Primary Production to Mitigate Water Quality Threats Project. Zone 1A
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DWLBC REPORT Primary Production to Mitigate Water Quality Threats Project Zone 1A Numerical Modelling Study: Conceptual Model Development 2008/12 Primary Production to Mitigate Water Quality Threats Project Zone 1A Numerical Modelling Study: Conceptual Model Development Nikki Harrington, Karen Chambers and Jeff Lawson Resource Allocation Division Department of Water, Land and Biodiversity Conservation January 2007 Report DWLBC 2008/12 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 The 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 2008 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 978-1-921528-00-2 Preferred way to cite this publication Harrington NM, Chambers K & Lawson J, 2007, Primary Production to Mitigate Water Quality Threats Project. Zone 1A Numerical Modelling Study: Conceptual Model Development, DWLBC Report 2008/12, 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 2008/12 iii Zone 1A Numerical Modelling Study: Conceptual Model Development Report DWLBC 2008/12 iv Zone 1A Numerical Modelling Study: Conceptual Model Development CONTENTS FOREWORD...........................................................................................................................iii EXECUTIVE SUMMARY .........................................................................................................1 1. INTRODUCTION...............................................................................................................3 1.1 BACKGROUND..........................................................................................................3 1.2 OBJECTIVES .............................................................................................................3 1.3 METHODOLOGY .......................................................................................................5 2. PREVIOUS STUDIES IN ZONE 1A ..................................................................................7 3. PHYSICAL CHARACTERISTICS OF ZONE 1A ..............................................................9 3.1 TOPOGRAPHY ..........................................................................................................9 3.2 CLIMATE....................................................................................................................9 3.3 LAND USE .................................................................................................................9 3.4 SURFACE WATER ....................................................................................................9 4. GEOLOGICAL SETTING................................................................................................11 5. HYDROGEOLOGY OF ZONE 1A...................................................................................13 5.1 OVERVIEW AND STRATIGRAPHIC MODEL OF ZONE 1A ...................................13 5.2 TERTIARY CONFINED SAND AQUIFER (DILWYN FORMATION) ........................15 5.2.1 General Characteristics .....................................................................................................15 5.2.2 Water Sources ...................................................................................................................15 5.2.3 Water Outflows...................................................................................................................18 5.2.4 Groundwater Flow and Hydraulic Heads ...........................................................................18 5.2.5 Aquifer Properties ..............................................................................................................22 5.2.6 Groundwater Salinity..........................................................................................................22 5.2.7 Summary of Tertiary Confined Sand Aquifer Conceptual Model.......................................22 5.3 UPPER TERTIARY AQUITARD (DILWYN CLAY, NARRAWATURK MARL AND MEPUNGA FORMATIONS) ............................................................................23 5.3.1 General Characteristics .....................................................................................................23 5.3.2 Groundwater Flow..............................................................................................................23 5.3.3 Aquitard Properties ............................................................................................................24 5.3.4 Groundwater Salinity..........................................................................................................24 5.3.5 Summary of Tertiary Aquitard Conceptual Model..............................................................24 5.4 GAMBIER LIMESTONE (UNCONFINED AQUIFER)...............................................25 5.4.1 General Characteristics .....................................................................................................25 5.4.2 Water Sources ...................................................................................................................25 5.4.3 Water Outflows...................................................................................................................32 5.4.4 Groundwater Flow..............................................................................................................34 Report DWLBC 2008/12 v Zone 1A Numerical Modelling Study: Conceptual Model Development CONTENTS 5.4.5 Aquifer Properties ..............................................................................................................34 5.4.6 Groundwater Salinity..........................................................................................................35 5.4.7 Water Balance for the Unconfined Aquifer in Zone 1A......................................................35 5.4.8 Summary of Gambier Limestone conceptual model..........................................................41 5.5 PLIO-PLEISTOCENE SANDS AQUIFER (BRIDGEWATER FORMATION)............45 5.5.1 General Characteristics .....................................................................................................45 5.5.2 Water Sources ...................................................................................................................45 5.5.3 Rainfall Recharge ..............................................................................................................45 5.5.4 Groundwater Flow..............................................................................................................45 5.5.5 Aquifer Properties ..............................................................................................................46 5.5.6 Groundwater Salinity..........................................................................................................46 5.5.7 Summary of Bridgewater Formation Conceptual Model....................................................46 6. APPLICATION OF THE CONCEPTUAL MODEL TO DEVELOPING THE NUMERICAL MODEL AND ITS LIMITATIONS..............................................................47 6.1 SUMMARY ...............................................................................................................47 6.2 LIMITATIONS OF THE CONCEPTUAL MODEL .....................................................47 7. CONCLUSIONS AND RECOMMENDATIONS...............................................................49 UNITS OF MEASUREMENT .................................................................................................51