- 07 Nov 2023
- 16 Minutes to read

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# 1D river build tab

- Updated on 07 Nov 2023
- 16 Minutes to read

- Print

The 1D River Build Tab contains the buttons which can help you with building your 1D river networks within Flood Modeller.

Select from the categories below for further details.

Structure (weir, sluice, orifice and bridge) nodes

## Insert mode

### Map

Checking this box allows you to build your 1D river network directly on the map view.

### Table

Checking this box allows you to build your 1D river network within the 1D river network table.

### Multiple

Checking this box keeps the node type selected to allow you to easily insert multiple units of the same type.

## River

### River Section

Clicking on this button inserts a River Section unit into your model network. River Sections model the flow of water in open channels based on 1D shallow water or Saint-Venant equations.

### CES Section

Clicking on this button inserts a Conveyance Estimation System (CES) section into your model network. The CES Section offers an alternative method of calculating conveyance for a River Section, using the Depth-Integrated Reynolds-Averaged Navier-Stokes Method.

### Muskingum

Clicking on this button inserts a Muskingum Routing unit into your model network. This unit models the flow of water in open channels based on the continuity equation and the Muskingum storage relationship.

### Muskingum R

Clicking on this button inserts a VPMC Routing (MUSK-VPMC) into your model network. This unit models the flow of water in open channels using a Variable Parameter Muskingum-Cunge method to route the flow.

### Muskingum V

Clicking on this button inserts a VPMC Routing section (MUSK-RSEC) into your model network. This unit models the flow of water in open channels using a Variable Parameter Muskingum-Cunge method to route the flow. Wavespeed and attenuation parameters are derived from user-defined geometric and roughness factors, and the method is otherwise identical to the VPMC Routing node.

### Muskingum X

Clicking on this button inserts a VPMC Cross Section unit (MUSK-XSEC) into your model network. This unit uses the same method as the VPMC Routing Unit, but with the added ability to derive wavespeed and attenuation curves from cross-section details.

### Interpolate

Clicking on this button inserts an Interpolated Section into your model network. This unit calculates a weighted average of the river or conduit section properties upstream and downstream to produce a hybrid section according to its location. For example, in the case of sparse cross sectional data, interpolates can be used to ensure smooth gradations between channel properties.

### Replicate

Clicking on this button inserts a Replicated Section into your model network. This is a quick method for adding a cross-section which has exactly the same dimensions as the cross-section immediately upstream. It can be lower or higher than the upstream section.

### Full Arch Conduit

Clicking on this button inserts a Full Arch Conduit unit into your model network. This unit models a closed conduit, or culvert, where the cross section is a full arch with a horizontal invert. A minimum of two Full Arch conduits are required, one for each end of the conduit.

### Sprung Arch Conduit

Clicking on this button inserts a Sprung Arch Conduit unit into your model network. This unit models sprung arch section conduits. A minimum of two Sprung Arch conduits are required, one for each end of the conduit.

### Rectangular Conduit

Clicking on this button inserts a Rectangular Conduit unit into your model network. This unit models rectangular cross section closed conduits or culverts. The cross section is specified by the invert level, width and height of the conduit.

### Symmetrical Conduit

Clicking on this button inserts a Symmetrical Conduit unit into your model network. This unit models closed-topped symmetrical conduits or culverts of irregular section. If the conduit to be modelled is not of rectangular, circular, full arch, or sprung arch type then the Symmetrical Conduit should be used. A minimum of two Symmetrical conduits is required, one for each end of the conduit reach.

### Asymmetrical Conduit

Clicking on this button inserts an Asymmetrical Conduit unit into your model network. This unit models closed-topped conduits or culverts of irregular shape. If the conduit to be modelled is not symmetric or of rectangular, circular, full arch, or sprung arch type then the Asymmetrical Conduit should be used. Additionally, if Manning’s friction formula is to be used then the Asymmetrical Conduit should be used instead of the Symmetrical one. A minimum of two Asymmetrical conduits is required, one for each end of the conduit reach.

### Circular Conduit

Clicking on this button inserts a Circular Conduit unit into your model network. This unit models a closed conduit, or culvert, where the cross section is circular. The cross section is specified by the invert level and diameter. A minimum of two Circular Conduits are required, one for each end of the conduit.

