The flood study was undertaken in two stages. The aims of each stage of the flood study are:
Stage 1 - Hydrological Analysis
Collate all the relevant data on Council's existing stormwater drainage system;
Develop a hydrological model to investigate the drainage system performance for the
5, 10, 20, 100, 200 year ARI storms and the PMF;
Identify the flooding problem areas for existing development conditions within the
study area;
Identify the flooding problem areas for ultimate development conditions (represented
by all of the study area utilising OSD).
Stage 2 - Hydraulic Analysis
Estimate the extent of flooding and flood levels for the PMF, 20 and 100 year ARI
floods for existing development conditions, and
Estimate the 20 and 100 year ARI flood levels and extent of flooding for ultimate
development conditions.
Study Scope
The scope of the Stage 1 flood study was to use a hydrological model to estimate peak pipe and
overland flows throughout the North Parramatta Precinct. The peak overland flows were used
in the hydraulic modelling in Stage 2 to estimate peak flood levels and flood extents.
Design Rainfall Intensities used for the estimation of peak flows were obtained from Baulkham
Hills Shire Council "Design Guidelines for Subdivisions / Developments." Storm durations
from 5 minutes to 4.5 hours were used to produce rainfall patterns from which the D NS
model estimates peak pipe and overland flows.
The results presented in this report are the worst case peak flow for each set of storm durations for a particular ARI storm. Where flood levels are noted, all levels refer to Australian Height Datum (m, AHD)
