Evaluation and generalization of temperature-based methods for calculating evaporation

Seven temperature-based equations, each representing a typical form, were evaluated and compared for determining evaporation at two climatological stations (Rawson Lake and Atikokan) in north-western Ontario, Canada. The comparison was first made usings the original constant values involved in each equation, and then using the recalibrated constant values. The results show that when the original constant values were used, larger biases existed for most of the equations for both stations. When recalibrated constant values were substituted for the original constant values, six of the seven equations improved for both stations. Using locally calibrated parameter values, all seven equations worked well for determining mean seasonal evaporation values. For monthly evaporation values, the modified Blaney-Criddle method produced least error for all months for both stations, followed by the Hargreaves and Thornthwaite methods. The Linacre, Kharrufa and Hamon methods showed a significant bias in September for both stations. With properly determined constant values, the modified Blaney-Criddle, the Hargreaves and Thornthwaite methods can be recommended for estimating evaporation in the study region, as far as temperature-based methods are concerned. Copyright (C) 2001 John Wiley & Sons, Ltd.