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Subcatchment Data Fields (InfoWorks)

Subcatchment data can be edited on either the Subcatchment Grid Window of the Subcatchments Grid or the Subcatchment Property Sheet.

Most data can be edited on the grid, but some fields cannot be displayed in the grid format.

To view and edit all subcatchment data, use the Property Sheet.

The following describes all the data which can be used to define a subcatchment. For details of results fields, see the Subcatchment Results Data Fields (InfoWorks) topic.

Fields that are common to the majority of objects can be found in the Common Fields topic.

Subcatchment Data

Database Table Name: hw_subcatchment

Field Name

Description

Database Field

Data Type

Size

Units

Precision

Default

Error Lower Limit

Error Upper Limit

Warning Lower Limit

Warning Upper Limit

Subcatchment ID

A unique name for the subcatchment.

subcatchment_id

Text

64

0

System type

Choose the System type from the drop-down list. See System Type for more information.

Database Value

Description

Help Text

STORM

Storm Rainfall collection system

FOUL

Foul Wastewater collection system (UK terminology)
SANITARY Sanitary Wastewater collection system (US terminology)
COMBINED Combined Rainfall and wastewater collection system
OVERLAND Overland Overland floodwater collection system
OTHER Other Other system type

system_type

Text

64

0

Other

Drains to

The type of object to which this subcatchment drains. Choose an object type from the dropdown:

Option

Help Text

Node

The Node ID field is enabled, allowing you to specify to which node the subcatchment drains.

Link

The Node ID and Link Suffix fields are enabled, allowing you to specify to which link the subcatchment drains.

Subcatchment

The To subcatchment ID field is enabled, allowing you to specify another subcatchment to which this one drains.

Multiple links

The Lateral links and Lateral weights fields are enabled, allowing you to specify to which links the subcatchment drains.
2D point source The 2D point source ID field is enabled, allowing you to specify to which 2D point source the subcatchment drains.

drains_to

Text

20

0

Node ID

Displayed when Drains to is set to Node or Link.

The name of the node to which this subcatchment drains. The name can be either typed in or selected from a dropdown.

node_id

Text

64

0

Link suffix

Displayed when Drains to is set to Link.

The link suffix of a single link that the subcatchment drains to. In order for a subcatchment to drain to a single link, both the Node ID and Link suffix fields must be filled-in.

When running a simulation, the simulation engine applies runoff from the subcatchment laterally along the link identified by the Node ID and Link suffix fields.

link_suffix

Text

1

0

To Subcatchment ID

Displayed when Drains to is set to Subcatchment.

The name of another subcatchment to which this subcatchment drains. This name can be either be typed in or chosen from the dropdown.

to_subcatchment_id

Text

64

0

2D point ID

Displayed when Drains to is set to 2D point source.

The name of the 2D point source to which this subcatchment drains. The name can be either typed in or selected from a dropdown.

2d_pt_id Text 64 0

Lateral links

Displayed when Drains to is set to Multiple links.

A series of records defining all the lateral links which a subcatchment can drain.

The records are entered on the Lateral links grid which is displayed when you click .

Field Name

Description

Node ID

The node to which this lateral link drains. The name of the node can either be typed in or selected from a dropdown.

Link suffix

The link suffix to which this lateral link drains.

Weight

If the Lateral weights field is set to User, then this field is enabled and is used to specify the proportion of the total weight that is to be assigned to this lateral link. The total of all links included in the grid must add up to 1.

If the Lateral weights field is set to Length, this field is read-only and displays the calculated weight values. These values are calculated to be proportional to the length of the associated links and normalised so that the sum of all weights adds up to 1.

If no link exists in the network with an ID corresponding to the Node ID and Link suffix specified in a grid row, then the weight is zero for that row.

If a change is made to the network (after the grid values have been saved by clicking OK), and the grid editor is re-opened, the Length-based weights will be updated, if the change affects the weighting. For example, if an entry in the grid row is saved but it does not have a corresponding link (therefore Weight=0), and a corresponding link is subsequently created in the network and the grid editor is re-opened, then a non-zero weight, determined by the new link’s length, will be displayed.

The Length-based weights are also updated during the validation process. Therefore, it is not necessary to re-open the grid editor in order to update the weights before performing a simulation.

For lateral links, the flow from a subcatchment is connected laterally. However, if any link is a control, then the flow into that link will be connected at the upstream node unless that node is an outfall, in which case it will be connected at the downstream node. If the nodes at both ends of a link are outfalls, then the flow will be lost.

lateral _links

Structure

0

Lateral weights

Displayed when Drains to is set to Multiple links.

The method by which the weighting for the Lateral links is to be set can be chosen from the dropdown. Set to either User, to indicate that the user is to specify the proportion of the subcatchment drainage that is assigned to each link, or to Length (default), to indicate that weightings are to be calculated by the system.

lateral_weights

Text

10

0

Length

Limit drain to capacity

A check in the box indicates that the runoff, from a subcatchment to its Drains to object, is to be limited to a value which is specified in the Capacity limit field.

If unchecked, no limit is applied.

limit_drain_capacity Boolean 0
Capacity limit

Displayed when the Limit drain to capacity box is checked.

The maximum runoff that goes to this subcatchment's Drains to object.

Note: If the Capacity limit is set to 0 (default), no limit is applied, and all runoff goes to this subcatchment's Drains to object.

