW