Integration of a numerical model in curvilinear coordinates with sand mining component for bottom morphology simulation

Abstract

Numerical models for calculating bottom morphology are increasingly popular because of their long-term forecasting capabilities as well as their ability to identify causes. However, the simulation of bottom morphology, in addition to natural factors, is also governed by economic activities, especially sand mining. In this paper, we propose the development of the numerical model in curvilinear coordinates combined with a sand mining component that simulates the bottom morphology of the Tien river segment in the Mekong Delta as a study area. The modeling theory relies on the Reynolds equation system, which is combined with the suspended sediment transport equation in a two-dimensional curvilinear coordinate system. The process of averaging is performed over the depth. The suspended sediment transport equation incorporates a source function that describes the upward or downward movement of particles. In the model for bottom morphology, a component for sand mining is included, which accounts for the rate at which sand is extracted from the riverbed. This component is integrated into the equation governing the continuity of the bed load. The findings demonstrate that the numerical model effectively captures the changes in the river’s bottom morphology resulting from sand mining. Specifically, when the sand mining component is employed, the model accurately represents the actual development of the bottom morphology in river segments where sand mining occurs. Furthermore, the downstream bed alterations are significantly influenced by sand mining activities. By incorporating the sand mining component into the model, it becomes a valuable tool for simulating the bottom morphology in river segments subjected to sand mining, thus aiding in sand mining planning and the management of disaster risks associated with bank erosion.