Hello, User
Thank you for raising this issue. In the EFDC model, assigning identical tidal values to all open boundary cells is often a simplified configuration, especially when tidal data lacks spatial detail or when the boundary area is relatively small. However, if the open boundary cells are spaced several kilometers apart, tidal wave propagation theory suggests there should be differences in phase and amplitude between those locations.
Applying uniform values under such conditions may introduce errors in simulating flow dynamics and sediment distribution, particularly in areas that are sensitive to tidal forcing.
However, the use of high spatial resolution tidal data is extremely rare and, in many cases, practically unfeasible. In reality, tide gauge stations may be spaced tens to even hundreds of kilometers apart along the coastline, making it challenging to construct a spatially detailed tidal boundary field.
Therefore, if the model requires high accuracy in representing the tidal field, it is important to carefully weigh the trade-off between technical complexity and the availability of input data in order to determine the most appropriate boundary condition setup. In our typical applications, we usually apply a single uniform boundary band.