2D finite element pollutant transport model for accidental mass release in rivers

Abstract

A numerical model to simulate the accidental pollutant transport in rivers was developed using the two-dimensional finite element method. RAM4 is developed as the scalar transport module of the software RAMS (River Analysis and Modeling System) which can provide a graphical user interface for various river topographies and has recently been released as a beta version. The significance of RAM4 is that it is able to treat the pollutant mass itself, which is instantaneously released at a certain point of a river. The development of this ability was motivated by the inadequacy of the previous method, whereby the instantaneous mass release was expressed by defining some initial concentration at a source point. This method is not able to balance the injected mass value in accordance with the numerical time step size and the magnitude of flow velocity at this point. RAM4 was connected with the RAMS graphic user interface so that the source point and the released mass value can be controlled with a user-friendly graphical tool. The hydrodynamic module of RAMS, named RAM2, is currently undergoing beta-testing. Therefore, RAM4 was applied to the real river using the popular hydrodynamic model, RMA2, in TABS-MD. Using the obtained flow field computed by RMA2, the model has been simulated for a number of example scenarios of mass dumping accidents in the Han River of Korea in order to verify the applicability of this method in a real situation.