How the runoff above the limit is modelled is determined in the Exceedance flow type field.

capacity_limit Double Q 5 0 0
Exceedance flow type

Displayed when the Limit drain to capacity box is checked.

Determines how the flow above the Capacity limit is modelled. The choices are:

Lost - the exceedance flow is lost from the system.

2D mesh - the exceedance flow is included in the 2D simulation.

Note: If the Exceedance flow type is set to 2D mesh, the subcatchment must Drain to a node within a 2D mesh element. It can be any type of node except Outfall or Outfall 2D.
exceed_flow_type Text

Total area

The full area of the subcatchment, including those parts that do not drain into the system you are modelling. This item is for your information, and is not essential.

total_area

Double

CA

3

0

Contributing area

The area that drains into the system you are modelling. You must enter a value here, even if it is just zero.

contributing_area

Double

CA

3

0

x

The X co-ordinate for the centre of the subcatchment boundary region.

x

Double

XY

1

y

The Y co-ordinate for the centre of the subcatchment boundary region.

y

Double

XY

1

Slope

The average gradient at which the subcatchment drains to the node.

If the 1 link for the node the subcatchment drains to is a conduit then default ground slope = (u/s ground level - d/s ground level) / length, otherwise default is zero.

Note that for the RAFTS model, the minimum value for the average gradient that will be used in the calculation of RAFTS B is 0.002 even if a lower value is specified in this field.

catchment_slope

Double

S

3

Standard percentage runoff

Displayed when either:

  • The Runoff volume type of a runoff surface, referenced by an associated land use, is set to UKWIRPaved or UKWIRPrev.
  • The subcatchment does not reference a land use, or the land use does not reference a runoff surface.

Standard percentage runoff used to calculate runoff from pervious surfaces when using the UKWIR Model.

A value may be entered manually or populated from selected WRAP soil type or HOST soil class.

To populate from soil class, set the flag to #D select which data source to use to provide SPR values from the SPR calculation field and set a WRAP soil type or HOST soil class as appropriate.

ukwir_soil_runoff Double 2 0 1 0.1 0.6
SPR calculation

Displayed when either:

  • The Runoff volume type of a runoff surface, referenced by an associated land use, is set to UKWIRPaved or UKWIRPrev.
  • The subcatchment does not reference a land use, or the land use does not reference a runoff surface.

Source of soil class SPR values, which can be used to determine Standard percentage runoff for use with the UKWIR Model.

Database Value

Description

Help Text
WRAP WRAP Select WRAP soil class to provide SPR value
HOST_Soils HOST predominant soils Select HOST soil class to provide SPR value
HOST_FEH HOST FEH 1999 Select HOST soil class to provide SPR value
soil_class_type Text 12

WRAP soil type

Displayed when either:

  • The SPR calculation is set to WRAP.
  • The Runoff volume type of a runoff surface, referenced by an associated land use, is set to NewUK or Wallingfrd.
  • The subcatchment does not reference a land use, or the land use does not reference a runoff surface.

Choose the WRAP soil class number from the dropdown.

Essential for the Wallingford Procedure UK runoff model.

May be used to provide Standard percentage runoff values for the UKWIR Model.

soil_class

Long Integer

0

1

5

HOST soil class HOST soil class used to provide Standard percentage runoff values for the UKWIR Model. soil_class_host Long Integer 0 1 29

Maximum soil moisture capacity

Displayed when either:

  • The Runoff volume type of a runoff surface, referenced by an associated land use, is set to ReFH.
  • The subcatchment does not reference a land use, or the land use does not reference a runoff surface.

Maximum soil moisture capacity.

Calculated via the Calculate ReFH Parameters dialog when the Unit Hydrograph Definition is set to ReFH.

max_soil_moisture_capacity

Double

RD

2

0

0

Curve number

SCS Runoff Curve Number

A list of curve number values that can be used can found here.

curve_number

Double

2

0

100

Drying time

Displayed when either:

  • The Runoff volume type of a runoff surface, referenced by an associated land use, is set to CNSWMM.
  • The subcatchment does not reference a land use, or the land use does not reference a runoff surface.

Time in days for a fully saturated soil to dry completely. Typical values range from 2 to 14 days.

drying_time Double TD 2 0.001

Rainfall profile

The source of the rainfall data to be applied to the subcatchment during a simulation. The interpretation of this field depends on whether you are using a Rainfall Event or TSDB data for simulation.

Note: For model networks created using Version 8 onwards, or updated pre-version 8 ones or ones copied from another database:

The same Rainfall profile must be specified for all subcatchments that use the same RTK hydrograph.

Rainfall Event

This specifies the name of the rainfall profile applied to this subcatchment. Each profile within a Rainfall Event has a unique name. You must set a value in this field, or set the field flag to #D to use the User Defined Default.

If the field does not contain a valid rainfall profile ID, the following action is taken when you run a simulation:

  • if the Rainfall Event contains a single profile, this profile is applied in the simulation. This makes the assumption that if there is only one profile, you will want to apply it to the whole model
  • if the Rainfall Event contains more than one profile, InfoWorks ICM uses the first profile in the event. A warning is included in the simulation log file

When using a Rainfall Event containing rain-gauge boundary data, the Rainfall Profile is over-ridden and depends on which rain-gauge boundary contains the point defined by the subcatchment’s X and Y fields (if these are set) or the Drainage node (if they are not set). See Spatially Varying Rainfall.

TSDB Data (On-premisedatabases only)

This specifies the name of the TVD connector that will apply rainfall to this subcatchment.

