ICM

SWMM5 Conversion – Subcatchments from SWMM 5 in InfoWorks ICM


SWMM5 Conversion – Subcatchments from SWMM 5 in InfoWorks ICM

Information from the following sections of the SWMM5 project file are imported to InfoWorks ICM Subcatchment objects:

[SUBCATCHMENTS]

[POLYGONS]

[SUBAREAS]

[INFILTRATION]

[HYDROGRAPHS]

[RDII]

[SUBCATCHMENTS] Section

SWMM5 [SUBCATCHMENTS] are imported as InfoWorks ICM Subcatchments.

Geometry of the Subcatchment boundary is determined from the X and Y coordinate data in the [POLYGONS] section of the SWMM5 project file.

Each Subcatchment has three surfaces to represent it:

Impervious surface with depression storage

Impervious surface with no depression storage

Pervious surface

SWMM5 Description InfoWorks ICM Data Field
Name Subcatchment ID Subcatchment ID
Rgage Name of rain gauge assigned to Subcatchment.

Raingauge is defined in [RAINGAGES] section

Rainfall Profile
OutID Name of node or Subcatchment that receives runoff from Subcatchment Node ID

In SWMM5 the Out ID may be a Subcatchment. This is not supported in InfoWorks ICM. If a node with name OutID cannot be found, OutID will be imported to User Text 2 and a warning will be added to the log.

Area Area of Subcatchment Total Area
%Imperv Percent impervious area of Subcatchment Used to calculate Runoff Area Percentages. See Subcatchment Surface Areas below.
Width Characteristic width of Subcatchment Dimension
Slope Subcatchment Slope (percent) Slope (%)
Clength Total Curb Length User Number 1

(No InfoWorks ICM equivalent)

Spack Name of snow pack object associated with the Subcatchment.

Snow pack object is defined in the [SNOWPACKS] section

User Text 3

(Not currently supported)

Subcatchment Surface Areas

Each Subcatchment is represented by three surfaces. The areas of these surfaces are calculated as follows:

Runoff Area 1 (%) = %Imperv x %Zero/100 (1)
Runoff Area 2 (%) = %Imperv – (%Imperv x %Zero/100) (2)
Runoff Area 3 (%)= 100 – %Imperv (3)

Where:

%Imperv= Percentage of impervious area ([SUBCATCHMENTS] section)

%Zero = Percentage of impervious area that has no depression storage ([SUBAREAS] section)

Runoff Surfaces

Data from the SWMM5 [SUBAREAS] and [INFILTRATION] sections is imported into the InfoWorks ICM Runoff Surfaces.

The importer creates a Runoff Surface for each unique set of runoff characteristics. A Land Use is created for each unique set of runoff surfaces.

All surfaces use Routing Model type SWMM.

Impervious surfaces use Runoff Volume Type Fixed with Fixed Runoff Coefficient of 1.0.

[SUBAREAS] Section

SWMM5 Description InfoWorks ICM Data Field
Subcat Subcatchment Name Used to determine to which Subcatchments the Runoff Surface applies.
Nimp Manning’s n for overland flow over the impervious sub-area Runoff Routing Value

(Surface Type = Impervious

Runoff Volume Type = Abs)

Nperv Manning’s n for overland flow over the pervious sub-area Runoff Routing Value

(Surface Type = Pervious

Runoff Volume Type = Abs)

Simp Depression storage for impervious sub-area Initial Loss Value

(Surface Type = Impervious

Initial Loss Type = Abs)

Sperv Depression storage for pervious sub-area Initial Loss Value

(Surface Type = Pervious

Initial Loss Type = Abs)

%Zero Percent of impervious area with no depression storage Used to calculate Runoff Area Percentages See Subcatchment Surface Areas above.
RouteTo
SWMM5 RouteTo Description
IMPERVIOUS Pervious area runoff runs onto impervious area
PERVIOUS Impervious runoff runs onto pervious area
OUTLET Bboth areas drain to the Subcatchment’s outlet

(Default)

Routing to OUTLET only supported. If the routing is to IMPERVIOUS or PERVIOUS a warning message will be added to the import log.
%Rted Percent of runoff routed from one type of area to another

[INFILTRATION] Section

The SWMM5 Subcat field in the [INFILTRATION] Section is used to determine to which Subcatchments (and Runoff Surfaces) the Infiltration data is applied.

The Infiltration model used (and therefore which fields are defined) is defined in the SWMM5 [OPTIONS] section.

Horton Infiltration

SWMM5 Description InfoWorks ICM Data Field
MaxRate Maximum infiltration rate on Horton curve Horton Initial
MinRate Minimum infiltration rate on Horton curve Horton Limiting
Decay Decay rate constant of Horton curve Horton Decay
DryTime Time it takes for fully saturated soil to dry Horton Drying Time
MaxInf Maximum infiltration volume possible Horton Max Infiltration Volume

Green-Ampt Infiltration

SWMM5 Description InfoWorks ICM Data Field
Suction Soil capillary suction Green Ampt Suction
Conduct Soil saturated hydraulic conductivity Green Ampt Conductivity
InitDef Initial soil moisture deficit (volume of voids / total volume) Green Ampt Deficit

Curve Number Infiltration

SWMM5 Description InfoWorks ICM Data Field
CurveNo SCS Curve Number Curve Number field of Subcatchment Object
Conduct Soil saturated hydraulic conductivity Not imported

(No InfoWorks ICM equivalent)

DryTime Time it takes for fully saturated soil to dry Not imported

(No InfoWorks ICM equivalent)

Unit Hydrograph Data

Unit Hydrograph data is provided in the [RDII] and [HYDROGRAPHS] Sections of the SWMM5 input file.

[RDII] Section

Data in the [RDII] Section of the SWMM5 file is imported into InfoWorks ICM Subcatchment objects.

SWMM5 Description InfoWorks ICM Data Field
Node Node name Used to identify the Subcatchment to which the node drains. If the node does not have a Subcatchment, a dummy Subcatchment will be created to allow the hydrograph to function.
UH Group Name of RDII unit hydrograph group specified in the [HYDROGRAPHS] section RTK Hydrograph field of Subcatchment to which node drains
SewerArea area of the sewershed which contributes RDII to the node Contributing Area field of Subcatchment to which node drains

[HYDROGRAPHS] Section

Data in the [HYDROGRAPHS] Section of the SWMM5 file is imported as InfoWorks ICM RTK Hydrographs.

SWMM5 Description InfoWorks ICM Data Field
Name Unit hydrograph group name RTK Hydrograph ID

If specific months are specified for the unit hydrograph group in the SWMM file, an InfoWorks ICM RTK Hydrograph will be created for each month, named as <SWMM5 Name>_<Month>.

Raingage Name of rain gage used by UH group Rainfall profile field of Subcatchment
Month Month of the year See Name for more details.
R1, R2, R3 Response ratios for the short-term, intermediate-term, and long-term UH responses, respectively R1, R2, R3
T1, T2, T3 Time to peak (hours) for the short-term, intermediate-term, and long-term UH responses, respectively T1, T2, T3
K1, K2, K3 Recession limb ratios for short-term, intermediate-term, and long-term UH responses, respectively K1, K2, K3
Dmax Maximum initial abstraction depth available Not imported

(No InfoWorks ICM equivalent)

Drec Initial abstraction recovery rate Not imported

(No InfoWorks ICM equivalent)

D0 Initial abstraction depth already filled at start of the simulation Not imported

(No InfoWorks ICM equivalent)

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