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USGS · 70015471

Distillation irrigation: A low-energy process for coupling water purification and drip irrigation

Abstract

A method is proposed for combining solar distillation and drip irrigation to simultaneously desalinize water and apply this water to row crops. In this paper, the basic method is illustrated by a simple device constructed primarily of sheets of plastic, which uses solar energy to distill impaired water and apply the distillate to a widely spaced row crop. To predict the performance of the proposed device, an empirical equation for distillate production, dp , is developed from reported solar still production rates, and a modified Jensen-Haise equation is used to calculate the potential evapotranspiration, et , for a row crop. Monthly values for et and dp are calculated by using a generalized row crop at five locations in the Western United States. Calculated et values range from 1 to 22 cm month −1 and calculated dp values range from 2 to 11 cm month −1 , depending on the location, the month, and the crop average. When the sum of dp plus precipitation, dp + P , is compared to et for the case of 50% distillation irrigation system coverage, the results indicate that the crop's et is matched by dp + P , at the cooler locations only. However, when the system coverage is increased to 66%, the crop's et is matched by dp + P even at the hottest location. Potential advantages of distillation irrigation include the ability: (a) to convert impaired water resources to water containing no salts or sediments; and (b) to efficiently and automatically irrigate crops at a rate that is controlled primarily by radiation intensities. The anticipated disadvantages of distillation irrigation include: (a) the high costs of a system, due to the large amounts of sheeting required, the short lifetime of the sheeting, and the physically cumbersome nature of a system; (b) the need for a widely spaced crop to reduce shading of the system by the crop; and (c) the production of a concentrated brine or precipitate, requiring proper off-site disposal.

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BibTeXRIS

Jim Constantz. 1989. Distillation irrigation: A low-energy process for coupling water purification and drip irrigation. https://doi.org/10.1016/0378-3774(89)90019-x

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