Groundwater Secure Allocations, Future SAFE Entitlements Baseflow Separation Analysis Documentaiton of Method Baseflow Separation Analysis Documentaiton of Method Published by the Victorian Government Department of Sustainability and Environment Melbourne, May 2012 © The State of Victoria Department of Sustainability and Environment 2012 This publication is copyright. No part may be reproduced by any process except in accordance with the provisions of the Copyright Act 1968. Authorised by the Victorian Government, 8 Nicholson Street, East Melbourne. ISBN 978-1-74287-531-6 (online) For more information contact the DSE Customer Service Centre 136 186 Disclaimer This publication may be of assistance to you but the State of Victoria and its employees do not guarantee that the publication is without flaw of any kind or is wholly appropriate for your particular purposes and therefore disclaims all liability for any error, loss or other consequence which may arise from you relying on any information in this publication. Accessibility If you would like to receive this publication in an accessible format, such as large print or audio, please telephone 136 186, or through the National Relay Service (NRS) using a modem or textphone/teletypewriter (TTY) by dialling 1800 555 677, or email [email protected] This document is also available in PDF format on the internet at www.dse.vic.gov.au i Groundwater SAFE (Secure Allocations, Future Entitlements) Baseflow Separation Analysis Documentaiton of Method About Secure Allocation, Future Entitlements (SAFE) Project Secure Allocations, Future Entitlements (SAFE) was a project funded by the Australian Government through the National Water Commission’s Raising National Water Standards Program to progress the management of groundwater in Victoria. The SAFE project will ensure all of Victoria’s groundwater is included in an appropriate planning and reporting framework and that there is consistency in the way groundwater is managed across the state. This includes developing: • Boundaries: groundwater catchment boundaries that cover all groundwater in the state instead of only part of it; • Resource Share Guidance: making resource share decisions for the State of Victoria; and • Making a change: the approach to moving from the current management framework to a new framework. This report is part of the development of guidance for making resource share decisions for the State of Victoria. The Water Act (1989) provides the overarching policy for water management in Victoria. The objective of additional guidance is to describe an approach that is consistent with the requirements of the Water Act (1989), and provides further detail on how decisions could be made. This report is part of the development of an approach to move from the current management framework to the proposed management framework. The project team recognised the importance of not just recommending changes, but outlining how this could be achieved. This provides a concrete approach to implementation of the recommendations, along with supporting information that assists in making the decision to implement. Objective of this Report The objective of the report “Baseflow Separation and Analysis” was to quantify the baseflow component of streamflow across Victoria over time using a digital recursive filter. Outputs were presented in a format that enabled an understanding of the significance of groundwater baseflow to surface water flow for each station. Report Summary Baseflow analysis using a consistent method was completed for 180 stations, representing the bulk of unregulated gauging stations in Victoria. The Lyne and Hollick digital filter was applied to daily flow volume data for each station with a constant filter parameter of 0.98 adopted. The difference between the total streamflow and the baseflow was calculated as an estimate of the surface runoff (quickflow). The daily baseflow index (BFI, calculated as the baseflow volume relative to the total streamflow) was also calculated for each time step. ii Groundwater SAFE (Secure Allocations, Future Entitlements) Baseflow Separation Analysis Documentaiton of Method Key outcomes Output data for each station includes total stream flow, baseflow, quickflow and baseflow index. This allows detailed interpretation, including: • Seasonal and annual flow duration curves of streamflow, baseflow and surface runoff for each location; • Daily variability of BFI for each month; • Assessment of trends in baseflow over time (at a subset of locations); and • Control charts to help identify deviation in baseflow from reference behaviour in a predictive manner (at a subset of locations). How this report was used This information will help to improve the understanding of the volume and