Investigating the Quality Status of Haraz River Using Numerical Modeling

Rivers are amongst the most important sources of water supply all over the world. Increasing urban development, industrial activities and a significant increase in the volume of urban effluents have polluted rivers and in many places water quality of these vital resources have been seriously endangered. In this study, using the QUAL2K numerical model, the quality status of Haraz River has been investigated and the impact of effluents entering the river has been identified. According to the results of qualitative modeling of the river in 2016, at kilometer 48, where the Amol diversion dam is located, the BOD rate suddenly increases which is due to the reduction of flow velocity and discharge and the increase in the discharge of pollutants to the river related to workshops and factories. In spring and summer the concentration of dissolved oxygen is critical in the reaches from Amol diversion dam to the estuary of the river by the Caspian Sea. In terms of acidity, the water of Haraz River is alkaline. The EC parameter also decreases along the river due to the gradual deposition of soluble and suspended solids into the water. The concentration of nitrate in water also increases after the diversion dam, although it is not significant in total.