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Displaying and Calculating Catchment Areas

Product Documentation
Intermediate
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Use the Catchment Area command to analyze water runoff and display the surface drainage area. The data obtained from running this command helps you perform H&H (hydrology and hydraulics) tasks, such as designing detention ponds, storm sewers, and other tasks aimed at the prevention of soil erosion.

The command defines the surface region with a depression low point (catchment point), delineates the region with a boundary, and calculates the area of the catchment region.

NoteUse the Create Catchment From Surface or Create Catchment From Object command to create catchment objects which can be exported to Autodesk Storm and Sanitary Analysis for review.

You can use a water drop path utility, to determine an accurate placement of catchment regions and catchment points.

Note

The Catchment Area command performs the analysis only on the selected surface region and does not account for overflow situations occurring in the neighboring surface regions.

Tutorial Exercise: Analyzing Surface Water Runoff

To display a catchment region and calculate its area

  1. Locate an area of interest in the drawing.
  2. Optionally, perform the following steps:
    1. Click Analyze tabGround Data panelCatchments Catchment AreaAt the Command prompt, enter CreateSurfaceWaterDrop.

      This command creates a polyline that represents the water drop path from a point on the selected region to the depression point in this region.

    2. Select the water drop path polyline, right-click, and choose Properties.
    3. In the Properties manager, under Geometry, navigate to the last vertex and copy and paste the X- and Y-coordinate values (comma-separated with no space) into a text file.
  3. Click Analyze tabGround Data panelCatchments Catchment AreaAt the Command prompt, enter CatchmentArea.
  4. In the Catchment Area dialog box, click the Value column for the Catchment Layer property and click to select an existing layer, or create a layer in the Create Layer dialog box.
    Best Practice

    It is useful to place the catchment region on a separate layer. Then you can control visual style elements, such as color and line types.

  5. Click the Value column for the Catchment Object Type, and select a line type.
    Tip

    If you select 2D Polyline, you can use the AutoCAD Area command on the catchment region. If you select 3D Polyline, you can use the elevation values of the polyline vertices for analysis.

  6. Click the Value column for the Catchment Marker property, and specify whether you want to mark the catchment point.
  7. Click in the Value column of the Catchment Marker Style property, and then select a style in the Catchment Marker Style dialog box. Click OK.
  8. If more than one surface is available in the drawing, click the surface on which to perform the catchment region analysis, or press Enter to select a surface in the Select A Surface dialog box.
  9. Specify a catchment location. You can either paste the coordinates that you copied in Step 2 or click in the desired location.

    The catchment region boundary appears on the drawing, and the value of the region area displays at the command line.

  10. Repeat Step 11 for other coordinates or locations.

Ribbon

Analyze tab Ground Data panel Catchments Catchment Area

Command Line

CatchmentArea

Dialog Box

Catchment Area


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