U.S. GEOLOGICAL SURVEY
Water-Resources Investigations Report 00-4156
The U.S. Geological Survey's Chesapeake Bay River Input Program has updated the nutrient and suspended-sediment load data base for the Susquehanna, Potomac, Patuxent, and Choptank Rivers using a multiple-window, center-estimate regression methodology. The revised method optimizes the seven-parameter regression approach that has been used historically by the program. The revised method estimates load using the fifth or center year of a sliding 9-year window. Each year a new model is run for each site and constituent, the most recent year is added, and the previous 4 years of estimates are updated. The fifth year in the 9-year window is considered the best estimate and is kept in the data base. The last year of estimation shows the most change from the previous year's estimate and this change approaches a minimum at the fifth year. Differences between loads computed using this revised methodology and the loads populating the historical data base have been noted but the load estimates do not typically change drastically. The data base resulting from the application of this revised methodology is populated by annual and monthly load estimates that are known with greater certainty than in the previous load data base.
Abstract
Introduction
Purpose and scope
Description of study area
Acknowledgments
Methods of load estimation
Monitoring record
Regression model
Historical load estimates
Revised procedure for load estimate
Background
Description of revised methods
Comparison of historical and revised load estimates
Summary and conclusions
References cited
Appendixes
A. Annual load estimates for the River Input monitoring stations on the
Susquehanna, Potomac, Patuxent, and Choptank Rivers
B. Percent differences between historical and revised load estimates
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For more information about USGS activities in Maryland, Delaware and the District of Columbia contact:
Director
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Baltimore, MD
21237
Telephone: (410) 238-4200
Fax: (410) 238-4210
or access the USGS Water Resources of Maryland, Delaware, and District of Columbia home page at: http://md.water.usgs.gov/.
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