If the field does not contain a valid TVD connector ID, the following action is taken when you run a simulation:

  • If the network contains exactly one TVD connector that has rainfall as its output, that rainfall is applied in the simulation. This makes the assumption that if there is only one such TVD connector, you will want to apply it to the whole model.
  • If the network contains more than one TVD connector that has rainfall as its output, rainfall from the TVD connector with the alphabetically-first ID is applied in the simulation. A warning is included in the simulation log file.

When using TSDB spatial rainfall data, the above rules are overridden and rainfall is allocated to each subcatchment based on its location (given by its X,Y fields or by the location of drainage node if these are not set) or on the area covered by the subcatchment (if you use the option for area-averaged rainfall )

rainfall_profile

Text

64

0

Evaporation profile

The source of the evaporation data to be applied to the subcatchment during a simulation. The interpretation of this field depends on whether you are using a Rainfall Event or TSDB data for simulation.

Rainfall Event

This specifies the name of the evaporation profile which is applied to this subcatchment during a simulation.

Each profile within a Rainfall Event has a unique name.

If no evaporation profile is specified, it is assumed that the evaporation profile is the same as the Rainfall profile.

If an evaporation profile is defined but does not match any profile IDs in the evaporation data in the event, then evaporation will be set from the first profile.

Note: If the routing model is PDM, then SIM calculates the current evaporation rate for a subcatchment regardless of the time delay of the PDM descriptor if a valid evaporation profile is specified.

ReFH routing does not support independent evaporation.

If the Rainfall has an absolute start time, then so must evaporation data.

TSDB Data(On-premisedatabases only)

This field specifies the name of the TVD connector that applies evaporation to this subcatchment.

evaporation_profile

Text

64

0

Use area-averaged rain

Applicable when using spatial rainfall from Events or TSDB on-premisedatabases only).

Check this option to calculate rainfall for the subcatchment as the area-average of the rainfall of all rainfall polygons or radar cells that overlap the subcatchment. Any areal reduction/calibration factors set for the rainfall polygons are incorporated in the calculation of the area-averaged rainfall.

A rainfall profile is created for each subcatchment which is then passed to the simulation engine.

If this option is not checked, the rainfall polygon or radar cell that contains the centroid of the subcatchment will be used to provide rainfall data for the entire subcatchment. The rainfall rate for every radar cell is sent to the simulation engine as a separate rainfall profile, and the engine checks the centroids to determine which profile to use.

See Spatially Varying Rainfall and Using Spatial Rainfall in Simulations for further details.

Note: The simulation engine can process up to 2,147,483,647 TSDB generated rainfall profiles in a single simulation. Therefore if radar images with more cells than this are imported, spatial rain zones must be used to crop them to less than 2,147,483,647 cells for any given simulation (and similarly for subcatchment-averaged rainfall, where per-subcatchment profiles also need to be taken into account).
area_average_rain Boolean 0

Dimension

This field is required by the Large Catchment runoff model and the Desbordes runoff model (representing catchment length) and the SWMM runoff model (representing catchment width). It is not used by the standard Wallingford Procedure runoff model or the SPRINT runoff model.

Calculated as the radius of a circle with area = Contributing Area.

catchment_dimension

Double

L

1

0

ReFH/ReFH2 Parameters

Displayed when either:

  • The Runoff volume type of a runoff surface, referenced by an associated land use, is set to REFH.
  • The subcatchment does not reference a land use, or the land use does not reference a runoff surface.

A series of records that define the ReFH parameters for the subcatchment. The records are entered on the Calculate ReFH/ReFH2 Parameters dialog.

Catchment descriptors can be loaded from the FEH CD-ROM or downloaded from the web. See Importing Catchment Parameters from the FEH CD or Web Service for further information.

Database Table Name: hw_sub_refh_desc

Position in Data Structure

Field Name

Help Text

Database Field

Data Type

Size

Units

Default

Error Lower Limit

Error Upper Limit

Warning Lower Limit

Warning Upper Limit

1

BFIHOST

Catchment descriptor

Baseflow index

bfihost

Double

0

1

0

2

PROPWET

Catchment descriptor

Proportion of time the catchment soil moisture deficit (SMD) was below 6mm during the period 1961-1990.

propwet

Double

0

1

0

3

DPLBAR

Catchment descriptor

Mean drainage path length

dplbar

Double

0

0

4

DPSBAR

Catchment desciptor

Mean drainage path slope

dpsbar

Double

0

0

5

URBEXT1990

Extent of urban and suburban land cover.

Value derived from Land cover data based on satellite imagery taken around 1990

urbext1990

Double

0

1

0

6

URBEXT2000

Extent of urban and suburban land cover.

