The IL is the elevation of the bottom of a pipe, channel, or other structure, and it is usually measured in relation to the GL, which is the elevation of the ground surface at a specific location. In MiTS 2 software, when changes are made to the GL value and users reanalyze the design, the value of IL will not change instead the depth of the drainage will change.
For example, observe the value of GL, Outgoing IL and Depth shown in both Image 1 (before changing the GL value) and Image 2 (after changing the GL value). We can see that the value of Outgoing IL is constant before and after changing the GL. In contrast, the depth shows different values after changing the GL. Thus, when there are changes or adjustments made to the GL, the IL should be rechecked by users.
Image 1 – Before changing the GL value
Image 2 – After changing the GL value
Changing the IL manually might consume a lot of time especially when there are a lot of nodes involved. Hence, to simplify the process of IL adjustment, users can utilise the adjustment feature provided under the Spread Input tab. This feature allows users to adjust the IL individually or by batch. Follow steps below to adjust the IL value.
- Ensure that “Drain” and “Spread Input” button is active
- Go to spread input tab > Select the drain involved > Click on the adjustment button
(Note: Users can select multiple nodes at once by clicking on the node interested while pressing “ctrl” button on keyboard or Press “ctrl” + “A” on keyboard to select all)
- A “Rules to Update Invert Level Dialog” will pop up. For the “Update Rules”, users have the option either “Adjust from current IL” or “Adjust from GL” shown after clicking on the dropdown button.
- Users can choose “Adjust from GL” and the new IL will be deduced based on the current GL value. Input the desired value for “Set IL higher (or lower) than GL by” and press OK.
(Note: A positive value indicates higher than GL value and negative value indicates lower than GL value)