Changes in Self-Purification Capacity of the Karun River in 2008 and 2014 using QUAL2Kw Model within Ahvaz

The Karun River receives large quantities of domestic wastewater, industrial effluents, and agricultural drainage water during its course. Since every river has a certain capacity for accepting incoming pollutants and for self-purification, knowledge of the trend of changes in self-purification capacity is of great importance. This research studied changes in the self-purification capacity of the Karun River in the 42-kilometer distance between the Zergan and Kot Amir stations in 2008-2009 and 2013-2014. Changes in the parameters of pH, EC, and BOD in these two years were first simulated for the two months of August and January using the calibrated Qual2Kw model. The observed data was then compared with the calculated data using the square of the correlation coefficient (R2) and the mean absolute error (MAE). Results showed the Karun River could not purify itself with respect to the EC parameter in 2008-2009 and with respect to the BOD parameter in 2013-2014. Moreover, the best simulation of the model was achieved for the pH parameter, and the simulations for the BOD and EC parameters were the second and third best, respectively.