---
title: "Hydraulic Units Modelling Components | Technical Reference"
slug: "hydraulic-units-modelling-components"
description: "Find the technical reference for hydraulic units icons and modelling components."
tags: ["1D river modelling"]
updated: 2022-10-21T14:55:11Z
published: 2022-10-21T14:55:11Z
canonical: "help.floodmodeller.com/hydraulic-units-modelling-components"
stale: true
---

> ## Documentation Index
> Fetch the complete documentation index at: https://help.floodmodeller.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Hydraulic Units Modelling Components

Flood Modeller model networks are built up from a series of individual 'building blocks' known as hydraulic units. Each unit represents a particular hydraulic attribute of the modelled network, e.g. a river section, a junction or a weir.

The icon associated to each unit is used in the following places within the Flood Modeller 1D Interface:

- Buttons on the 1D Build toolbar - the Flood Modeller interface contains multiple banks of toolbar buttons. The majority of these are used to add new hydraulic units to a model. Each of these buttons display the icon that corresponds to the unit type that will be added
- Network Panel - each unit added to a model will appear with the associated icon displayed adjacent to the given node name.
- Map View - when a model is visualised the network is defined by the linking of appropriate hydraulic unit icons.

The following section lists the available units that can be utilised when constructing a model, together with a brief definition and links to more detailed descriptions.

## Hydraulic Unit Icons

| Icon | Pop up | Function |
| --- | --- | --- |
| ![FloodModeller_FlowTimeBoundary16](https://cdn.document360.io/5074bc26-a9ef-4bf4-b1de-a5c6ce628aca/Images/Documentation/FloodModeller_FlowTimeBoundary16.png) | Flow Time Boundary | Inserts a [Flow Time Boundary](/v1/docs/flow-time-boundry) Unit. |
| ![FloodModeller_FlowHeadBoundary16](https://cdn.document360.io/5074bc26-a9ef-4bf4-b1de-a5c6ce628aca/Images/Documentation/FloodModeller_FlowHeadBoundary16.png) | Flow Head Boundary | Inserts a [Flow Head Boundary](/v1/docs/flow-head-boundary) Unit. |
| ![FloodModeller_HeadTimeBoundary16](https://cdn.document360.io/5074bc26-a9ef-4bf4-b1de-a5c6ce628aca/Images/Documentation/FloodModeller_HeadTimeBoundary16.png) | Head Time Boundary | Inserts a [Head Time Boundary](/v1/docs/stage-time-boundary) Unit. |
| ![FloodModeller_NormalCriticalDepthBoundary16](https://cdn.document360.io/5074bc26-a9ef-4bf4-b1de-a5c6ce628aca/Images/Documentation/FloodModeller_NormalCriticalDepthBoundary16.png) | Normal / Critical Depth Boundary | [NCDBDY unit](/v1/docs/normal-critical-depth-boundary) generates a downstream flow-head relationship based on section data |
| ![FloodModeller_USSCSHydrograph16](https://cdn.document360.io/5074bc26-a9ef-4bf4-b1de-a5c6ce628aca/Images/Documentation/FloodModeller_USSCSHydrograph16.png) | US SCS Hydrograph | Inserts a [US Soil Conservation Service Boundary Hydrograph](/v1/docs/us-scs-method) Unit. |
