Procedure for using the Contributing Area Utility of DRAINMOD

 

For the following example, two areas contributes surface runoff to a third field.  This can useful in agricultural yield analysis, wetland analysis, or similar situation where adjacent area(s) contribute surface or subsurface waters.  DRAINMOD simulations are performed for each of the contributing area and their water losses are included as an input to the receiving area.

A schematic of the example scenario is shown below.

 

 

 

 

 

1. Review the Quick Start Tutorial entitled Running a Simulation.

 

2. Open the wcwf1 project file

 

3. The Project Window will open and Project Settings in the Navigation Tree will be selected.  In the Ouput Options section, check the  "Hourly Surface Runoff / Water Loss" box.

 

 

 

4.  You will then choose the "Surface Runoff" or the "Water Loss" button

(Remember that "Surface Runoff" is for creating a file with surface runoff only and "Water Loss" is for creating a file with both surface runoff and subsurface drainage added together)

 

 

5. Click Simulate.  When the simulation completes, a SRO file entitled wcwf1.SRO will be generated in the DRAINMOD/Outputs folder.

 

6. Open the wcwf2 project and perform steps 2 - 5.  This will generate the wcwf2.SRO file.

 

7. Click the Utilities Menu Button and choose Contributing Area Runoff.

 

 

 

8. In the File Name box, enter wf1f2 and click Open.

 

 

 

9. When prompted to Create the File, click Yes.

 

 

 

10. When the Contributing area run window opens, click ADD.

 

 

 

11. When the Open Surface Runoff File window open, click the wcwf1.SRO file and then click Open. If you do not see the wcwf1.SRO file, navigate to your DRAINMOD/Outputs folder.

 

 

 

12. Back in the Contributing area run window, click on the wcwf1.SRO file in the Surface Runoff File (*.SRO) list box.  This will allow you to edit the values below.  Enter 1 for Time of Concentration, 2.7 for Contributing Area, and 1.67 for IUH Adjustment Factor.

 

 

13. Repeat steps 10 - 12 for the wcwf2.SRO file.  Enter 1 for Time of Concentration, 4.8 for Contributing Area, and 1.67 for IUH Adjustment Factor.

 

14. Click Create.

 

15. A message box will pop up letting you know that the wf1f2.OVR file has been generated. Click OK.  The wf1f2.OVR file contains the combined hourly runoff or waterloss from both the wcwf1 and wcwf2 project outputs.  The OVR format is similar to a rainfall file.

 

 

 

 

16. Open the wcwf3 project. You will get a Missing File error message letting you know that the OVR file has not been specified under the Manage Input Files > Hydrology section.

 

 

Click Close. This error was purposely left in to illustrate how to to add / change the OVR file for a project.

 

17 . In the Navigation Tree, click on Manage Input Files > Hydrology.  Make sure that the Runoff File (*.OVR) box is checked under the Contributin Runoff File section.  Click Browse to navigate to the OVR file created in Step 14.

 

 

18. Select the wf1f2.OVR file located in the DRAINMOD/Inputs folder and click Open.

 

19. You will taken back to the Manage Input Files > Hydrology section.  Enter 3 in the Field Ratio box.  The field ratio was deternied as follows.

 

wcw1 field area = 2.7 ha

 

wcw2 field area = 4.8 ha

 

wcw3 field area = 2.5 ha

 

Contributing Runoff File Field Ratio = ( 2.7 + 4.8 ) / 2.5 = 3

 

 

20. In the Project Setting screen, in the Surface Water section make sure the Contributing Area Runoff option is checked.

 

 

 

21. Click Simulate

 

 

 

22. Click 'OK' once the simulation is complete.