Abstract: To address the issue of low water resource utilization caused by intense evaporation in plain reservoirs in arid regions,we have chosen black high-density polyethylene floating balls as a means to combat evaporation and promote water conservation.This study examines the response mechanism of water surface evaporation and the distribution of water energy balance components under floating ball coverage throughout the non-freezing period using theoretical analysis,modeling,and outdoor experiments.On this basis,we developed a calculation model of water surface evaporation.Our results indicate that,when compared to uncovered water surfaces,the overall net radiation absorption rate decreases by approximately 12.6% under a 73% floating ball coverage.The average monthly latent heat flux required for evaporation decreases by 61.8% to approximately 148.73 W/m².The sensible heat flux and heat storage flux of water body also experience significant changes.By accounting for modifications in energy and aerodynamic terms,our model for calculating surface evaporation under covered conditions demonstrates high precision.

Key words: floating ball, water-saving materials, energy balance, evaporation model, utilization efficiency of water resource