Reduction of Evaporation

While Mansfield's research was directed at reducing evaporation on small storages such as farm dams SMHEA decided to conduct an experiment on Lake Eucumbene. Studies had indicated that a relatively small degree of success would be cost effective.

The trials proved unsuccessful because it was not possible to maintain the film in place on the vast expanses of Lake Eucumbene. With the strong winds in the area, wave action resulted in the breaking up of the film but an even larger problem was the result of the strong winds piling up the film on the downwind shores of the lake.

As was the case with cloud seeding, one problem was to measure the success of the attempt to modify the process (rainfall increase or evaporation reduction). Bill Priestley's Division of Meteorological Physics was asked to assist in measurement of evaporation from the lake. With their usual scientific thoroughness they decided that a methodology for estimating lake evaporation would require measurement of water temperature, wind run and temperature/humidity profile immediately above the lake surface.

SMHEA designed, built and installed three rafts supporting masts on which cup anemometers, thermographs and hygrographs were installed. The project was stopped after 12 months because strong winds made it impossible to obtain meaningful measurements from the rafts. As Allan points out, although the project was not successful the attempt was indicative of the SMHEA's willingness to have a go, and of the innovation which SMHEA engineers brought to their work.

Bureau of Meteorology