Defaults and options
    • 28 Jul 2022
    • 14 Minutes to read
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    Defaults and options

    • Dark

    Article Summary

    The 1D options window is accessed from the Home tab of the main toolbar. The window provides a range of settings that affect how you work with the currently active 1D network. Consequently the 1D options window can only be accessed when you have a 1D network (or 1D event file – which is effectively a partial network) loaded into the Project panel.

    The window displays a series of tabs that group together related settings. After making any changes to the displayed settings click the OK button to apply them in your current Flood Modeller session. These settings will then be applied with all 1D networks in all projects you then work on. The cancel button will close the 1D options window without saving any of your changes.

    Your 1D options settings are stored by Flood Modeller when you shut down the interface and so will be applied in subsequent sessions also (until you change the 1D options again).

    The content of each tab is detailed in this section.



    The settings available on the General tab are:

    Export/Clipboard delimiter

    Enables you to select the delimiter between data fields when importing and exporting data to and from data grids in the property sheets. When importing data from an Excel spreadsheet, it is advisable to select Tab as the delimiter (this is the default delimiter when copying from Excel to the clipboard). Comma can be chosen for importing from and exporting to comma separated variable (CSV) formats, and any other single delimiting character can be chosen by selecting "Other" and inserting the required character in the box below.

    Global option to force failure if specified event data file (*.ied) does not exist in any 1D simulation run

    Global option to force failure if maximum section depth + dflood is exceeded (NB this defaults to on) in any 1D simulation run

    Automatic node labelling

    This option enables you to automatically assign node labels to channel sections using a user specified prefix coupled with an ascending numerical sequence. On inserting a new channel unit, the name given to the node label will begin with the prefix and end with the next available integer in the sequence. The number may be padded out with leading zeroes if the combined length would otherwise be shorter than that specified in the "Length to generate" box.

    Non-channel units will also be assigned automatic node labels, although for connectivity considerations, it is recommended that all channel units (i.e. River sections, Conduits, Replicates, Interpolates and Muskingum units) be entered first and then non-channel units added (with the Node labels option switched back to Manual assignation).

    Example: With "Automatically assign node labels" selected, with the prefix "CH" and length “6”, entering the following units in the order as they appear in the chart will give these results:


    Thus the non-channel units (QTBDY, SLUICE and HTBDY) are not connected to the River units as they do not share the same node label as any River unit. You can either subsequently edit the node labels of the individual non-channel units to coincide with those of the relevant river units, although this leads to gaps in the numerical sequence:


    Alternatively, you can enter all the river units first thus:


    and then, with the node labelling switched back to Manually assigned, one can enter the non-river units. Under manual assignation, the Node label editor dialog is displayed on inserting a new unit, enabling the user to enter one's own node labels:


    Data directory

    The "Specify a directory" option enables you to specify a directory that the Open and Save File dialogs will initially default to when loading and saving 1D network files. Alternatively, you can choose "Use directory of last opened/saved file" in which the aforementioned dialogs follow the last used directory. This will carry forward into the next session, i.e. when Flood Modeller is shut down and restarted

    Confirm deletion of nodes

    When this option is ticked a message will always be displayed prompting you to confirm you wish to delete the selected 1D nodes. If you have a lot of nodes to remove from a network (that are to be selected individually) then it may be more efficient to untick this option (although be careful as this may lead to the accidental deletion of required nodes).



    The settings available on the Appearance tab are:

    Restore defaults

    The Restore defaults button will reset the displayed columns in the Network table to only the first label in a unit (Label 1), the Unit type and Sub Unit type.

    Note that columns can be added or removed from the Network table using the "Select columns" menu option, accessed by right-clicking on the Network table. This displays a list of available columns in a pop-up window. You can then select the required column headers from the list and drag to the header section in the Network table, or vice versa.

    Show volume under hydrograph

    This checkbox determines whether a total volume figure is displayed on flow hydrographs. The volume is displayed as a label positioned in the upper right corner of the plot. The units will be either cubic metres or cubic feet depending on the model’s units setting.

    Nodes that can display a total volume figure are:

    • Flow time series results from any node

    • Input flow time series for hydrological boundaries

    Results Plots


    The settings available on the Results Plots tab define the default appearance of time series plots of 1D model results:

    • Time units section – specify default time units for new results plots, i.e. units that will be used in the initial display. These can also be edited in chart settings, accessed from the plot right-click menu.

    • Flow units section – specify default flow units for new results plots

    • Highlight point series – if this is set to on (box ticked) then when you click on a results plot the values at the closest point to the mouse cursor will be displayed. Note that this setting can be activated from the plot right-click menu also.