Value derived from CEH LAnd Cover Map 2000

urbext2000

Double

0

1

0

7

Urban extent choice

Select URBEXT1990 or URBEXT2000

urbext_choice

Long Integer

0

1

0

8

Cmax method

Cmax calculation option:

  • Design - Cmax is calculated using catchment descriptors. Cmax Value is calculated Cmax multiplied by Cmax factor
  • User - user entered value specified in Cmax Value field is used

Cmax Value field corresponds to subcatchment Maximum Soil Moisture Capacity field.

cmax_method

Long Integer

0

1

0

9

Cmax factor

Multiplying factor applied to calculated Cmax design value

cmax_factor

Double

0

0

10

Tp method

Tp calculation option:

  • Design - Tp is calculated using catchment descriptors. Tp Value is calculated Tp multiplied by Tp factor
  • User - user entered value specified in Tp Value field is used

Tp Value field corresponds to subcatchment Time to Peak field.

tp_method

Long Integer

0

1

0

11

Tp factor

Multiplying factor applied to calculated Tp design value

tp_factor

Double

0

0

12

Up method

Up calculation option:

  • Design - standard value of 0.65 is used. Up Value is 0.65 multiplied by Up factor
  • User - user entered value specified in Up Value field is used

Up Value field corresponds to subcatchment Unit Hydrograph Peak field.

up_method

Long Integer

0

1

0

13

Up factor

Multiplying factor applied to calculated Up design value

up_factor

Double

0

0

14

Uk method

Uk calculation option:

  • Design - standard factor of 0.8 is used. Uk Value i 0.8 multiplied by Uk factor
  • User - user entered value specified in Uk Value field is used

Uk Value field corresponds to subcatchment Degree of Kink field.

uk_method

Long Integer

0

1

0

15

Uk factor

Multiplying factor applied to calculated Uk design value

uk_factor

Double

0

0

16

Bl method

Bl calculation option:

  • Design - Bl is calculated using catchment descriptors. Bl Value is calculated Bl multiplied by Bl factor
  • User - user entered value specified in Bl Value field is used

Bl Value field corresponds to subcatchment Baseflow Lag field.

bl_method

Long Integer

0

1

0

17

Bl factor

Multiplying factor applied to calculated Bl design value

bl_factor

Double

0

0

18

Br method

Br calculation option:

  • Design - Br is calculated using catchment descriptors. Br Value is calculated Br multiplied by Br factor
  • User - user entered value specified in Br Value field is used

Br Value field corresponds to subcatchment Baseflow Recharge field.

br_method

Long Integer

0

1

0

19

Br factor

Multiplying factor applied to calculated Br design value

br_factor

Double

0

0

refh_descriptors

Array

0

RTK hydrograph

The name of the RTK Hydrograph associated with the subcatchment.

Any RTK Hydrographs already defined can be selected from the dropdown. Alternatively, a new one can be added or an existing one modified using the button located to the left of the field. This displays the non-visual object menu, from which you can select the appropriate option.

For model networks created using Version 8 onwards, or updated pre-version 8 ones, or ones copied from another database:

  • As SWMM5 associates RDII (Rainfall Derived Infiltration and Inflow) with nodes, ensure that the Drains to field is set to Node.
  • Only one RTK hydrograph can be specified for any subcatchment that drains to the same node.
  • All subcatchments which use the same RTK hydrograph must also use the same Rainfall profile.

unit_hydrograph_id

Text

64

0

Snow pack

The name of the Snow Pack associated with the subcatchment.

Any Snow Pack already defined can be selected from the dropdown. Alternatively, a new one can be added or an existing one modified using the button located to the left of the field. This displays the non-visual object menu, from which you can select the appropriate option.

snow_pack_id

Text

64

0

Baseflow calculation

Displayed when either:

  • The Runoff volume type of a runoff surface, referenced by an associated land use, is set to SRM.
  • The subcatchment does not reference a land use, or the land use does not reference a runoff surface.

Baseflow calculation method.

Database Value

Description

Help Text
PDM PDM Calculate baseflow using PDM model.
None None Do not carry out baseflow calculation.
baseflow_calc Text 4 0 PDM
Soil moisture deficit

Displayed when either:

  • The Runoff volume type of a runoff surface, referenced by an associated land use, is set to SRM.
  • The subcatchment does not reference a land use, or the land use does not reference a runoff surface.

Source of soil moisture deficit values.

Database Value

Description

Help Text
PDM PDM Obtain soil moisture deficit values from output from a PDM model.
Event Event Obtain soil moisture deficit values from Soil Moisture Deficit Data profiles in the Rainfall Event Editor
soil_moist_def Text 5 0 PDM
SRM runoff coefficient

Displayed when either:

  • The Runoff volume type of a runoff surface, referenced by an associated land use, is set to SRM.
  • The subcatchment does not reference a land use, or the land use does not reference a runoff surface.

Surface runoff coefficient used in the calculation of effective rainfall.

srm_runoff_coeff Double 2 1 0
SRM linear time constant 1

Displayed when either:

  • The Runoff volume type of a runoff surface, referenced by an associated land use, is set to SRM.
  • The subcatchment does not reference a land use, or the land use does not reference a runoff surface.

Time constant of cascade of two linear reservoirs.

srm_k1 Double HOURS 2 15.0 0
SRM linear time constant 2

Displayed when either:

  • The Runoff volume type of a runoff surface, referenced by an associated land use, is set to SRM.
  • The subcatchment does not reference a land use, or the land use does not reference a runoff surface.

Time constant of cascade of two linear reservoirs.

Used when runoff volume type of runoff surfaces referenced by associated land use is set to SRM.

srm_k2 Double HOURS 2 3.0 0
SRM time delay

Displayed when either:

  • The Runoff volume type of a runoff surface, referenced by an associated land use, is set to SRM.
  • The subcatchment does not reference a land use, or the land use does not reference a runoff surface.

Delay applied to rainfall start time.

srm_tdly Double HOURS 2 0.0 0
ARMA ID

The name of the ARMA error prediction model associated with the subcatchment.

