Introduction

TUFLOW has supported 1D/2D dynamic coupling since its initial 2D solver development in 1989. Traditionally, 1D linking and associated modeling has been applied using the TUFLOW 1D (ESTRY) solver. New in the 2023-03-AD Release, TUFLOW's 1D linking and solver options have been expanded to support the EPA Storm Water Management Model (referred to herein as SWMM).

As a result of the 1D SWMM inclusion within TUFLOW, modellers working with SWMM files now have a variety of options available:

Use SWMM, coupled directly to TUFLOW.
Conversion of SWMM 1D geometry to a TUFLOW compatible format for use by TUFLOW 1D (ESTRY) solver.

SWMM inclusion in TUFLOW (2023-03-AD or newer)

If you wish to model SWMM coupled dynamically to TUFLOW 2D, please refer to the TUFLOW SWMM Tutorials. Tutorials are provided for the following topics:

TUFLOW SWMM Module 1 - 1D SWMM Culverts
TUFLOW SWMM Module 2 - 1D SWMM Pipe Network / 2D TUFLOW Direct Rainfall Hydrology
TUFLOW SWMM Module 3 - 1D SWMM Pipe Network / 1D SWMM Urban Hydrology
TUFLOW SWMM Module 4 - 1D SWMM Pipe Network / 1D SWMM Urban Hydrology: Executing multiple different event simulations from a single model control file.

Conversion of SWMM to TUFLOW 1D (ESTRY)

As an alternative to direct coupling of SWMM with TUFLOW, a free utility tool is also available to assist with the conversion of SWMM inp files into a TUFLOW compatible format for simulation using TUFLOW 1D (ESTRY). The SWMM_to_TUFLOW utility is available for download from the TUFLOW website.

The SWMM_to_TUFLOW utility automates the conversion of SWMM 1D model geometry for culverts, pipes and open channels into a TUFLOW 1D (ESTRY) compatible GIS and tabular format.

Note: TUFLOW 1D does not include an inbuilt hydrology engine. As such, SWMM hydrology and boundary condition information is not processed by this utility. If EPA SWMM hydrology or boundary condition information is important for your model construction, please use direct coupling of EPA SWMM with TUFLOW.

SWMM_to_TUFLOW Utility Execution

Save the swmm_to_gis_w64.exe to the same folder as the SWMM file (.inp).
The utility requires GIS projection information to correctly translate the spatial information contained in the SWMM file (.inp) to either MapInfo *mif/*mid or ESRI/QGIS *.shp format. This is done by including a Projection file in the working directory. Create one of the following files, saved to the same folder location as the SWMM file (.inp).
The following error message will be produced if projection information is not provided:
```
ERROR - A Header.prj or Projection.prj file does not exist in folder
```
Create a batch file (*.bat) in the same folder as the SWMM file (.inp). Depending on the GIS output format you desire, use either of the following syntax in the batch file.
Double left mouse click the created batch file from Windows Explorer to execute the utility.

Utility Output

Depending on the features included in the SWMM file (.inp) the Utility may create three output file types for TUFLOW 1D (ESTRY):

Utility Output	MapInfo (mif/mid)	ESRI / QGIS (shp)
1D Invert Information	junctions.mif / mid	junctions_P.shp
1D Geometry Details (link type and size)	inp.mif / mid	conduits_L.shp
1D Cross-section Information	.csv files contained within the created XS Folder

Limitations

SWMM includes a larger range of inbuilt culvert geometry types than TUFLOW 1D (ESTRY). TUFLOW 1D primarily supports Circular (C) and Rectangular (R) as hardcoded culvert /pipe geometries. All others SWMM culvert types are converted to TUFLOW 1D Irregular (I) culverts, with an associated Height vs Width 1D cross-section to define the culvert geometry.
SWMM includes a variety of inbuilt pipe network inlet geometries. This information is not processed by the utility. It is the modellers responsibility to manually create depth / flow relationship information for the pit inlet database if using TUFLOW 1D. If you wish to use the inbuilt SWMM pipe network inlet geometries directly, please use direct coupling of SWMM with TUFLOW. Refer to TUFLOW SWMM Tutorial Module 2 and 3
TUFLOW 1D does not include an inbuilt hydrology engine. As such, SWMM hydrology and boundary condition information is not processed by this utility. If EPA SWMM hydrology or boundary condition information is important for your model construction, please use direct coupling of EPA SWMM with TUFLOW.

EPA SWMM to TUFLOW

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