ABSTRACT
There is a range of methods for measuring water storage losses. Most simply, the rate of loss of water depth in millimeters per day can be using a depth ruler mounted on a fixed post. Continuous floating covers are routinely used in swimming pool applications to retain heat and reduce evaporation. These covers provide an impervious physical barrier and are therefore very effective at reducing evaporation losses. Evaporation is the result of water molecules at the surface gaining enough energy to overcome the adhesive forces of subsurface water molecules escaping into the gaseous boundary layer. Rates of evaporation are greatest with wind, when a cold surface film reduces the resistance to molecular diffusion imposed by the gaseous and liquid thermal boundary layers. Ingress of wind-borne dust is also reduced, reducing water turbidity and salinity, and contamination from pesticide spray drift. The technology is particularly suited to supplying high quality water for drip irrigation systems, deployed for high value horticultural crops.
