Recent Developments in USGS SPARROW Modeling

Abstract:

Federal, state, and local agencies have invested billions of dollars to reduce the amount of pollution entering rivers and streams – and understanding the sources and transport of pollution is crucial for designing strategies to improve water quality. The United States Geological Survey’s (USGS) SPAtially Referenced Regression On Watershed attributes (SPARROW) model was developed to provide this type understanding for large hydrologic regions. In this talk I will describe new SPARROW models that the USGS has developed for streamflow, nutrients, and suspended sediment for different regions of the conterminous United States. These new models are based upon many improved datasets and simulate more recent conditions compared to previous SPARROW models. The list of modeled constituents was also expanded from only nutrients (nitrogen and phosphorus) to include streamflow and suspended sediment. These additional constituents, while of value in themselves, are also related to nutrient levels and provide a broader understanding of the factors affecting water-quality conditions in surface water. In addition to publishing reports documenting how each model was developed, the USGS has created interactive on-line tools that allow users to explore water-quality conditions in each region and map the importance of different sources of contaminants. The SPARROW predictions can be visualized using maps, graphs, and tables, and different geographic areas can be ranked based on how much they contribute to downstream receiving waters. The reach-scale predictions can also be exported as tabular or geospatial datasets. Finally, the predictions from the SPARROW models are being applied to important hydrologic and water-quality issues in each region. These regional issues include impacts from climate change, the importance of agricultural management practices, and localized water-quality impairment.