Numerical Modeling for Prediction of the Dissolved Oxygen Depletion Affected by Heated Water Discharged in Rivers

Abstract

In this research a numerical model is proposed to study the depletion of dissolved oxygen caused by discharge of heated water in the rivers. This problem was formulated by equations of momentum conservation, energy, turbulences and the relation between temperature and dissolved oxygen were used to describe the dissolved oxygen distribution along the study reach. The partial differential equations were simplified to obtain the system of linear equations that were then solved using Gauss-Elimination method .The numerical model was verified by conducting comparison of observed data from South-Baghdad power station with those computed by the model. The comparison results show an agreement with maximum absolute error (11%) and correlation factor of (0.921). The results of the study showed that increasing the bed roughness from 0.04m to 0.11m causes a longitudinal retardation of dissolved oxygen distribution about (26%) and vertical advance about (14%). Increasing the water-surface slope from 6 cm/km to 12 cm/km causes a longitudinal advance of dissolved oxygen depletion about (19%) and vertical retardation of about (16%) and Assumption of constant density of water causes a longitudinal and vertical retardation of dissolved oxygen depletion about 28% and 6% respectively.

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