Georges River Flood Data

This report details the flood gauging operations undertaken from 1700 hrs on March 21st, 1983 to 0200 hrs on March 22nd, 1983 and presents previous flood data collected on the Georges River. The Georges River has a total catchment area of approximately 650 square kilometres and flows into the south-western corner of Botany Bay about 15km south of Sydney. The tidal influence under low freshwater discharge conditions extends approximately 40km upstream and terminates at Liverpool Weir. Flood monitoring at selected sites as defined in Figure 1 is undertaken for floods in excess of a one in ten year frequency. Flood monitoring is commenced on receipt of Confidential/Preliminary Flood Warning advice when it is predicted that a stage level of 2.0 meters at the Liverpool Weir gauge (approximately 4.7m AHD) will be exceeded. The collection of this flood data has in the past and will in the future be used to calibrate physical modeIs which are constructed at the PWD Manly Hydraulics Laboratory and U.N.S.W. Water Research Laboratory. The current metering- lines, flood gauge location and automatic recorder locations are as follows: i) Current metering/flood level observations:

East Hills Footbridge Milperra Road Bridge Rabaul Road (gauge readings only) Lansdowne Bridge - Prospect Creek Irelands Bridge - Cabramatta Creek Mountbatten Bridge - Warwick Farm

ii) Automatic recorders are located:

Milperra Bridge (see note below) Lansdowne Bridge Cutler Road, Lansvale Scrivener Street, Warwick Farm Liverpool weir (upstream)

Note on Milperra - The Milperra automatic recorder is located immediately upstream of the road bridge. It consisted of two measurement points, however only the downstream one was operating at the time of the monitoring. The recorder has since been modified and now has only one measurement point.