Swamp Stomp

Volume 15, Issue 10

The droughts that have plagued the southwestern United States have led entrepreneurs to suggest reviving a water-saving technique that was last attempted half a century ago—reducing the amount of evaporation from reservoirs. If successful, a surface barrier comprised of cheap, non-toxic, and biodegradable chemicals that measure at two-millionths of a millimeter will be infused with water supplies in order to slow down the evaporation process. The necessary technology is yet to be proven, but demonstrated promising results during field tests in Texas last year.

More water evaporates from reservoirs each year than is consumed. This depletion of water levels due to evaporation is especially severe in arid regions. Subsequently, many researchers in the United States and Australia have looked into the possibility of reducing the amount of water lost during the evaporation process for years. Such enquires have resulted in chemicals derived from coconut or palm oil being successfully used on small bodies of water such as golf-course ponds and swimming pools. However, according to Moshe Alamaro, an engineer at the Massachusetts Institute of Technology in Cambridge, the same procedure cannot be practically applied to larger bodies of water, because the larger surface area would make the protective barrier susceptible to wind damage.

A field test was held last summer in Texas to attempt to overcome that difficulty, however. The test cost $325,000 and lasted from July to October. Flexible Solutions International, a company in Victoria, Canada that specializes in evaporation-reducing coatings for small bodies of water programed a boat to distribute the protective coating in a grid pattern across Lake Arrowhead, a 21-square-kilometer reservoir that provides water to Wichita Falls.

The Texas Water Development Board published the analysis of the test in January, and claimed that while the results were promising, they were far from conclusive. The report suggests that Lake Arrowhead lost an estimated 15% less water due to evaporation than a nearby reservoir of similar size and shape that was not treated. How much of an effect the coating had on this difference is unclear, however, as several variables such as stream inflows and seepage outflows were not taken into account during the analysis. Mark Wentzel, a hydrologist for the Texas Water Development Board and co-author of the report, claimed that the coating probably helped reduce evaporation, but “I wouldn’t stake my life on it.”

Alamaro claimed that if such a technique is to work on large bodies of water, then a much more aggressive technological approach is necessary. Advancements in radar and drone technology could be used reveal where the coating has been broken by sensing the way it dampens ripples on the water. Additional coating could then be applied to the vulnerable areas. This, he estimates, could potentially cut evaporation by 70%.

More Aqua, Alamaro’s company in Cambridge, Massachusetts, is currently working on developing a system that would use both diffusers and skimmers to maintain the coating on large bodies of water. More Aqua plan its own pilot test this summer near Palo Alto, California.

Water consultant William Mullican of Lubbock, Texas, a retired member of the Texas water board, claimed that although the Lake Arrowhead results were unclear, the results are no more ambiguous than the field tests of other water-sparing techniques such as cloud seeding and cutting down brush to prevent the moisture being sucked out of the soil.

He continued to say that there is every reason to attempt the technique again, “unless it starts raining.”