North Parramatta Precinct

Brief description

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)