An existing ARMA ID can be selected from the dropdown. Alternatively, a new one can be added or an existing one modified using the button located to the left of the field. This displays the non-visual object menu, from which you can select the appropriate option.

arma_id Text 64 0
Output lag

The fixed amount of time to delay the outflow from a subcatchment to its Drains to destination.

output_lag Double Min 2 0 0 0
Bypass runoff

Enabled when the Drains to field is set to Subcatchment.

A check in the box indicates that the outflow from a subcatchment that drains to another subcatchment is added to the total outflow of the Drains to destination subcatchment. If unchecked, the outflow will be applied as an additional input to the runoff surfaces of the destination subcatchment.

bypass_runoff Boolean 0

Unit hydrograph definition

Displayed when the Routing model of a runoff surface, referenced by an associated land use, is set to Unit or SCS Unit.

Method of calculation for the unit hydrograph.

Option

Description

Desbordes-Tc

For use with Unit Hydrograph Routing Model

Giandotti-Tc

For use with Unit Hydrograph Routing Model

Kirpich-Tc

For use with Unit Hydrograph Routing Model

Passini-Tc

For use with Unit Hydrograph Routing Model
Rational

For use with Unit Hydrograph Routing Model

SCS-Forest-Tc

For use with Unit Hydrograph Routing Model

SCS-Rural-Tc

For use with Unit Hydrograph Routing Model
SCS-User-Tc For use with SCS Unit Hydrograph Routing Model

User-Tc

For use with Unit Hydrograph Routing Model

User-Tp-Tb

For use with Unit Hydrograph Routing Model or SCS Unit Hydrograph Routing Model

Clark

See Note below.

ReFH

See Note below.

Snyder

See Note below.

Note: The Clark, ReFH and Synder options should not be selected when using the Unit or SCS Unit routing model. A validation message is displayed when one of these options is selected. If this occurs, please select a different Unit hydrograph definition when using the Unit or SCS Unit routing model. Alternatively you can use a different routing model (including Clark, ReFH or Snyder) by selecting the relevant model in the runoff surface of the associated land use.

uh_definition

Text

14

0

User-Tp-Tb

Time of concentration method

Displayed when the Routing model of a runoff surface, referenced by an associated land use, is set to Rational.

Method for calculating Time of concentration, tc (see Unit Hydrograph Model for details).

Option

Description
User Set value for Time of concentration, tc manually
Kraven

Calculate Time of concentration, tc using the Kraven method

Unifirm (Uniform flow velocity)

Calculate Time of concentration, tc using the Uniform velocity method

PWRI

Calculate Time of concentration, tc by specifying a PWRI coefficient

tc_method Text 25 0
Overland flow time

Displayed when Time of concentration method is set to Kraven or Uniform.

Travel time of overland flow. See Unit Hydrograph Model for details.

overland_flow_time Double MIN 2 0.01
Flood wave celerity
Displayed when:
  • Time of concentration method is set to Kraven (Enabled)
  • Time of concentration method is set to Uniform. (Read-only)

Velocity of flood wave. See Unit Hydrograph Model for details.

flood_wave_celerity Double V 3
Equivalent Manning's n

Displayed when:
  • The Routing model of a runoff surface, referenced by an associated land use, is set to Non-linear.

    May be used to calculate Storage factor K and Lag time tl.

    See Non-Linear Routing Model for details.

  • The Routing model of a runoff surface, referenced by an associated land use, is set to RAFTS.

    May be used in the calculation of RAFTS B on a subcatchment basis. The specified value must be within the range of 0.001 to 2.0. A default value of 0.025 is used if no other value is specified when the Per-surface RAFTS box is unchecked.

  • Time of concentration method is set to Uniform.

    Used in the calculation of Time of concentration, tc. See Unit Hydrograph Model for details.

  • Lag time method is set to User, Kimura or Flood velocity.

    Used to calculate Lag time. See Unit Hydrograph Model for details

equivalent_roughness Double 3
Hydraulic radius
Displayed when:
  • Time of concentration method is set to Uniform.

    Used in the calculation of Time of concentration, tc. See Unit Hydrograph Model for details.

  • Lag time method is set to Flood velocity.

    Used to calculate Lag time. See Non-Linear Routing Model for details.

hydraulic_radius Double L 1
PWRI coefficient

Displayed when Time of concentration method is set to PWRI.

Coefficient for calculating Time of concentration, tc.

See Unit Hydrograph Model for details.

pwri_coefficient Double RS_HOURS 2 0.00001

Time of concentration, tc

Displayed when:
  • The Routing model of a runoff surface, referenced by an associated land use, is set to Clark. (Enabled)
  • Time of concentration method is set to User. (Enabled)
  • Unit hydrograph definition is set to SCS-User-Tc or User-Tc. (Enabled)
  • Time of concentration method is set to Kraven, Uniform or PWRI. (Read-only)
  • Unit hydrograph definition is set to Desbordes-Tc, Giandotti-Tc, Kirpich-Tc, Passini-Tc, Rational, SCS-Forest-Tc or SCS-Rural-Tc. (Read-only)

Subcatchment response time. Used to define Unit Hydrograph.

time_of_concentration

Double

2

0

Timestep factor

Displayed when:
  • Unit hydrograph definition is set to Desbordes-Tc, Giandotti-Tc, Kirpich-Tc, Passini-Tc, SCS-Forest-Tc, SCS-Rural-Tc or User-Tc. (Enabled)
  • Unit hydrograph definition is set to SCS-User-Tc. (Read-only)

