Document Type

Dissertation - Open Access

Award Date


Degree Name

Doctor of Philosophy (PhD)




Reservoir evaporation reduction with monomolecular film was investigated during the summers of 1962 and 1963 at Pactola Reservoir, South Dakota. This study was conducted cooperatively by the United States Bureau of reclamation and the Agronomy Department of South Dakota State College. In this study, a material composed of hexadecanol and octadecanol was applied as a molten spray in 1962 and a powder form in 1963. The molten spray was dispensed from fixed and mobile dispensing units with the mobile unit being superior. The powder was also spread from a mobile unit. The average monolayer coverage during a 13-day period using molten spray was 50 percent with a rate of 0.55 lb. acre-1 day-1, while an average of 73 percent coverage was achieved during the 1963 98-day test, using the powdered material and a rate of 0.43 lb. acre-1 day-1 was used. As found in other field tests, wind speed was the primary controlling factor in maintaining a monolayer. An average wind speed of 5.8 miles per hour during the film treatment periods and the use of mobile dispensing units made it possible to achieve the high coverage. The resulting evaporation reduction due to the monolayer was evaluated by using the USBR simplified method and an energy-budget, mass-transfer method. The average evaporation reduction as calculated from the simplified method was 46 percent while the energy-budget, mass-transfer method gave an average reduction of 14 percent. Using results from the energy-budget method, a total of 215 acre-feet of water was saved and the average cost per acre-foot of water saved was $69.00.

Library of Congress Subject Headings

Reservoirs -- Evaporation control -- South Dakota
Pactola Reservoir (S.D.)


Includes bibliographical references




South Dakota State University