One-Dimensional Model Predictions of Carbonaceous Biological Oxygen Demand and Dissolved Oxygen for Hilla River Water Quality, Iraq

Abstract

The water quality of the Hilla River, located in Iraq, has been varying due to the presence of different illegal point and non-points sources along the river stream. This study highlighted the carbonaceous biological oxygen demand (CBOD) and dissolved oxygen (DO) levels for safe usage by applying the river and stream water quality model called QUẠL2K model, depending on the hydraulic and water quality data collected along 6.8 km passing through the main city (Hilla City) on October 2022 (low flow season) and January 2023 (high flow season). The modeling results showed that the simulated predictions are in good agreement with field data. The outputs revealed the two parameters (CBOD and DO) ranged between (1.425–3.075) mg/L and (9.5–10.65) mg/L, respectively, during low flow season and between (0.745–2) mg/L and (9.5–10.5) mg/L, respectively, during high flow season. The river CBOD levels along the river follow same pattern during the high and low flow seasons, but the DO levels behaved inversely. However, both parameters were within the acceptable limits. Thus, the river health can be considered good for basic human usage.