THE ROLE OF EVAPORATION IN EVALUATING THE WATER RESERVE OF ROMANIAN LAKES – A CASE STUDY

Evaporation is a component of the hydrologic balance and a meteorological factor which directly influences water balance, together with rainfall. The main objectives of this paper are: the spatial and temporal analysis of lake surface evaporation in Romania and the determination of the water volume lost through evaporation. This paper is based on the use of annual data series on evaporation measured at 21 lakes where this parameter is being monitored. In terms of methodology, our paper is based on the statistical analysis, and the estimation of the water volume lost through evaporation was done by extrapolating the values measured at the level of the evaporation basin to the entire surface of the lake (according to Drobot and Şerban,1999). In order to evaluate water losses caused by evaporation in relation to the water volume of lakes, the Izvorul Muntelui, Furculesti, Fântânele, Bezid and Dridu lakes were taken as case studies, the analysis was carried out for the years of maximum and minimum evaporation. The results of our analysis show that the volume of water lost through evaporation depends both on local climate conditions and also on the morphometrical characteristics of lakes. Thus, evaporation can reduce a lake volume by up to 10%, in the case of lakes with small surface areas (below 10 km2) and small water volumes.