Drainage - Flow Directions

Civil Designer 6.4, includes a function that calculates flow directions using the 8-point pour method.

This function is used to determine the route that water would flow over a grid surface from any given point (A). The end of the route is used to determine the catchment area in which A is situated. The algorithm for this is called the 8 point pour method as only 8 directions are assumed to exist for water to flow from any given point. These correspond to multiples of 45 degrees.

The flow direction calculation uses a DTM grid and so a DTM grid has to be created using the DTM Grid Volumes function before running the calculation. The grid needs to be of type Single Surface and not a Ground / Design type grid file.

If no grid has been generated the following error will appear:

Terrain Menu › Drainage › Flow Direction

The flow direction dialog is displayed

 

Water course pen	Choose the colour used for drawing the water route from the indicated point.
Water course cad output	Check if you want the route drawn as a cad polyline and choose which layer it will be drawn on.
Catchment area pen	Choose the colour used for drawing the area that will contribute to the same catchment area as the indicated point.
Catchment area cad output	Check if you want the catchment area drawn to a cad layer, and choose which layer it will be drawn to.

Press OK to accept any changes or Cancel to close the dialog losing the changes and ending the function.

The Print Manager will appear.

Click OK to continue.

The grid points are drawn in a colour denoting the flow direction from that point. The possible directions are one of the 8 main compass directions.

You are prompted: "Click to start tracking water course (Esc to quit)"

Click to start tracking the water course.
 

Irrespective of whether you chose a CAD output for the water course and/or catchment area, the water courses will get displayed. However only if you choose CAD output, will they remain there as CAD entities when you redraw the screen.

Some statistics about the calculation are printed to the Output Window.

If the Output Window is not shown, use

Window Menu › Toggle Output Window

to view it.