## Boundary nodes

### Flow-Time Hydrograph

Clicking on this button inserts a Flow Time Boundary into your model network. The unit models a discharge hydrograph (specifying flow versus time) as a boundary condition. Boundary data are required to input water into a modelled region and are usually applied at the upstream end(s) of the network, at the top of tributaries for example.

### Generic Rainfall/Runoff Hydrograph

Clicking on this button inserts a generic event rainfall-runoff boundary into your model network. The unit allows complete freedom to select different model components to be integrated within one hydrological boundary unit. Boundary data are required to input water into a modelled region and are usually applied at the upstream end(s) of the network, at the top of tributaries for example.

### FEH Hydrograph

Clicking on this button inserts an FEH Rainfall Runoff Method Boundary (FEHBDY) into your model network. The unit derives an inflow hydrograph from a catchment or sub-catchment, which acts a boundary condition equivalent to a Flow-Time boundary. Boundary data are required to input water into a modelled region and are usually applied at the upstream end(s) of the network, at the top of tributaries for example.

### ReFH Hydrograph

Clicking on this button inserts a ReFH Method Boundary (ReFHBDY) into your model network. The unit derives an inflow hydrograph from a catchment or sub-catchment, which acts a boundary condition equivalent to a Flow-Time Boundary, and can therefore form inputs to a hydrodynamic or routing model.

### ReFH 2 Hydrograph

This button adds a Revitalised Flood Hydrograph Rainfall-Runoff Method (ReFH2) into your model. The unit derives an inflow hydrograph for a catchment or sub-catchment, which then becomes a boundary condition, equivalent to a Flow Time Boundary, and can therefore form inputs to a hydrodynamic or routing model. This inflow can be applied at the upstream end of a reach or may be distributed over a reach in conjunction with the Lateral Inflow unit.

### FRQSIM Hydrograph

Clicking on this button inserts a FRQSIM Boundary into your model network. The unit derives an inflow hydrograph from a catchment or subcatchment using FRQSIM, a bespoke, fully distributed rainfall-runoff method. The generated hydrograph becomes a boundary condition equivalent to a Flow-Time Boundary. Boundary data are required to input water into a modelled region and are usually applied at the upstream end(s) of the network, at the top of tributaries for example.

### FSSR Hydrograph

Clicking on this button inserts a FSSR16 Boundary (FSSR16BDY) into your model network. The unit derives an inflow hydrograph from a catchment or sub-catchment. The hydrograph then becomes a boundary condition equivalent to a Flow-Time Boundary. Boundary data are required to input water into a modelled region and are usually applied at the upstream end(s) of the network, at the top of tributaries for example.

### Head-Time

Clicking on this button inserts a Head-Time Boundary into your model network. The unit allows the input of a stage hydrograph (specifying water level versus time) as a boundary condition. This is usually applied at the downstream end(s) of the network.

### Rainfall Evaporation

Clicking on this button inserts a rainfall evaporation boundary (REBDY) into your model network. The unit provides a rainfall and/or evaporation boundary condition. This is of particular interest where direct rainfall or evaporation forms a significant proportion of the water volume entering a system.

### Abstraction

Clicking on this button inserts an Abstraction Unit into your model network. The unit models a time dependent abstraction from an open channel system. Abstractions are also used to enable modelling of channel bifurcations.

### Tidal

Clicking on this button inserts a tidal boundary into your model network. The unit is essentially just a head-time boundary which can either be generated by analyzing field data and entering it as a Head Time Boundary, or by using numerical methods based upon the Admiralty Tide Tables and the Constituent Harmonics of the tide for a given location and date.

### Flow-Time

Clicking on this button inserts a Flow-Time Boundary into your model network. The unit represents a flow against stage rating relationship, usually used as a downstream boundary condition. This boundary condition is in essence a rating curve.

### Normal Depth

Clicking on this button inserts a Normal/Critical Depth Boundary (NCDBDY) into your model network. The unit is a downstream boundary which automatically generates a flow-head relationship based on section data. The options available are to apply normal depth (from Manning's equation), or critical depth. This is a simpler alternative to the QHBDY in which the rating table is explicitly supplied.

## Structure (weir, sluice, orifice and bridge) nodes

### Broad Crested Weir

Clicking on this button inserts a Broad Crested Weir into your model network. This is a general purpose unit for modelling a broad crested weir with a rectangular throat. It is also possible to model weirs with a parabolic or triangular control section by amending the input coefficients.

