Abstract: Individualistic mathematical models based on bioenergy theory are the latest research in modeling river habitats. This study explains the principles and method of individualistic population modeling based on bioenergy theory. Moreover, it presents the application of the model in the evaluation of red-trout habitats of the Red River in the National Park. Investigating the capabilities of the individualistic inSTREAM model as well as the results of bioenergy modeling presented in the present study showed that modeling presented in this study can make changes in different types of growth and habitat quality, as well as areas for biomonths with respect to both Biological and non-biological factors were used to distribute energy in the management and engineering of river ecosystems and to estimate ecological flows. This model is also applicable in the field of fisheries and aquaculture in order to provide more fish production and sustainable use of these resources assessment.
 
Introduction: Rivers have always played a significant role in human life in a way that the development of agriculture, desire for industrialization, and urbanization could not have been possible without rivers. Since the 1950s, the construction of structures, water control and convergence structures, bridges, and structures crossing the rivers has increased. Consequently, the flow regime, sediment, and the trend of rivers’ topographic and morphological changes altered greatly. Bank erosion plays an important role in the alluvial river and its bed load concentration, while it is also considered one of the human threats in river engineering. Flooding is another phenomenon that causes changes in sediment transport rates, which naturally increase with erosion and the river’s flow velocity erosion power. In addition, sedimentation rates in lower slope areas will increase. For this purpose, bank erosion of the river and hydraulic changes during the flood was investigated using CCHE2D (National Center for Computational Hydroscience and Engineering, two-dimensional) model.
 
Methodology: In this study, the morphological change of the river’s bed and bank was studied. The study area is about 4 km. The changes mentioned are due to floods with 25 years return period, which were studied in unsteady flow. Two-dimensional depth-averaged CCHE-Mesh software was used for meshing and construction of the study area topography, and the CCHE2D model was used to simulate hydrodynamic, sediment transport, and bank erosion. And CCHE has the ability to simulate one, two, and three-dimensional flow in aquatic zones, especially natural rivers in steady and unsteady states. In addition, the simulation of flow Hydrodynamics in alluvial streams and rivers, simulation of sediment transport in non-uniform sediment distribution mode, and investigation of changes and retreats of riverbanks are among the model capabilities. Furthermore, the possibility of the right bank erosion and change in flow direction due to the walls breaking was also studied. In this research, by using the model, the sensitivity of the flow characteristics, namely water depth and flow velocity and sediment transport, and the result of bank erosion in the River, are investigated with respect to the various Manning's roughness coefficient and three turbulent models, i.e., two zero equation eddy viscosity models, depth-averaged parabolic model, depth-averaged mixing length model and k - e standard model that is based on two equation eddy viscosity models.
 
Results and discussion: The novelty of this study is to investigate the bank erosion and the possibility of failure of the river bank wall in the study area in the flood with a 25 years return period in an unsteady state. The results of erosion and sedimentation at different coefficients of manning and three different eddy viscosity models indicate that the overall erosion and sedimentation process is almost the same for all of these different conditions. Still, there is a significant difference in their values and the amount of them. Finally, by comparing the erosion process that occurred in the study area, the mixing length eddy viscosity model yielded the closest response, followed by simulations. In unsteady hydrograph of water level, there is no significant change in the ratio of change in resistance coefficient. With the change of about 50,It means that changes of about 10 cm are negligible. The results indicated the erosion of the right bank of the river after the railway near the hole happened. This erosion may result in the destruction of the bank and lead the rivers to flow into holes (in 25 years return period flood, for unsteady flow, erosion prevailed over sedimentation). Furthermore, the high flow speed in the chute domain results in the demolition of its structure. In bridge extreme erosion may cause the bridge to collapse. Also, considerable erosion happens after the Chute in stilling basin and river bed. The velocity of about 12 m / s in the stilling basin is beyond the tolerance of the concrete structure and is likely to be eroded and destroyed.
 
Conclusion: Finally, in a flood with 25 years return period after erosion and fracture of the coastal wall of the River, part of the water flow diverts to the hole, initially causing water to enter the hole and also cause the flow lines to reduce and this means to increase velocity and more erosion in bed and banks of the river. A breakdown point that decreases the water level reduces the flow depth, increases the speed, and ultimately increases the erosion and flooding power of the flood stream. In addition to the river bed and banks, the structure, such as the chute, is also damaged due to the high velocity of the flow when the flood passes over it.