Timestep factor. Used to define Unit Hydrograph.

tc_timestep_factor

Double

2

1.0

0

Time to peak factor

Displayed when:
  • Unit hydrograph definition is set to Desbordes-Tc, Giandotti-Tc, Kirpich-Tc, Passini-Tc, SCS-Forest-Tc, SCS-Rural-Tc or User-Tc. (Enabled)
  • Unit hydrograph definition is set to SCS-User-Tc. (Read-only)

Time to peak factor. Used to define Unit Hydrograph.

tc_time_to_peak_factor

Double

2

1.0

0

Time to peak, tp

Displayed when:
  • Unit hydrograph definition is set to User-Tp-Tb. (Enabled)
  • The Routing model of a runoff surface, referenced by an associated land use, is set to ReFH. (Read-only)
  • Time of concentration method is set to User, Kraven, Uniform or PWRI. (Read-only)
  • Unit hydrograph definition is set to Desbordes-Tc, Giandotti-Tc, Kirpich-Tc, Passini-Tc, Rational, SCS-Forest-Tc, SCS-Rural-Tc, SCS-User-Tc or User-Tc. (Read-only)

Time of peak flow. Used to define Unit Hydrograph.

Note: If the Unit Hydrograph Definition is set to ReFH, then the Time to peak, tp is calculated via the Calculate ReFH Parameters dialog.

time_to_peak

Double

2

0

99999999

Base time, tb

Displayed when:
  • Unit hydrograph definition is set to User-Tp-Tb. (Enabled)
  • The Routing model of a runoff surface, referenced by an associated land use, is set to ReFH. (Read-only)
  • Time of concentration method is set to User, Kraven, Uniform or PWRI. (Read-only)
  • Unit hydrograph definition is set to Desbordes-Tc, Giandotti-Tc, Kirpich-Tc, Passini-Tc, Rational, ReFH, SCS-Forest-Tc, SCS-Rural-Tc, SCS-User-Tc or User-Tc. (Read-only)

Total runoff time for unit hydrograph.

base_time

Double

2

0

99999999

Lag time, tl
Displayed when:

Time from the centroid of the excess rainfall to the hydrograph peak.

lag_time

Double

2

0

99999999

Peaking coefficient

Displayed when the Routing model of a runoff surface, referenced by an associated land use, is set to Snyder or HEC Snyder.

Coefficient that represents the variation of unit hydrograph peak with subcatchment characteristics.

peaking_coeff

Double

2

0.4

0.94

Unit hydrograph peak

Displayed (read-only) when the Routing model of a runoff surface, referenced by an associated land use, is set to ReFH.

The dimensionless instantaneous unit hydrograph ordinate at time to peak. This is calculated via the Calculate ReFH Parameters dialog.

uh_peak

Double

2

0

0

Degree of kink

Displayed (read-only) when the Routing model of a runoff surface, referenced by an associated land use, is set to ReFH.

The dimensionless instantaneous unit hydrograph 'kink' factor. This is calculated via the Calculate ReFH Parameters dialog.

uh_kink

Double

2

0

0

Non-linear routing method

Displayed when Lag time method is set to User, Kimura or Flood velocity.

Method used to calculate K, p coefficients:

Database Value

Description

Help Text
User User Value specified in Storage factor K and Exponent e fields are used.
Izzard Izzard

Izzard method is used to calculate K, p coefficients.

See Non-Linear Routing Model for details.

Equivalent roughness Equivalent roughness

Equivalent roughness method is used to calculate K, p coefficients.

See Non-Linear Routing Model for details.

non-linear_routing_method Text 25 0 Izzard
Lag time method

Displayed when the Routing model of a runoff surface, referenced by an associated land use, is set to Non-linear.

Method used to calculate lag time:

Database Value

Description

Help Text
User User Value specified in Lag time, tl field is used.
Kimura Kimura

Kimura method is used to calculate lag time.

See Non-Linear Routing Model for details.

Flood velocity Flood velocity

Flood velocity method is used to calculate lag time.

See Non-Linear Routing Model for details.

lag_time_method Text 15 0 Kimura
Storage factor K
Displayed when:

Characteristic coefficient of catchment. See the Non-Linear Routing Model and the Cascade Routing Model for further information.

storage_factor Double 3 0.000001
Exponent p

Displayed when Non-linear routing method is set to User.

storage_exponent Double 3 0.000001
Internal routing

The method by which the surface of the subcatchment is to drain. Set to:

  • Direct to drain directly to the outlet of the subcatchment
  • To pervious to drain the impervious surfaces of the subcatchment to the pervious surfaces of the same subcatchment
  • To impervious to drain the pervious surfaces of the subcatchment to the impervious surfaces of the same subcatchment
internal_routing Text 16 Direct
Runoff routed internally (%)

Displayed when Internal routing is set to To pervious or To impervious, and determines what percentage of the runoff is routed to the selected surface. The remaining runoff is routed directly to the outlet.

percent_routed Double 3 100 0 100
Per-surface RAFTS B

Displayed when the Routing model of a runoff surface, referenced by an associated land use, is set to RAFTS.

Indicates if RAFTS B routing is applied on a runoff surface or a subcatchment basis. A check (x) indicates that RAFTS B routing is applied on a per surface basis.

rafts_per_surface Boolean
Degree urbanisation

Displayed when the Routing model of a runoff surface, referenced by an associated land use, is set to RAFTS and the Per-surface RAFTS box is unchecked.

