Evaporation loss and energy balance of agricultural reservoirs covered with counterweighted spheres in arid region

•Evaporation results in serious water loss from the surface of an agricultural reservoir.•Impact of counterweighted spheres on loss of water due to evaporation was studied.•Sphere coverage reduced evaporation and net radiation.•Saved agricultural water could be further utilized in irrigation areas.•The approach is economically feasible based on net profit per cubic meter of water.