University of Tehran Press Iranian Journal of Soil and Water Research 2008-479X 50 4 2019 08 23 Determine of The Importance of Longitude Dispersion Coefficient on Solute Transport in Rivers Using the Monte Carlo Simulation Determine of The Importance of Longitude Dispersion Coefficient on Solute Transport in Rivers Using the Monte Carlo Simulation 763 776 72489 10.22059/ijswr.2018.259654.667934 FA Elham Karami Cheme Department of Water Structures, Faculty of Agriculture, Tarbiat Modares University, Tehran, Iran Mehdi Mazaheri Department of Water Structures, Faculty of Agriculture, Tarbiat Modares University, Tehran, Iran Journal Article 2018 06 12 There are various parameters which are important in determining the dispersion coefficient in rivers, e.g. hydrodynamic parameters and river geometry. Thus it is a challenging task to determine this coefficient accurately. There are different empirical formulas to estimate the dispersion coefficient in rivers. These formulas are mostly accurate in the range of conditions they validated. It is important to know the conditions in which the dispersion coefficient effect is significant in rivers. Thus, in this conditions, one should determine it with more accuracy. The main purpose of this study is to present a new method for determining the situations in which, dispersion coefficient has significant effect on solute transport mechanism. The proposed method is based on the Monte Carlo simulation method. The method was verified and validated using several hypothetical and also a real test cases. The results show that the time pattern of pollution source is a key factor in the dispersion coefficient effects on solute transport mechanism. The main finding of the study is that, sometimes it is possible to consider the dispersion coefficient with large errors and no significant changes occur in results of the solute transport simulation. There are various parameters which are important in determining the dispersion coefficient in rivers, e.g. hydrodynamic parameters and river geometry. Thus it is a challenging task to determine this coefficient accurately. There are different empirical formulas to estimate the dispersion coefficient in rivers. These formulas are mostly accurate in the range of conditions they validated. It is important to know the conditions in which the dispersion coefficient effect is significant in rivers. Thus, in this conditions, one should determine it with more accuracy. The main purpose of this study is to present a new method for determining the situations in which, dispersion coefficient has significant effect on solute transport mechanism. The proposed method is based on the Monte Carlo simulation method. The method was verified and validated using several hypothetical and also a real test cases. The results show that the time pattern of pollution source is a key factor in the dispersion coefficient effects on solute transport mechanism. The main finding of the study is that, sometimes it is possible to consider the dispersion coefficient with large errors and no significant changes occur in results of the solute transport simulation. https://ijswr.ut.ac.ir/article_72489_5b548dc3de11808b9ed22d880a62de2a.pdf