1  Introduction

This tutorial will guide the user on how to set up a 2D lake hydrodynamic model and run a solution for EFDC. It will cover the preparation of the necessary input files for the EFDC model and the visualization of the output by using the EFDC+ Explorer (EE) Software.

The data used for this tutorial are from Hillsborough Water Atlas, Lake Thonotasassa, Florida, USA. All files for this tutorial are contained in the Demonstration Models of the Resources page folder file (DM-14_Lake_T_HYD-WQ_Model). Note that the model grid will contain more than 300 grid cells and use the dye module; therefore, a Demo version of EE, which only allows running models with less than 300 horizontal cells and without the dye, salinity, and particle tracking modules, will not be applicable. The user, however, can load and view the model without being able to edit, save edits, run, and view model output with this version.

Before beginning the first session, let's introduce the main form of the EE GUI to help you better understand our explanations in this document. Figure 1 is the main form of EFDC+ Explorer or EE User Interface.

Figure 1. EFDC+ Explorer main form.

2  Create a New Grid

This session will guide you to create a new simple grid with EFDC+ Explorer.

Lake Thonotosassa is located in Hillsborough County, Florida, USA, and has been chosen as an example of where to build a 2D model in EE

The gird generation process includes the following steps:

1. Open EE

2. Click New Model icon:  on the main menu of the EE interface. The Cartesian Grid Generator frame appears in Figure 2

3. In Grid Options, select Uniform Grid.

4. Click Set button to select projection as UTM Zone 17 in the northern hemisphere, as the lake is located in that zone (Figure 2.1)

Figure 2. Generate EFDC Model form.

4. RMC (Right Mouse Click) on the Bounding Polygons blank to open a pop-up menu. In the pop-up menu, select Add Files to browse the polygon file. The land boundary of the lake will be loaded here.

Figure 2.1. Set projection.

Figure 3. Add polygon file.

5. With the polygon file loaded, the X-Y Directions for the corners of the models are automatically defined. The user can also adjust the Cell Size and Number of Cells in Uniform Grid Options.

In this example, enter cell size is 100x100m for the Cell Size (m) then click the calculator symbol for the Number of Cells.

Figure 4. Loaded polygon file.

6. If the user adjust any options in Uniform Grid Options they must click the Generate button so that EE can generate the changes.

7. Click on Remove Dry, this will remove all cells outside of the polygon.

8. Click OK button to finish grid generation. An overview of the created grid is shown in the General tab (Figure 5).

9. Save the model by selecting the Save button and create a new directory.

3.2 Assigning the Depth/Water Surface Elevations

This step assigns the initial depth or water surface elevations. There are two options for setting the surface water elevation, namely, use Constant and use Scatter (XYZ) data.

1. RMC on Water Depth/Elevation button then click Assign Elevation button (Figure 10)

Figure 10. Assigning water depth/surface elevation.

2. Select Constant to assign a constant water surface elevation of 11.5 m in the Constant box. (Figure 11).

Figure 11. Assigning water surface elevation (use constant option).

3. After selecting this option for assigning water surface elevation, click Apply Defined Conditions button, then click the OK button to finish.

4  Boundary Conditions

This section will teach you how to prepare and assign the boundary conditions to the model cell configuration. In this Lake 2D case, there are two flow boundaries; one is runoff inflow to the lake, and the other is outflow through a gate. Thus, we should prepare two-time series of inflow and outflow boundaries. In other cases, the number of time series for boundary conditions might be much more, such as those for hydraulic structures, pressure boundaries, or include time series for temperature, salinity, and water quality boundaries.

4.1 Set Time Series

To set the boundary time series, take the following steps:

1. Select the External Forcing Data tab. (Figure 12)

2. RMC on Flow button and select Add New Data Series to edit the flow boundary. (Figure 13)

Figure 12. Create flow time series.

3. Enter the Number of Series into the box. There are two flow boundaries as mentioned so it should be “2”.

4. Give a Series Name for associated time series. In this case, title “Inflow” for Series 1, and “Outflow” for Series 2. (remember to press Enter after each input)

5. To import Inflow time-series data, click on the Import data from file button  on the Toolbar.

In the ASCII Data Import form as shown in Figure 4-2.

(1) Browse to the “Inflow.dat” file and select the data format as EE Dat or WQ Data.

(2) Modify the Import Settings parameters as Figure 4-2 shows.

• Header Rows to Skip: 0

• Data Base Date: 1/1/2012

• Import from Data Column: 2

• Conversion Factor: 1

(3) Click OK to import the data series; the Import Data form will appear to select import options.

(4) Click OK in the Import Data window to close the form and finish importing data (Figure 13).

(5) Save the model

Figure 13. Import flow time series.

Figure 14. Data series: Inflow.

6. Click to the View Time series plot icon to view the current time series.

Figure 15. Time series plot of inflow.