A fraction between 0.0 and 2.0, which describes the degree of urbanisation for the subcatchment.

degree_urbanisation Double 3 0 2
RAFTS adapt factor

Displayed when the Routing model of a runoff surface, referenced by an associated land use, is set to RAFTS and the Per-surface RAFTS box is unchecked.

A calibration factor used to calculate the storage factor that is output for each subcatchment.

rafts_adapt_factor Double 3
RAFTS B

Displayed when the Routing model of a runoff surface, referenced by an associated land use, is set to RAFTS and the Per-surface RAFTS box is unchecked.

The storage delay time coefficient.

rafts_b Double 3
RAFTS n

Displayed when the Routing model of a runoff surface, referenced by an associated land use, is set to RAFTS.

A storage non-linear exponent.

rafts_n Double 3 -0.285

Connectivity (%)

The percentage of foul flow for this subcatchment that drains into the system. Foul flow is derived from population, per capita flow and profile. If you leave this field blank, the software uses the default from the land use definition

connectivity

Long Integer

0

0

100

Wastewater profile

The reference for the wastewater profile that applies to this subcatchment. This refers to the profile number in the Wastewater event. You associate a Wastewater Event with the network when setting up a simulation. See Editing Trade and Waste Water Events and scheduling a Run.

The wastewater profile contains dimensionless values that the software multiplies by the base wastewater flow to give a time varying aspect. If you leave this field blank, the software uses the default from the land use definition. If you enter a zero in this field, the software does not apply foul flow to this subcatchment

wastewater_profile

Long Integer

0

0

999

Population

The number of people in the subcatchment. The software uses this, together with the average flow per person and diurnal variation in the wastewater profile, to determine the amount of foul flow.

Population can be defined to a precision of two decimal places. This supports the use of much more detailed models. You could even define individual properties as subcatchments.

If you leave this field blank the software calculates the population from the contributing area and the population density in the land use definition

population

Double

2

0

SUDS controls

A series of records defining the SUDS controls structure parameters for the subcatchment. The records are entered on the SUDS Controls grid which is displayed by clicking . See the SUDS Controls Grid topic for further information.

Each SUDS structure may have one or more SUDS control objects associated with it. The SUDS control objects are defined on the SUDS control tab of the Subcatchment Grid. However, a new SUDS control can also be added using the button located to the left of the field. This displays the Insert New SUDS control Object option that allows you to add the new object.

Trade flow

The nominal trade flow for the subcatchment. Throughout a simulation, the software multiplies this by the time varying factors from the trade profile, and the trade profile factor.

trade_flow

Double

Q

5

0

Additional foul flow

An additional flow that is added to the nominal wastewater flow (NWF) draining into the system (NWF= per capita flow X population X connectivity). The time varying multiplier from the wastewater profile applies to the total wastewater flow, (total wastewater flow = NWF plus additional foul flow).

additional_foul_flow

Double

Q

5

0

Base flow

The base infiltration flow into the system from this subcatchment. This is a constant inflow into the system.

base_flow

Double

Q

5

0

Trade profile

The reference for the trade profile that applies to this subcatchment. This refers to the profile number in the Trade event. You associate a Trade Event with the network when setting up a simulation. See Editing Trade and Waste Water Events and Scheduling a Run.

A trade profile represents the flow from an industrial source. It contains dimensionless values that the software multiplies by the trade flow to give a time varying aspect.

trade_profile

Long Integer

0

0

999

Ground infiltration ID

The name of the ground infiltration type for the subcatchment.

Any ground infiltation objects already defined can be selected from the dropdown. Alternatively, a new one can be added or an existing one modified using the button located to the left of the field. This displays the non-visual object menu, from which you can select the appropriate option.

ground_id

Text

64

0

Ground infiltration node

The name of the node which receives the ground water inflow within this subcatchment. This field is only enabled when a Ground infiltration ID has been specified. Choose a Ground infiltration node from the dropdown list. If no Ground infiltration node is specified, then any groundwater inflow goes to the same destination as the runoff.

Note:
  • If the subcatchment drains to a node, ground infiltration is only included in the Total outflow if the same node is specified as the Ground Infiltration node and the 'drains to' Node ID, or if the Ground infiltration node is not assigned.
  • The ground water cannot flow to an outfall type of node.

ground_node

Text

64

0

Baseflow lag

The base flow lag is displayed when either:
  • The Routing model or Runoff volume type of a runoff surface, referenced by an associated land use, is set to ReFH. (Read-only)

    When set to ReFH, the Baseflow Lag is calculated via the Calculate ReFH Parameters dialog.

  • The subcatchment does not reference a land use, or the land use does not reference a runoff surface. (Enabled)

baseflow_lag

Double

RS_HOURS

2

0

0

Baseflow recharge

The Baseflow recharge donor correction (multiplying factor) is displayed when either:
  • The Routing model or Runoff volume type of a runoff surface, referenced by an associated land use, is set to ReFH. (Read-only)

    When set to ReFH, the Baseflow recharge is calculated via the Calculate ReFH Parameters dialog.

  • The subcatchment does not reference a land use, or the land use does not reference a runoff surface. (Enabled)

baseflow_recharge

Double

2

0

0

Surfaces management

The Surfaces Management Editor displays the subcatchment runoff areas in a graphical format.