| ![FloodModeller_FSSR16Boundary16](https://cdn.document360.io/5074bc26-a9ef-4bf4-b1de-a5c6ce628aca/Images/Documentation/FloodModeller_FSSR16Boundary16.png) | FSSR16 Boundary | Inserts a [Flood Studies Supplementary Report 16 Boundary Hydrograph](/v1/docs/fssr16-method) Unit. |
| ![FloodModeller_FEHBoundary16](https://cdn.document360.io/5074bc26-a9ef-4bf4-b1de-a5c6ce628aca/Images/Documentation/FloodModeller_FEHBoundary16.png) | FEH Boundary | Inserts a [Flood Estimation Handbook Boundary Hydrograph](/v1/docs/feh-method-feh-rainfall-runoff-method) Unit. |
| ![FloodModeller_RainfallEvaporationBoundary16](https://cdn.document360.io/5074bc26-a9ef-4bf4-b1de-a5c6ce628aca/Images/Documentation/FloodModeller_RainfallEvaporationBoundary16.png) | Rainfall / Evaporation Boundary | [REBDY](/v1/docs/rainfall-evaporation-boundary) unit provides a rainfall and/or evaporation boundary inflow into a model network |
| ![FloodModeller_FRQSIMBoundary16](https://cdn.document360.io/5074bc26-a9ef-4bf4-b1de-a5c6ce628aca/Images/Documentation/FloodModeller_FRQSIMBoundary16.png) | FRQSIM Boundary | [FRQSIM](/v1/docs/frqsim-method) unit provides a bespoke, fully distributed rainfall-runoff method to generate an inflow hydrograph for a catchment or sub-catchment |
| ![FloodModeller_ReFHBoundary16](https://cdn.document360.io/5074bc26-a9ef-4bf4-b1de-a5c6ce628aca/Images/Documentation/FloodModeller_ReFHBoundary16.png) | ReFH Boundary | [ReFHBDY unit](/v1/docs/refh-method-refh-rainfall-runoff-method) is an alternative method (to FEH) to derive an inflow hydrograph for a catchment or sub-catchment. |
| ![FloodModeller_Abstract16](https://cdn.document360.io/5074bc26-a9ef-4bf4-b1de-a5c6ce628aca/Images/Documentation/FloodModeller_Abstract16.png) | Abstract | Inserts an [Abstraction](/v1/docs/abstration) Unit. |
| ![FloodModeller_QRating16](https://cdn.document360.io/5074bc26-a9ef-4bf4-b1de-a5c6ce628aca/Images/Documentation/FloodModeller_QRating16.png) | Q Rating | Inserts a [Rating Curve](/v1/docs/rating-curve) Unit. |
| ![FloodModeller_IrrigationDemand16](https://cdn.document360.io/5074bc26-a9ef-4bf4-b1de-a5c6ce628aca/Images/Documentation/FloodModeller_IrrigationDemand16.png) | Irrigation Demand | Enables specification of abstraction rules to define an irrigation system |
| ![FloodModeller_Gauge16](https://cdn.document360.io/5074bc26-a9ef-4bf4-b1de-a5c6ce628aca/Images/Documentation/FloodModeller_Gauge16.png) | Gauge | [Gauge units](/v1/docs/gauge-updating-unit) can be applied to real-time forecasting applications where there is a need to improve existing models in real time by an updating process |
| ![FloodModeller_Bend16](https://cdn.document360.io/5074bc26-a9ef-4bf4-b1de-a5c6ce628aca/Images/Documentation/FloodModeller_Bend16.png) | Bend | Inserts a [Culvert Bend](/v1/docs/culvert-bend) Unit. |
| ![FloodModeller_CulvertOutlet16](https://cdn.document360.io/5074bc26-a9ef-4bf4-b1de-a5c6ce628aca/Images/Documentation/FloodModeller_CulvertOutlet16.png) | Culvert Outlet | Inserts a [Culvert Outlet](/v1/docs/culvert-outlet) Unit. |