7. Select the up/down arrow buttons to edit the other time series.

8. Repeat Step 5 to import “Outflow.dat" to the model (Figure 16). The time series plot of outflow is shown in Figure 17.

Figure 16. Data series: outflow.

Figure 17. Time series plot of outflow.

9. Click OK to finish editing the boundary time series.

After completing the above steps, the user has prepared all the required boundary time series. Now, we will assign these boundary time series to the model cells. Figure 18 shows the location of inflow and outflow for this lake case. Thus, we have to assign these cells with associated time series for in/outflow prepared in the previous session.

Figure 18. Locations of inflow and outflow for the lake.

4.2 Assigning a Boundary Condition

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

1. Click the 2DH View icon  on the main form of EE (Figure 1).

2. Choose Boundaries in the Viewing Layer Control .

3. Enable Edit grid by turning on the icon  (see Figure 19)

4. RMC on the inflow location cell and select Add New Boundary Group (Figure 20)

Figure 19. Enable to edit Boundaries layer.

Figure 20. RMC on the inflow cell to add a boundary condition.

5. Enter the Boundary Group Name by typing “Inflow” and select boundary types (Figure 21). Then click OK button, the Flow Boundary Conditions form appears in the Forcing Assignment frame, select "Inflow" for Flow Table (Figure 22), then click OK button.

Figure 21. Enter Boundary Group Name and select Boundary Group Type.

Figure 22. Assign the corresponding time series.

6. Apply the same process for assigning the outflow boundary cell. Figure 23 presents the boundary conditions after assigning the inflow and outflow boundaries.

Figure 23. Inflow and Outflow boundaries assigned.

5  Model Timing

After completing the previous sections, the user has almost completed the hydrodynamic model of a lake. This section will guide the user on how to set up the model simulation time and model time steps.

1. Select Timing/ Linkage tab and RMC on Timing button

2. Enter the duration of start/ end of the simulation. Note that the boundaries time series should always cover this simulation duration period. Otherwise, the model will not run.

3. Enter the Time of Start, Number of Reference Periods, Duration of Reference Periods and Time Step as Figure 24. These values are explained in the Table 1.

Figure 24. Model run time.

4. RMC on Linkage button and set Link EFDC Results to EFDC+ Explorer and set Linkage Output Frequency to 60 minutes. EFDC will record the output every 60 minutes to display the model results in the EE. (Figure 25). Note that a smaller output frequency will create a larger output file.

Figure 25. Setting linkage output frequency.

6  Hydrodynamic Model Setup

This section will guide the user on how to set the hydrodynamic model for the EFDC model’s application of the wet and dry conditions to optimize the simulation time. For this condition, we should make the following settings:

1. Select Modules tab then LMC on plus sign of Hydrodynamics to expand all sub-tabs. RMC on each sub-tab to adjust settings.

2. Select Shallow Water then RMC, the form of Shallow Water Options appears

3. Enter values for the Dry Depth and the Wet Depth. Then click OK button. Note that the wet depth should always be greater than the dry depth. (Figure 26).

Figure 26. Hydrodynamic model setup.

4. Return to select Model Grid tab, RMC on Grid sub-tab and enter the number of vertical layers required into the box. In this case, we will set the vertical layers equal to 5 (Figure 27). Click OK button.

5. Save the model.

Figure 27. Setting the vertical layers

7  Running EFDC+

This section runs the EFDC model and includes the following steps:

1. Click the Run EFDC icon on the main form

Figure 28. Run EFDC+.

2. Select the Browse iconnext to the Executable text box to browse to the EFDC executable file (Figure 29) as default, the EFDC+ executable file is located in the EEMS installation folder (e.g. C:\Program Files\DSI\EEMS10.3)

3. To save time when running the model, the user can increase the number of OMP threads.

3. Click the Run EFDC+ button to run the model (Figure 29).

Figure 29. Browse to the EFDC+ executable file.

If all settings are correct, the model will start running, and you will see the MS-DOS Window appear showing the model results as shown in Figure 30.

Figure 30. EFDC+ run window.

8  Visualizing the EFDC Model Output

This session will teach you how to view the model simulation results. Once the model simulation is completed, click the Refresh Output button in the toolbar to load the model outputs. These three icons  on EE’s main form (Figure 1) are used to view the model simulation results in 2DH View, 2DV View or 3D View, respectively.

1. Select the 2DH View icon

2. In View Layer Control, select Add a New EFDC View Layer (Figure 31). The user should see View Options window with Primary Group and Parameter to display.

3. Figure 32 is an example of showing the vector and magnitude velocity field results. Similarly, the user can select other parameters to show the model results.

4. Right mouse-click on the Velocity vector layer to modify the vector arrow sample or change the vector color and scale factor (See Figure 32)

Figure 31. View Layer Control and View Options.

Figure 32. Visualizing the EFDC model output.