Water Availability in the Paroo a Report to the Australian Government from the CSIRO Murray-Darling Basin Sustainable Yields Project
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Water Availability in the Paroo A report to the Australian Government from the CSIRO Murray-Darling Basin Sustainable Yields Project November 2007 Murray-Darling Basin Sustainable Yields Project acknowledgments The Murray-Darling Basin Sustainable Yields Project is being undertaken by CSIRO under the Australian Government's Raising National Water Standards Program, administered by the National Water Commission. Important aspects of the work were undertaken by Sinclair Knight Merz; Resource & Environmental Management Pty Ltd; Department of Water and Energy (New South Wales); Department of Natural Resources and Water (Queensland); Murray-Darling Basin Commission; Department of Water, Land and Biodiversity Conservation (South Australia); Bureau of Rural Sciences; Salient Solutions Australia Pty Ltd; eWater Cooperative Research Centre; University of Melbourne; Webb, McKeown and Associates Pty Ltd; and several individual sub-contractors. Murray-Darling Basin Sustainable Yields Project disclaimers Derived from or contains data and/or software provided by the Organisations. The Organisations give no warranty in relation to the data and/or software they provided (including accuracy, reliability, completeness, currency or suitability) and accept no liability (including without limitation, liability in negligence) for any loss, damage or costs (including consequential damage) relating to any use or reliance on that data or software including any material derived from that data and software. Data must not be used for direct marketing or be used in breach of the privacy laws. Organisations include: Department of Water, Land and Biodiversity Conservation (South Australia), Department of Sustainability and Environment (Victoria), Department of Water and Energy (New South Wales), Department of Natural Resources and Water (Queensland), Murray-Darling Basin Commission. CSIRO advises that the information contained in this publication comprises general statements based on scientific research. The reader is advised and needs to be aware that such information may be incomplete or unable to be used in any specific situation. No reliance or actions must therefore be made on that information without seeking prior expert professional, scientific and technical advice. To the extent permitted by law, CSIRO (including its employees and consultants) excludes all liability to any person for any consequences, including but not limited to all losses, damages, costs, expenses and any other compensation, arising directly or indirectly from using this publication (in part or in whole) and any information or material contained in it. Data is assumed to be correct as received from the Organisations. Citation CSIRO (2007). Water availability in the Paroo. A report to the Australian Government from the CSIRO Murray-Darling Basin Sustainable Yields Project. CSIRO, Australia. 88 pp Publication Details Published by CSIRO © 2007 all rights reserved. This work is copyright. Apart from any use as permitted under the Copyright Act 1968, no part may be reproduced by any process without prior written permission from CSIRO. ISSN 1835-095X Photo on cover: Claypan depression in Nocolenche Nature Reserve by Richard Kingsford, courtesy of NSW Department of Environment and Climate Change (NSW DECC) Director’s Foreword Following the November 2006 Summit on the Southern Murray-Darling Basin, the Prime Minister and Murray-Darling Basin state Premiers commissioned CSIRO to report on sustainable yields of surface and groundwater systems within the Murray-Darling Basin. This report from the CSIRO Murray-Darling Basin Sustainable Yields Project details the assessments for one of 18 regions that encompass the Basin. The CSIRO Murray-Darling Basin Sustainable Yields Project is providing critical information on current and likely future water availability. This information will help governments, industry and communities consider the environmental, social and economic aspects of the sustainable use and management of the precious water assets of the Murray-Darling Basin. The project is the first rigorous attempt worldwide to estimate the impacts of catchment development, changing groundwater extraction, climate variability and anticipated climate change, on water resources at a basin-scale, explicitly considering the connectivity of surface and groundwater systems. To do this, we are undertaking the most comprehensive hydrologic modelling ever attempted for the entire Basin, using rainfall-runoff models, groundwater recharge models, river system models and groundwater models, and considering all upstream-downstream and surface- subsurface connections. We are complementing this work with