Author details

the profile of 2007. The bank heights at the bank erosion zones were more than 6 meters. It is seen that the major bank erosion in the channel was reasonably predicted by the model. Although the simulated location and amount of the bank erosions do not match exactly to the observation, the general trend of the bank erosion simulation is quite satisfactory. The observed bank erosion at CS 70 and CS 78 were about 500 and 800 m, respectively. As discussed earlier, the model-predicted incision in the main channel was less than the observed. The error is mainly attributed to lacking of desirable data of sediment transport. Secondly, the Chuoshui River in the study reach is of braided pattern with several major branches. Even the general trend of channel aggradation/degradation can be simulated; the sedimentation trend

Morphodynamics of fluvial systems is complex involving channel bed change, bank erosion, and channel migration, and it results in soil loss, water quality deterioration, and property damages. Numerical models can be applied to simulate the system behavior by considering involved key physical mechanisms and processes, such as main and secondary flow, sediment transport processes and bank slope mass

The capabilities for simulating the secondary helical flow effects on suspended sediment and bed-load sediment transport have been developed and implemented to the CCHE2D model. The vertical profile for the main velocity and the secondary helical current were assumed to be the power law and linear distribution, respectively. Rouse's distribution for suspended sediment concentration was adopted. For general applications, the curvature of the flow instead of the channel was used for the helical flow calculation. The bank toe and surficial erosion and mass failure mechanisms have also been developed with the mass wasted bank materials being transported as bed load. The current model was designed for banks with cohesive and homogeneous materials. The mesh stretching technique was developed and used to adjust dynamically the moving boundary, internal mesh nodal position, and associated interpolation. These are important to simulate rivers with significant

Several sets of curved channel experimental data with different channel geometries, flow rates, sediment sizes, etc. were utilized to validate the developed sediment transport and morphodynamic simulation capabilities in good agreement. Bank erosion capabilities were tested first using a sine-generated channel and then the field case of Chuoshui River, Taiwan. The developed dynamic meshing method handled the moving boundary problem satisfactorily. The simulated and observed bank retreats in the studied Chuoshui River reach can be 500–800 m, which is agreed reasonably well. Because bank erosion occurred mainly in typhoon seasons, simulations used only flow discharges larger than 4000 cms. The computed bed change and bank erosion in one reach of this highly mobile braided river were

This work is supported by the Water Planning Institute, Department of Water

Resources, Taiwan, the project of USDA Agricultural Research Service under Specific Research Agreement No. 58-6060-8-008, monitored by the National

in each branch is difficult to control. More research is necessary.

Current Practice in Fluvial Geomorphology - Dynamics and Diversity

4. Major outcomes and conclusions

bank line movement due to erosion.

Acknowledgements

46

compared with reasonable agreements to observations.

Sedimentation Laboratory, and the University of Mississippi.

failure, etc.

Yafei Jia<sup>1</sup> \*, Yaoxin Zhang<sup>1</sup> , Keh-Chia Yeh2 and Chung-Ta Liao<sup>2</sup>

1 National Center for Computational Hydroscience and Engineering, The University of Mississippi, MS, USA

2 Disaster Prevention and Water Environment Research Center, National Chiao Tung University, Taiwan

\*Address all correspondence to: jia@ncche.olemiss.edu

© 2019 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
