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Main Title Comparison of Two Regression-Based Approaches for Determining Nutrient and Sediment Fluxes and Trends in the Chesapeake Bay Watershed.
Author D. L. Moyer ; R. M. Hirsch ; K. E. Hyer
CORP Author Geological Survey, Reston, VA. National Water-Quality Assessment Program.; Virginia Dept. of Environmental Quality, Charlottesville. Water Div.; Maryland Dept. of Natural Resources, Annapolis.; Environmental Protection Agency, Annapolis, MD. Chesapeake Bay Program.
Year Published 2012
Report Number USGS/SIR-2012-5244
Stock Number PB2013-105005
Additional Subjects Nutrients ; Sediments ; Chesapeake Bay ; Watersheds ; Ecosystems ; Monitoring ; Regression analysis ; Rivers ; Seasonal variations ; Trends ; Water quality ; Water resource management
Library Call Number Additional Info Location Last
NTIS  PB2013-105005 Some EPA libraries have a fiche copy filed under the call number shown. 07/26/2022
Collation 132p
Nutrient and sediment fluxes and changes in fluxes over time are key indicators that water resource managers can use to assess the progress being made in improving the structure and function of the Chesapeake Bay ecosystem. The U.S. Geological Survey collects annual nutrient (nitrogen and phosphorus) and sediment flux data and computes trends that describe the extent to which water-quality conditions are changing within the major Chesapeake Bay tributaries. Two regression-based approaches were compared for estimating annual nutrient and sediment fluxes and for characterizing how these annual fluxes are changing over time. The two regression models compared are the traditionally used ESTIMATOR and the newly developed Weighted Regression on Time, Discharge, and Season (WRTDS). The model comparison focused on answering three questions: (1) What are the differences between the functional form and construction of each model. (2) Which model produces estimates of flux with the greatest accuracy and least amount of bias. (3) How different would the historical estimates of annual flux be if WRTDS had been used instead of ESTIMATOR. One additional point of comparison between the two models is how each model determines trends in annual flux once the year-to-year variations in discharge have been determined. All comparisons were made using total nitrogen, nitrate, total phosphorus, orthophosphorus, and suspended-sediment concentration data collected at the nine U.S. Geological Survey River Input Monitoring stations located on the Susquehanna, Potomac, James, Rappahannock, Appomattox, Pamunkey, Mattaponi, Patuxent, and Choptank Rivers in the Chesapeake Bay watershed.