Numerical Modelling of Thermal Stratification in Dam Reservoir Using CE-QUAL-W2 Model (Case study: Yamchi Dam)

One of the effective issues on water resources quality like dam reservoirs and other water bodies is thermal stratification. For studying the stratification in reservoirs, turbulence dynamic and internal flows must be analyzed in reservoir. Because of many phenomena that effect on stratification, studying this phenomenon is possible just with use of dynamic models. In this way using numerical models beside yield measurements are unavoidable.

Due to the water usage of Yamchi dam as a drinking water and irrigation, studying the water quality has more importance, so in this research for studying the status of thermal stratification of Yamchi dam, modeling of temperature with CE-QUAL-W2 software in one year period from (May, 2015) until (April, 2016) was done. The value of observed temperature from various points of the reservoir were compared with modeled data and with the results of modeled data, variation trend of the stratification phenomena in Yamchi dam was studied.

In this research, the value of the observed temperature was in good agreement with modeled data. The results showed that the stratification phenomena happen in reservoir and lasts about 4 months in the year. This phenomenon begins at the late May and improves in July and reaches its peak in August. At last, it would end in early September. From the September due to decrease of the temperature, stratification in the reservoir is declined and Turbulence is also seen in Autumn and Winter. This turbulence continues until late May.