Modelling turbidity

Step-by-step Guide

InfoWorks WS Pro can model concentrations of dissolved substances travelling through a network. This includes turbidity—cloudiness due to silt or other particulates—caused by a burst pipe or similar incident. You can model turbidity with different scenarios that include mitigation or no mitigation to see how they compare. In this example, you will simulate a turbidity incident and then a hydrant flush to see how it impacts turbidity.

Start by creating a new scenario:

1. Open the BridgeNet network.
2. In the Scenarios toolbar, click Create scenario.
3. In the Create New Scenario dialog box, enter the name “Ex3 – Base”. This will be the scenario with no mitigation involved.
4. Click OK.

Next, pick a node in a location with a hydrant nearby downstream, so that a simulated hydrant flush will have a measurable impact on turbidity.

5. In this example, in the GeoPlan, double-click node ST28366403, with the idea that the pipe immediately upstream has burst.

6. In the Properties window, expand Water Quality Turbidity Profile.
7. In the Water Quality Turbidity cell, click the More button (…).

8. In the Node window, Under Date Time, expand the drop-down and set the date to February 5, 2022 in the proper date format for your region.
9. Leave the time set to 00:00:00.
10. Leave the Turbidity set to 0.
11. In the second row, set the same date.
12. Adjust the time to 13:00:00.
13. Set the Turbidity to 500.
14. In the third row, set the same date.
15. Adjust the time to 15:00:00.
16. Leave the Turbidity set to 0.
17. Click OK.

To create the second scenario:

18. In the toolbar, click the Manage scenarios button.
19. In the Scenario notification, click Network.
20. In the Manage Network Scenarios dialog box, click Create.
21. In the Create New Scenario dialog box, New Scenario Name field, type Ex3 – Mitigation.
22. Enable Copy an existing scenario.
23. In the Scenario to copy drop-down, ensure that Ex3 – Base is selected.

24. Click OK.
25. In the Manage Network Scenarios dialog box, select the Ex3 – Mitigation scenario.
26. Click Select.

Ensure you are working in the Ex3 – Mitigation scenario before continuing to the next step.

27. In the GeoPlan, double-click a nearby hydrant downstream from the node where the turbidity is being modeled to open its properties.

28. In the Properties panel, expand Hydrant Flow Profile.
29. In the Hydrant Profile cell, click the More (…) button.

30. In the Hydrant Profile window, set the start date and time to February 5, 2022 at midnight, or 00:00:00.
31. Leave the Opening set to 0.
32. In the second row, set the same date.
33. Adjust the time to 14:00:00.
34. Set the Opening value to 100 to simulate that the hydrant is fully open.

Note that this is one hour after the pipe burst and introduction of turbidity at the node you selected earlier.

35. In the third row, set the same date.
36. Adjust the time to 15:30:00.
37. Set the Opening value to 0 to simulate that the hydrant is closed.
38. Click OK.

To set a maximum flow value, limiting the simulated flow rate of water coming out of the hydrant and avoid interfering with other customers in the area:

39. In the Properties window, in the Maximum Flow field, enter a value of 15.0.

40. Commit all changes to the server before continuing.

Now, create a new run:

41. In the Model Group window, right click Run Group and select New > Run.
42. In the Schedule Hydraulic Run dialog box, in the Title field, enter the name “Ex3 Turbidity”.
43. From the Model Group window, drag the BridgeNet network into the Schedule Hydraulic Run dialog box and drop it into the Network group box.

The Control and Demand Diagram populate automatically.

44. Enable Experimental.
45. Under Run Parameters, leave the Start date and time set to May 2, 2022 at 00:00:00.
46. Set the End date and time to May 3, 2022 at 00:00:00.
47. Set the computational accuracy to 0.01 l/s.

The computational accuracy is generally increased for water quality simulations to provide more accurate and stable results. This increase also helps to provide results in parts of the network with low flows.

48. In the Run Type group box, expand the drop-down and select Water Quality.

Notice that because you are simulating turbidity, rather than a chemical or pollutant, you do not bring any Solute Data into the Water Quality Options dialog box.

49. In the Turbidity group box, enable Do Turbidity Analysis.
50. Click OK.
51. In the Schedule Hydraulic Run dialog box, Scenarios tab, ensure that only the Ex3 – Base and Ex3 – Mitigation scenarios are enabled.
52. Click Run.

53. When the run is complete, from the Model Group window, drag-and-drop the Ex3 - Base results into the GeoPlan.

Next, create a new contour theme:

54. Right-click an empty part of the GeoPlan and select Properties & Themes.
55. In the GeoPlan Properties and Themes dialog box, Contours row, Theme column, click Edit.

56. In the Contours: Base Theme dialog box, in the toolbar, click Add New.
57. In the Name field, enter the name “Turbidity”.
58. Expand the Field drop-down and select sim.turbidity as the source result for the theme.
59. Adjust the Value count to an appropriate number—in this example, it is set to 8.
60. Optional: Customize fill colors.
61. Click OK.

62. In the GeoPlan Properties and Themes dialog box, Display column, deselect Customer Point and Polygons for a less cluttered visual layout.

63. Click Apply.
64. Click OK.

The turbidity incident being simulated is resolved quickly within the 24-hour timeline. Instead of clicking the Play button to watch the entire simulation, limit the scale of the timeline:

65. In the Replay toolbar, click Jump to/replay options.
66. In the Replay Options dialog box, adjust the slider to set the Time to 12:00:00.
67. Click Set Start Time.
68. Click OK.

69. In the GeoPlan, click at different points on the timeline bar until you see the color representing turbidity at the node you selected. In this example, turbidity is shown as orange.

You can now graph various nodes within the area of turbidity to see how it changes over time.

70. Click and drag the Ex3 – Mitigation results to the GeoPlan to see how they differ from the Ex3 – Base results.
71. Click through the timeline until you see the color representing turbidity appear.

Notice it dissipates faster than the Ex3 – Base results due to the hydrant opening at 2 o’clock.