| ![FloodModeller_CulvertInlet16](https://cdn.document360.io/5074bc26-a9ef-4bf4-b1de-a5c6ce628aca/Images/Documentation/FloodModeller_CulvertInlet16.png) | Culvert Inlet | Inserts a [Culvert Inlet](/v1/docs/culvert-inlet) Unit. |
| ![FloodModeller_TidalBoundary16](https://cdn.document360.io/5074bc26-a9ef-4bf4-b1de-a5c6ce628aca/Images/Documentation/FloodModeller_TidalBoundary16.png) | Tidal Boundary | Inserts a [Tidal Harmonics Boundary](/v1/docs/tidal-harmonics-boundary) Unit. |
| ![FloodModeller_NotionalWeir16](https://cdn.document360.io/5074bc26-a9ef-4bf4-b1de-a5c6ce628aca/Images/Documentation/FloodModeller_NotionalWeir16.png) | Notional Weir | Inserts a [Notional Weir](/v1/docs/notional-weir) Unit. |
| ![FloodModeller_Pump16](https://cdn.document360.io/5074bc26-a9ef-4bf4-b1de-a5c6ce628aca/Images/Documentation/FloodModeller_Pump16.png) | Pump | Inserts a [Open Channel Pump](/v1/docs/pump) Unit. |
| ![FloodModeller_RoundNosedBroadCrestedWeir16](https://cdn.document360.io/5074bc26-a9ef-4bf4-b1de-a5c6ce628aca/Images/Documentation/FloodModeller_RoundNosedBroadCrestedWeir16.png) | Round Nosed Broad Crested Weir | Inserts a [Round Nosed Broad Crested Weir](/v1/docs/round-nosed-broad-crested-weir) Unit. |
| ![FloodModeller_GeneralPurposeWeir16](https://cdn.document360.io/5074bc26-a9ef-4bf4-b1de-a5c6ce628aca/Images/Documentation/FloodModeller_GeneralPurposeWeir16.png) | General Purpose Weir | Inserts a [General Purpose Weir](/v1/docs/weir) Unit. |
| ![FloodModeller_SharpCrestedWeir16](https://cdn.document360.io/5074bc26-a9ef-4bf4-b1de-a5c6ce628aca/Images/Documentation/FloodModeller_SharpCrestedWeir16.png) | Sharp Crested Weir | Inserts a [Sharp Crested Weir](/v1/docs/sharp-crested-weir) Unit. |
| ![FloodModeller_GatedWeir16](https://cdn.document360.io/5074bc26-a9ef-4bf4-b1de-a5c6ce628aca/Images/Documentation/FloodModeller_GatedWeir16.png) | Gated Weir | Inserts a [Gated Wei](/v1/docs/gated-weir)r Unit. |
| ![FloodModeller_VerticalSluice16](https://cdn.document360.io/5074bc26-a9ef-4bf4-b1de-a5c6ce628aca/Images/Documentation/FloodModeller_VerticalSluice16.png) | Vertical Sluice | Inserts a [Vertical Sluice Gate](/v1/docs/sluices) Unit. |
| ![FloodModeller_RadialSluice16](https://cdn.document360.io/5074bc26-a9ef-4bf4-b1de-a5c6ce628aca/Images/Documentation/FloodModeller_RadialSluice16.png) | Radial Sluice | Inserts a [Radial Sluice Gate](/v1/docs/sluices) Unit. |
| ![FloodModeller_BridgeUSBPR197816](https://cdn.document360.io/5074bc26-a9ef-4bf4-b1de-a5c6ce628aca/Images/Documentation/FloodModeller_BridgeUSBPR197816.png) | Bridge (USBPR 1978) | Inserts a [USBPR Bridge](/v1/docs/us-bpr-bridge) Unit. |
| ![FloodModeller_BridgeArch16](https://cdn.document360.io/5074bc26-a9ef-4bf4-b1de-a5c6ce628aca/Images/Documentation/FloodModeller_BridgeArch16.png) | Bridge (Arch) | Inserts an [Arch Bridge](/v1/docs/arch-bridge) Unit. |
