The Priestley-Taylor Evaporation Model Applied to a Large, Shallow Lake in the Netherlands

Abstract

The applicability of the model of Priestley and Taylor (1972) for evaporation of saturated surfaces is examined for the former Lake Flevo (The Netherlands). This lake had an area of about 460 km2 and an average depth of 3 m. Daily values of evaporation in the period July–September 1967, determined with the energy-budget method, are compared with the corresponding estimated values obtained by the Priestley-Taylor model. The agreement appears to be satisfactory. The diurnal variation of the parameter α of the Priestley-Taylor model is found to be pronounced. From standard meteorological observations at Oostvaardersdiep, a station at the perimeter of the lake, and an energy-budget model of Keijman (1974) an indirect extension of the available time series is obtained. In this way energy-budget data for the period April–October 1967 became available. Analysis of this data set leads to the preliminary conclusion that α has a seasonal variation. This is due to the fact that there is a linear relation between the daily latent heat flux LE and the equilibrium latent heat flux LEEQ with a nonzero intercept.