Modeling hydrodynamic of flow and water quality parameters in Karkheh riverine system using FASTER model

Nowadays, mathematical modeling is increasingly used in order to evaluate the spatial and temporal changes of the concentrations of water quality parameters in rivers and reservoirs. In this research, the FASTER model was used for water quality modeling. For simulation of the hydrodynamic conditions of flow, continuity and momentum equations (known as Saint- Venant equations), are numerically solved using the Crank-Nicholson central scheme with a staggered method and varying grid size. The Advection Dispersion Equation (ADE) has been solved using the finite volume technique. According to the available data, the parameters of nitrogen and dissolved oxygen (DO) for a reach of Karkheh River between Paye-Pole and Hamidiyeh stations were analyzed and simulated and Abdel khan hydrometric station was selected as a survey station. For solving the hydrodynamics of flow, it is necessary that Manning roughness coefficient (n) be calibrated in FASTER model. With adjusting of this factor, value of 0.028 was chosen. In this study 4 Dispersion Coefficients (DL), including Fischer et al, Seo and cheong, Kashefipour and Kashefipour and Falconer equations were used. Comparison of the measured nitrogen and dissolved oxygen concentrations and the corresponding model results showed that the Fischer dispersion model and Kashefipour- Falconer dispersion model performed relatively well for nitrogen and dissolved oxygen, respectively. Also according to the concentrations of water quality parameters that have been evaluated in this specified reach of Karkheh River, the concentration of dissolved oxygen is desirable for public purposes for different conditions of water temperature and river discharge. The concentration of nitrogen has low limitations for consumption.