Guiding Principles for Sustainable Groundwater Management
This paper is derived from the Sustainable Groundwater Use Project commissioned by the Murray Darling Basin Commission in 2001 as part of their Watermark program (REM, 2003). The project was managed by Resource & Environmental Management Pty Ltd, with a team made up from IAH members who are some of the most experienced hydrogeologists in Australia. Permission from MDBC and REM to use this material is gratefully acknowledged.
Project Team Stuart Richardson (REM) Ray Evans (Salient Solutions Australia) Hugh Middlemis (Aquaterra) John Ross (Parsons Brinckerhoff – formally PPK) Paul Howe (REM) John Hillier (John Hillier & Associates) Phil Dyson (Phil Dyson & Associates) Resource & Environmental Management Pty Ltd Suite 12, 15 Fullarton Road, KENT TOWN SA 5067 AUSTRALIA Telephone: 618 8363 1777 Facsimile: 618 8363 1477 Acknowledgements Scott Keyworth (MDBC); Michael Williams, George Gates and Rob Braatan (NSW Department of Infrastructure, Planning, and Natural Resources); Steve Barnett (South Australian Department of Water Land and Biodiversity Conservation); David Free (Queensland Department for Natural Resources and Mines); Gordon Walker (Victorian Department of Sustainable Environment); Ross Brodie (Commonwealth Bureau of Rural Sciences); Mirko Stauffacher (CSIRO Land and Water).
Table of Contents
1 INTRODUCTION .............................................................................................. 3 1.1 Key Issues 1.2 Murray-Darling Basin Context 2 3 4
A FRAMEWORK FOR CONJUNCTIVE RESOURCE MANAGEMENT OVERVIEW ................................................................................................... 6 2.1 Overview of the Framework 6
3 3.1 3.2 3.3 3.4 3.5 3.6
FRAMEWORK FOR CONJUNCTIVE RESOURCE MANAGEMENT – GUIDING PRINCIPLES ............................................................................... 12 Introduction Identification of Resource Management Issues Identification and Quantification of Water Users and Uses Confirmation of the (External) Decision Environment Technical Assessments Surface Water and Groundwater (One-Resource) Balances 3.6.1 Assessing Impacts from the Use of Groundwater 3.6.2 Guiding Principles for Technical Assessments 3.7 Defining User Provisions 3.7.1 Agreed Trade-Offs 3.7.2 Integrated Modelling 3.7.3 Stakeholder Consultation 3.7.4 Guiding Principles for Defining User Provisions 3.8 Planning and Implementation 3.8.1 Operating Rules 3.8.2 Policy Framework 3.8.3 Guiding Principles for Planning and Implementation 3.9 Monitoring and Evaluation 12 12 12 13 13 14 16 17 20 21 21 22 22 25 25 25 26 27
REFERENCES ............................................................................................... 29
List of Tables, Figures, Appendices
TABLES Table 1 Table 2 Table 3 Key Tasks in a Conjunctive Management Framework Classification of Approaches to Estimating Sustainable Yield Classification System for Stream-Aquifer Interactions
FIGURES Figure 1 Figure 2 Figure 3 Figure 4 Allocation Versus Yield for Groundwater Management Units Within the Murray-Darling Basin Decision Framework for Conjunctive Resource Management Within the Murray-Darling Basin Types of Stream-Aquifer Interactions Evaluation Framework
Agencies, water authorities and catchment management organisations throughout the world have progressively embraced the concept of sustainable groundwater management over the past decade. They now are beginning to realise the need to; (a) agree on an approach to defining sustainable yield, (b) the need to better quantify the sustainable yield in different groundwater systems, (c) the need to implement best practice management plans, and (d) the need to identify systems that are stressed and seen to be over-allocated and/or overused. A further difficulty in managing groundwater resources within large groundwater basins arises from different approaches being adopted in different regions, along with generally poor levels of investment in estimating sustainable yields, and an approach that in many instances is inspired by an urgent need when difficulties become apparent. The often poorly understood interaction between surface water and groundwater resources has traditionally meant that each component is managed as a separate resource. This typically results in the separate estimation of the sustainable yield of surface and groundwater systems, when, in fact, their yields are interdependent.A focus on surface water management (eg. the Cap on surface water diversions in the MurrayDarling Basin) can have an indirect impact on groundwater resources due to an unintended transfer of development pressure. This paper presents a framework for groundwater management (using a conjunctive management approach) that can be applied to the management of groundwater at a local to basin-wide scale. The framework is supported by a series of guiding principles and approaches that, together, will allow practitioners to deal with issues that are currently encountered. Although the framework was originally designed for best-practice management of groundwater resources within the Murray-Darling Basin in southeast Australia, the principles can be applied globally.
