Open boundary setting

I use EFDC_Explorer to do the hydrodynamic simulation of the bay. There are three open boundary conditions totally. Due to the lack of water level data, I use the water level data on bay’s entrance as the open boundary water pressure value. But the simulate results is not good.
Could you please give me some suggestions about how to set pressure time series if we lack of relative data for that?
Thanks a lot!


Hello Sophie,

Do you have data for any boundaries ? Which waterbody are you working on ? Usually, if you have water level data for some period, you could do harmonic analysis and find out the harmonic constituents and use harmonic boundary as your open boundary. If you have water level at one boundary and know the time lag at another boundary then you could convert the water level at one location and use that time lag and modify the boundary to use for the location where you don’t have data.


Hi, Janesh,

Thanks for your reply. My research waterbody is bay area with both freshwater inflow and sea water intrusion.
I have no data for any boundary. Another question is how to do harmonic analysis using EE? Or could you please give me some methods about how to find out the harmonic constituents?
Right now, If I use the entrance data to represent the open boundary condition, the amplitude of the simulation result doesn’t match (usually to small and couldn’t reach to the peak and especially for the points inside the bay. For the point which is near the entrance, it has the good result. So, I’m wondering is there any method to set the open boundary water level by adjusting the data I have right now.

I’m so appreciate it for your any answer.
Thanks a lot,


Currently, EE can only use harmonic constituents and then create the time series to assign the boundary conditions. EE doesn’t extract the harmonic constituents from the time series of water surface elevation. There are programs such as Xtide or matlab program “World Tides and Currents” that allows to do the harmonic data analysis based on your measured data. If you are using the measured data at one location then specify that same data at another location, then you might have to modify your amplitude and time lag in order to properly specify the boundary. If you don’t know exactly how the tides change at different locations, then you might have to do some trial and error method to get the reasonable amplitude multiplier and time lag shift. You could use large regional scale models such as ADCIRC to predict the tide at different locations and then use the output from that model as input into EFDC model. I hope it helps.