Lower Fitzroy River Groundwater Review
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Lower Fitzroy River Groundwater Review A report prepared for Department of Water W.A. FINAL Version 15 May 2015 Lower Fitzroy River Groundwater Review 1 How to cite this report: Harrington, G.A. and Harrington, N.M. (2015). Lower Fitzroy River Groundwater Review. A report prepared by Innovative Groundwater Solutions for Department of Water, 15 May 2015. Disclaimer This report is solely for the use of Department of Water WA (DoW) and may not contain sufficient information for purposes of other parties or for other uses. Any reliance on this report by third parties shall be at such parties’ sole risk. The information in this report is considered to be accurate with respect to information provided by DoW at the time of investigation. IGS has used the methodology and sources of information outlined within this report and has made no independent verification of this information beyond the agreed scope of works. IGS assumes no responsibility for any inaccuracies or omissions. No indications were found during our investigations that the information provided to IGS was false. Innovative Groundwater Solutions Pty Ltd. 3 Cockle Court, Middleton SA 5213 Phone: 0458 636 988 ABN: 17 164 365 495 ACN: 164 365 495 Web: www.innovativegroundwater.com.au Email: [email protected] 15 May 2015 Lower Fitzroy River Groundwater Review 2 Executive Summary Water for Food is a Royalties for Regions initiative that aims to lift agricultural productivity and encourage capital investment in the agricultural sector in a number of regions across Western Australia. In the West Kimberley region, the lower Fitzroy River valley is seen as a priority area where water resources can be developed to support pastoral diversification. This report presents the findings of a review into the groundwater resources of the region, beginning with a synthesis of the results of recent hydrogeological, ecological and cultural investigations. In short, these studies have confirmed the ecological significance of the Fitzroy River and the strong ties that local Aboriginal people have with the river and its floodplain for cultural and heritage purposes. The nature of surface water – groundwater interactions in the catchment is extremely complex, and there is insufficient knowledge of the potential ecological response to altered hydrological regimes. This applies to surface water levels and flows, as well as groundwater levels and fluxes. The level of existing knowledge for the different aquifer systems in the lower Fitzroy River valley is generally poor as there have been no previous catchment-scale investigations that have collected and assimilated consistent hydrogeological data. However, isolated knowledge of aquifer thicknesses, bore yields, groundwater quality and monitoring records does exist around water supplies for towns such as Fitzroy Crossing and Camballin, and Aboriginal communities. Similar information and knowledge has also been acquired as part of the exploration and regulatory processes for mining and unconventional gas activities. The review has identified the regional Canning Basin aquifers as offering the greatest opportunities for large scale groundwater development in the lower Fitzroy River valley; the combined Poole Sandstone and Grant Group aquifers, as well as the Devonian limestone, are seen as particularly prospective resources. Groundwater in these aquifers is generally of low-moderate salinity and bore yields are suitable for sustaining large developments. There are two main advantages of developing the regional aquifers over the shallow alluvial aquifers that follow the main rivers. Firstly, they have large volumes of groundwater in storage and can therefore withstand the effects of short-term climate variability on recharge rates. Secondly, they will generally be less connected to groundwater-dependent assets of ecological and cultural significance at the ground surface. However, previous studies in the region have already shown that this assumption does not always hold, as part of the 15 May 2015 Lower Fitzroy River Groundwater Review 3 Fitzroy River is thought to be sustained by discharge from the deep Poole Sandstone during the dry season. Despite the opportunities offered by the regional aquifers, there are a number of significant knowledge gaps that need to be addressed in order to give potential investors confidence of groundwater resource availability, and to enable the determination of sustainable extraction limits. It must be stressed that the determination of extraction limits requires considerable hydrogeological process understanding and stakeholder involvement, and the volume of water that can be pumped sustainably is only a fraction of the total volume of water in