Murray-Darling Basin Context
Around 11% (1240 gigalitres in 2000/01) of the water used within the Murray-Darling Basin (the Basin) is groundwater pumped from the various unconsolidated, sedimentary and fractured rock aquifers (excluding the Great Artesian Basin aquifer). Although this may seem like a small volume, there is a large reliance on groundwater for consumptive use in drought years, and in some areas away from the main river and tributary systems, it is the only source of water. Around 80% of groundwater pumped from the aquifers is used for irrigation and many of the management issues related to the protection of groundwater resources are linked to the irrigation industry. There are also many valuable ecosystems within the Basin that rely on groundwater. In some regions of the Basin, groundwater levels are rising at rapid rates due to the increased recharge following the widespread clearance of deep rooted native vegetation, and it is predicted that future salt accessions to river systems will severely degrade healthy ecosystems, and lower the quality of water for irrigation and potable uses. In other regions of the Basin, groundwater resources have been over-allocated and declining aquifer pressures are putting at risk the sustainability of irrigation industries and domestic/ municipal water supplies, and the health of groundwater dependent ecosystems. The degree of over-allocation of groundwater is demonstrated in Figure 1.
Figure 1. Allocation versus Yield for Groundwater Management Units within the MurrayDarling Basin. GMUs that lie below the “100% line” are over-allocated.
There are currently two major groundwater management issues under consideration in irrigated regions of the Basin: • • Water access and security of supply (quality and quantity); and Rising water tables and salinisation (including salt returns to the river systems).
The significance and importance of these two issues varies according to jurisdiction, groundwater flow system and catchment. A wide range of groundwater flow systems operate within the Basin, each defined on the basis of geology and geomorphology.
Strategies and tools required to manage groundwater issues within each flow system vary with their biophysical nature, and local economic and social requirements. The poorly understood interaction between surface water and groundwater resources has traditionally meant that surface water and groundwater have been managed as separate resources. The focus on surface water management has had indirect impact on groundwater resources. For example, the Cap on river diversions within the Basin does not address groundwater processes; and consequently there has been an unintended transfer of development pressure from surface water resources to groundwater resources. This pressure has triggered growth in new groundwater allocations in emerging irrigation areas and activated groundwater licences in areas where groundwater embargoes were in place. Studies commissioned by the MDBC have identified that groundwater derived baseflow to un-regulated streams can vary between 4% and 76% of flow (SKM, 2001), indicating the variability and complexity of this issue. There is a danger that the integrity of other MDBC river health initiatives could be threatened by increasing groundwater use in the absence of a “one-resource” approach to managing linked surface water and groundwater systems. The need for a better conjunctive (or integrated) approach to the management of rivers and aquifers within the Basin has also been recognised by the States. Recent work indicates that current estimates of sustainable yield for connected groundwater/surface water systems within the Basin is 550 GL/yr higher than the estimated 2000/01 extractions. The question is how much of this potential increase in extractions of 550 GL/yr will come from stream flow ? In well-connected systems, it is possible that a much higher percentage of extracted groundwater will come from streams, although rainfall, overbank flooding and valley side contributions will continue to be significant. Taking a range of 50% to 100% (for connected systems only) it is estimated that stream flow could be reduced by between 275 and 550 GL/yr. Against this background, the MDBC commissioned the Sustainable Groundwater Use Project (as part of the Watermark program) in 2001 to develop guiding principles and an integrated Basin-wide framework for best-practice management of groundwater resources within the Basin using a conjunctive management framework.