timing of groundwater contributions to stream flows and will form an important dataset for use in the development of groundwater entitlement volumes. It also represents the establishment of a method by which future studies may be undertaken. Figure 1 illustrates how this report fits into the overall SAFE project. FigFigureure 1:1 :Diagram Diagram showing showing how howthis report this reportfits into fits the intooverall the SAFE overall project SAFE project iii Groundwater SAFE (Secure Allocations, Future Entitlements) Baseflow separation and analysis DOCUMENTATION OF METHOD Draft A 23 March 2012 Baseflow separation and analysis DOCUMENTATION OF METHOD Draft A 23 March 2012 Sinclair Knight Merz ABN 37 001 024 095 Floor 11, 452 Flinders Street Melbourne VIC 3000 PO Box 312, Flinders Lane Melbourne VIC 8009 Australia Tel: +61 3 8668 3000 Fax: +61 3 8668 3001 Web: www.globalskm.com COPYRIGHT: The concepts and information contained in this document are the property of Sinclair Knight Merz Pty Ltd. Use or copying of this document in whole or in part without the written permission of Sinclair Knight Merz constitutes an infringement of copyright. LIMITATION: This report has been prepared on behalf of and for the exclusive use of Sinclair Knight Merz Pty Ltd’s Client, and is subject to and issued in connection with the provisions of the agreement between Sinclair Knight Merz and its Client. Sinclair Knight Merz accepts no liability or responsibility whatsoever for or in respect of any use of or reliance upon this report by any third party. The SKM logo trade mark is a registered trade mark of Sinclair Knight Merz Pty Ltd. Documentation of Method Contents 1. Introduction 1 2. Method 2 2.1. Data review 2 2.2. Baseflow separation 4 2.3. Flow duration curves 5 2.4. Daily variability assessment 6 2.5. Trend analysis 7 2.6. Control charts 8 3. Site details 10 4. References 22 SINCLAIR KNIGHT MERZ I:\VWES\Projects\VW06627\Deliverables\r01reb_BaseflowMethod.docx PAGE i Documentation of Method Document history and status Revision Date issued Reviewed by Approved by Date approved Revision type Draft A 23/3/2012 B. Neal B.Neal 23/3/2012 Distribution of copies Revision Copy no Quantity Issued to Draft A 1 1 DSE Printed: 23 March 2012 Last saved: 23 March 2012 06:14 PM File name: I:\VWES\Projects\VW06627\Deliverables\r01reb_BaseflowMethod.docx Author: Rachel Brown Project manager: Rachel Brown Name of organisation: Department of Sustainability and Environment Name of project: Baseflow separation and analysis Name of document: Documentation of Method Document version: Draft A Project number: VW06627 SINCLAIR KNIGHT MERZ I:\VWES\Projects\VW06627\Deliverables\r01reb_BaseflowMethod.docx PAGE ii Documentation of Method 1. Introduction DSE is currently undertaking the SAFE project to reform Victoria’s groundwater management framework. The SAFE project will redefine groundwater management units, establish management guidelines and determine appropriate entitlement volumes (EVs). These EVs will take into account the connective nature of groundwater systems, including their importance to groundwater dependent ecosystems and interaction with surface waters. This current project contributes to the SAFE project by quantifying the baseflow component of streamflow across Victoria over time using a digital recursive filter. This information will help to improve the understanding of the volume and timing of groundwater contributions to streamflow and will form an important dataset for use in the development of groundwater EVs. For this purpose, this current study aims to: Generate a Statewide data set of baseflow indices (BFIs) to streams using a consistent method; Undertake analysis of this data set to allow more detailed interpretation, including: Seasonal and annual flow duration curves of streamflow, baseflow and surface runoff for each location; Daily variability of BFI for each month; Assessment of trends in baseflow over time (at a subset of locations); and Control charts to help identify deviation in baseflow from reference behaviour in a predictive manner (at a subset of locations). These activities were undertaken in a staged approach, with data outputs progressively provided to DSE throughout the course of the project. In total, approximately 180 streamflow gauge locations were analysed in this study. This document provides an overview of the approach used to undertake the baseflow separation and the subsequent analysis. A brief summary of the data used for the study is also included, to provide an understanding of the basis of the analysis. Data outputs generated through this analysis have been provided in a package of text files and spreadsheets. SINCLAIR KNIGHT MERZ I:\VWES\Projects\VW06627\Deliverables\r01reb_BaseflowMethod.docx