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

This report details the flood gauging operation undertaken\r\non 5th and 6th August, 1986 and presents the data\r\ncollected for the Georges River catchment in Sydney.\r\n\r\nThe Georges River catchment area is approximately 960\r\nsquare kilometres and is shown in Figure 2.1. The main arm\r\nof the river begins its course near the Cataract Dam, and\r\nexits into Botany Bay. The main channel is joined\r\nthroughout its course by minor streams and creeks, and also\r\nby the Woronora River; which exits into the Georges River.\r\n\r\nThe catchment area comprises a large part of the south\r\nwestern urban area of the city of Sydney, and the floods\r\nthat have occurred in the catchment have at times caused\r\nsignificant damage to property.\r\n\r\nTo rationalise future development of the area in the face\r\nof potential flood threats, various numerical and physical\r\nmodels have been developed by both the University of N.S.W.\r\nWater Research Laboratory, and the Public Works\r\nDepartment's Manly Hydraulics Laboratory. The success of\r\nthe models in predicting the flooding characteristics of\r\nvarious flood events depend upon collecting specific flood\r\ndata over a series of floods· for model calibration and\r\nverification. To this end, all known information regarding\r\nprevious floods has been documented (Ref. 1), but there is\r\na need for more comprehensive flood data, especially for\r\nmajor floods.\r\n\r\nManly Hydraulics Laboratory's Data Collection Section was\r\nrequested by the Department's Rivers and Ports Branch to\r\nco-ordinate and undertake flood monitoring at various sites\r\nover the area which is being modelled. These monitoring\r\nsites appear in Figure 1.1. A previous report (Ref. 1)\r\ndetails the results of gauging of minor floods undertaken\r\nin 1978 and 1983.\r\n\r\n\r\nFlood gauging on the 5th and 6th August, 1986 was carried\r\nout by personnel from Manly Hydraulics Laboratory, Rivers\r\nand ports Branch and the Water Research Laboratory.\r\n\r\nThe general extent of the flooding can be seen in Plates\r\n1.1 - 1.3.\r\n\r\nThe current metering lines, flood gauge locations and\r\nautomatic recorder locations from which data was collected\r\nare as follows:\r\n\r\ni) Current metering/gauge observations at:\r\n\r\n1. East Hills Footbridge\r\n2. Milperra Road Bridge\r\n3. Mountbatten Bridge\r\n4. Lansdowne Bridge\r\n\r\nii) Automatic recorders located at:\r\n\r\n1. Milperra Bridge\r\n2. Cutler Road, Lansvale\r\n3. Liverpool. Weir.\r\n\r\nData collection from the Irelands Bridge current metering\r\nstation and the Scrivener Street auto recorder is also\r\nspecified under the Georges river flood data collection\r\nprogram, but inaccessibility to the bridge and equipment\r\nmalfunction respectively, precluded data collection from\r\nthese sites on this occasion.