2 A FRAMEWORK FOR CONJUNCTIVE RESOURCE MANAGEMENT - OVERVIEW
2.1 Overview of the Framework
A decision-making framework for conjunctive resource management has been developed and is presented in Figure 2. The key tasks outlined in the framework and associated inputs and outputs are summarised in Table 1 (contained at the end of this section). The framework describes a process (highlighting the key guiding principles) that is a guide for water and catchment managers when preparing water management or water sharing plans. The focus of the process is on planning for sustainable groundwater use, but it also has application to the issues relating to salinity and watertable impacts from irrigation. Rather than prescribing a set of actions that should be followed in every case, and recognising that groundwater management in many areas has already evolved some considerable distance (and continues to do so), a set of guiding principles is proposed to be used as an aid to working through the process. It is anticipated that these principles and guidelines will allow practitioners to deal with issues that are currently encountered, as most agencies are being required to regulate (through legislation) valuable water resources. This regulation is occurring in an environment where the main challenge is the need to strike an acceptable balance between consumptive and environmental uses (often dictated by non-technical biases), and to satisfy expectations that a groundwater allocation is an asset that is absolutely quantifiable and secure. This framework mainly addresses the technical aspects of developing a conjunctive resource management plan. There are also social and economic considerations required to satisfy all stakeholders that the user provisions (yield) are appropriate for their system. This section of the document provides a broad description of the process associated with the conjunctive resource management framework shown in Figure 2. A more detailed description of the process, supported by the guiding principles that need to be considered in a logical process is provided in Section 3.
Decision Framework for Conjunctive Water Resource Management within the Irrigated Regions of the Murray–Darling Basin
POLICY and ENVIRONMENTAL DRIVERS
IDENTIFY CONJUNCTIVE RESOURCE MANAGEMENT ISSUES Groundwater Use Impacts on Rivers River Management Impacts on Groundwater Primary management issues: Primary management issues: Recharge protection (instream and flood) Baseflow protection (especially low flow) Natural flow variability (frequency, timing and duration) Saline discharges
IDENTIFY and QUANTIFY WATER USES and USER
Environment Stock Domestic Irrigation Urban Other industry
Cap and other policies Integrated catchment management
IDENTIFY and QUANTIFY WATER USES and USER
Water requirements and needs Policy, economic and social framework
COSTS/IMPACTS Ecosystem impacts Regulation Salinisation Water logging Resource depletion IGIM approach management Subsidence and infrastructure damage Impact on surface flows SURFACE WATER and GROUNDWATER (”One-Resource”) BALANCES Investigation Steps Knowledge generation Conceptualisation Modelling system PEER REVIEW behaviour Reporting BENEFITS and OPPORTUNITIES RegionalRegulation development Social wellbeing Ecosystem service Conservation management
GUIDING PRINCIPLES FOR TECHNICAL ASSESSMENTS Aquifer classification Site specifics System robustness Reporting Stream – aquifer Quality assurance interaction Timing of water fluxes Minimum datasets
DEFINE USER PROVISIONS
GUIDING PRINCIPLES FOR DEFINING USER PROVISIONS Provision for GDEs and Application of surface water rules Response Zone Management to groundwater users Storage depletion, recharge Definition of zones for and beneficial uses groundwater extractions Planning time-frames Groundwater pumping when Uncertainty, variability and risk river is dry Managed aquifer response Enhanced groundwater recharge Predictive modelling with flooding Trade between groundwater and surface water
SCIENCE INPUT AND UNDERPINNING
PLANNING and IMPLEMENTATION
DEVELOP CONJUNCTIVE RESOURCE MANAGEMENT PLAN Operating rules Policy framework
GUIDING PRINCIPLES FOR PLANNING and IMPLEMENTATION Access and trading Precautionary approach
MONITORING AND EVALUATION
The framework consists of the following six key stages: • • • • • • Identification of resource management issues; Identification and quantification of water users and uses; Confirmation of the (external) decision environment; Technical assessments; Planning and implementation; and Monitoring and evaluation.
