Simulation of Water Pollution Load Reduction in the Zayandehrood River, Isfahan, Iran Using Qual2kw Model

Today, due to the usage of rivers for transferring urban and industrial wastewaters as well as agricultural drainage water, they are exposed to different sources of pollution. Therefore, knowing the trend of qualitative changes of rivers is effective for controlling pollution sources. In this study, the water quality of Zayandehrood River was investigated and for simulation of qualitative data, Qual2kw model was used. The information used includes qualitative information of the river water and hydrometric, meteorological and contaminants information. The investigated parameters were BOD, DO, and nitrate which were taken from 12 stations. Simulation of qualitative data by Qual2kw model for BOD and DO parameters suggests that there is a suitable match between the measured and simulated data, but simulation for nitrate parameter was not performed well. The results of model indicated that due to withdrawal of water for agricultural uses, the river water’s flow rate was very low at terminal stations. Furthermore, dissolved oxygen concentration in these stations was very low, while the chemical oxygen demand concentration was very high due to entry of industrial and human wastewater. For this reason, the river is no longer able to receive organic load and does not have self-purification capability.