Evaporation reduction from farm dams using air-bubble plume destratification

Abstract: The objective of this paper is to assess the effectiveness of destratification by air- bubble plumes in reducing evaporation from shallow and deep dams in Australia, based on modelling. DYRESM was applied to model the thermodynamics and evaporation from a farm dam in Queensland under different destratification conditions and two different depths: 6.5 and 13.5 metres. The results showed that destratification can reduce surface temperature and evaporation from both shallow and deep waters, but higher effectiveness is expected in deep lakes. This occurs because the bottom water of a deep lake is colder than the surface water during almost the entire year, which is a condition necessary for reducing the surface water temperature and, consequently evaporation rates, under destratification conditions. However, the reduction in surface water temperature and evaporation will not be significant during hot weather periods (that is, when the difference between the surface water temperature and the air temperature is high). Under this condition, the cooled surface water will be rapidly heated and the destratification system will only contribute to further increasing the heat stored in the water.