The blue boxes in Figure 2 identify the key stages of the process and the brown boxes and bullets within each blue box highlight some the issues and guiding principles associated with each stage of the process. The process begins with the identification of the key issues (such as protection of high value uses) that may have to be resolved through the planning process (recognising that these may change as the technical assessments are undertaken). The next step in the process involves identification and quantification of water users and uses. The primary reason for this step in the process is to make sure that stakeholders and users are identified explicitly and represented “around the table” from the outset. The framework recognises that surface water and groundwater are two components of the one resource. In most catchments, there are significant linkages between these components, and changes in one system can influence the other. The conjunctive assessment and management of water resources involves acknowledging the different attributes of surface and groundwater systems, but assessing the yield of the resources by recognising their linkages, and developing management approaches to obtain maximum benefit for economic, environmental and social values. The benefits of a “one resource”: approach and recognition of the importance of the surface water-groundwater interaction (for connected streams at least) can be far reaching and may ultimately affect regional development in some catchments. Improved water efficiency and farm productivity are likely outcomes, and in over-allocated areas, there is likely to be economic rationalisation with changed crop types and irrigation patterns, with some irrigation properties or parts of properties likely to return to dryland farming. Important ecosystems will be afforded greater protection and there will be better recognition of environmental values. While most of the key issues will be identified at the start of the process, these are likely to change as the assessment and evaluation process progresses. An understanding of the external decision making environment is important because this often provides the constraints and opportunities for the implementation of water management policy. Legislative and policy frameworks (usually state-based) control the process of development and the implementation of water plans. The challenge is being able to implement a best-practice technical approach that is not necessarily recognised by existing legislative or policy controls, and is also acceptable on a socio-economic basis as well.
The technical assessment process occurs once the issues and planning requirements are confirmed. This is the point in the process where data and information are collated to allow a description of the biophysical systems, and calculation of the water balance to inform the process used to define user provisions (e.g. sustainable yield). The bulk of the guiding principles developed within this project are associated with the technical assessment step in the process. There are several important guiding principles related to the technical assessment process (described in Section 3) including the need for classification of aquifer systems to help prioritise investment in aquifer management, classification of stream aquifer interaction, recognition that surface water and groundwater form a single resource, the need to develop minimum datasets to allow calculation of sustainable yield, management of risk and quality assurance. The aim of the technical assessments stage is to provide a sound basis for the definition of user provisions. User provisions are most likely defined by the sustainable yield, which is needed to allow a series of decisions to be made about allocating groundwater to competing water demands in a defined planning timeframe. A number of guiding principles are proposed relating to topics such as the needs of groundwater dependent ecosystems, the possibility of controlled aquifer storage depletion, protection of recharge/discharge (sources and quantum) and planning timeframes. The user provisions will be determined from a process of consultation and integrated modelling to arrive at the agreed trade-offs. The process also needs to recognise that extraction of groundwater up to the sustainable yield will still result in some level of impact, but the impact may be viewed (by the stakeholders) as acceptable following a discussion of the trade-offs. Equally, definition of sustainable yield is neither the start nor finish of the process. Continual reviews of concepts and estimates of sustainable yield as better information is generated will promote better decision-making processes and outcomes for all stakeholders. There are several ways to define sustainable yield. As an example, the definition of sustainable yield proposed by the National Groundwater Committee of Agriculture and Resource Management Council of Australia and New Zealand, is as follows: Sustainable yield is the groundwater extraction regime, measured over a specified planning timeframe that allows acceptable levels of stress and protects the higher value uses that have a dependency on water. An estimated volume of sustainable yield of groundwater is the key step in a process that, for high priority aquifers, can be complex. In one sense, the rigour of undertaking the process to arrive at the sustainable yield is as valuable as the final number itself. In essence, sustainable yield is not just a number; it is as much the concept of deriving a working knowledge of the aquifer in question. Once the sustainable (or acceptable) yield is defined then a conjunctive resource management plan can be developed and implemented. The key elements of a plan are the operating rules, policy framework, targets and monitoring and evaluation strategy. This paper does not focus on the detail of development and implementation of plans (other than the development of a monitoring and evaluation strategy), but there are two guiding principles presented; access and trading, and the precautionary approach to implementation of conjunctive management principles.
