Urban Junction and Outfall Nodes
  • 03 Aug 2022
  • 2 Minutes to read
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Urban Junction and Outfall Nodes

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A common feature of urban systems are manholes and connections between pipes. These are represented by adding Junction nodes to your urban network.

You may have multiple inflow pipes (represented by Urban Conduit Links ) connected to a Junction node. Multiple outflow pipes from a Junction node are also allowed if using the most theoretically-accurate version of the solver (Dynamic Wave routing). If using Steady or Kinematic Wave routing, only a single outflow pipe is allowed.

Another way for water to leave the urban network is via Outfall nodes. These are terminal downstream nodes for urban networks and at least one Outfall node is necessary for Dynamic Wave routing. Only a single inflow pipe can be connected to an Outfall node, and no outflow pipes are allowed.

External Urban Inflow can also enter the system at Junction and Outfall nodes, we will discuss this at a later point in this guide. Excess water at a Junction node can either be lost from the urban system, or be allowed to pond and subsequently drain back into the system.

Flood Modeller provides all the functionality required to easily Add a Junction/Outfall node, Move a Junction/Outfall node and to Delete urban Junction and Outfall nodes. Multiple options to View node properties enable you to edit parameters when Working with junction nodes and Working with outfall nodes.

In additional to editing urban Junction and Outfall nodes individually, the urban Multi Edit & View tool is designed to easily Visualise urban networks and Edit multiple components of urban networks.

If using one of the simplified versions of the urban solver (Steady or Kinematic Wave routing), Flow-Divider nodes can be used to specify divisions in flow. These must be connected to exactly two outflow pipes. These are explained further in the Urban Structures and Features section.

Storage units within the urban system can also be represented. This is done using Storage nodes. These are also explained further in the Urban Structures and Features section.

More on 1D urban modelling

Flow between nodes is defined by Urban Conduit Links. These provide details of the pipes themselves, such as the geometry, dimensions and roughness.

Your network may also consist of other Urban Structures and Features. This may include units for storage, pumps to allow water to be lifted to higher elevations, or devices used to regulate flows within the system, such as weirs.

Urban Inflow will also be required to specify water entering the network. This can be defined directly, or a combination of Rain Gage and Subcatchment nodes can be utilised.

To set up Urban Simulations, details of timing and run-type must be provided alongside other simulation options. Climatology inputs can also be specified. Urban simulations can be run individually, or in batches.

If you encounter issues with urban modelling, exploring the Urban Diagnostics will help identify problems and resolve warnings and errors.

Multiple options are provided for viewing Urban Results, including plots with animation functionality to show water level changing over time. Each chart can be fully formatted to customise as needed, alongside providing various methods for exporting the data for post-processing or use in reports.

You may also be interested in linking your 1D urban network to a 1D river network or to 2D components. Details of this can be found in the Integrated Modelling section of this manual.


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