Georges River Flood Data August 5th-6th, 1986

Brief description

This report details the flood gauging operation undertaken
on 5th and 6th August, 1986 and presents the data
collected for the Georges River catchment in Sydney.

The Georges River catchment area is approximately 960
square kilometres and is shown in Figure 2.1. The main arm
of the river begins its course near the Cataract Dam, and
exits into Botany Bay. The main channel is joined
throughout its course by minor streams and creeks, and also
by the Woronora River; which exits into the Georges River.

The catchment area comprises a large part of the south
western urban area of the city of Sydney, and the floods
that have occurred in the catchment have at times caused
significant damage to property.

To rationalise future development of the area in the face
of potential flood threats, various numerical and physical
models have been developed by both the University of N.S.W.
Water Research Laboratory, and the Public Works
Department's Manly Hydraulics Laboratory. The success of
the models in predicting the flooding characteristics of
various flood events depend upon collecting specific flood
data over a series of floods· for model calibration and
verification. To this end, all known information regarding
previous floods has been documented (Ref. 1), but there is
a need for more comprehensive flood data, especially for
major floods.

Manly Hydraulics Laboratory's Data Collection Section was
requested by the Department's Rivers and Ports Branch to
co-ordinate and undertake flood monitoring at various sites
over the area which is being modelled. These monitoring
sites appear in Figure 1.1. A previous report (Ref. 1)
details the results of gauging of minor floods undertaken
in 1978 and 1983.


Flood gauging on the 5th and 6th August, 1986 was carried
out by personnel from Manly Hydraulics Laboratory, Rivers
and ports Branch and the Water Research Laboratory.

The general extent of the flooding can be seen in Plates
1.1 - 1.3.

The current metering lines, flood gauge locations and
automatic recorder locations from which data was collected
are as follows:

i) Current metering/gauge observations at:

1. East Hills Footbridge
2. Milperra Road Bridge
3. Mountbatten Bridge
4. Lansdowne Bridge

ii) Automatic recorders located at:

1. Milperra Bridge
2. Cutler Road, Lansvale
3. Liverpool. Weir.

Data collection from the Irelands Bridge current metering
station and the Scrivener Street auto recorder is also
specified under the Georges river flood data collection
program, but inaccessibility to the bridge and equipment
malfunction respectively, precluded data collection from
these sites on this occasion.

Full description

Georges River Flood Data August 5th-6th, 1986