Investigation of the effects of Beheshtabad River Water Abstraction on Downstream Water Quality

The river is one of the most important water sources for drinking and agriculture. Therefore, evaluating and modeling the water quality of rivers and examining its qualitative effects on human life, living things, and the environment is undeniable. In this study, the water quality of the Beheshtabad River was simulated using the QUAL2Kw simulation model. The water quality of this river in its two tributaries was analyzed by designing two scenarios to improve it downstream. The simulated qualitative parameters (temperature, Ec, TS, DO, BOD, COD, pH, nitrate, orthophosphate, ammonium, and fecal coliform) were simulated in two scenarios with different flow rates. The results show that by preventing the discharge of water from the upstream rivers (Kiar and Juneqan) due to high pollution and also the addition of water from Bagh-e-Rostam spring along the route, the water quality of this river will improve downstream. Including BOD concentration will improve from 7.32 to 4.23 mg /L, COD parameter concentration will improve from 19.30 to 12 mg/L, DO parameter concentration from 4.9 to 5.9 mg/L, and fecal coliform parameter concentration from 1500 to MPN/100 mL160.