Evaporation Reduction with Reflective Covers

by Keith R. Cooley, (A.M.ASCE), Res. Hydro.; U.S. Water Conservation Lab., Phoenix, AZ,
Lloyd E. Myers, (F.ASCE), Assoc. Deputy Administrator; Western Region, Agri. Res. Service, U.S. Dept. of Agr., Berkeley, CA,

Serial Information: Journal of the Irrigation and Drainage Division, 1973, Vol. 99, Issue 3, Pg. 353-363

Document Type: Journal Paper


Floating reflective covers appear promising as a means of reducing evaporation from open water surfaces. Eight light-colored materials were studied using buried and exposed wall tanks to simulate a range of field conditions. Tested on the 2.1-m diam buried tanks were asphalt-concrete blocks, white butyl rubber, foamed butyl rubber, Mini-Vaps, Styrofoam, and foamed wax blocks. The same foamed wax blocks and two continuous wax covers of different melting points were tested on the 2.7-mediam exposed wall tanks. Efficiencies ranged from 23–79% reduction and from 36–87% reduction on the buried and exposed wall tanks, respectively. Styrofoam and the lower melting point continuous wax layer were the most efficient. The three wax covers and the two butyl rubber covers were the most economical, saving water for between $0.12 and $0.28 per 1,000 lc ell ($0.44 to $1.07 per 1,000 gal). These costs are less than most alternative methods of providing additional water supplies.

Subject Headings: Walls | Evaporation | Rubber | Foaming (material) | Water conservation | Water surface | Asphalt concrete | Professional societies

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