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Factors Affecting Stream Nutrient Loads: A Synthesis of Regional SPARROW Model Results for the Continental United States†
Article first published online: 22 AUG 2011
DOI: 10.1111/j.1752-1688.2011.00577.x
© 2011 American Water Resources Association. This article is a U.S. Government work and is in the public domain in the USA
Issue
JAWRA Journal of the American Water Resources Association
Volume 47, Issue 5, pages 891–915, October 2011
Additional Information
How to Cite
Preston, S. D., Alexander, R. B., Schwarz, G. E. and Crawford, C. G. (2011), Factors Affecting Stream Nutrient Loads: A Synthesis of Regional SPARROW Model Results for the Continental United States. JAWRA Journal of the American Water Resources Association, 47: 891–915. doi: 10.1111/j.1752-1688.2011.00577.x
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Publication History
- Issue published online: 10 OCT 2011
- Article first published online: 22 AUG 2011
- Received October 7, 2010; accepted March 17, 2011.
Keywords:
- computational methods;
- geospatial analysis;
- statistical models;
- nutrients;
- nonpoint-source pollution;
- point-source pollution;
- watershed management;
- watersheds;
- rivers/streams;
- landscape;
- modeling;
- empirical modeling;
- SPARROW models
Preston, Stephen D., Richard B. Alexander, Gregory E. Schwarz, and Charles G. Crawford, 2011. Factors Affecting Stream Nutrient Loads: A Synthesis of Regional SPARROW Model Results for the Continental United States. Journal of the American Water Resources Association (JAWRA) 47(5):891-915. DOI: 10.1111/j.1752-1688.2011.00577.x
Abstract: We compared the results of 12 recently calibrated regional SPARROW (SPAtially Referenced Regressions On Watershed attributes) models covering most of the continental United States to evaluate the consistency and regional differences in factors affecting stream nutrient loads. The models – 6 for total nitrogen and 6 for total phosphorus – all provide similar levels of prediction accuracy, but those for major river basins in the eastern half of the country were somewhat more accurate. The models simulate long-term mean annual stream nutrient loads as a function of a wide range of known sources and climatic (precipitation, temperature), landscape (e.g., soils, geology), and aquatic factors affecting nutrient fate and transport. The results confirm the dominant effects of urban and agricultural sources on stream nutrient loads nationally and regionally, but reveal considerable spatial variability in the specific types of sources that control water quality. These include regional differences in the relative importance of different types of urban (municipal and industrial point vs. diffuse urban runoff) and agriculture (crop cultivation vs. animal waste) sources, as well as the effects of atmospheric deposition, mining, and background (e.g., soil phosphorus) sources on stream nutrients. Overall, we found that the SPARROW model results provide a consistent set of information for identifying the major sources and environmental factors affecting nutrient fate and transport in United States watersheds at regional and subregional scales.