ABSTRACT
Pan evaporation measurements are useful in water use projections, such as forecasts of irrigation water demand for crops, estimates of losses from percolation ponds used for ground water recharge, and the design of ponds for concentrating brines and effluents from waste disposal facilities. Pan evaporation rates are affected by the relative clarity of the water and by relative aridity or moistness of the pan’s upwind fetch. Pan evaporation rates are used to estimate lake evaporation by reducing the pan rates by a fraction called the pan coefficient. Class-A evaporation pans are used by the National Weather Service (NWS) at hundreds of locations to measure evaporation. The data collected from these pans are used to estimate lake evaporation or evapotranspiration rates, although the construction of the pan does not simulate natural conditions. The exchange of heat between the pan and surrounding water, characteristic of floating pans is advantageous for simulation.
