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The Delete Bottom Elevation tool is used to clear the bottom elevation of the nodes within a defined area or in the gridline.

To view the bottom elevation of grid nodes, select the grid layer in the Layer Control, then RMC to display options, and select Show Labels / Bottom Elevation as shown in Figure 1. The bottom elevation values of nodes is then displayed. The following steps describe how to remove the bottom elevation of selected grid nodes.

  • Select the grid layer in the Layer Control by LMC on that grid layer
  • Set the mouse in the selection mode, hold the Shift key and LMC on two grid nodes either on the same grid line segment or different gridline segments. The grid block will be highlighted.  Next, release Shift, then RMC to show options, and select the Delete Bottom Elevation, as shown in Figure 2. As a result, the bottom elevation of nodes will be removed.
    • To update the view of the bottom elevation of grid nodes after using the Delete Bottom Elevation, select show labels for bottom elevation as mentioned in Figure 1, the grid nodes whose bottom elevation has been removed will display as NaN labels as shown in Figure 3.

    When building an EFDC model, we need a bottom elevation (or bathymetric data file) assigned to the model grid. However, we just have cross-section files in the model domain. So, how do we create a bottom elevation file for the model grid by using this cross-section?

    This page will provide steps to do this.

    As described in the ..., Grid+ allows the creation of data points from the grid cells that already have the grid's elevation. So, we have to take data point values from cross-sections and then assign them to grid cells.

    Info

    The grid used for generating the bottom elevation file does not have to be the same as your model grid. The density of points in the bottom elevation file will be based on the grid's resolution.


    1. Load the cross-sections file, and after that, generate a grid to cover the cross-section, as shown in Figure 1. To show the color ramp of the cross-section, press Alt+C, then set Min. and Max. values.
    2. Draw a polyline to cover grid cells with cross-section by selecting Add a new polyline button from the toolbar, as shown in Figure 2.
    3. Press the S key from the keyboard (selection mode), select the overlay layer in Layer Control panel, then click on the polyline, then it will be highlighted, as shown in Figure 3.
    4. Next,


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    Figure 1
    Figure 1

    Figure 1  Show bottom elevation labels of grid nodesLoad cross-sections with a generated grid.


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    Figure 2
    Figure 2

    Figure 2  Delete Bottom Elevation optionDraw polyline to select grid cells with cross-section.



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    Figure 3
    Figure 3


    Figure 3  Bottom Elevation labels of grid nodes after using the Delete Bottom Elevation Select the interpolate grid elevation option.



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    Figure 4
    Figure 4
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    Figure 4 A Modify Bottom Elevation optionShow bottom elevation of cells.


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    Figure 5
    Figure 5

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    Figure 5  Modify Selection form.

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    Figure 6  Show bottom elevation labels of a grid.

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