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GSSHA- Variable Stage Boundary Condition

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I will like to know how GSSHA handles the variable stage (water surface elevation) boundary conditions. Does the GSSHA water depth results for a cell are being forced with this overland flow boundary condition if the feature point is located within the same cell or the boundary condition is being applied at the cell and GSSHA is allow to compute the hydrodynamics for this cell? In other words, does the GSSHA water depth results will be identical to the boundary condition applied at the same cell.


Also, what does GSSHA does between the variable stage overland boundary condition? Does it compute the hydrodynamics at each time step for the boundary condition or does it linearly interpolate between boundary condition steps? For example, if the time step of my boundary condition is 5 minutes but the computational time step of GSSHA is 1 sec, does GSSHA computes the hydrodynamics each 5 minutes using the latest boundary condition data or does it interpolate the values between each 5 minutes?

Any comments or feedback will be greatly appreciated. Please feel free to ask any question if my doubt was not clear.

Thanks in advance,

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I think the solution cell water depth will correspond to the water surface elevation you specify in the overland boundary condition and this water depth will be applied in each of the GSSHA overland flow model time steps to adjacent cells.  This option is useful for coastal storm surge or levee break modeling.  I have not personally looked at the code to guarantee that the water depth at the cell is kept at that boundary condition throughout the simulation though.  Also, to answer the second part of your question, I do not know how GSSHA interpolates between water surface elevation values.  My suggestion is to experiment with GSSHA and try to determine what it does with your water surface elevation values and then you can interpolate the water surface elevation values yourself as needed.


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