The impacts of shade on evaporation rates and temperatures in stock watering troughs

Abstract

We have demonstrated experimentally that the use of a shade over a stock watering trough will significantly lower water temperatures and evaporation rates. During the 14day period of our trials undertaken during summer, peak temperatures in a shaded trough were on average 6.4¦C lower than the average peak in an unshaded trough. Average evaporation rates in a shaded trough were 7.1 mm/day from a shaded trough compared with 11.1 mm/day from an identical unshaded trough. A mathematical model was used to obtain predictions of trough thermal behaviour in other conditions of humidity, air temperature, wind, and solar radiation than those occurring during the trials. These results show that the measured effects of shading on reducing trough evaporation rates and water temperatures can be expected to be appreciable over a wide range of other environmental conditions as well.