RIVER BASIN REPORT HOPKINS BASIN (SECOND EDITION) 26 March 2001 Flood Data Transfer Project Department of Natural Resources and Environment This project has been supported by the Prepared by: Natural Heritage Trust 390 St.Kilda Rd. Melbourne 3004 Helping Communities Ph: (03) 9272-6666 Helping Australia Fax: (03) 9272-6611 DEPARTMENT OF NATURAL RESOURCES AND ENVIRONMENT River Basin Report - Hopkins Basin (Second Edition) DISTRIBUTION RECORD Copy Company/Position Name No. 1 Department of Natural Resources and Environment Ian Gauntlett 2 Project File VV8159.001 3Library VV8159.093.2 VV8159.093.Rev2 (i) DEPARTMENT OF NATURAL RESOURCES AND ENVIRONMENT River Basin Report - Hopkins Basin (Second Edition) REVISION LIST Revision Revision Description of Approved Date Number Date Revision By Revision Effected A 24/5/2000 Issued for Client Comments D B Sheehan 24/5/2000 0 13/11/00 Issued for General Distribution D B Sheehan 16/11/00 1 12/12/00 Project 3 report merged in D B Sheehan 12/12/00 2 26/3/01 Amended for Beaufort mapping D B Sheehan 27/3/01 VV8159.093.2 VV8159.093.Rev2 (ii) DEPARTMENT OF NATURAL RESOURCES AND ENVIRONMENT River Basin Report - Hopkins Basin (Second Edition) DEPARTMENT OF NATURAL RESOURCES AND ENVIRONMENT RIVER BASIN REPORT - HOPKINS BASIN (SECOND EDITION) TABLE OF CONTENTS PAGE NO. 1 INTRODUCTION 1 1.1 Objectives, Scope of Works and Deliverables 1 1.2 Areas of Responsibility 2 1.3 Report Contents 4 2 FLOODING CHARACTERISTICS 5 2.1 Available Information 5 2.2 Drainage Characteristics 5 2.3 Flood Frequency 7 2.4 Extent and Characteristics of Flooding 7 3 CATALOGUING AND MAPPING METHODOLOGY 8 3.1 Overview 8 3.2 GIS Content 8 4 INTERPRETIVE MAPPING 10 4.1 Coverage 10 4.2 Scope and Objectives of the Interpretive Mapping 10 4.3 Information Used 11 4.4 Criteria for Delineation of Floodways and 1% AEP Flood Extents 12 4.5 Basis of Floodway and 1% AEP Flood Extent Delineation 14 5 INTERPRETIVE MAPPING (FOR BALLARAT AND PYRENEES) 19 5.1 Scope and Objectives of the Interpretive Mapping 19 5.2 Information Used 19 5.3 Criteria for Delineation of Floodways and 1% AEP Flood Extents 20 VV8159.093.2 VV8159.093.Rev2 (iii) DEPARTMENT OF NATURAL RESOURCES AND ENVIRONMENT River Basin Report - Hopkins Basin (Second Edition) 5.4 Basis of Floodway and 1% AEP Flood Extent Delineation 22 6 MAPPING OUTPUT 23 6.1 Hard Copy Mapping 23 6.2 Digital Mapping 24 7 ASSESSMENT OF DATA AND CONCLUSIONS 30 7.1 Assessment of Data and Interpreted Extents 30 7.2 Conclusions 31 8 ASSESSMENT OF DATA AND CONCLUSIONS (FOR BALLARAT AND PYRENEES) 32 8.1 Assessment of Data and Interpreted Extents 32 8.2 Conclusions 33 9 BIBLIOGRAPHY 34 APPENDIX A MAPPING METHODOLOGY APPENDIX B LIST OF CONTACTS MADE APPENDIX C FLOOD FREQUENCY INFORMATION VV8159.093.2 VV8159.093.Rev2 (iv) DEPARTMENT OF NATURAL RESOURCES AND ENVIRONMENT River Basin Report - Hopkins Basin (Second Edition) 1 INTRODUCTION 1.1 Objectives, Scope of Works and Deliverables The objectives of the digital data transfer project as stated in the Project Brief were: • To produce and deliver high quality, consistent and comprehensive GIS layer and hardcopy map products showing a range of flood data for urban and rural flood plains in Victoria. • To deliver, in hardcopy and digital form, a series of flood information reports based on Municipal and river basin boundaries. • As part of the above, to reorganise the storage of existing flood and related information within FPM (Floodplain Management Group of NRE). There are four major elements of the project: a) Collection and transfer of NRE and other authorities flood information - a data review and management process. b) Recording and analysing the flood information in a Geographical Information System (GIS). c) Reorganisation of the source flood data under a new cataloguing system for re- storing at NRE. d) Preparation of reports and mapping to record a), b) and c) A key output of the flood data transfer project is the formulation of Flood Data Maps which detail all captured data and Flood Planning Maps which provide 1% AEP1 Flood Extent and Floodway delineation. Both the 1% AEP Flood Extent and Floodway mapping are critical input to the flood management and land use control processes being developed by the CMA's and Local Government. Dialogue with municipalities was a key element of the project. This included soliciting information from them and seeking advice regarding towns to be mapped in detail and the accuracy and presentation of reports and mapping. The Floodway and 1% AEP Flood Extent mapping has only been carried out for locations where information was available and of sufficient quality to justify delineation. Hence, the extent of Floodway and 1% AEP Flood Extent mapping is not a comprehensive coverage of all flood plains or all flooding problem