Cross-section

This is a transverse view of part of a pipe or channel system that shows the shape of the conduit. This can be prismatic, with a fixed shape such as a trapezoid, or irregular, with a complex shape and/or sections with different slopes. With cross-sections, the convention is to view the channel looking in the downstream direction, with left and right banks and overbank areas seen this way.

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Regular cross-sections are defined by key dimensions such as diameter, depth or base width. Irregular sections are defined by a series of X-Y coordinates. The origin of the X or horizontal transverse coordinate is a station defined on the left side of the channel. A standard datum such as Australian Height Datum (AHD) is used as the basis for the vertical Y coordinates.

In DRAINS the X-Y values must be given in strict order. This allows the program to model overhangs and, using the roof option, closed conduits with unusual shapes such as ovoid or egg-shaped pipes.

Cross-sections can be considered to occur at points along a longitudinal section.  In this sideways view, pipes, pits and channels bed can be shown, along with energy and hydraulic grade lines.

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