Wellington Water Limited - Wellington CBD Modelling

This modelling study was undertaken to assist Wellington Water Limited (WWL) with management of stormwater in the catchment. The model will be used to produce flood maps for various design storm events with the current/existing land use and and may subsequently be used to assess options for upgrading the stormwater system to mitigate flooding in the catchment. It may also be used for testing the impacts of increased rainfall intensity and sea level due to climate change and in detailed design of remedial options.

A model of the Southern CBD stormwater catchment was developed using InfoWorks ICM software together with the following input:

  • Network data (GIS shape files)
  • LiDAR derived digital elevation model (DEM)
  • Raster layers representing hydrology curve number, hydrology initial losses, and surface roughness
  • As constructed drawing of the network supplied by WWL
  • Site inspections undertaken by Awa Environmental Ltd staff
  • Engineering judgement

The model has been built to a high level of detail and includes all known sumps, manholes, pipes, inlets and outlets.  Larger open channels have been modelled as one-dimensional river reaches and a fine mesh has been used in the two-dimensional model domain