| ![FloodModeller_BridgePierLoss16](https://cdn.document360.io/5074bc26-a9ef-4bf4-b1de-a5c6ce628aca/Images/Documentation/FloodModeller_BridgePierLoss16.png) | Bridge (Pier-Loss) | Inserts a [Pier Loss Bridge](/v1/docs/pier-loss-bridge) Unit. |
| ![FloodModeller_Orifice16](https://cdn.document360.io/5074bc26-a9ef-4bf4-b1de-a5c6ce628aca/Images/Documentation/FloodModeller_Orifice16.png) | Orifice | Inserts an [Orifice](/v1/docs/orifice) Unit. |
| ![FloodModeller_InvertedSyphon16](https://cdn.document360.io/5074bc26-a9ef-4bf4-b1de-a5c6ce628aca/Images/Documentation/FloodModeller_InvertedSyphon16.png) | Inverted Syphon | Inserts an Inverted Syphon Unit (same as [Orifice](/v1/docs/orifice) Unit). |
| ![FloodModeller_Outfall16](https://cdn.document360.io/5074bc26-a9ef-4bf4-b1de-a5c6ce628aca/Images/Documentation/FloodModeller_Outfall16.png) | Outfall | Inserts an Outfall Unit (same as [Orifice](/v1/docs/orifice) Unit). |
| ![FloodModeller_FloodReliefArch16](https://cdn.document360.io/5074bc26-a9ef-4bf4-b1de-a5c6ce628aca/Images/Documentation/FloodModeller_FloodReliefArch16.png) | Flood Relief Arch | Inserts a Flood Relief Arch Unit (same as [Orifice](/v1/docs/orifice) Unit). |
| ![FloodModeller_BernoulliLoss16](https://cdn.document360.io/5074bc26-a9ef-4bf4-b1de-a5c6ce628aca/Images/Documentation/FloodModeller_BernoulliLoss16.png) | Bernoulli Loss | Inserts a [Bernoulli Loss](/v1/docs/bernoulli-losses) Unit. |
| ![FloodModeller_GeneralHeadLoss16](https://cdn.document360.io/5074bc26-a9ef-4bf4-b1de-a5c6ce628aca/Images/Documentation/FloodModeller_GeneralHeadLoss16.png) | General Head Loss | Inserts a [General Head Loss](/v1/docs/general-headloss) Unit. |
| ![FloodModeller_Blockage16](https://cdn.document360.io/5074bc26-a9ef-4bf4-b1de-a5c6ce628aca/Images/Documentation/FloodModeller_Blockage16.png) | Blockage | Represents a [channel blockage](/v1/docs/blockage-unit) using the proportion of the flow area obstructed. |
| ![FloodModeller_FlowHeadControl16](https://cdn.document360.io/5074bc26-a9ef-4bf4-b1de-a5c6ce628aca/Images/Documentation/FloodModeller_FlowHeadControl16.png) | Flow Head Control | Inserts a [Flow Head Control](/v1/docs/flow-head-control) Unit. |
| ![FloodModeller_CrumpWeir16](https://cdn.document360.io/5074bc26-a9ef-4bf4-b1de-a5c6ce628aca/Images/Documentation/FloodModeller_CrumpWeir16.png) | Crump Weir | Inserts a [Crump Weir](/v1/docs/crump-weir) Unit. |
| ![FloodModeller_FlatVWeir16](https://cdn.document360.io/5074bc26-a9ef-4bf4-b1de-a5c6ce628aca/Images/Documentation/FloodModeller_FlatVWeir16.png) | Flat-V Weir | Inserts a [Flat V weir](/v1/docs/flat-v-weir). This is a long-based weir with a triangular longitudinal profile and a transverse symmetrical V-shaped crest having small side-slopes (common in UK). |
| ![FloodModeller_SyphonSpillway16](https://cdn.document360.io/5074bc26-a9ef-4bf4-b1de-a5c6ce628aca/Images/Documentation/FloodModeller_SyphonSpillway16.png) | Syphon Spillway | Inserts a [Syphon Spillway](/v1/docs/siphon-spillway) Unit. |
| ![FloodModeller_RiverSection16](https://cdn.document360.io/5074bc26-a9ef-4bf4-b1de-a5c6ce628aca/Images/Documentation/FloodModeller_RiverSection16.png) | River Section | Inserts a [River Section](/v1/docs/river-section-overview) Unit. |
