The Quality Study and Simulation by Qual2k Model in Dez River, Iran

According to the standard of Krenkel and Novotny (1980), the proposed concentrations of different water quality variables are categorized into four different groups. In this category, group 1 (A1, B1) represents a water quality which is suitable for all general applications. Group 4 is the worst water quality which is inappropriate for most applications. Moravej et al. (2017) investigated the water quality of the Karun River using the water quality index and GIS (Geographic Information system) time series modeling during 2007-2012. The results showed that the water quality index decreases (at the point where it joins the Dez River) meaning that lower quality of the river water is due to pollutants entering into the river at the downstream of the Dezful station. So, it is necessary to have control measures in this river. Recently, IRWQISC indicator has been presented by researchers of the Iranian Environmental Protection Agency. Hamedi et al. (2015) used the IRWQISC indicator to determine the changes in river flow volume due to seasonal variation. In addition, Azami et al., (2015) reviewed changes of the IRWQISC indicator for Tjan River. Bagherian Marzouni et al. (2014) conducted “DO” and “BOD” parameters in the Karun River with Q2k model. The results showed that by changing the entry points of the pollutants into the river (especially in low-flow condition) we will achieve the environmental goals for the river water. Nakhaei and Shahidi (2010), using the Qual2k model, showed that the water quality at the downstream of the Zayandehrood River is very poor due to the input of industrial pollutants. Rafiee et al. (2013) simulated the sources of pollutants input into the Gargar River in Khuzestan province, by Qual2k model. The results showed that the Qual2k model is sensitive to inflow and input pollutants such as BOD and Nitrate (NO3-N).In this study, the qualitative changes of the Dez River have been investigated using the Kerincell Standard and IRWQISC indicator in recent years. Then, the qualitative status of the river was simulated by Qual2k model. This model was calibrated and verified to forecast the water quality of the Dez River in the future.