6.4 SWMM Outputs

Model outputs are written by both SWMM and TUFLOW, which can be used to visualize model results. SWMM writes a report file (rpt) and an output file (out) in the TUFLOW results folder with the simulation prefix followed by “_swmm.” The report file can be viewed with a text editor. The output file can be viewed in EPA SWMM or 3^rd party tools that support this format, such as PySWMM.

TUFLOW-SWMM models also output a GeoPackage time-series output file. The file is written to the “plot” subfolder within the results folder and ends with “_ts.gpkg.” This file is referenced in the TUFLOW tpc file (see Section 15.2.1) which includes the other time-series outputs such as 1D ESTRY and 2D PO. The QGIS TUFLOW Viewer can read the SWMM results using the Load Results - Time series option from the File menu and selecting the tpc (load all time-series results) or GPKG time-series file (only load SWMM results). When the SWMM GPKG time-series file is loaded, point and line layers will be loaded, representing the node and channel results. The layer symbology can be modified to dynamically represent the model result magnitude for the current QGIS time. Profiles can be also be generated for the 1D network. Animations can be created from these results (in combination with 2D results if desired). These layers can also be used to select channels or nodes to display time series results in the TUFLOW Viewer plot windows, and can be combined with ESTRY or PO outputs. Documentation for the QGIS TUFLOW Plugin and TUFLOW Viewer are available in the TUFLOW Wiki.

The GeoPackage time-series file contains all of the SWMM output for nodes and links (polylines). For nodes this includes, “Depth”, “Water Level”, and more. For Conduits this includes, “Flow”, “Channel Depth”, “Velocity”, “Channel Capacity” and more. Descriptions of these datasets are in the SWMM documentation. In addition, TUFLOW writes two datasets, “Flow from 2D” and “Cumulative Volume from 2D”, for nodes that describe flow between the 1D and 2D domains. “Flow from 2D” represents the inflow from the 2D model to the node where negative values represent flows from the 1D domain to the 2D. “Cumulative Volume from 2D” represents the total volume that goes into (positive) or out of the 1D domain from the 2D.