Viewing Opt | Velocities displays the velocity vectors and magnitudes for the model. The velocities from a run are stored in the EFDC_Explorer linkage file EE_VEL.OUT file. The first option the user needs to select is the layering option. There are three ways to handle the layers; depth averaged, a specified layer or display all layers. For the All Layers option, the vectors for each cell are to correspond to the layer, blue for layer 1 and red for layer KC.

The Velocity Opts frame controls the type of velocity plot to display. These options can be combined. For example, the user can plot the 2D vectors over cells that have been colored based on vertical velocity magnitudes. The details of the formats of the color ramps and vector styles is adjusted using the Display Options form. The vertical velocity can be displayed for each layer, or depth averaged, by selecting the Vertical Velocity checkbox and the appropriate Layer Setting. When Vertical Velocity is selected all the time series extracted are also in the Z direction.

The Show Flow checkbox, when checked, causes EFDC_Explorer to report flows instead of velocities when LMC'ing on the form and when cutting a profile.

EFDC computes the velocities on the south and west faces of a cell. These are the velocities saved in the linkage file. When displaying the velocity field, EFDC_Explorer transforms the cell face velocities in IJ space to cell centered velocities in XY space. When computing fluxes, EFDC_Explorer uses the IJ space cell face velocities.

Profile Tool

EFDC_Explorer provides a quick method for displaying a velocity profile or a flow profile, if the option "Show Flows" is checked. While in the velocity view, RMC on a cell located on one side of the desired profile location. A popup menu will ask the user if they want to generate a "Profile". When clicked the message "Starting i, j = ?,?". Now select the end point with the Right Button". Press OK to continue. If the next mouse click is a RMC, EFDC_Explorer will extract the velocities or flows from the cells between the two cells selected, inclusive. Multiple profiles can be extracted, However, they will all be for the current time.

Water Flux Tool

Another method to extract flows across certain cell boundaries is provided via the Flux Tool. This method calculates the flow across one or more flux lines contained in the P2D file. Selecting the Flux Tool button display the option form shown in Figure 1.

Figure 1 Water flux tool control options.

The water flux tool computes either total discharge across the section or on a layer by layer basis, based on the options selected on the ViewPlan form. If a single snapshot is selected then the results will be displayed in a dialog box and also placed onto the clipboard. If Show Time-series is selected then the user must specify which flow component desired. The following is a description of each type:

Total Flow:The absolute value of the total flux across the section.

EW Flow:The sum of the flows in the EW (based on the cell map, i.e. EW=I component flow)

NS Flow:The sum of the flows in the NS (based on the cell map, i.e. NS=J component flow)

Dominant Flow:Computes the total flow across the section and assigns a sign based on dominance.
The Dominant Flow option is the most useful for most applications.

If the "Poly File" has more than one section/flux line defined, EFDC_Explorer will compute the fluxes for all the defined lines (up to 10 max). Figure 2 shows an example of total discharge using the dominant flow option for the San Francisco Bay application.

Figure 2 Water Flux tool example results using Dominant Flow.

 Velocity Profile

The Velocity Profile feature allows the user to pass a straight line over the model domain for the cells in which a 2-D velocity profile is to be displayed. This feature is different from the longitudinal profile that is located on the top menu on View Plan. The user may access this function with RMC within the model domain to select the Profile option as shown in Figure 3. The location where the user RMCs, that would be the starting point for the new profile. The user is then prompted to the end the line with another RMC. Multiple lines may be created and plotted together by starting a new profile where the user is asked whether to add, reset or abort the new profile. If the user selects "add", then the multiple profiles would be plotted on the same plot.

Figure 3 ViewPlan: Velocity Profile Selection.

An example of the profile is shown in Figure 4.

Figure 4 ViewPlan: Velocity Profile.

Downstream Projection for Velocities:

This feature allows the user to specify an orientation angle (degrees clockwise from north, looking downstream) in order to plot velocity magnitude of upstream and downstream flow during the EE data extraction. It is accessed by RMC when in the Velocities viewing option as shown in Figure 3.

If the user has selected All Layers in the Layer Settings then the user can optionally plot the average current velocity for the water column entirely or partly. This feature is primarily used when an exact comparison of model results with measured data is required in cases where the depth below the surface of the measuring device is known. For the settings shown in Figure 5 EE will produce the plot shown in Figure 6 for all layers. From (%) is used to indicate the percentage of the water column to be displayed from the bottom of the water column up to the To (%). For example, in a 10 m water column, from 10% to 90% means the velocity magnitude it will be plotted from 1 m above the bottom and up to 9 m from the bottom.

Figure 5 ViewPlan: Time Series – Velocity Orientation Output.

Figure 6 Velocity Projection Plot for all layers (layers 2, 4, 6, 8 hidden for clarity).

Velocity Rose

This feature allows the user to view the speed and direction distribution at a given cell over a user defined period of time. To plot the velocity rose, velocities viewing option should be selected in the ViewPlan and the user can select the location of interest with RMC. This tool is available for all layers as well as depth averaged and displays a rose as shown in Figure 7. The location of the cell being displayed is shown in the bottom left hand corner of the form. The velocity roses can be attached to the ViewPlan or can be floating as a separated window. If desired, the velocity rose can be attached to plan view by clicking on the Show rose on the ViewPlan under the Export drop down menu. The user may export the rose plot as a metafile, bitmap or ASCII file from the Export menu.

The Format menu provides options for editing the labels, setting the scale, and adjusting the sectors. The user may also save the defined rose plot format and reload it at a later time, or use it for another cell to apply the same formatting style with the Save and Load options.

Figure 7 Time Series: Rose Plots for Velocity.

Multiple velocity roses may be displayed in ViewPlan by selecting the Show on ViewPlan option and change the value to 1 as result shown in Figure 8. Selecting Export | Save will save the layout and magnitude categories as set by the user and later loaded again to maintain the format.

Figure 8 Multiple Velocity Rose Plots.