Simulation Study of Water Quality Variation in Latian Reservoir

The water quality of the Latiyan reservoir, which is supplying about 30% of Tehran’s water needs, has deteriorated because of extensive basin development and construction activities during recent years. The one-dimensional water quality model HEC-5Q was applied to this dam. The model was calibrated and validated against field data and shown to reproduce the observed thermal, oxygen and salinity stratification successfully. The result of this simulation indicates that there is a seasonal stratification in the Latiyan reservoir, which forms at the beginning of fall, and the turn over occurs at the end of winter. The changes of dissolved oxygen are between 1 and 12 mg/L. The critical situation considering dissolved oxygen occurs at the bottom of the reservoir by the end of summer. The changes of total dissolved solids are between 125 and 220 mg/L, affected mostly by leaching and turn over in the reservoir.