# Inline Banks in InfoWorks ICM

The inline bank is a flexible link which can serve a number of purposes.  It can be used as 1D irregular weir connecting between two 1D nodes or it can be used to allow a 1D-2D Linear connection in an inline sense (as opposed to a lateral sense).  For example, the 1D-2D linear connection can be used to represent flow onto a 2D representation of a bridge deck, or allow flows from a channel represented in 1D to connect to a 2D representation (or vice versa) or represent the spill of flow into a 2D storage area.  The inline bank could also potentially be used to represent a linear gully connection into the drainage network.

The inline bank is a linear feature, similar to the banklines, but allows the inline connection of between 2D and 1D based on the weir equation (shown in the help under the ‘River Reach-Bank Flows’ topic.  It is a very flexible piece of functionality both in a pipe network context and a river context as it will allow the transfer of flow between 1D and 2D, and vice versa, along a number of mesh elements.

The first step is to set up a bankline.  This can be digitised using the New Objects tool.  The bank line essentially governs the connectivity between the 1D and 2D.  The bankline needs elevations, discharge coefficients and modular limits associated with it.  If required the elevations can be gathered from any open ground model by selecting the bankline and going to Model->Sample line elevations from ground model.

Figure 1: The bankline data as sampled from the ground model.

The next step is to add an Outfall (it is important that this is an outfall node and not a 2D outfall).  This outfall can be added anywhere within the 2D zone you want to connect to and that when digitised, the inline bank link between the 1D node (break node, manhole etc…) and the outfall node will intersect the aforementioned bankline.  A ground level should be added to the outfall but it will not be used in the hydraulic calculations.

Figure 2: The Outfall Node property sheet. Note the very high ground level. For a 1D-2D Inline Bank, the outfall does not get used in the hydraulic calculations, instead the inline bankline and elevation values govern the 1D-2D connectivity.

Now draw a link between the 1D node and the outfall and set the type to Inline Bank.  Select the inline bank and the bankline and go to Model->Inline Bank->Build section data from selected bankline.  This will populate the section data part of the inline bank. The next step is to select the inline bank and go to Model->Inline Bank->Build Inline bank 2D connection.  This will populate the 2D Zone ID based on the location of the outfall node that the inline bank is connected to.

Figure 3: The Inline Bank Property Sheet. Note the 2D Zone ID is populated with the relevant name of the adjacent 2D Zone to which the inline bank is connected to.

The final step is to remesh your 2D zone which will enable the inline bank section to be added as a breakline in the 2D mesh and you’ll be left with something similar to the below where the red line is the bankline governing the control of flow between the 1D and 2D and the yellow line is the inline bank link.

Figure 4: The connected 1D-2D inline bank as picked up in the 2D mesh.

The inline bank can also be used in a 1D only sense, in which case it will act as a geo-referenced irregular weir.  This will happen if you set the Outfall to a 2D outfall type or the 2D Zone ID field is not populated with a 2D zone ID.

In the 1D-2D sense, any 2D flow which reaches the inline bank line can flow into the 1D system based on the weir equation.  Water can also flow vice versa when appropriate.  If you have no flow crossing the inline bank then either water levels are not high enough to transfer or the discharge coefficient and modular limit parameters are missing.

Figure 5: 2D flow reaching an inline bank line. If set up correctly flow should be transferred to the 1D system at the inline bank.

RTC definition can also be added to the inline bank to allow time-varying geometry to be added to the inline bank.  See the blog on Breach modelling in Infoworks ICM (http://blog.innovyze.com/2014/04/10/breach-modelling-in-infoworks-icm/) for more details.