A nested hydrodynamic model incorporating flooding and drying

A one-way nested version of the hydrobiological model DIVAST (Depth Integrated Velocity and Solute Transport) is introduced. The nested model allows flooding and drying of intertidal areas, a process often present in areas where nesting is required but usually excluded from nested models due to the added complexity and instabilities. An overview of the nesting procedure used in the model is presented. The model was tested in Cork Harbour where extensive flooding and drying occurs and results show that the model is capable of reproducing hydrodynamic activity to a high degree of accuracy. Substantial computational savings are also achieved. It has been found that the location of nested open boundaries can significantly affect model accuracy; the placement of nested boundaries must therefore be given careful consideration. Fine and coarse grid models were used to investigate the relationship between temporal and spatial resolution and model accuracy. The results demonstrate the applicability and benefits of nesting.