areas. The Flood Data maps provide a record of available past mapping and as such known problem areas. Ã$QQXDOÃ([FHHGDQFHÃ3UREDELOLW\ VV8159.093.2 VV8159.093.Rev2 1 DEPARTMENT OF NATURAL RESOURCES AND ENVIRONMENT River Basin Report - Hopkins Basin (Second Edition) The project requires delivery of three levels of reporting, namely: • Flood Mapping Reports - are, as stated in the Brief, to provide an easy to use reference source for flood information at the municipal scale in support of planning and other related activities; • River Basin Reports - are, as stated in the Brief, to provide an easy to use reference source for flood information at the river basin scale. The river basin reports will be a major source document on flooding for CMA's in the delivery of floodplain management services. • A Glenelg-Hopkins Catchment Management Report - an aggregate report covering those parts of the three river basin reports within the Glenelg-Hopkins CMA operating area. Digital maps in GIS format facilitate access to flood information that can be readily, reviewed, analysed and amended. This River Basin Report is for the entire Hopkins Basin. It consists of extracts from detailed sections of the previous report prepared by Egis (River Basin Report – Hopkins River Basin, 1 May 2000) for mapping in the municipalities of Ballarat and Pyrenees, as well as descriptions of new mapping in the municipalities of Ararat, Corangamite, Moyne, Southern Grampians and Warrnambool. 1.2 Areas of Responsibility The area covered by the Hopkins Basin are shown in Figure 1.1, Locality Plan. Figure 1.1 highlights the following: • Glenelg Hopkins Catchment Management Authority has jurisdiction over the entire Hopkins Basin. • Parts of the Shire of Pyrenees and City of Ballarat are within the Hopkins Basin. These municipalities were mapped by Egis as part of a previous project. • Parts of the Shire of Moyne, Rural City of Ararat, Shire of Southern Grampians and all of the City of Warrnambool (all within the project area), and part of the Shire of Corangamite (outside the project area) are within the Hopkins Basin. These municipalities contain new mapping. The particular areas of responsibility for each municipality are summarised in Table 1.1. The river systems covered are the Hopkins and Merri Rivers. VV8159.093.2 VV8159.093.Rev2 2 DEPARTMENT OF NATURAL RESOURCES AND ENVIRONMENT River Basin Report - Hopkins Basin (Second Edition) WIMMERAWIMMERA BASINBASIN NORTHNORTH CENTRALCENTRAL POMONALPOMONAL CMACMA WIMMERAWIMMERA ARARATARARAT LODDONLODDON CMACMA LEXTONLEXTON BASINBASIN BUANGORBUANGOR CITYCITY OFOF RURALRURAL CITYCITY MAROONAMAROONA BEAUFORTBEAUFORT BALLARATBALLARAT GLENELGGLENELG OFOF ARARATARARAT BURRUMBEETBURRUMBEET BASINBASIN SHIRESHIRE OFOF WILLAURAWILLAURA PYRENEESPYRENEES BALLARATBALLARAT GLENELGGLENELG HOPKINSHOPKINS DUNKELDDUNKELD DUNKELDDUNKELD CMACMA STREATHAMSTREATHAM SHIRESHIRE OFOF SKIPTONSKIPTON SHIRESHIRE OFOF LAKELAKE BOLACBOLAC SHIRESHIRE OFOF SOUTHERNSOUTHERN GRAMPIANSGRAMPIANS GOLDENGOLDEN PLAINSPLAINS CORANGAMITECORANGAMITE PENSHURSTPENSHURST HH OO PP KK II NN SS CORANGAMITECORANGAMITE HH OO PP KK II NN SS CMACMA BB AA SS II NN % CARAMUTCARAMUT BB AA SS II NN CORANGAMITECORANGAMITE 0 10 20 SHIRESHIRE OFOF MOYNEMOYNE SHIRESHIRE OFOF MOYNEMOYNE BASINBASIN Kilometres MORTLAKEMORTLAKE HAWKESDALEHAWKESDALE SHIRESHIRE OFOF WOOLSTHORPEWOOLSTHORPE CORANGAMITECORANGAMITE PORTLANDPORTLAND L E G E N D TERANGTERANG CAMPERDOWNCAMPERDOWN BASINBASIN River Basin Boundaries Municipal Boundaries COBDENCOBDEN CMA Boundaries PORTPORT FAIRYFAIRY WARRNAMBOOLWARRNAMBOOL Study Area Boundary OTWAYOTWAY CITYCITY OFOF BASINBASIN WARRNAMBOOLWARRNAMBOOL BASINBASIN Hopkins PETERBOROUGHPETERBOROUGH Basin Figure 1.1 – Hopkins Locality Plan VV8159.093.2 VV8159.093.Rev2 3 DEPARTMENT OF NATURAL RESOURCES AND ENVIRONMENT River Basin Report - Hopkins Basin (Second Edition) Table 1.1 - Hopkins Basin Responsibilities Municipality Extent of Responsibility for River and Creeks Ararat - Hopkins River and tributaries upstream of Aston’s Road near Chatsworth - Fiery Creek and Tributaries upstream of Myuna Lane near Woorndoo Ballarat Upper reaches of Mount Emu Creek’s tributaries Corangamite Mount Emu Creek (shared with Moyne) and tributaries Moyne - Merri River System upstream of the City of Warrnambool’s boundary near the township of Bushfield - Hopkins River System upstream of the City of Warrnambool’s boundary at the Princes Highway, Allansford - Mount Emu Creek (shared with Corangamite) Pyrenees Upper reaches of Mount Emu Creek and tributaries Southern Upper reaches of the Merri and Hopkins Rivers tributaries Grampians Warrnambool Merri and Hopkins Rivers within the City boundary 1.3 Report Contents The following sections of the report cover: Section 2. Flooding