| ![FloodModeller_CESSection16](https://cdn.document360.io/5074bc26-a9ef-4bf4-b1de-a5c6ce628aca/Images/Documentation/FloodModeller_CESSection16.png) | CES Section | [CES Section](/v1/docs/ces-section) uses the Depth-Integrated Reynolds-Averaged Navier-Stokes Method to calculate conveyance for a River Section. |
| ![FloodModeller_Interpolate16](https://cdn.document360.io/5074bc26-a9ef-4bf4-b1de-a5c6ce628aca/Images/Documentation/FloodModeller_Interpolate16.png) | Interpolate | Inserts an [Interpolate](/v1/docs/interpolate) Unit. |
| ![FloodModeller_Replicate16](https://cdn.document360.io/5074bc26-a9ef-4bf4-b1de-a5c6ce628aca/Images/Documentation/FloodModeller_Replicate16.png) | Replicate | Inserts a [Replicate](/v1/docs/replicated-section) Unit. |
| ![FloodModeller_SymmetricalConduit16](https://cdn.document360.io/5074bc26-a9ef-4bf4-b1de-a5c6ce628aca/Images/Documentation/FloodModeller_SymmetricalConduit16.png) | Symmetrical Conduit | Inserts a [Symmetrical Conduit](/v1/docs/symmetrical-conduit) Unit. |
| ![FloodModeller_AsymmetricalConduit16](https://cdn.document360.io/5074bc26-a9ef-4bf4-b1de-a5c6ce628aca/Images/Documentation/FloodModeller_AsymmetricalConduit16.png) | Asymmetrical Conduit | Inserts an [Asymmetrical Conduit](/v1/docs/asymmetrical-conduit) Unit. |
| ![FloodModeller_FullArchConduit16](https://cdn.document360.io/5074bc26-a9ef-4bf4-b1de-a5c6ce628aca/Images/Documentation/FloodModeller_FullArchConduit16.png) | Full Arch Conduit | Inserts a [Full Arch Conduit](/v1/docs/full-arch-conduit) Unit. |
| ![FloodModeller_SprungArchConduit16](https://cdn.document360.io/5074bc26-a9ef-4bf4-b1de-a5c6ce628aca/Images/Documentation/FloodModeller_SprungArchConduit16.png) | Sprung Arch Conduit | Inserts a [Sprung Arch Conduit](/v1/docs/sprung-arch-conduit) Unit. |
| ![FloodModeller_RectangularConduit16](https://cdn.document360.io/5074bc26-a9ef-4bf4-b1de-a5c6ce628aca/Images/Documentation/FloodModeller_RectangularConduit16.png) | Rectangular Conduit | Inserts a [Rectangular Conduit](/v1/docs/rectangular-conduit) Unit.. |
| ![FloodModeller_CircularConduit16](https://cdn.document360.io/5074bc26-a9ef-4bf4-b1de-a5c6ce628aca/Images/Documentation/FloodModeller_CircularConduit16.png) | Circular Conduit | Inserts a [Circular Conduit](/v1/docs/circular-conduit) Unit. |
| ![FloodModeller_RiverMuskingham16](https://cdn.document360.io/5074bc26-a9ef-4bf4-b1de-a5c6ce628aca/Images/Documentation/FloodModeller_RiverMuskingham16.png) | River Muskingum | Inserts a [Muskingum](/v1/docs/muskingum-routing) Unit. |
| ![FloodModeller_RiverMuskinghamXSec16](https://cdn.document360.io/5074bc26-a9ef-4bf4-b1de-a5c6ce628aca/Images/Documentation/FloodModeller_RiverMuskinghamXSec16.png) | River Muskingum-XSEC | Inserts a [Variable Parameter Muskingum Cunge Cross Section](/v1/docs/vpmc-cross-section) Unit. |
