Estimating water surface evaporation losses under floating coverage: Modeling and Application

In arid and semiarid regions, floating covers can effectively reduce water surface evaporation to save water. However, the physical process of water surface evaporation greatly changes under floating coverage, and the open water surface evaporation estimation models cannot accurately quantify the water surface evaporation under floating coverage. A novel combination model for estimating water surface evaporation was developed, which can accurately estimate the water surface evaporation under floating coverage. (1) In view of the influence of the size and shape of the pore water formed by floating covers on the wind function in the water surface evaporation process, a wind function with the fetch of the evaporating water surface and wind speed as independent variables was established, and the calculation model of the aerodynamic term was modified. (2) Aiming at the influence of the variations in the energy consumed by water evaporation and water temperature stratification on the estimation of water surface evaporation under floating coverage, the energy balance equation and equilibrium temperature of the water body under floating coverage were established, and the calculation model of the radiation term was modified. Finally, the established evaporation combination model was verified by an experiment on water surface evaporation covered by spheres. The results showed that the estimation model established could accurately quantify the water surface evaporation under floating coverage. For arid and semiarid areas, the new evaporation estimation model can effectively help in decision-making for water surface evaporation prevention and water savings and promote water resource management.