Using Catchment Area In Civil 3d 2009

In the world of land development, it is often helpful to to accurately measure the area of drainage basins for both pre-development and post-development conditions. This will allow the designer to size storm drainage inlets and pipes and to create a detention pond. AutoCAD Civil 3D offers a simple tool to accomplish this.

The command is found under the Surfaces > Utilities pulldown menu.

Once the command is launched, a dialog box will appear so that the user can apply specific settings.

Catchment Layer is used to set the layer for the basin outline the program is about to draw. It is often helpful to set up beforehand two different layers for these outlines, one for pre-development conditions and another for post-development conditions.

Catchment Object Type specifies what kind of entity is going to be used. The choices are 2D Polylines which are all drawn at elevation zero and 3D Polylines which have elevations set at each vertex from the surface used to draw the object.

Catchment Marker simply specifies whether or not a marker is used at the downstream (or catchment) point and Catchment Marker Style dictates what style is applied to the marker. A Marker Style can be set up to show a dot or an "X" or virtually anything the designer wishes.

Once these settings are adjusted and OK is hit, the user may now select any location on a surface and the catchment area is drawn.

If desired, default settings for Layer, object type and Marker can be adjusted for the user who does not want to have to set them every time the utility is employed within a specific drawing. Simply go the the Settings tab > Surfaces collection > Commands then find Catchment Area. Right-click then choose Edit Command Settings. The following dialog box will appear where the default values can be set. Remember that these can be adjusted in a drawing template so that all new drawings can be pre-set with these adjustments.