    • Minimum print margin – set margin to be used if you send a results plot to a printer. Note that this can also be edited in chart settings, accessed from the plot right-click menu.



    The Units tab relates to settings specific to particular types of 1D model units (i.e. nodes). Provided settings are:

    Convert reservoirs

    In earlier versions of the Flood Modeller 1D calculation engine (known as “ISIS1D”) reservoir units were configured differently, not allowing the specification of connected lateral inflows or centroid coordinates (easting and northing).A function is provided here to upgrade the currently active network (if it was originally built using v2.1 or earlier of ISIS1D) by converting the reservoir units to the current format.

    Check for tidal boundaries with dates set in the form

    If you are re-running or editing an existing 1D network it may have been defined with discrete date/times entered for the tidal boundary data (rather than generic timings, e.g. hours from time zero). If you then also use discrete dates to define your simulation and these dates do not match your tidal boundary then the simulation will fail to run correctly. A check is therefore provided by Flood Modeller. If this option is ticked (on) then Flood Modeller will warn you if you load a network containing tidal boundaries defined with dates (note you will then still have to edit these units manually).

    Delete empty reservoir / junction units on deletion of connected spill units

    If this option is ticked then Flood Modeller will try to automatically tidy up your network when you delete spill units from a 1D network.If this action leaves reservoirs or junctions that were connected to the deleted spills, connected to nothing then they will also be deleted from the network.

    If you plan to then connect different spills to these units then you may not want this option ticked.

    Use culvert inlet wizard

    The culvert inlet wizard provides tools to set up culverts that follow CIRIA guidance and thus the wizard is aimed mainly at 1D networks for the UK. If this option is not ticked you can define your culvert inlets just by entering data manually in the associated unit parameters window (i.e. same procedure as for other node types).

    Set user defined special markers

    River sections can have various markers set against different locations across the section, e.g. panel markers to signify changes in conveyance, bank edge markers, levees, etc. There is also a column in each river cross section data table for special markers. Some of these will perform particular functions, but in addition you can add an additional two user defined markers. These will not affect hydraulic calculations, but can be used to flag particular aspects in a river section, e.g. start of a particular wildlife habitat. The default settings for these markers are “User1” and “User2”.

    Once you’ve edited these markers they will be selectable from the list accessed by clicking in the special markers column of the cross section data table (in the River section properties window).

    External Programs


    The External programs tab provides a browse button for you to specify a default text editor that Flood Modeller will utilise to display 1D model diagnostics files. The installation of Flood Modeller will set this initially to your default system text editor, e.g. Notepad. To change this click on the browse button (to the right of the current text editor entry) and select the appropriate executable file for your chosen text editor.

    Model Build


    The Model build tab provides a number of settings that affect the model building process. These are as follows:

    Intelligent insert

    This function enables you to perform the following common build functions, thus saving time and ensuring the correct model connectivity:

    • Adding a spill in parallel with a structure

    • Replicating the section to the downstream face of the structure and setting its distance to next section as zero

    • If the structure is a bridge, replicating the section data into the bridge unit

    • Adding multiple structures in parallel

    Adding structures into a model involves a number of processes; this functionality replicates these processes into one combined operation. The "intelligent insert" function will copy the adjacent section, insert the structure between the two sections, possibly adding a spill bypass around (or over) the structure and linking all the units together (ensuring the correct longitudinal chainage values are also assigned). Also, for bridge units, the river cross-section data is replicated within the bridge unit.

    When adding a new structure in a 1D model, the intelligent insert is performed automatically if this option is checked (see Model build form above).

    When a structure is added to your network a pop-up window is displayed (see below), which allows for a spill to be automatically added in parallel, and also for multiple structures (e.g. multiple-barrelled culverts, sluice complexes) to be added, ensuring the correct connectivity, e.g. junctions added upstream and downstream to link the parallel units.


    Automatic interpolation

    This function allows you to add multiple interpolate sections (or replicate sections for geometric conduits) at a user-specified minimum distance spacing. It is accessed by highlighting a reach (group of sections) in the Network table, right-clicking on the table and selecting Model Build > Auto-Interpolate

    Adding extra interpolates enables you to refine the distance spacing between cross-sections without the need for extra surveyed sections to aid stability in, for example, steep channels or low flow scenarios.

    The settings here in the Model build tab related to this functionality are:

    • Maximum spacing between successive cross-sections (Maximum Dx). Any sections with a spacing of less than this will be untouched; NB any units inserted between two existing units will be equally spaced with the largest possible distance so that the maximum distance criterion is satisfied.