storage. There is a need to map extents of the main aquifers and their relationships to adjacent aquitards; to understand and quantify groundwater recharge processes; to map groundwater flow directions and to estimate residence times. There is also a need to better define potential constraints. While a lot of the water-dependent ecological and cultural assets of the region have already been mapped, it is unknown which of these – besides the Fitzroy River – are groundwater dependent. There is also limited understanding of environmental water requirements and the potential changes to ecology that could arise under an altered hydrological regime. A comprehensive technical work program has been recommended to address the knowledge gaps that have greatest bearing on future groundwater development opportunities. This program includes a regional airborne geophysics survey, the establishment of a meaningful and enduring groundwater monitoring network, a regional-scale groundwater recharge and flow investigation of the most prospective aquifers, focused investigations at sites identified for targeted development, and an assessment of the level of groundwater dependence of known water-related assets. It is also recommended that the WIN database be updated with the large volume of historical information on water level monitoring and water quality analyses that currently reside in technical reports and thus cannot be easily analysed. 15 May 2015 Lower Fitzroy River Groundwater Review 4 Contents Executive Summary 2 Contents 4 List of Figures 6 List of Tables 8 1. Introduction 10 1.1 Potential Constraints on Developing Water Resources 10 1.2 Scope and Objectives 14 2. The Fitzroy Catchment 15 2.1 Physical Description and Climate Conditions 15 2.2 Geological and Hydrogeological Setting 16 2.4 Land Use and Cultural Values 21 2.5 Surface Water Hydrology 24 2.5.1 Surface Water Flows 24 2.5.2 Control Structures 26 2.5.3 Surface Water Salinity 27 2.6 Ecology 27 2.7 History of Proposals to Use Water Resources of the Fitzroy River Valley 30 3. Overview of Recent Work 32 3.1 Hydrogeological Investigations 32 Northern Australia Sustainable Yields (2008-09) 32 Fitzroy River integrated ground and surface water hydrology assessment (2008- 11) 33 Surface water – groundwater interactions in the lower Fitzroy River, WA (2008- 11) 34 Regional AEM Survey 36 3.2 Ecological 36 Northern Australia Sustainable Yields (2008-09) 36 Northern Australia Water Futures Assessment (2008-12) 37 Northern Australia Aquatic Ecological Assets Project (2011) 39 3.3 Cultural ties to water resources 40 Indigenous socio-economic values and river flows (2008-10) 41 Comparison of Knowledge Bases 42 15 May 2015 Lower Fitzroy River Groundwater Review 5 4. Knowledge of the Groundwater Systems 43 4.1 Regional Aquifers 43 4.1.1 Overview 43 4.1.2 Devonian Limestone 47 4.1.3 Fairfield Group 50 4.1.4 Poole Sandstone and Grant Group 51 4.1.5 Noonkanbah Formation 54 4.1.6 Liveringa Group 56 4.1.7 Wallal Sandstone / Erskine Sandstone /Alexander Formation 60 4.2 Alluvial Aquifer 61 Data Availability 61 Groundwater Recharge 62 Groundwater Flow and Discharge 62 Groundwater Residence Times 64 Aquifer Properties 64 Estimated Groundwater Storage 64 Bore Yields and Groundwater Salinities 64 4.3 Surface Water-Groundwater Interactions 65 4.3.1 Regional Context 65 4.3.2 Detailed Understanding for the Lower Fitzroy River 66 4.3.3 Broader-Scale Insights from the AEM Survey 70 4.3.4 Potential Impacts of Future Groundwater Pumping on River Flow 70 5. Existing and Potential Future Groundwater Users 73 5.1 Licensed Allocations 73 5.1.1 Overview 73 5.1.2 Town and Community Water Supplies 75 5.2 Groundwater Dependent Ecosystems 75 5.2.1 Identified Ecological Values 75 5.2.2 Groundwater Dependence of Ecological Values 77 5.2.3 Identifying Likely Impacts of Changes in Groundwater Levels to GDEs 78 5.3 Cultural and Heritage Values 79 5.4 Mining and Unconventional Gas 80 6. Development Opportunities and Constraints 83 6.1 Prospective Groundwater Resources 83 Poole Sandstone / Grant Group 83 Devonian Limestone 84 15 May 2015 Lower Fitzroy River Groundwater Review 6 Alluvial Aquifer 84 6.2 Managed Aquifer Recharge 85 6.3 Targeted Development Areas 86 7. Critical Knowledge Gaps 88 7.1 Knowledge Required to Facilitate Allocation of the Alluvial Aquifer 88 7.2 Knowledge Required for Regional Aquifers 89 7.2.1 To Better Understand Development Opportunities 89 7.2.2 To Better Understand Development Constraints 89 8. Recommendations for work to address knowledge gaps 91 8.1 Update the WIN Database 92 8.2 Regional geophysics survey 92 8.3 Establish a representative monitoring network 93 8.4 Groundwater dependence of water-related ecosystems 95 8.5 Regional groundwater resource investigation 95 8.6 Technical investigations in targeted areas 96 8.7