Whilst the process can be rigorous, the outcomes, however, can never be certain. There will always be technical errors in the system either inflicted by uncertainties within the analytical processes used in estimating the water balance, or by unforseen aspects of the natural environment. Then there are the social and economic consequences that need to be fully considered when developing plans. These aspects may mean that the best technical initiatives are delayed or not adopted. It is of paramount importance, that, having quantified user provisions and allocated resources according to a predictive framework, to monitor and evaluate the system to ensure there is in fact convergence on the targets specified within the specified timeframes.
Table 1. Key Tasks in a Conjunctive Management Framework
Stage Identify Issues
• Determine key sustainability and
conjunctive management issues (in consultation with all stakeholders) for the catchment and/or operating environment
• Knowledge of the stresses within the biophysical, social and economic setting
• A focus for the assessment and planning
Identify and Quantify Water Users and Uses Confirm External Decision Environment
• Determine the volume and quality of water
required by consumers and the environment
• Records of groundwater use, identification
of groundwater dependent ecosystems and quantification of environmental water use, land use data, location of production wells
• A clear understanding of the stakeholders and the relative magnitude of potential water requirements. • An understanding of the constraints and
opportunities available from external processes.
• Review existing legislation, policy and
management plans to confirm the scope of the decision making environment.
• Legislation, policy and management plans
(water, environmental and land)
• Social and economic studies for different land uses and scenarios
• A clearer understanding of the
environmental, social and economic consequences and risks
• Characterisation of stream-aquifer linkages • Literature and information review to identify
data sources and collate data and environmental water requirements • Characterisation and quantification of key processes for recharge/discharge, flow, water quality and ecosystem dependence • Identification of planning timeframe(s) and data deficiencies
• Analyse data to quantify data quality and
site-specific linkages (fluxes, levels, temporal and spatial variability, etc.) • Assess Robustness of system to help prioritise further investigations (next stage)
• Multi-disciplinary technical team, including hydrogeologists, hydrologists, ecologists • Groundwater and surface water data, topography, geology, ecology, water use • Robustness estimate and characterisation
of hydrogeology/hydrology from stage 1 • Water planning input on allocation & water use strategies; operating environment
• Development of conceptual model • Stream-aquifer linkage classification, and
indication of potential impacts on quality or beneficial use category, and quantity • Prioritisation of further investigations
• Classify stream-aquifer linkages • Develop conceptualised model of water
resource system and undertake system water balance to check model validity
• Ecological input on environmental water
needs (notably GDE and/or riparian needs)
• Selected modelling approach to investigate
• Improved water efficiency, and potential
• Economic rationalisation
• Agree on the conceptual model across all • Develop/update/calibrate modelling tools • Scenario modelling of conjunctive
management and sustainability issues • Analyse results for scenario modelling and formulate scenarios to better meet targets • Provide feedback to all stakeholders on the modelling of the key issues
• Outcomes of previous two stages • Data/analysis for model development and
calibration, and statistical/probability analysis • Site-specific detailed features for streamaquifer interaction and GDEs • Stakeholder constraints
• Quantify effects in terms of water balances,
water levels & quality and EWPs • Quantify spatial/temporal variations • Quantify probability of depletion/recovery • Find balance between extraction & EWPs
Define User Provisions
• Sustainable water resource system yield,
allocation and EWP strategy/policy
• Use modelling tool to quantify water
Planning and Implementation
balance and quality components (including EWPs) in an allocation planning process applied to specified timeframe, accounting for hydrological variability
• Use modelling tool to investigate and set
operating rules for resource management, consistent with allocation policy
• Modelling tool (not necessarily numerical) • Water planning policies • Stakeholder engagement
• Share of the water resource • Conjunctive resource management options • Stakeholders informed re water balance
components, quality and risk/probability
