Study of flow in Rua island on Dong Nai river using 3D numerical method

Abstract

Erosion and bank erosion are processes occurring to the riverbed and are issues closely related to the people and society. Rua Island is located in Thanh Hoi commune, Tan Uyen town, Binh Duong province which is one of serious bank erosion areas in the downstream of the Dong Nai river. Riverbank erosion in Rua islet in general has been going on for a long time and the rate of bank erosion has increased after the Tri An hydropower project came into operation and river-bed sand mining activities accelerated. At present, the Rua Islet is in danger of being cut in two at the position of Rua neck. Therefore, researching to determine the mechanism and cause of landslide of Rua Islet in order to point out effective measures to prevent landslide is urgent. A three-dimensional numerical modeling has been developed for the river section in this island to study the flow structure. This model was calibrated with observation data in 2017. Using this model flow in the entire river section was simulated. The calculation results clearly showed the three-dimensional structure of the flow at this river section, especially at the curved sections where bank erosion often occurs. Calculation results also show the distribution of bottom stresse in the river section, it is a parameter that is crucial to the process of changing of the river bed.