Energy budget and thermal structure of the reservoirs in the arid regions, Case study: Saveh Dam Reservoir

Knowing the rate of evaporation from surface water resources such as channels، reservoirs and lakes is essential for precise management of water balance. In this study، monthly evaporation was determined by Bowen Ratio Energy Budget (BREB) method for Alghadir Lake (Saveh، Iran) from 1995-2007. Some variations have been observed on the estimated evaporation of the energy budget at different years، ranging from 151 cm for 1997 to 174 cm for 2005. Also، there is no specific monthly evaporation pattern for all the years، but evaporation rates were low in Jan and Feb and highest during the Jul and Aug. Surveying of lake thermal structure showed that inflow and outflow energy fluxes to this water volume have large variations and incoming solar shortwave radiation، incoming atmospheric longwave radiation and longwave atmospheric radiation emitted from the water surface are largest energy fluxes for this small and deep lake.