The Urban Storage Node
  • 26 Aug 2022
  • 3 Minutes to read
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The Urban Storage Node

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Article Summary

Storage nodes are used to represent storage units within your urban system.

External Urban Inflow can also enter the system at a Storage node.


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Rules of Junction nodes

A Junction node may have multiple inflow Conduit Links connected. Multiple outflow links from a Junction node are also allowed if using Dynamic Wave routing. If using Steady-State or Kinematic Wave routing, only a single outflow link is possible from a Junction node; an Urban Divider Node may be suitable if two outflow links are required.

Storage label/name

The Junction node name by default will be provided by parameters setup in the Urban Model Defaults menu.

Junction node parameters


The x and y coordinates of the Junction node are shown in these fields. These values are automatically populated based on the node location on the map.


This field allows for an optional text description. The field will be blank by default.


This field allows for an optional text tag, to allow you to categorise units. The field will be blank by default.


Inflows can be specified for a Junction node. These can be external direct, dry weather or RDII inflows. If inflows are not defined, the Junction node will only receive inflow from any Urban Subcatchment Nodes with the Junction node label selected as the subcatchment outlet.


Addition of pollutants is not currently available within the software. If your model already contains defined pollutants, these will be unaffected, however you will not be able to access the pollutant editor form.

Invert elevation

The invert elevation of the Junction is provided in this field. By default this value will be provided by parameter setup in the Urban Model Defaults menu.

Maximum depth

The maximum depth of the Junction, from ground surface to invert, is provided in this field. If zero, then the distance from the invert to the top of the highest connecting link will be used. By default this value will be provided by parameter setup in the Urban Model Defaults menu.

Initial depth

This field contains the initial water depth in the Junction at the start of the simulation. By default this value will be 0.

Surcharge depth

This field specified the additional depth of water beyond the maximum depth that is allowed before the Junction floods. This parameter can be used to simulate bolted manhole covers. By default this value will be 0.

Evaporation Factor

Fraction of evaporation occurred. Default value is 0 (no evaporation); full evaporation occurs if this value is set to 1.

Seepage Loss

This field is set to NO by default. Clicking in the field provides access to 3 dots to the right, which then provide access to the Storage Seepage Editor window. Here a user can specify soil properties that determine seepage loss through the bottom and sloped sides of the Storage unit.

Setting a Storage node curve

It is necessary to specify a Storage Curve to describe the Storage unit shape (i.e. how the surface area varies with water depth). This can either be in FUNCTIONAL or TABULAR form.

A FUNCTIONAL curve is of the form:

Area = A (Depth)B + C

Where the coefficient A, exponent B and constant C are then provided in the Coefficient, Exponent and Constant fields below.

A TABULAR curve is specified manually. Double-click in the Cruve Name field to open the Curve Editor and define a new curve.

Top Tips to Define Curve

If no curve is defined and the field is shown blank (or with a *), we recommend double-clicking the field to open the Curve Editor and entering a name for your curve, alongside the data required. It is also possible to name your curve in the field initially before double-clicking on this name, however the name then must be provided a second time in the Curve Editor window.

If you have previously defined a curve (and so a curve name is provided in the field), you can double-click the name to edit the details.

If you would like to define a new curve whilst retaining the previous curve, click in the field and use the Backspace key to delete the name so the field is blank. Then double-click to enter the Curve Editor, and enter your curve details (with a new name!) When you return to the Divider node properties, you will now notice your previous curve and new curve are both available from the drop-down.

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