Water Quality and Temperature Stratification Of Zanjan Taham Dam with CE-QUAL-W2 Software

for sustainable development, water recourses quality control has special importance. In this way, recognizing the stratification of reservoirs is very important. Also surveying water quality in the case for salinity of surface water resources of dams that figures as the main resource of drinking water of a country is one of the challenges of water resources management. For studying the stratification in reservoirs, turbulence dynamic and internal flows must be analyzed in reservoir. Because of many phenomenons that effect on stratification, studying this phenomenon is possible just with the using of dynamic models. In this way using numerical models beside yield measurements are unavoidable.
Because of the the Taham dam's water usage as for drinking water of Zanjan city, so studying the water quality of has more importance, so in this research for studying the status of the water quality of taham dam, modeling of temperature and TDS (Total dissolved solids) with CE-QUAL-W2 software in one year period from (December 21, 2011) until (December 20, 2012) was done. The value of observed temperature and TDS were compared with modeled data. With the results of modeled data, variation trend of said parameters and the stratification phenomena in taham dam was studied.
In this research, the value of the observed temperature and salinity were in good agreement with modeled data. The results showed that the stratification phenomena happens in reservoir and lasts 8 months in the year. This phenomena begins at the end of March and improves in August and September (with 20 degrees difference between temperature of upper and lower water layers). Turbulence is also seen from January until March. In fall, because of decreasing the difference between temperature of upper and lower water layers, stratification in the reservoir is decreased and in winter it disappears. Results also shows the salinity stratification happens simultaneous with temperature stratification in the reservoir.
From the view point of stratification, Taham dam is in the case of Thermal Monomictic reservoirs. In fall and summer seasons, the value of salinity for all of depths of dam is a constant value. This process is continued until May and after this time because of beginning the stratification phenomenon the difference between layers in depth increase and at summer the difference become maximum.