### Crump Weir

Clicking on this button inserts a Crump Weir into your model network. The unit models a triangular profile weir with a 1:2 sloping front face and a 1:5 sloping back face.

### Flow-Head Control Weir

Clicking on this button inserts a Flow-Head Control unit into your model network. The unit imposes a specified flow discharge relationship at a channel control point such as a flume or weir.

### Flat-V Weir

Clicking on this button inserts a Flat-V Weir into your model network. The unit models a long-based weir with a triangular longitudinal profile and a transverse symmetrical V-shaped crest having small side-slopes.

### Gated Weir

Clicking on this button inserts a Gated Weir into your model network. The unit models flow through a gated weir where the crest elevation can vary with time.

### Labyrinth Weir

Clicking on this button inserts a Labyrinth Weir into your model network. A labyrinth weir is a structure designed to convey large flows at low heads by increasing the effective length of the weir crest with respect to the channel breadth. Although generally less efficient than other weir types of the same effective length, the available increase in weir length more than compensates for this.

### Notional Weir

Clicking on this button inserts a Notional Weir into your model network. The Notional Weir acts as a broad crested weir with a rectangular control section for free flow only. For drowned flow, the water levels are set as identical on each side of the weir.

### Sharp Crested Weir

Clicking on this button inserts a Sharp Crested Weir into your model network. The Sharp Crested Weir represents a full width sharp crested weir in free or drowned mode with forward or reverse flow. They are often used as measuring devices - particularly for measuring small flows.

### Siphon Weir

Clicking on this button inserts a Siphon weir into your model network. The unit models flow through a self-priming siphon spillway. A siphon is essentially a short discharge conduit located above the hydraulic grade line. The existence of sub-atmospheric pressure allows water to be sucked up above the upstream free surface level before it is discharged at a lower level downstream.

### General Weir

Clicking on this button inserts a General Weir into your model network. This is a general purpose unit for modelling a broad crested weir with a rectangular throat. By amending the input coefficients, it is also possible to model weirs with a parabolic or triangular control section.

### Spill

Clicking on this button inserts a Spill unit into your model network. The Spill calculates the flow over a jagged or irregular weir. It can be used to model in-line flows over irregular weirs, as well as lateral flows, such as those over embankments between two open channels or between an open channel and a flooded area.

### Orifice

Clicking on this button inserts an Orifice into your model network. This models flow through an orifice, short culvert, flood relief arch, outfall or inverted syphon using either the equations for weir control or surcharged flow depending on the upstream and downstream water levels.

### Radial Sluice

Clicking on this button inserts a Radial Sluice into your model network. The unit models a bank of radial sluice gates each of which can be in 11 operating modes depending on upstream and downstream water levels and the gate settings.

### Vertical Sluice

Clicking on this button inserts a Vertical Sluice into your model network. The unit models a bank of vertical sluice gates each of which can be in 11 operating modes depending on upstream and downstream water levels and the gate settings.

### Floodplain Section

Clicking on this button inserts a Floodplain Section into your model network. This unit calculates the flow along a floodplain. It will typically be used to connect two Reservoirs, which represent storage on the floodplain, but can also be used to model lateral flows such as those over embankments, under weirs or friction-flow conditions, and in-line flows where normal depth conditions prevail.

### Bernoulli Loss Unit

Clicking on this button inserts a Bernoulli Loss Unit into your model network. The unit uses Bernoulli’s equation to model head losses, such as those caused by changes in cross sections across open channel constrictions or expansions.

### Arch Bridge

Clicking on this button inserts an Arch Bridge into your model network. The unit computes the afflux at a single arch or multiple arched bridges using the HR Wallingford method. The area under each arch is calculated from the soffit and the springing level, assuming that the arch shape is parabolic.

### USBPR Bridge

Clicking on this button inserts a USBPR Bridge into your model network. The unit computes the afflux at bridges using the methodology developed by the US Bureau of Public Roads (US BPR) and requires that the network has a River section, ideally at the point of maximum backwater, and a River section downstream, ideally where normal water level has been achieved.

