BOD and DO modeling for Tigris River at Baghdad city portion using QUAL2K model


This study was conducted within Baghdad portion of Tigris River, which is significant due to the presence of various drains joining the river. Water samples have been collected from Tigris River along different points between Alfahama to Al-Zafarania and were analyzed for various water quality parameters during low flow season (November). The study involves application of QUAL2K model to simulate and predict the dissolved oxygen (DO) and biochemical oxygen demand (BOD5) profiles of Tigris River in a stretch of 49.97 kilometer. Remote sensing &GIS technique (ERDAS 9.2 & Global Mapper 11) used in this study as supported software to provide some QUAL2K input data related to the river geometric parameter. The simulation results were verified and showed that the predicted values were in agreement with the measured values. Model output showed that DO in the entire river was within limit of not less than 4 mg/L. For CBOD, the entire river may be divided into three reaches; first one is extended from AlFahama (0 km) to Alkadhmiah (9 km) and have CBOD concentration of 2 mg/L and the second reach has CBOD range (2–4) mg/L in which begins from Alkadhmiah and extend to near Aldora refinery. The third reach extends from Aldora refinery to Al-Zafaraniah (49.97) in the south before river confluence with Diyala River which has CBOD concentrations of more than 4 mg/L. The most polluted zone in the river located downstream of Aldora refinery and extend to the last segment due to the industrial discharge of pollutants to the river. Two strategies were suggested to control the level of CBOD in the river. First strategy suggest that the CBOD of the discharged effluent from industries should not exceed at least 50 mg/L to keep the CBOD of the entire river within limits of not more than 4 mg/L. While the second strategy does not give significant results in which the level of CBOD increase even with reduction in the pollution load (point source).