The 12d Model Stormwater Drainage Design will improve the productivity of designers by giving them powerful techniques and tools for the design and analysis of Stormwater Drainage Systems for urban and highway drainage.

Stormwater Drainage – Day 2

  • Create catchments and assign catchment areas to nodes (pits)
  • Define bypass routes
  • Analyse the network using Rational Hydrology and HGL check
  • Resize links (pipes) to achieve freeboard at pits
  • Export reports for checking
  • Plot longsections that include hydraulic results


  • Attended Stormwater Drainage – Day 1 OR
  • Have an excellent working knowledge of creation and editing of Drainage Strings in 12d Model


At the end of the course, participants will be familiar with the Hydrological and Hydraulic models available in 12d Model, and have designed and analysed the network using Rational Hydrology and HGL check hydraulics.

Course Summary

This course builds on from the material covered in Stormwater Drainage – Day 1 and uses the network of pits and pipes created in that course.

We cover the techniques for hydrological and hydraulic analysis and design
of the network using RATIONAL HYDROLOGY.

  • Creating catchments, measuring areas, and the automatic and manual methods of assigning catchment areas to pits.
  • Defining bypass flow routes, and how these are used to analyse width of gutter flow and ponding at sag pits.
  • Defining inlet rating curves for pits.
  • Using drafted flowpaths, to calculate Tc values.
  • Using 12d Model to calculate Ku and Kw factors.
  • Analysing the system using 12d Model’s Rational Hydrology Engine.
  • Calculating the HGL, and determining pipe flows and velocities.
  • Calculating bypass flows and ponding depths at sag pits.
  • Designing the system using the Rational Engine.  Resizing pipes, and resetting invert levels based on HGL/freeboard requirements.
  • Modelling an open channel and headwalls to carry discharge from the piped network.
  • Producing Hydrology and Hydraulic Reports.