    • Calculate interpolate locations on map - ticking this option Flood Modeller will calculate coordinates for all new interpolates added by positioning them equally spaced between existing river sections. If this option is not ticked then the new interpolates will appear on one side of the current map view and you will need to utilise the Move Nodes function to position them where you want them.

    These settings should always be reviewed prior to using the automatic interpolation function.

    Default values

    Sometimes you may wish to set model or run-time defaults differently from those set by Flood Modeller.

    The defaults are stored in your formsed.ini file, which is stored in the folder; “<user>\AppData\Roaming\Flood Modeller”, but selected defaults can be adjusted in the Model build tab here. These are:

    • Time units

    • Spill coefficient

    • Model surcharged bridges as orifices

    • Use total or static head in the culvert headloss calculations

    • Manhole unit calibration coefficient

    Flood Modeller will then automatically update the formsed.ini file when you apply these changes in 1D Options (i.e. click OK).

    The defaults are stored in the user’s formsed.ini file, which is now stored in the CH2M Hill/Flood Modeller folder beneath the user’s roaming Application Data folder (e.g. <user>\AppData\Roaming\Flood Modeller). The line (format: keyword=value ) must be stored immediately underneath the [ModelDefaults ] section, but otherwise anywhere within the file, e.g.


    A list of currently available changeable model defaults and description is given below:



    Flood Modeller Default

    Acceptable values


    Sets the default time units for time-dependent units, e.g. QTBDY, HTDDY, units with RULES, etc.










    Sets the default coefficient for a SPILL unit


    (floating point number)


    If set to 1, sets the “automatic switch to orifice” mode when surcharged for an ARCH or USBPR BRIDGE unit





    Sets the head calculation method based on TOTAL or STATIC head for the CULVERT INLET and OUTLET unit





    Sets the default calibration coefficient for a MANHOLE unit


    (floating point number)

    Additional details about default values

    Run-time parameters

    The user may also set default run-time parameters to override those set as defaults by Flood Modeller. This enables the user to apply their own run-time preferences.

    Again, these defaults are stored in the user’s formsed.ini file, which is now stored in the CH2M HILL/Flood Modeller folder beneath the user’s roaming Application Data folder (e.g. <user>/AppData/>AppData/Roaming/Flood Modeller. The line (format: keyword=value ) must be stored immediately underneath the [1D E vent Details ] section, but otherwise anywhere within the file, e.g.

    [1D Event Details]

    Tip: Create and save a 1D Simulation file (.ief) File with your desired run-time parameters. Close Flood Modeller (to ensure formed.ini is not overwritten later on exit). View the ief file in a text editor and copy the entire block beginning with [1D Event Details] to the formsed.ini file. Model start and end times should then be removed. Save the formsed.ini file.

    Run forms interface

    The process used by the 1D Simulation interface (ifrf) when applying defaults is as follows:

    1. Apply 1D default values.

    2. Override 1D default values with any read from the formsed.ini file.

    3. Override combined default values with those read from the 1D Simulation (*.ief) File.

    4. On save, only mandatory outputs and parameters which differ from the combined default values are saved.

    Computational Engine

    When running a simulation, the 1D computational engine applies the same stages 1-3 above. Any user-set defaults are output to the on-screen run log.

    Mandatory outputs – file names, start time and run mode (e.g. Unsteady) – are ignored by the computational engine; however, these will be read in by the 1D simulation interface. Note: If requiring to run in Adaptive timestepping mode by default, this flag must be set (AdaptiveTimestep=1) in the formsed.ini file.

    Although a valid entry, it is not recommended to store simulation end time*(Finish=…)* in formsed.ini, unless of course one is planning to run every simulation of the same length.


    The run forms interface only saves changes from the combined (Flood Modeller and user’s) defaults. Therefore, a different user’s defaults may give different behaviour using the same ief file. It is therefore imperative that any user defaults are provided when porting a model to a different user or machine.

    HEC-RAS importing

    When importing section data from HEC-RAS Flood Modeller will utilise the coordinate data in HEC-RAS to fully geo-reference the imported sections. The coordinate of each point in the cross section is not provided in a HEC model and has to be calculated, by placing the section points along the section “cut line”. Flood Modeller will check that the cumulative section length from the combination of all point to point distances matches the cut line length. There will likely be discrepancies in these calculations due to rounding errors and potential wrongly entered or modified data. Thus, you can specify an acceptable tolerance that Flood Modeller will check the calculated errors in each section against. If the tolerance is exceeded then the geo-referencing will be aborted for the selected section and thus be left only partially defined.

    Problem sections will be highlighted in red when viewed in the map to signal that they require further investigation.

    The tolerance value is in the system distance units (i.e. metres or feet) and a typical value would be <1.

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