Modeling Known Rainfall Events and Forecast Data in SewerOPS

Product(s): SewerOPS
Version(s): CONNECT Edition
Area: Modeling


OpenFlows SewerOPS uses an existing SewerGEMS model so wastewater and stormwater operators can manage the system. While using storm data based on known depths and dimensionless curves is common for some analysis and design of a stormwater or wastewater system, these types of storms are less practicable to use theoretical storms to base operational decisions on. For that reason, SewerOPS offers two options. Rain Files can be used to model actual historical precipitation as a basis to make operational decisions. Forecast data can also be used to model the impact of a major storm event and the impact on a system.

Further Information

There are two storm types available in SewerOPS: Rain File and Forecast. Note that application of the storm data may already have been done ahead of time. If that is the case, the operator would only need to change scenarios to apply the storm data. The workflow below has further information if the data needs to be applied. 

Rainfall File

The advantage to using rain files with historical precipitation data is that it allows an operator to see the impact of an actual storm event on a system during an operational event, like a pipe shut down. This will allow teams to be prepared in case a similar storm event occurs. Rain files from storms with high and low precipitations can be modeled to see how the impact of the storm event may change as conditions change. 

The following standard formats are supported for rain files:

  • Hourly and fifteen minute precipitation data from over 5,500 reporting stations retrieved using NOAA's National Climatic Data Center (NCDC) Climate Data Online service (space delimited format only).
  • The older DS-3240 and related formats used for hourly precipitation by NCDC.
  • The older DS-3260 and related formats used for fifteen minute precipitation by NCDC.
  • HLY03 and HLY21 formats for hourly rainfall at Canadian stations, available from Environment Canada.
  • FIF21 format for fifteen minute rainfall at Canadian stations, also available from Environment Canada.
  • A standard user-prepared format where each line of the file contains the station ID, year, month, day, hour, minute, and non-zero precipitation reading, all separated by one or more spaces.

Below is an example of the rain gauge file type from one of the SewerOPS sample files. The sample files can be found at C:\Program Files\Bentley\SewerOPS\Samples.

Note: Storm data will likely already be entered for existing SewerOPS models. If you would like information on applying to data to a model, see the Workflow section below.


Bentley pulls forecast data from a NOAA server that posts new forecast simulations from the their HRRR v3 meteorological model. At top of every hour, NOAA posts a new 18 hour forecast as a large projected grid file (GRIB file format).

When the Bentley web service sees a new post, it will download and digest the updated forecast hourly, that way it is always prepared to answer query requests from SewerOPS in the form of point time series data, with precipitation data in 15 min increments.

Forecast data is based on the latitude and longitude and may already be applied to a model intended to use this information. However, the forecast data may need to be updated before you compute the model. To do this, go to the Administration tab, then select Storm Data > Storm Data. In the Storm Data editor, you will see table on the left that says Rain File and Forecast. Expand the Forecast item if needed, then select the forecast for your model. Click the Refresh button. This will take you to the Bentley web service and update the forecast data. When you compute a scenario with the forecast data applied, the most recent forecast precipitation will be used in the calculation.

Forecast data is currently only available in North America. You need to include a negative sign for the longitude, as that is indicative of the Western Hemisphere. 


If you need to apply rain files or forecast data to a model, you can use the information below. The storm data is added to a model by going to the Administration tab, then selecting Storm Data > Storm Data. This will open the Storm Data editor.

For Rain File data, either click on the New button and select "Rain File" or right-click on Rain File from the list and choose New > Rain File.

In the Storm Event Input tab, click the ellipsis ("...") button next to the Rain File cell and browse to the rain file you will be using. Choose the Rain Data File Type and the Rain Units. Once that is done, click the New button under the "Rain File Storm Events" section in the lower right of the Storm Data Editor. The Label cell will be filled in with a default label; you can change this as needed. For the Station ID column, enter the name of the station that the storm data is from. In the example from the screenshot above, this would be "RainGauge". Then enter the Time Interval. From the example above, this is 1 hour.

For Forecast data, either click on the New button and select "Forecast" or right-click on Forecast from the list and choose New > Forecast. Enter the latitude and longitude for your site, making sure that you include a negative sign before the longitude value (forecast data is currently only available in North America.) Once you enter the latitude and longitude, click the Refresh button. This will take you to the Bentley web service and update the forecast precipitation with the most recent model data. 

Once the data is entered, go to Administration > Storm Data > Global Storm Events. This will list the existing Rainfall Runoff alternatives. In the appropriate alternative, select the storm data (either the rain file or forecast data) from the pulldown menu in the Global Storm Event column. The storm event will now be associated with the scenario.

For information on using Scenarios and Alternatives see the following link: Scenario and Alternative Management.

See Also

OpenFlows SewerOPS Overview

OpenFlows SewerOPS TechNotes and FAQs