• • • •
Drought management (and recovery) rules EWP’s for GDEs Hotspot management rules
Maximising the effectiveness of high stream flow/flood flow conditions
• Identify monitoring targets to assess
• Optimise monitoring network/data
Monitoring and Evaluation
• Identify data gaps or weak data areas
where improved information and knowledge is required
• Outcomes from previous stages • Monitoring data
• Report on assessment of performance in relation to targets • Optimal monitoring network/system Status reports to stakeholders • Report on assessment of performance in relation to targets • Prioritise further work
• Review performance and identify any need
for further investigation/monitoring/modelling
3 FRAMEWORK FOR CONJUNCTIVE RESOURCE MANAGEMENT – GUIDING PRINCIPLES
This section contains a more detailed description of the key stages within the framework (summarised in Figure 2) and the guiding principles that support the framework.
Identification of Resource Management Issues
The first part of the process involves the identification of conjunctive resource management issues that need to be addressed. The issues may be related to protection of the resource for consumers or it may be an issue associated with protection of water for dependent ecosystems. Identification of the key issues at the start of the process creates focus for the assessments and helps set objectives and obtains agreement on the desired outcomes amongst the community and other stakeholders. Examples of issues that may be significant include: • • • • Protection of baseflow; Access to flood flows; Salinity management; Achieving equity between water users.
While most of the key issues will be identified at the start of the process, these are likely to change as the assessment and evaluation process progresses. Stakeholder consultation during the identification of the key issues is recommended.
Identification and Quantification of Water Users and
The next step in the process involves identification and quantification of water users and uses. The level of certainty in an estimate of water use will vary considerably. For example, irrigation use is often metered and relatively easy to quantify, but environmental water requirements (EWR) are usually unknown or not expressed volumetrically. Often, water use information is only available after a water plan has been implemented, and so use of this information is normally part of the performance monitoring or review process. The availability of information on water use (both consumptive and environmental) will directly affect the reliability of the technical assessments and definition of user provisions. Although there is an increasing emphasis on incorporating EWR issues into legislation and policy in most jurisdictions, eg in Australia (Clifton and Evans, 2001), there is a key knowledge gap in identifying groundwater dependent ecosystems (GDEs) and quantifying EWRs in volumetric and quality terms. With little effort being put into GDE/EWR research programs, despite their crucial nature, there is little information available that can be readily applied to specific catchments. Under these circumstances, it is possible that the required priority may not be given to groundwater-dependent ecosystems and overdevelopment can easily result. To ensure sustainable resource management where
quantification of EWRs is lacking, a precautionary approach needs to be adopted, with a volume set aside to protect GDEs if there is likely to be substantial groundwater dependence or alternatively, access restrictions based on water level/water quality responses and triggers.
Confirmation of the (External) Decision Environment
An understanding of the external decision making environment is needed to understand the opportunities and constraints provided by existing legislation and planning policy. For example, it will be difficult to implement detailed operating rules where the taking of a water resource is unregulated. The context of water management in an area where there are well-developed strategies for integrated catchment management (ICM) needs to be described and considered to avoid potential conflict. For example, an ICM strategy for revegetation for dryland salinity control could be in conflict with maintenance of a groundwater resource for consumptive use if the re-vegetation strategy targets areas with high recharge potential. There may also be instances where particular features of a catchment are non-negotiable and will not be traded at any cost, such as a world heritage listed wetland. In addition, there may be substantial social and economic factors that need to be considered in determining sustainable yield and conjunctive use approaches in plans. To fully assess these aspects specialist studies may be required to complement the technical and environmental studies.