| ![FloodModeller_RiverMuskinghamVPMC16](https://cdn.document360.io/5074bc26-a9ef-4bf4-b1de-a5c6ce628aca/Images/Documentation/FloodModeller_RiverMuskinghamVPMC16.png) | River Muskingum-VPMC | Inserts a [Variable Parameter Muskingum Cunge Routing](/v1/docs/vpmc-routing) Unit. |
| ![FloodModeller_RiverMuskinghamRSec16](https://cdn.document360.io/5074bc26-a9ef-4bf4-b1de-a5c6ce628aca/Images/Documentation/FloodModeller_RiverMuskinghamRSec16.png) | River Muskingum-RSEC | Inserts a [Variable Parameter Muskingum Cunge Routing Section](/v1/docs/vpmc-routing-section) Unit. |
| ![FloodModeller_JunctionOpen16](https://cdn.document360.io/5074bc26-a9ef-4bf4-b1de-a5c6ce628aca/Images/Documentation/FloodModeller_JunctionOpen16.png) | Junction | Inserts a [Junction](/v1/docs/junction) Unit. |
| ![FloodModeller_JunctionEnergy16](https://cdn.document360.io/5074bc26-a9ef-4bf4-b1de-a5c6ce628aca/Images/Documentation/FloodModeller_JunctionEnergy16.png) | Energy Junction | Whereas the Open Junction unit equalises water levels at the junction, the [Total Energy Junction](/v1/docs/total-energy-junction) equalises the total energy head at all nodes |
| ![FloodModeller_Manhole16](https://cdn.document360.io/5074bc26-a9ef-4bf4-b1de-a5c6ce628aca/Images/Documentation/FloodModeller_Manhole16.png) | Manhole | Simulates discharge through a [manhole](/v1/docs/manhole-unit) from a surcharged culvert |
| ![FloodModeller_Comment16](https://cdn.document360.io/5074bc26-a9ef-4bf4-b1de-a5c6ce628aca/Images/Documentation/FloodModeller_Comment16.png) | Comment | Inserts a [Comment](/v1/docs/comment) Unit. |
| ![FloodModeller_WindShear16](https://cdn.document360.io/5074bc26-a9ef-4bf4-b1de-a5c6ce628aca/Images/Documentation/FloodModeller_WindShear16.png) | Wind Shear | Models the effects of [wind shear](/v1/docs/wind-shear) on open-channel sections, which may be of particular significance in wide rivers and estuaries. |
| ![FloodModeller_SpillUnit16](https://cdn.document360.io/5074bc26-a9ef-4bf4-b1de-a5c6ce628aca/Images/Documentation/FloodModeller_SpillUnit16.png) | Spill Unit | Inserts a [Spill](/v1/docs/spill) Unit. |
| ![FloodModeller_FloodPlainSection16](https://cdn.document360.io/5074bc26-a9ef-4bf4-b1de-a5c6ce628aca/Images/Documentation/FloodModeller_FloodPlainSection16.png) | Flood Plain Section | Inserts a [Floodplain Section](/v1/docs/floodplain-section) Unit. |
| ![FloodModeller_Reservoir16](https://cdn.document360.io/5074bc26-a9ef-4bf4-b1de-a5c6ce628aca/Images/Documentation/FloodModeller_Reservoir16.png) | Reservoir | Inserts a [Reservoir](/v1/docs/reservoir) Unit. |
| ![FloodModeller_Pond16](https://cdn.document360.io/5074bc26-a9ef-4bf4-b1de-a5c6ce628aca/Images/Documentation/FloodModeller_Pond16.png) | Pond | Inserts a [Pond](/v1/docs/pond) Unit. |
| ![FloodModeller_LateralInflow16](https://cdn.document360.io/5074bc26-a9ef-4bf4-b1de-a5c6ce628aca/Images/Documentation/FloodModeller_LateralInflow16.png) | Lateral Inflow | Lateral Inflow unit distributes total inflow from a boundary between across multiple river reaches or reservoirs. Inputs can be divided according to reach length, surface area or user specified proportions. |