Simulation of Eutrification and Dissolved Oxygen Changes Probability in Artificial Lakes

Chitgar artificial lake, located in urban District 22 of Tehran Municipality, northwest of Tehran, has a volume of 10 million m3, an average depth of 10m and an area of 224 hectares and is Iran’s largest man-made lake. The most important water resources of the district, which can support the lake, are the Kan River, the district’s runoff, the middle part watersheds runoff, and the treated wastewater of the urban region. In this study, the way to take water from each resource individually or together are discussed, and twelve different choices of resources to maintain the lake water are considered. In this research, WQRRS model has been run to each of the 12 aforementioned choices individually to predict phosphorus concentration as a nutrient in the lake for each one. This simulation has been done during a five-year period, which is assumed to be a typical period of time. In this way, it would be possible to predict the throphic level of the needed input data to run the model: quality factors, meteorological data, and geometrical characteristics of the reservoir, the characteristics of inflow and also the needed coefficients for the model. These data have been collected from hydrometric and meteorological stations of the region and also from the results of other studies. After running the model, the simulation results show that choices 2 and 4 are the best resources to support the lake water and have the fewest difficulties in regard the eutrification problem. The results also show that DO concentration in Kan River is at an acceptable level.