North Parramatta Precinct

The flood study was undertaken in two stages. The aims of each stage of the flood study are:\r\n\r\n#Stage 1 - Hydrological Analysis\r\n* Collate all the relevant data on Council's existing stormwater drainage system;\r\n* Develop a hydrological model to investigate the drainage system performance for the\r\n5, 10, 20, 100, 200 year ARI storms and the PMF;\r\n* Identify the flooding problem areas for existing development conditions within the\r\nstudy area;\r\n* Identify the flooding problem areas for ultimate development conditions (represented\r\nby all of the study area utilising OSD).\r\n#Stage 2 - Hydraulic Analysis\r\n* Estimate the extent of flooding and flood levels for the PMF, 20 and 100 year ARI\r\nfloods for existing development conditions, and\r\n* Estimate the 20 and 100 year ARI flood levels and extent of flooding for ultimate\r\ndevelopment conditions.\r\n\r\n#Study Scope\r\n\r\nThe scope of the Stage 1 flood study was to use a hydrological model to estimate peak pipe and\r\noverland flows throughout the North Parramatta Precinct. The peak overland flows were used\r\nin the hydraulic modelling in Stage 2 to estimate peak flood levels and flood extents.\r\n\r\nDesign Rainfall Intensities used for the estimation of peak flows were obtained from Baulkham\r\nHills Shire Council "Design Guidelines for Subdivisions / Developments." Storm durations\r\nfrom 5 minutes to 4.5 hours were used to produce rainfall patterns from which the D NS\r\nmodel estimates peak pipe and overland flows.\r\n\r\nThe 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)\r\n