Narellan Creek Overland Flood Study (Vol 1) - Flipbook - Page 84
Narellan Creek Catchment
Flood Study
The mainstream flooding areas were delineated by hand based on whether the floodwater
came from a formal watercourse. All other areas located away from the main watercourses
were assumed to be impacted by overland inundation.
The 0.5m freeboard was added to the filtered 1% AEP water level results documented in
Section 5.4.3 to produce a mainstream flood planning level grid. The mainstream flood
planning level grid was then extended laterally until it intersected higher ground. For
overland flow areas, no lateral extension of the filtered 1% AEP extent was completed
owning to the shallow depth of inundation. The mainstream and overland FPA were
subsequently combined to produce the flood planning area shown in Figure 59.
Also included on Figure 59 are
