A comprehensive coastal ecosystem model coupled with 3D hydrodynamic model with non-hydrostatic flow was developed to understand the processes of accumulation of anoxic water masses (and hydrogen sulfide) in borrow pits and their upwelling to shallow region. This model was applied to the borrow pit in Mikawa Bay and compared to the observed data. To examine the effectiveness of the model, the numerical results were compared with those of a hydrostatic pressure model. The comparison proved the non-hydrostatic model to be much more adequate at simulating the stratification structure and the vertical mixing in the pit. Moreover, it turned out that the non-hydrostatic model also reproduces reasonably the upwelling process under strong wind conditions. The model we developed can evaluate environmental situation after borrow pits remediation, and the approach will contribute to effective restoration.
