U. S. Geological Survey - Michigan Water Science Center

USGS Michigan Water Science Center

Uncertainty in the Great Lakes Water Balance

Prepared in Cooperation with the Great Lakes Commission

By: Brian. P. Neff and J. R. Nicholas

U.S. Geological Survey Scientific Investigations Report 2004-5100


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Abstract

This report describes the Great Lakes hydrologic system and methods used to quantify individual components of the water balance. Potential sources of uncertainty are identified and, where appropriate, alternate or additional data, models, and estimation methods suitable for reducing uncertainties are discussed. Finally, approximate uncertainties of all components are identified, compared, and assessed within the context of net basin supply. Results indicate that average uncertainties in monthly estimates of individual water-balance components may range from 1.5 percent to 45 percent. These uncertainties may cause uncertainties in monthly net basin supply estimates of approximately 2,600 ft 3/s to 33,500 ft3/s for individual Great Lakes.

Citation:

Neff, Brian P. and J. R. Nicholas, 2005, Uncertainty in the Great Lakes Water Balance, Date Posted: November 23, 2005: U.S. Geological Survey Scientific Investigations Report 2004-5100, 42 p. [https://pubs.water.usgs.gov/sir2004-5100/]

Contents

Abstract
Introduction
Purpose and Scope
Geographic and Hydrologic Setting
Components of the Great Lakes Water Balance
Inflows
Over-Lake Precipitation
Runoff
Ground-Water Discharge
Diversions
Outflows
Connecting-Channel Flow
Lake Superior Outflow
Lakes Michigan-Huron Outflow
Lake Erie Outflow
Lake Ontario Outflow
Evaporation
Diversions
Consumptive Use
Change in Storage
Methods for Quantifying Components and Potential Uncertainties
Inflows
Over-Lake Precipitation
Runoff
Gaged Areas
Ungaged Areas
Uncertainty In Total-Runoff Calculations
Ground-Water Discharge
Diversions
Outflows
Connecting-Channel Flow
Lake Superior Outflow
Lakes Michigan-Huron Outflow
Lake Erie Outflow
Lake Ontario Outflow
Evaporation
Diversions
Change in storage
Current Approaches to Deriving Net Basin Supply
Component NBS
Residual NBS
Relative Magnitude of Uncertainties in NBS Estimates
Summary and Conclusions
Acknowledgments
References Cited

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For further information, contact:
 
Jim Nicholas, Director
U.S. Geological Survey
Michigan Water Science Center
6520 Mercantile Way, Suite 5
Lansing, MI 48911-5991
 
mi_dc@usgs.gov
 
or visit our Web site at:
 
http://mi.water.usgs.gov

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