Evaporation from Lake Michie, North Carolina 1961-71

Water-Resources Investigations Report 73-38

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The Geological Survey, in cooperation with the city of Durham, N. C., collected evaporation data at Lake Michie, Durham's 480-acre water-supply reservoir, for 10 consecutive years from September 1961 to September 1971. Wind speed, air temperature, and water temperature-collected continuously-were used in conjunction with water-budget data to calibrate the semi-empirical mass-transfer equation, E Nu(eo - ea), where E is evaporation; N is the mass-transfer coefficient, which is a constant for a given lake; u is wind speed; eo is the vapor pressure of the saturated air at the water surface; and ea is the vapor pressure of the surrounding air. For evaporation expressed in inches, the mass-transfer coefficient for Lake Michie is 0.0036.

During the study period the average annual evaporation from Lake Michie was 37.9 inches. Within-year variation of evaporation from the lake is sinusoidal, with a high during July averaging 4.71 inches and a low during January averaging 1.45 inches.

Evaporation from Lake Michie was 0.72 (or about three-quarters) of the evaporation from the National Weather Service evaporation pan at Chapel Hill. This ratio, called a pan coefficient, was not constant throughout the year, ranging from an average of 0.57 for April to 1.09 for December.

Study Area

Additional publication details

Publication type:
Publication Subtype:
USGS Numbered Series
Evaporation from Lake Michie, North Carolina 1961-71
Series title:
Water-Resources Investigations Report
Series number:
Year Published:
U.S. Geological Survey
Contributing office(s):
South Atlantic Water Science Center
iv, 27 p.
United States
North Carolina
Other Geospatial:
Lake Michie