Runoff area, Area measurement type and Land use ID values can be viewed and edited in the Surfaces Management Editor.

surface_management Array 0

Land use ID

The name of the land use that applies to this subcatchment. The land use definition contains default values for various subcatchment parameters and a list of Runoff Surfaces available in the subcatchment.

Any Land use objects already defined can be selected from the dropdown. Alternatively, a new one can be added or an existing one modified using the button located to the left of the field. This displays the non-visual object menu, from which you can select the appropriate option.

New land use and runoff surfaces can also be defined from the grid editor using the Land use and Runoff surface tabs.

land_use_id

Text

64

0

PDM Descriptor

The name of the PDM descriptor that applies to this subcatchment.

The PDM descriptor contains all the PDM model parameters required when runoff volume type of the runoff surface referenced by the associated land use is set to PDM, or when Baseflow calculation is set to PDM.

Any PDM Descriptors already defined can be selected from the dropdown. Alternatively, a new one can be added or an existing one modified using the button located to the left of the field. This displays the non-visual object menu, from which you can select the appropriate option.

pdm_descriptor_id Text 64 0
Build-up/washoff land uses

A series of records that define the SWMM build-up/washoff land uses which apply to this subcatchment. These are entered on a grid which is displayed by clicking on the button.

Database Table Name: hw_swmm_coverage

Field Name

Help Text

Database Field

Data Type

Size

Units

Precision

Default

Error Lower Limit

Error Upper Limit

Warning Lower Limit

Warning Upper Limit

Build-up/washoff land use The SWMM Build-up/Washoff Land Use model can be selected from a list. land_use Text 64
Area The percentage of this subcatchment that the SWMM build-up/washoff land use applies to. sediment_fraction Text 4 0 0 100
swmm_coverage Structure

Area measurement type

Database Value

Description

Absolute

Absolute

area for each surface type is specified as an absolute value

Percent

Percent

area for each surface type is specified as a percentage of the contributing area

area_measurement_type

Text

8

0

Absolute

Runoff area 1 (%)

The Runoff Area fields define how much of the subcatchment belongs to the particular runoff surface type. The Runoff Area (%) fields are only populated if the Area Measurement Type is Percent. The value is a percentage of the contributing area.

Runoff Surface IDs defined in the Land Use associated with the subcatchment are displayed read-only on the property sheet next to the appropriate area value. To change the runoff surfaces edit the current Land Use or attach a different Land Use.

Define the runoff characteristics of the Runoff Surface on the Runoff Surface Grid Window in the Subcatchments Grid.

area_percent_1

Double

3

0

Runoff area 2 (%)

see Runoff area 1

area_percent_2

Double

3

0

Runoff area 3 (%)

see Runoff area 1

area_percent_3

Double

3

0

Runoff area 4 (%)

see Runoff area 1

area_percent_4

Double

3

0

Runoff area 5 (%)

see Runoff area 1

area_percent_5

Double

3

0

Runoff area 6 (%)

see Runoff area 1

area_percent_6

Double

3

0

Runoff area 7 (%)

see Runoff area 1

area_percent_7

Double

3

0

Runoff area 8 (%)

see Runoff area 1

area_percent_8

Double

3

0

Runoff area 9 (%)

see Runoff area 1

area_percent_9

Double

3

0

Runoff area 10 (%)

see Runoff area 1

area_percent_10

Double

3

0

Runoff area 11 (%)

see Runoff area 1

area_percent_11

Double

3

0

Runoff area 12 (%)

see Runoff area 1

area_percent_12

Double

3

0

Runoff area 1 absolute

The Runoff Area fields define how much of the subcatchment belongs to the particular runoff surface type. The Runoff Area (Absolute) fields are only populated if the Area Measurement Type is Absolute.

The InfoWorks ICM Native unit for these fields is Hectares.

Runoff Surface IDs defined in the Land Use associated with the subcatchment are displayed read-only on the property sheet next to the appropriate area value. To change the runoff surfaces edit the current Land Use or attach a different Land Use.

Define the runoff characteristics of the Runoff Surface on the Runoff Surface Grid Window in the Subcatchments Grid.

area_absolute_1

Double

CA

3

0

Runoff area 2 absolute

see Runoff area 1 absolute

area_absolute_2

Double

CA

3

0

Runoff area 3 absolute

see Runoff area 1 absolute

area_absolute_3

Double

CA

3

0

Runoff area 4 absolute

see Runoff area 1 absolute

area_absolute_4

Double

CA

3

0

Runoff area 5 absolute

see Runoff area 1 absolute

area_absolute_5

Double

CA

3

0

Runoff area 6 absolute

see Runoff area 1 absolute

area_absolute_6

Double

CA

3

0

Runoff area 7 absolute

see Runoff area 1 absolute

area_absolute_7

Double

CA

3

0

Runoff area 8 absolute

see Runoff area 1 absolute

area_absolute_8

Double

CA

3

0

Runoff area 9 absolute

see Runoff area 1 absolute

area_absolute_9

Double

CA

3

0

Runoff area 10 absolute

see Runoff area 1 absolute

area_absolute_10

Double

CA

3

0

Runoff area 11 absolute

see Runoff area 1 absolute

area_absolute_11

Double

CA

3

0

Runoff area 12 absolute

see Runoff area 1 absolute

area_absolute_12

Double

CA

3

0

Points

An array of X/Y values defining the geometry of the subcatchment

boundary_array

Array

XY

0

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