Extracting the tidal database from ADCIRC to use as an open boundary in EFDC

In EFDC model, often times we need to do modeling in coastal areas. In coastal areas, the flow exchange takes place between the freshwater and the salt water. So, to model coastal areas we need to use the open boundary condition. Commonly used open boundary condition types are water surface elevation (clamped boundary) and harmonic boundary conditions.

If we have measured water surface elevation, then we can use water surface elevation boundary at the open boundary. However, sometimes there are some occasions where we don’t have the data available to us. Under these cases, we can go to the ADCIRC database and then extract the harmonic constituents for the specified location.

The database for ADCIRC can be found here. I used this program / database to extract for the gulf of mexico. After you download the database for your area you will find 4 files on the downloaded folder. They are tides.in , tides_ec2001.FOR (this may be different if you have downloaded for different location), ec2001.tdb and ec2011.grd file. The file with extension (FOR) can be compiled and run to extract the data for any location.

The sample output from the ADCIRC program is as follows:

ADCIRC output

ADCIRC output

The data then extracted can be used to specify open boundary in EFDC model.


I hope this piece of information will be helpful to you. Please let me know if there is any issue using these type of extracted tidal data.



3 comments on “Extracting the tidal database from ADCIRC to use as an open boundary in EFDC

  1. Hi I am try to set up a streamline(no flow boundary condition) boundary with tidal elevations specified at the Southern boundary and no flow on the Northern boundary.

    Question: do I set up the boundary as a river input with no flow or as a jet source with no flow. I know it can be done but I am having difficulty finding any information on it. Just wondering how you would go about it.

  2. Are you trying to set up no flow boundary condition in EFDC model ? By no flow condition, what do you mean ? Did you mean zero flux ? In EFDC there is no default flux boundary condition. You need to modify your code in order to use the flux boundary conditions.

    • I have a model set-up with 2 open boundaries. 1 is set up using pser.inp and is the dominant driving force in the bay. The other open boundary is suspected to have very little flow through it and must be set-up as a streamline boundary to rise and fall with surface elevations but show no flow in or out. I have set the open boundary up as a second river input with flow equal to 0 and specified temp and salt equal to those at the flow boundary.

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