detailed surface water accounting across the Basin – never before has surface water accounting been done in such detail in Australia, over such a large area, and integrating so many different data sources. To deliver on the project CSIRO is drawing on the scientific leadership and technical expertise of national and state government agencies in Queensland, New South Wales, Victoria, the Australian Capital Territory and South Australia, as well as the Murray-Darling Basin Commission and Australia’s leading industry consultants. The project is dependent on the cooperative participation of over 15 government and private sector organisations contributing over 100 individuals. The project has established a comprehensive but efficient process of internal and external quality assurance on all the work performed and all the results delivered, including advice from senior academic, industry and government experts. The project is led by the Water for a Healthy Country Flagship, a CSIRO-led research initiative which was set up to deliver the science required for sustainable management of water resources in Australia. The Flagship goal is to achieve a tenfold increase in the social, economic and environmental benefits from water by 2025. By building the capacity and capability required to deliver on this ambitious goal, the Flagship is ideally positioned to accept the challenge presented by this complex integrative project. CSIRO has given the Murray-Darling Basin Sustainable Yields Project its highest priority. It is in that context that I am very pleased and proud to commend this report to the Australian Government. Dr Tom Hatton Director, Water for a Healthy Country National Research Flagships CSIRO Executive Summary Background The CSIRO Murray-Darling Basin Sustainable Yields Project is providing governments with a robust, basin-wide estimate of water availability on an individual catchment and aquifer basis, taking into account climate change and other risks. It will be the most comprehensive basin-wide assessment of water availability undertaken to date. This report describes the assessment undertaken for the Paroo region. While key aspects of the assessment and modelling methods used in the Project are contained in this report, fuller methodological descriptions will be provided in a series of project technical reports. Executive The Paroo region is situated in the far north-west of the Murray-Darling Basin (MDB). Located predominantly in southern Queensland the region represents 3.4 percent of the total area of the MDB. The region is based around the ephemeral Paroo River. The population of the region is less than 700 (Or less than 0.1 percent of the MDB total). Settlements include Wanaaring, Hungerford and Eulo. The predominant land use is broad-acre livestock grazing for beef and wool Summary production. There is no commercial forestry in this part of the MDB, and the relatively few farm dams are primarily for stock watering. Current surface water diversions for irrigation make up less than 0.1 percent of the MDB total, and groundwater use is also less than 0.1 of the MDB total. (This excludes use from the confined aquifers of the Great Artesian Basin, which are the major water sources for the region). There are no major dams and very little irrigation. The numerous wetlands of the Paroo region are amongst the most important in the MDB. Wetlands of national importance include Currawinya Lakes (a Ramsar site), the Paroo River Waterholes and the Paroo Distributary Channels. The Paroo River Wetlands in New South Wales are now listed as a Ramsar site. These wetlands include the Nocoleche Nature Reserve and two of the many lakes of the Paroo Overflow which are about 120 km south of the Nocoleche Nature Reserve. The Paroo Overflow Lakes are outside of the Paroo region as defined for this study, but are considered in this report as they are dependent on floodwaters from the Paroo River. The Lakes are on the floodplain south of Wanaaring in New South Wales where floods typically dissipate without reaching the Darling River. Only the Currawinya Lakes (Numalla and Wyara) and the Paroo Overflow Lakes are assessed in this report. Key messages The key messages relating to climate, surface water resources, groundwater and the environment are presented below for scenarios of current and possible future conditions. The scenarios assessed are defined in Chapter 1. Historical climate and current development (Scenario A) The average annual rainfall over the entire Paroo region is 311 mm. Modelled average annual runoff is 17 mm, or about 2 percent of the total runoff for the MDB. Most of the rainfall and runoff occurs in summer and early autumn. Runoff and river flows are intermittent with the majority occurring as large infrequent floods. Analysis of the pre-development flows along the Paroo River indicates that it changes