Development of a CFD based dam evaporation model

Development of a CFD based dam evaporation model

Current trends of increased temperature and reduced rainfall in primary areas of agricultural production are driving Water Use Efficiency (WUE) research in Australia. Irrigation accounts for approximately 70% of fresh water use. Much of this stored in a million or so small dams, accounting for 9% of the total stored or 7000 GL. Approximately one half of this may be lost due to evaporation, but precise figures are unknown due to a lack of understanding of the relevant dam thermodynamics and associated evaporation physics. Work has commenced through an Australian Centre for Sustainable Catchments (ACSC) grant to develop a Computational Fluid Dynamics Dam Evaporation Model (DamCFD) to adequately quantify this loss, which constitutes a major economic limiting factor to Australia, and also gross inefficiency in terms of the environmental sustainability our fresh water resource. The aim of the project is to use CFD modeling to incorporate aerodynamic, heat transfer and thermodynamic theory to predict the evaporation of agricultural water, with storage morphology and characteristics of the surrounding terrain treated as important input parameters. Consideration of the flow of air, water and heat is required principally to simulate the vertical temperature profiles, air stability and the advective accumulation of warm surface water at the downwind end of the dam. It is intended that the development of this research capability at USQ will promote increased understanding of the complexities involved in open water evaporation. This will lead to more accurate estimates and better strategies for managing and controlling the evaporative loss of fresh water in Australia.