Finite Element Long-Term Analysis of the Salt Water Exclusion Process in an Estuarine Reservoir

A method for predicting the salt water exclusion process or the time-varying salinity in an estuarine reservoir system is presented which may be a powerful tool when the reservoir flow is well mixed and predominantly one-dimensional. The method that views the reservoir as a onedimensionally distributed system is a great improvement over the conventional one based upon the salt balance equation for a lumped system.Coupling the open channel flow equations with the convection-dispersion equation, the flow of water and the transport of water density are simultaneously analyzed in terms of the interaction between water movement and density.The quasilinearized basic equations to be solved are cast into numerical versions by use of the finite element method and the implicit time-integration scheme to build a versatile and tough model for salinity and flow prediction.Inclusion of timedependent local injection or withdrawal of water and salt in the model is done by boundary and lateral flow treatments.The method presented in this paper is applied to the New Mam-Keum Estuarine Reservoir in the Republic of Korea, now under consideration, and the result of the five-year analysis under some assumed conditions is presented as an illustrative example.