Narellan Creek Overland Flood Study (Vol 1) - Flipbook - Page 18
Narellan Creek Catchment
Flood Study
the definition of flood behaviour that was provided as part of the 8Narellan Creek Flood
Study9 (Worley Parsons, 2015) to take account of new developments as well as additional
datasets.
A detailed review of the XP-RAFTS and TUFLOW models developed for the 2015 Study was
completed. This review identified the need for several updates to the TUFLOW hydraulic
model. This included:
Inclusion of work as executed terrain to represent new developments.
Inclusion of additional stormwater infrastructure.
Inclusion of additional cuvlerts (e.g., The Northern Road crossing of Narellan Creek)
Lake Yandel9ora low and high flow pipe representation was updated
Hydraulic roughness in riparian areas was refined
Harrington Parkway bridge was included
Harrington Park Lakes representation was updated. This included updates to lake and
creek bathymetry, inclusion of various low and high flow pipes as well as modifications
to the initial water levels.
The updated TUFLOW model was calibrated against data collected following the February
2007 flood as well as the June 2016 flood, which was not available at the time the 2015
study was completed. A good calibration outcome was achieved to these events.
The updated TUFLOW model was used to re-simulate the full range of design floods (from
the 50% AEP flood up to the probable maximum flood) and produce a range of flood
mapping. This included floodwater depths, velocities, water levels, hazard and hydraulic
categories. Floodwater extents for the 1% AEP and PMF from this study are provided on
Figure 2.
The study did acknowledge the potential for the Nepean River to significantly influence
flood levels in the lower parts of the Narellan Creek catchment. Therefore, the results of
the Narellan Creek catchment flood simulations were
