Evaporation model of Lake Qaroun as influenced by lake salinity1

Abstract

AbstractA model for estimating monthly and annual evaporation of Lake Qaroun was developed using the energy budget concept. The evaporation is estimated from the amount of solar radiation, atmospheric long‐wave radiation, back radiation and evaporative energy. A modification is made to the energy equation to allow the calculation of evaporation from saline lakes by analyzing data from four evaporation pans with different salinities.The model simulations were checked against evaporation rates measured by Mankarous WF (1979. Hydrology of Lake Qaroun. MSc thesis, Faculty of Engineering, Cairo University, Cairo, Egypt). The monthly comparison shows that the model gives an acceptable accuracy with a relative error ranging from −12.4 to +12.9%. The model produces reliable results in terms of annual prediction with a maximum percent error of 3% and the minimum of −2.7%. The standard deviation of differences indicates that there is a good probability of obtaining simulated values within 0.8 mm (in May) to within 22.2 mm (in December) of measured values. Copyright © 2001 John Wiley & Sons, Ltd.