Calculating the Volume of a Lake
To illustrate the capability of using the Grids | Calculate | Volume command, consider the application of calculating the volume of water within a lake. This application requires that a grid file be created which defines the lake bottom. The other surface is defined as a horizontal planar surface that defines the water surface of the lake.
To calculate the volume of a lake:
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Create the grid file for the lake. If the lake bottom is defined as the depth of the water, use negative Z values so that the lake appears as a basin rather than a hill. It is also recommended that data points be added beyond the limits of the lake shore so that the surface is above the level of the lake in those areas.
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Select the Grids | Calculate | Volume command.
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Specify the grid file for the lake in the Open Grid dialog and click Open .
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In the Grid Volume dialog, click the Grid File option in the Lower Surface group.
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In the Upper Surface group, click the Constant option. Enter the value for the lake surface into the Z = box. For example, if you are using depth in your grid file as a negative value, the Z = value for your horizontal (lake) surface should be zero.
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Click OK and the volume and area calculations are reported. The volume of the lake is reported as the Positive Volume.
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To save the information, use the File | Save As command in the Grid Volume Report window and specify a name and file extension.