Interfacing Near- and Far-Field Models to Simulate Submerged Freshwater Discharge Mixing in Seawater

A 3D interfacing zonal (TDIZ) model was developed for the submerged bottom-flow- discharge from a sea-bottom freshwater drainage facility and used to analyze both initial mixing in the near field and the advection-dispersion process in the far field with ambient water flow. The mixing characteristics of the freshwater discharge and the applicability of the model for each field were verified using data from field measurements. The predicted salinity distribution and the minimum dilution at the water surface were generally in agreement with the field measurement data, and the vertical concentration distribution of the discharged water and the mixing behavior were also well simulated. When the advection-dispersion process by ambient water flow was analyzed, the TDIZ model in which initial mixing in the near field was considered gave better results than a far-field advection-dispersion model, which considered the discharge boundary conditions in terms of a simple point source.