Skip to main content

Running Simulations

Once the network geometry and properties are defined, you must run hydraulic simulations to verify performance and demonstrate compliance with LLFA requirements.

Configuring Storm Parameters​

  1. Navigate to the Simulation tab on the Right Sidebar.
  2. Method: Select either FSR (Flood Studies Report) or FEH (Flood Estimation Handbook) depending on the age of your project or specific approving authority requirements.
  3. Rainfall Profile: We recommend keeping this set to "Summer & Winter" to ensure both high-intensity and high-volume profiles are tested to find the true critical storm.
  4. Storm Durations: The platform defaults to testing a broad range of durations (from 15 minutes up to 10080 minutes / 7 days). Leave this broad spectrum enabled, as attenuation tanks often reach critical capacity during 24-48 hour storms.
  5. Return Periods: Add the required testing frequencies. A standard UK test suite involves:
    • 1 Year (to prove no surcharging)
    • 30 Year (to prove no surface flooding)
    • 100 Year + 40% Climate Change (to size attenuation and check exceedance)

Executing the Simulation​

Click the Simulate All Storms button. The frontend will compile your network geometry into an input payload and send it to the backend Python engine.

The engine utilises PySWMM to solve the dynamic wave routing equations across all selected return periods, profiles, and durations simultaneously. A progress bar will indicate the status of the batch run.

Reviewing the Results​

1. The Schedule Panel​

When the simulation finishes, open the Schedule Panel (bottom half of the screen). This tabular view summarises the absolute worst-case result for every node and pipe across all tested storms.

  • Green: The node is operating normally.
  • Orange (Surcharged): The water level has risen above the pipe soffit, but has not breached the cover level.
  • Red (Flooded): The Hydraulic Grade Line has exceeded the cover level. The exact volume of flooded water (m3m^3) will be displayed.

2. The Long Section Chart​

To visually understand why a node is flooding:

  1. Select a run of pipes on the canvas.
  2. The Long Section Chart (tab next to the Schedule Panel) will display the profile of the selected pipes.
  3. Use the Storm Selector dropdown to pick a specific storm event (e.g., 100yr + 40% CC, 360 min Winter).
  4. A blue line representing the peak Hydraulic Grade Line (HGL) will be drawn over the pipes. If this line breaches the top grey line (Cover Level), you will see exactly where the bottleneck is occurring.

3. Reporting​

Once your design meets all criteria (no red flooded nodes in the 30-year event, manageable exceedance in the 100-year event), navigate to the Export tab to generate a professional PDF Simulation Report. This report includes all critical storm outputs, flow control sizing, and attenuation volumes required for LLFA submission.