SPARROW Watershed Modeling: Estimation of Nutrient and Sediment Transport
Principal Investigators: Dale M. Robertson and
David A. Saad
Period of Project: October 2005 – Continuing
Declining water quality in rivers and streams has been linked to excessive losses of nutrients from their watersheds, particularly nitrogen and phosphorus. Excess nutrients are a major problem for water managers because they can cause algal blooms that increase costs to treat drinking water, limit recreational activities, and be toxic to humans and wildlife. Nutrient over-enrichment can also lead to eutrophication in downstream waterbodies, and deplete them of oxygen (hypoxia) that can threaten fish and other aquatic animals. Excessive nutrients can create problems both locally and regionally; one of the principal causes for the increasing size of the Gulf of Mexico hypoxic zone is believed to be the increasing supply of nitrogen delivered to the Gulf from the Mississippi River Basin.
To investigate regional nutrient contributions, the USGS National Water Quality Assessment (NAWQA) developed regional SPARROW models to assess conditions at a basinwide scale and provide predictions of water quality in unmonitored streams. These studies are part of NAWQA's broader status and trends assessments of stream chemistry, which are also investigating pesticides and ecosystem health. Since 2005, Wisconsin Water Science Center researchers have been modeling nutrients in three key river basins: the Mississippi/Atchafalaya River Basin (MARB); the U.S. portion of the Great Lakes Basin and the Ohio, Upper Mississippi and Red River Basins (MRB3); and the Mid-Continental Region of North America that includes the entire international Great Lakes basin (United States and Canada).
SPARROW (SPAtially Referenced Regressions On Watershed attributes) is a mass-balance watershed modeling technique for relating water-quality measurements to nutrient inputs and other watershed attributes. The SPARROW model relies on a network of monitoring stations and watershed measurements. SPARROW tracks the transport of nutrients 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. The system uses calibrated models to predict long-term average loads, concentrations, yields, and source contributions (and associated error estimates) for all stream reaches within the modeled watersheds. SPARROW models have been developed for a variety of water-quality constituents and time periods.
Other Model Results:
Additional SPARROW Information: