Table of Contents

1 Introduction

2 Create a New Grid

3 Assigning the Initial Conditions

3.1 Assigning the Initial Bottom Conditions

3.2 Assigning the Depth/Water Surface Elevations

3.3 Assigning the Bottom Roughness

4 Assigning the Boundary Conditions

4.1 Preparing the Flow Boundary

4.2 Preparing the Tidal Level Boundary

4.3 Assigning Time Series to the Boundary Location Cells

4.3.1 Assigning the Flow Boundary

4.3.2 Assigning Tides Boundary

5 Hydrodynamics Settings

6 Setting Vertical Layers

7 Model Timing

8 Running EFDC+

9 Visualizing the EFDC Solution

1 Introduction

This tutorial document will guide you how to setup a coastal hydrodynamic model by using the EFDC_Explorer (EE). It will cover preparation of the necessary input files for the EFDC model and visualization of the output by using the EFDC_Explorer (EE) Software.

The data used for this tutorial are from Tra Khuc Estuary in Vietnam. All files for this tutorial are found in Data folder downloadable from the EEMS website.

Before going to each session, let us first introduce the EE main form in order to better understand our explanation hereafter. Build a 3D Coastal Model (Level 2 Step-by-Step Guidance)#Figure 1 is the main form of EFDC_Explorer or EE User Interface. The functions of individual icons are described in Knowledge Base.

Figure 1. EFDC Explorer main form.

2  Create a New Grid

This section will guide you in how to create a new simple gird with EFDC_Explorer. For a complicated grid the user is recommended to use specialized grid generation software such as CVLGrid.

Tra Khuc Estuary in Quang Ngai province, Vietnam is chosen as the example of building a 3D coastal model in EE.

The gird generation process includes following steps:

1. Open EE
2. Click Generate New Model icon as  on the main menu of EE interface. Then Generate EFDC Model frame appears shown in Build a 3D Coastal Model (Level 2 Step-by-Step Guidance)#Figure 2
3. Select CVLGrid in the Grid Type. The user should click the Browse button to select grid file name as Trakhuc.cvl in Grid folder as shown in Build a 3D Coastal Model (Level 2 Step-by-Step Guidance)#Figure 2.  In the other hand, EE also supports the user to import various format of grid file with the option Import Grid.
4. Click Generate button in Build a 3D Coastal Model (Level 2 Step-by-Step Guidance)#Figure 2 to finish. A dialog will pop up to show the grid information (see Build a 3D Coastal Model (Level 2 Step-by-Step Guidance)#Figure 3).

Figure 2. Generate EFDC Model form.

Figure 3. New created grid information.

    5. Save the model by selecting this button  and create a new directory as shown in Build a 3D Coastal Model (Level 2 Step-by-Step Guidance)#Figure 4.

Figure 4. New model saved.

3  Assigning the Initial Conditions

This section will guide you in how to assign the initial conditions such as the bathymetry, water level and bottom roughness.

Figure 5. Assigning the initial conditions.

3.1 Assigning the Initial Bottom Conditions

1. Select the Domain/Initial Conditions & Bottom Roughness and click the Assign button (see Build a 3D Coastal Model (Level 2 Step-by-Step Guidance)#Figure 5).
2. A polyline file is used to define the area to assign the bathymetry data. To assign this browse in the Poly File form to "Domain.p2d".
3. Next browse to the bathymetry data file in the Data File form. This bathymetry file is simply a general xyz format.
4. There are a number of options for the for user to modify the assigned. In this case, we choose in the Bathymetry Assignment Options we select Interpolated Data and Both. This will take the nearest neighbor data points to interpolate for the cells where there is no data coverage.
5. Click the Apply button to take the effect before hitting the Done button (see Build a 3D Coastal Model (Level 2 Step-by-Step Guidance)#Figure 6)

Figure 6. Assigning the bathymetry.

3.2 Assigning the Depth/Water Surface Elevations

The next step is to assign the initial depth or water surface elevations. There are two options for setting the surface water elevation which are Use Constant and Use Point Measurements/Gridded Data.

1. Click Assign button
2. Browse in the Poly File form to "Domain.p2d"
3. Next, browse to the water surface elevation data file "IC_WSEL.dat" in the Data File form.
4. Checked on Use Point Measurements/Gridded Data
5. The user click Apply button then click Done button to finish.

Figure 7. Assigning water surface elevation.

3.3 Assigning the Bottom Roughness (Z0)

1. Click the Assign button in the Bottom Roughness (Z0) box (Build a 3D Coastal Model (Level 2 Step-by-Step Guidance)#Figure 5).
2. Browse in the Poly File form to "Domain.p2d"
3. Next, browse to the bottom roughness data file "IC Bot Roughness.dat" in Data folder in the Data File form.
4. Checked on Use Point Measurements/Gridded Data
5. Click the Apply button before hitting the Done button as shown in Build a 3D Coastal Model (Level 2 Step-by-Step Guidance)#Figure 8.

Figure 8. Assigning bottom roughness.

4 Assigning the Boundary Conditions

This section will guide you how to prepare for the boundary conditions and assign it to the model cell configuration. In this coastal case there are two flow boundaries; one is river discharge from the upstream and the other is tidal level. Thus, we should prepare two time series of inflow and tidal level boundaries for this particular case. In order to set a boundary time series the steps outlined below should be taken.

4.1 Preparing the Flow Boundary.

1. Select the Domain/Boundary Conditions. (See Build a 3D Coastal Model (Level 2 Step-by-Step Guidance)#Figure 9).
2. Click to the E button  which is next to Flow to edit the flow boundary. (Build a 3D Coastal Model (Level 2 Step-by-Step Guidance)#Figure 9)
3. Enter the Number of Series into the box which in this case is 1.
4. Give a Title for associated time series, in this case "River".
5. Click Import Data button, browse to "BC_Flow.dat" file in Data folder
6. Select EE DAT or WQ Data format then click OK button. (See Build a 3D Coastal Model (Level 2 Step-by-Step Guidance)#Figure 10).
7. Enter "-1" in Import Data form then click OK button. (See Build a 3D Coastal Model (Level 2 Step-by-Step Guidance)#Figure 11).

8. Click to the Current button  to view the current time series. If there are a number of layers then check Sum Layers to show total flow. (See Build a 3D Coastal Model (Level 2 Step-by-Step Guidance)#Figure 12). Close timeseries data plot

9. Click OK button in Data Series: Flow form to finish editing the boundary time series.

Figure 9. Assigning flow boundary conditions.

Figure 10. Editing the boundary time series (01).

Figure 11. Editing the boundary time series (02).

Figure 12. Flow time series plot.

4.2 Preparing the Tidal Level Boundary.

1. Click to the E button  which is next to Water Level (See Build a 3D Coastal Model (Level 2 Step-by-Step Guidance)#Figure 13)
2. Enter the Number of Series, which is 1 for this case (see Build a 3D Coastal Model (Level 2 Step-by-Step Guidance)#Figure 14)
3. Enter the Title of Series as "Tides"
4. Open "BC_Water Level.dat" file in Data folder, the copy and paste into the Data Series: Water surface form.
5. Click Current button in the form to see the timeseries plot (see Build a 3D Coastal Model (Level 2 Step-by-Step Guidance)#Figure 15). Close timeseries data plot.
   
6. Click OK to finish.

Another option for setting the open boundary is the Harmonic Boundary Series (Harmonic Boundary Series)

Figure 13. Assigning tidal boundary conditions.

Figure 14. Preparing the tidal boundary series.

4.3 Assigning Time Series to the Boundary Location Cells.

When all required boundary time series are prepared the next step is to assign those boundary time series to the model cells. Figure 14 shows the location of inflow and tidal level for the TraKhuc case.

In order to assign the flow boundary, the following steps should be taken

1. Click to the ViewPlan icon  on the main form (See Build a 3D Coastal Model (Level 2 Step-by-Step Guidance)#Figure 16).
2. Choose Boundary C’s in the Viewing Opt’s .
3. Check Enable Edit and Show Grid (See Build a 3D Coastal Model (Level 2 Step-by-Step Guidance)#Figure 17).
4. RMC on the inflow location cell/ choose New (See Build a 3D Coastal Model (Level 2 Step-by-Step Guidance)#Figure 18).
5. Enter the boundary group ID: River (See Build a 3D Coastal Model (Level 2 Step-by-Step Guidance)#Figure 18).
6. Select boundary types. It is dependent on your current boundary type to choose the suitable boundary type. In this case, we have a flow boundary so we choose number 1 (See Build a 3D Coastal Model (Level 2 Step-by-Step Guidance)#Figure 18).
7. Select the associated times series for this inflow boundary, "Flow" (See Build a 3D Coastal Model (Level 2 Step-by-Step Guidance)#Figure 19).
8. Click OK to complete.
9. The boundary cells might have multiple cells to present the real river width. In order to assign the multiple cells, click Add by Polyline button in the form of Build a 3D Coastal Model (Level 2 Step-by-Step Guidance)#Figure 19, you need to browse to the "US_BC Line.p2d" in the Data folder as shown in Build a 3D Coastal Model (Level 2 Step-by-Step Guidance)#Figure 20 then click Apply button.
10. Click All button to assign river flows to all cells ( See Build a 3D Coastal Model (Level 2 Step-by-Step Guidance)#Figure 21)
11. The inflow is now divided to the number of assigned cells. (See Build a 3D Coastal Model (Level 2 Step-by-Step Guidance)#Figure 22).

Figure 16. Locations of inflow and open tidal boundaries.

Figure 17. Assigning boundary condition cells.

Figure 18. Create new boundary condition with RMC on the inflow cell.

Figure 19. Assign the corresponding time series.

Figure 20. Assigning boundary cells by a polyline.

