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] 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:
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) |
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| Nperv | Manning's n for overland flow over the pervious sub-area | Runoff Routing Value
(Surface Type = Pervious Runoff Volume Type = Abs) |
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| 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 |
|
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) |