### Pier-Loss Bridge

Clicking on this button inserts a Pier-Loss Bridge into your model network. The unit computes the afflux at bridges using the formula derived by Yarnell after analyzing data from over 2000 lab and full scale experiments/tests. It requires that the network has a River section, ideally at the point of maximum backwater, and a River section downstream, ideally where normal water level has been achieved. The unit offers the option to define both faces of the bridge if they differ significantly.

## Connector nodes

### Open Junction

Clicking on this button inserts an Open Junction into your model network. The Junction unit is applied at the division of a single channel into several channels or the confluence of many channels into one. It may also be used to connect an open channel directly to a conduit if entry and exit losses are insignificant.

### Total Energy Junction

Clicking on this button inserts a Total Energy Junction into your model network. The Total Energy Junction is a unit which provides an alternative to the traditional Open Junction unit. Whereas the Open Junction unit equalises water levels at the junction, the Total Energy Junction equalises the total energy head at all nodes.

### Lateral Inflow

Clicking on this button inserts a Lateral Inflow into your model network. The unit acts as a distributor to apportion the inflow across multiple river reaches or reservoirs as opposed to applying a point inflow from a boundary to a single node. The total inflow from such a boundary can be divided according to reach length, surface area or user specified proportions (that must total 1.0).

### Reservoir

Clicking on this button inserts a Reservoir Unit into your model network. The Reservoir is used primarily for unsteady flows and relates the rate of water level rise to the net discharge. The Reservoir makes the assumption that the water levels are identical in all nodes attached to it in the same way as the Junction. In unsteady mode, it will ensure conservation of mass so that, for example, the overbank spills from a channel are accounted for and may drain back as the flood subsides.

### Manhole

Clicking on this button inserts a Manhole Unit into your model network. The unit simulates discharge through a manhole from a surcharged culvert modelled as a conduit unit. The manhole outlet can be connected to a dummy boundary unit for linking to TUFLOW, or to a reservoir to represent overland storage.

### Online Pond

Clicking on this button inserts a Pond unit into your model network. The unit is used primarily for unsteady flows and relates the rate of water level rise to the net discharge. It includes the action of one or two simple outlet structures and is intended mainly for use in flood routing models.

### Gauge

Clicking on this button inserts a Gauge unit into your model network. The unit is a method of specifying a time series of observed water level or discharge at a given node (or nodes) so that the model can self-adjust to meet these conditions; it can also be used to project error in model forecasting.

## Other nodes

### Blockage

Clicking on this button inserts a Blockage Unit into your model network. The blockage unit is intended to be simple to implement and widely applicable. It is based around a single time-varying parameter p, which represents the proportion of flow area obstructed.

### Breach

Clicking on this button inserts a Breach unit into your model network. The unit operates in conjunction with a Spill unit to model a breach in an embankment, bank or dam and must have the same labels as the corresponding Spill unit.

### Pump

Clicking on this button inserts a Pump Unit into your model network. The unit models the behaviour of a generalised open channel pump. Time dependent switching is available, along with options to control the pump using automatic controllers and the logical RULES subunit.

### General Loss

Clicking on this button inserts a General Loss Unit into your model network. The General Headloss unit models a generalised channel head loss and can operate either in upstream mode (where flow velocities are obtained from the node upstream of the headloss) or in downstream mode (where flow velocities are obtained from the downstream connected node).

### Culvert Bend

Clicking on this button inserts a Culvert Bend into your model network. The unit models losses associated to bends within a culvert. It can operate either in upstream mode (where flow velocities are obtained from the unit upstream of the culvert bend) or in downstream mode (where flow velocities are obtained from the downstream connected unit). When in upstream control the Culvert Bend must be placed immediately downstream of a channel section (for instance a River Section or Conduit type unit). Similarly, when in downstream control, the unit must be placed immediately upstream of a River Section or Conduit type unit.

### Culvert Inlet

Clicking on this button inserts a Culvert Inlet into your model network. The unit models losses at the inlet of a culvert (with an optional trash screen). The unit must be placed immediately upstream of a properly formed conduit or river reach (two or more consecutive Conduit or River Section nodes).

### Culvert Outlet

Clicking on this button inserts a Culvert Outlet into your model network. The unit models losses at the exit of a culvert. It is primarily designed to model the losses associated with the expansion in flow area that is normally found at a transition between a culvert and an open channel. It must be placed immediately downstream of a properly formed conduit or river reach (two or more consecutive Conduit or River Section nodes) Other nodes.