4.3.2 Assigning Tides Boundary

In order to assign the tides boundary, the following steps should be taken:

1. Click to the ViewPlan icon  on the main form (See Build a 3D Coastal Model (Level 2 Step-by-Step Guidance)#Figure 16).
2. Choose Boundary C’s in the Viewing Opt’s .
3. Enable editing the grid by checking Enable Edit  (See Build a 3D Coastal Model (Level 2 Step-by-Step Guidance)#Figure 17)
4. RMC on the tidal location cell and select New (See Build a 3D Coastal Model (Level 2 Step-by-Step Guidance)#Figure 23)
5. Enter the Boundary Group ID,  "Ocean" (See Build a 3D Coastal Model (Level 2 Step-by-Step Guidance)#Figure 23)
6. Select the appropriate boundary type. In this case, the river flows to the east, so choose "4" for the "Open BC:East"  as shown in Build a 3D Coastal Model (Level 2 Step-by-Step Guidance)#Figure 23.

Figure 23. Set the tidal boundary.

7. Select the water level time series that created earlier, "Tides" as shown in Build a 3D Coastal Model (Level 2 Step-by-Step Guidance)#Figure 24.

Figure 24. Assign tides boundary.

9. The open boundary often contains a lot of cells so it is not convenient to use the feature of Add to Adjacent cells that was used when we assigned the inflow boundary. In order to select multiple cells, we can to draw a line across all the cells as open boundaries. Then, click to Add by Polygon button (Build a 3D Coastal Model (Level 2 Step-by-Step Guidance)#Figure 24).

10. Browse to "Open_BC Line.p2d" in Data folder then click Apply and then OK button. (See Build a 3D Coastal Model (Level 2 Step-by-Step Guidance)#Figure 25).

11. Click Set All button in Build a 3D Coastal Model (Level 2 Step-by-Step Guidance)#Figure 24 to assign tides to all cells.

12. The tides is now assigned to all open BC cells. (See Build a 3D Coastal Model (Level 2 Step-by-Step Guidance)#Figure 26).

Figure 25. Selecting multiple BC cells by polyline/polygon.

Figure 26. Tidal BC cells assigned.

5  Hydrodynamics Settings

In order to optimize simulation time, the EFDC model can be set so that dry cells are ignored with Wetting and Drying frame. In this case we should set this condition as following:

1. Select Hydrodynamics/ Wetting & Drying box
2. Set Flag is equal to -99.
3. Entering the Wet/Dry Depth. Remember that the wet depth should always greater than the dry depth. (Build a 3D Coastal Model (Level 2 Step-by-Step Guidance)#Figure 27)

Figure 27. Hydrodynamic Model Setup.

4. Click Modify button in Turbulence Options to set turbulence diffusion ( See Build a 3D Coastal Model (Level 2 Step-by-Step Guidance)#Figure 28)

6 Setting Vertical Layers

The hydrodynamic model is ready for running test now. Normally a model is run for one vertical layer for initial calibration and more vertical layers are added later. To increase the number of vertical layers:

1. Open the Domain/ Grid tab and enter the number of vertical layers into the box as in this case the vertical layers are equal to 5 layers. (Build a 3D Coastal Model (Level 2 Step-by-Step Guidance)#Figure 29).
2. Save the model project.

Figure 29. Setting the Vertical Layers.

7 Model Timing

We have now almost completed the hydrodynamic model. The final step is to set the model simulation time and model time steps.

1. Select Timing/ Linkage and Model Run Timing (Build a 3D Coastal Model (Level 2 Step-by-Step Guidance)#Figure 27)
2. Enter duration of starting/ ending the simulation. Note that the boundaries time series should be always covered this simulation duration period. Otherwise the model will not run.

Figure 30. Setting the model run time.

3. Select the EFDC_Explorer Linkage tab to set the frequency of the output of the EFDC results. Setting this to 60 minutes means that EFDC will save the output every 15 minutes for display of the model results in the EE. (Build a 3D Coastal Model (Level 2 Step-by-Step Guidance)#Figure 31). Note that, smaller output frequency will create a larger output file.

Figure 31. Setting Linkage Output Frequency.

8  Running EFDC+

1. Select the Setting icon on the main form to browse to the EFDC+ executable file. (Build a 3D Coastal Model (Level 2 Step-by-Step Guidance)#Figure 32).

Figure 32. Browse to the EFDC executable file.

2. Select the Run EFDC icon to on the main form and click the Run EFDC+ button to run the model (Build a 3D Coastal Model (Level 2 Step-by-Step Guidance)#Figure 33).

Figure 33. Run EFDC settings.

If you have correctly followed this example the model will start running and you will see the MS-DOS Window appear to shown the model results as see in Build a 3D Coastal Model (Level 2 Step-by-Step Guidance)#Figure 34. Note that you can hit any characters on the keyboard to pause the simulation and check the model results. If you want to exit the simulation hit the same key, if you want to continue run then hit any other key.

Figure 34. Running EFDC Window.