DWLBC REPORT Assessment of Surface Water Resources of Patawalonga Catchment and the Impact of Farm Dam Development 2007/09 Assessment of Surface Water Resources of Patawalonga Catchment and the Impact of Farm Dam Development Kim Teoh Knowledge and Information Division Department of Water, Land and Biodiversity Conservation January 2006 Report DWLBC 2007/09 Knowledge and Information Division Department of Water, Land and Biodiversity Conservation 25 Grenfell Street, Adelaide GPO Box 2834, Adelaide SA 5001 Telephone National (08) 8463 6946 International +61 8 8463 6946 Fax National (08) 8463 6999 International +61 8 8463 6999 Website www.dwlbc.sa.gov.au Disclaimer Department of Water, Land and Biodiversity Conservation and its employees do not warrant or make any representation regarding the use, or results of the use, of the information contained herein as regards to its correctness, accuracy, reliability, currency or otherwise. The Department of Water, Land and Biodiversity Conservation and its employees expressly disclaims all liability or responsibility to any person using the information or advice. Information contained in this document is correct at the time of writing. © Government of South Australia, through the Department of Water, Land and Biodiversity Conservation 2007 This work is Copyright. Apart from any use permitted under the Copyright Act 1968 (Cwlth), no part may be reproduced by any process without prior written permission obtained from the Department of Water, Land and Biodiversity Conservation. Requests and enquiries concerning reproduction and rights should be directed to the Chief Executive, Department of Water, Land and Biodiversity Conservation, GPO Box 2834, Adelaide SA 5001. ISBN-13 978-1-921218-45-3 Preferred way to cite this publication Teoh, K 2006, Assessment of Surface Water Resources of Patawalonga Catchment and the Impact of Farm Dam Development. DWLBC Report 2007/09, Government of South Australia, through Department of Water, Land and Biodiversity Conservation, Adelaide. FOREWORD South Australia’s unique and precious natural resources are fundamental to the economic and social wellbeing of the State. It is critical that these resources are managed in a sustainable manner to safeguard them both for current users and for future generations. The Department of Water, Land and Biodiversity Conservation (DWLBC) strives to ensure that our natural resources are managed so that they are available for all users, including the environment. In order for us to best manage these natural resources it is imperative that we have a sound knowledge of their condition and how they are likely to respond to management changes. DWLBC scientific and technical staff continues to improve this knowledge through undertaking investigations, technical reviews and resource modelling. Rob Freeman CHIEF EXECUTIVE DEPARTMENT OF WATER, LAND AND BIODIVERSITY CONSERVATION Report DWLBC 2007/09 iii Assessment of Surface Water Resources of Patawalonga Catchment and the Impact of Farm Dam Development Report DWLBC 2007/09 iv Assessment of Surface Water Resources of Patawalonga Catchment and the Impact of Farm Dam Development ACKNOWLEDGEMENTS The writer wishes to thank the following people for their assistance in the preparation of this report. Department of Water, Land and Biodiversity Conservation David Cresswell, Martin Fidge, Robin Leaney, Edward Pikusa, Doug McMurray, Bruce Murdoch. Patawalonga Catchment Water Management Board Keith Downard, Marion Santich, Pedro Schultz. Transport, Energy and Infrastructure David Kemp Water Data Services Bruce Nicholson. Australian Water Environments Geoff Fisher. Richard Clark and Associates Richard Clark, who acts as the peer reviewer for this report. Report DWLBC 2007/09 v Assessment of Surface Water Resources of Patawalonga Catchment and the Impact of Farm Dam Development Report DWLBC 2007/09 vi Assessment of Surface Water Resources of Patawalonga Catchment and the Impact of Farm Dam Development CONTENTS FOREWORD...........................................................................................................................iii ACKNOWLEDGEMENTS........................................................................................................v EXECUTIVE SUMMARY .........................................................................................................1 KEY FINDINGS ...................................................................................................................2 CONCLUSIONS ..................................................................................................................3 RECOMMENDATIONS .......................................................................................................4 1. INTRODUCTION.............................................................................................................5 1.1 PURPOSE ................................................................................................................5 1.2 BACKGROUND........................................................................................................5 1.3 APPROACH TO STUDY ..........................................................................................5 2. CATCHMENT DESCRIPTION, DAMS AND WATER USE ESTIMATION.....................7 2.1 GENERAL DESCRIPTION.......................................................................................7 2.2 FARM DAMS AND WATER STORAGES...............................................................10 2.3 LAND USE AND INFERRED IRRIGATION VOLUMES .........................................13 3. DATA DESCRIPTION AND ANALYSES .....................................................................17 3.1 RAINFALL DATA....................................................................................................17 3.1.1 Processing rainfall data ................................................................................................. 17 3.1.2 Rainfall data analysis – temporal variation and trends.................................................. 19 3.2 EVAPORATION DATA ...........................................................................................21 3.3 STREAMFLOW DATA............................................................................................21 3.3.1 Flow analysis ................................................................................................................. 23 3.3.2 Heathfield WWTP discharge ......................................................................................... 25 3.3.3 Transmission losses ...................................................................................................... 26 4. MODELLING METHODOLOGY, NODES AND INPUTS .............................................27 4.1 OVERVIEW ............................................................................................................27 4.2 MODEL CONSTRUCTION.....................................................................................28 4.2.1 Rainfall and evaporation data........................................................................................ 28 4.2.2 Flow data used for calibration........................................................................................ 33 4.2.3 Identification of minor subcatchments ........................................................................... 33 4.2.4 Estimation of impervious areas and selection of models .............................................. 34 4.2.5 Selection of rural runoff models and parameters .......................................................... 36 4.2.6 Dam nodes .................................................................................................................... 36 4.2.7 Diversion weir (loss) and routing nodes ........................................................................ 37 Report DWLBC 2007/09 vii Assessment of Surface Water Resources of Patawalonga Catchment and the Impact of Farm Dam Development CONTENTS 5. FLOW CALIBRATION AND INITIAL RESULTS..........................................................39 5.1 METHODOLOGY ...................................................................................................39 5.2 ASSUMPTIONS......................................................................................................39 5.3 CALIBRATION........................................................................................................41 5.4 RESULTS ...............................................................................................................44 5.4.1 Catchment yield – current development scenario ......................................................... 44 5.4.2 Morphettville Racecourse, Oaklands Park, Park Lands Creek ..................................... 45 5.4.3 Runoff coefficient........................................................................................................... 45 5.4.4 Model catchment boundary ........................................................................................... 45 6. FARM DAM SCENARIO MODELLING: RESULTS, DISCUSSION.............................47 6.1 SCENARIOS ..........................................................................................................47 6.2 WITHOUT FARM DAMS ........................................................................................47 6.3 DAM USAGE INCREASED TO 100% OF DAM CAPACITY ..................................48 6.4 MAXIMUM FARM DAM DEVELOPMENT, WITH AND WITHOUT LOW FLOW BYPASSES ............................................................................................................48