Prediction of Thermal Stratification in Proposed Bakhtyari Reservoir with CE-QUAL-W2

Construction and operation of dams have two main effects on streams. At first it increases detention time and then leads to thermal stratification. Changing of water quality is the result of these effects and the outflow has different physical, chemical and biological characteristics from inflow. In this study thermal regime in proposed Bakhtyari reservoir was simulated with CE-QUAL-W2 model. The inputs are reservoir topography, hydrological and meteorological data. As there is no chance to calibrate or verify the model, they will be done in monitoring and operation period. Three different inflow scenarios were simulated based on dry, normal and wet year. Simulation results represent that in dry year stratification starts at April and remains up to September, but the results of normal year indicates that Stratification is between May and November. In wet year because of short detention time, thermal gradient variation is different from dry and normal year and temperature of middle layers imitate inflow water temperature. In all scenarios a stagnant layer could be seen in downward of outlet structure(700mASL). It is concluded that in dry years which dam has a major effect in inflow regime, turnover is mostly conform thermal stratification theories in reservoirs.