Skip to main content
U.S. flag

An official website of the United States government

Evaporation from Lake Michie, North Carolina 1961-71

January 1, 1973

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.

Publication Year 1973
Title Evaporation from Lake Michie, North Carolina 1961-71
DOI 10.3133/wri7338
Authors W.L. Yonts, G. L. Giese, E. F. Hubbard
Publication Type Report
Publication Subtype USGS Numbered Series
Series Title Water-Resources Investigations Report
Series Number 73-38
Index ID wri7338
Record Source USGS Publications Warehouse
USGS Organization South Atlantic Water Science Center