1D Urban Networks
    • 21 Aug 2022
    • 4 Minutes to read
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    1D Urban Networks

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    Article Summary

    A 1D simulation always requires a network to represent the 1D components. When modelling a pipe drainage system, a 1D urban network describes the system itself.

    The urban network file also contains details about the simulation associated to the network. Unlike 1D river modelling, you do not create new urban simulations independently of networks - you can run the simulation associated to the urban network, or create a new urban network for a new simulation.

    Flood Modeller provides functionality to load and save existing urban networks, or create new networks.

    To work on a loaded urban network, ensure you have Selection Mode set to 1D Urban. Viewing the network on the Map view may be easier if Labels are added.

    If adding new components to the network, you will also find it helpful to edit your Model Defaults.

    How to set the Selection Mode

    Selection Mode is displayed at all times at the bottom of the map view. When building and editing 1D urban networks, you must be in 1D Urban selection mode. Right-click anywhere on the Map view to access a menu allowing you to adjust the selection mode.


    Selection mode can also be turned on and off using the toggle provided on the 1D Urban Build tab.

    How to add labels to the map

    On the Home tab, check-boxes allow you to add labels and icons to the map view. If your urban network a geo-referenced, a basemap can also be added from here.

    The 1D Urban Build tab also provides general urban network functionality, including the check-boxes allow you to add labels and icons to the map view.

    How to edit Model Defaults

    The urban Model Defaults window is accessed from the 1D Urban Networks section of the Project panel. Click the network name to highlight it, then right-click and select Model Defaults from the menu.

    The window contains three tabs all containing default settings that will be applied as you build your urban network, and to the associated simulation. All of these can be left at their pre-set values, although you may find your urban modelling easier to adjust these to suit your project.

    The ID Labels tab specifies a prefix and incremental number to be provided as the name/label of new nodes and links added to your urban network. These labels can also be edited further within individual nodes/links once created.

    The Subcatchment tab specifies defaults to be applied to new subcatchments.

    The Area can be left at 0 and new Subcatchments will have the area automatially calculated from the shape drawn on the map. There are also several Additional Subcatchment parameters that can be specified here.

    The Infiltration Model can be selected from a drop-down. Note that if you adjust this model, a pop-up will ask if you want to apply the adjustment to any existing Subcatchments. The same infiltration model must be applied to all Subcatchments, and is specified in the Model Settings. It is recommended to select your infiltration model before adding any Subcatchments.

    The Nodes/Links tab specifies the remaining defaults to be applied to the urban network.

    Default values for Node parameters can be defined. The Link length will apply to Conduit links, alongside Pump, Orifice, Weir and Outlet links. This value can be left at 0 and new links will have the length automatially calculated from the line drawn on the map. A default geometry and roughness can also be provided as Additional link parameters.

    The Units to be used are chosen here. We recommend these are selected prior to building your urban network.

    The Offset convention can be adjusted from depth to elevation if required. Conduit links can have an offset specified at the inflow and outflow ends. This setting indicates whether these offset values are depths (distance from the invert level of the inflow/outflow node) or elevations. 

    Routing Settings are also provided here. Dynamic Wave is the most sophisticated routing method available. More on the routing methods can be found in the Urban Simulations section. In Dynamic Wave routing, the Force Main equation may apply to calculate friction losses if your Conduits become pressurised.

    Related topics:

    Technical details on the Urban Model Defaults.

    More on 1D urban modelling

    Features of the underlying system such as manholes, connections between pipes, and outfalls, are represented using Urban Junction and Outfall Nodes. These specify divides in flow, and details of water leaving the system.

    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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