The technical assessments form a major part of the process with the intention being to estimate the sustainable yield and provide information for the definition of user provisions. The outcome from definition of user provisions is agreement to the sustainable yield that provides equity amongst users. The four main components of the technical assessments process are knowledge generation, conceptualisation, modelling the system behaviour and reporting. The importance of peer review and quality assurance at this point in the process is emphasised. This part of the process also involves consideration of the costs/impacts of using groundwater under the “no-plan scenario” (such as ecosystem impacts) and benefits/opportunities from developing a groundwater resource, such as the economic development that it can bring. The costs and benefits analysis is not often undertaken explicitly in water planning, but can help to assess the implications of trade-offs undertaken when defining user provisions. There are several guiding principles developed within this paper that need to be considered at this point in the process. The main guiding principle governing the technical approach is the need to assess surface water and groundwater as “one resource”. Other guiding principles relate to aquifer, and stream-aquifer interaction classification, performance and monitoring indicators, minimum datasets understanding uncertainty and variability, reporting and management of risk.
Surface Water and Groundwater (One-Resource) Balances
The cornerstone to the assessments process is the recognition that surface water and groundwater are two inter-related components of the one resource, and changes in one system can have a significant influence on the other. However, one resource should not dominate over the other during the assessment process. Therefore, ideally the sustainability issues of both the surface and groundwater resources of a catchment need to be assessed together. Although this is rarely undertaken at present, it is achievable because the same basic analytical approaches and tools (models) are involved in the assessment of each resource. The goal is to conjunctively assess and manage the one resource for sustainability over a specified management timeframe, avoiding allocation of the resource twice (from “separate” pools of surface and groundwater) and minimising impacts from irrigation. The conjunctive assessment and management of water resources involves acknowledging the different attributes of surface and groundwater systems within management approaches to obtain maximum benefit (within a specified timeframe) for economic, environmental and social values. The integration of knowledge of surface water and groundwater at the assessments stage allows the development and testing of conjunctive use strategies such as aquifer storage and recovery, protection of ecosystems and opportunistic cycling of the use of each resource within wet and dry periods. It is considered that the framework should be applied not only to water resources management in systems where there are connections between aquifers and streams, but also in systems that are disconnected. It has been shown that even in disconnected surface-groundwater systems; the use of one resource can affect the other. Disconnected stream-groundwater areas tend to be associated with unregulated stream sections or mid to lower alluvial areas of catchments. The connected recharge and discharge areas may be distant but should not be ignored in the water management planning. The framework emphasises that all groundwater and surface water systems have some degree of effective connection, thus the conjunctive management of “the one resource” should be adopted, especially where the aquifer system is not robust. Investigations There are four main areas of investigation that need to occur as part of the assessment process, they are: • • • • Knowledge generation; Conceptualisation; Modelling system behaviour; and Reporting.
Knowledge generation aims to provide an understanding of how the groundwater system works which provides the information required to develop the conceptual models of the hydrogeological and hydrological system. Typically knowledge generation involves collection of data to define the spatial distribution of aquifers, to characterise aquifer hydraulic properties, estimate recharge and discharge,
to quantify surface water – groundwater interactions and to develop the pre- and postwater balances. The conceptual model establishes the architecture or framework for the predictive analysis by explaining the nature and behaviour of groundwater systems, and the way in which systems are likely to respond both spatially and over time. All assessments must be underpinned by an analysis of the entire aquifer system of interest, not just the lowest salinity resource areas or an administrative region imposed as a result of where the groundwater users are located. A conceptual model that includes all elements of the biophysical system within a dynamic water balance framework must support this analysis. In higher-priority aquifers, the analysis should be based on distributed parameter predictive mathematical models. Outcomes from the conceptualisation process include: • • • classification of the linkages between surface and groundwater systems, and identification of the potential for impacts; conceptualisation of the systems in practical terms, detailing the flow and water quality processes involved so that detailed models can be developed; a check on the applicability of the conceptualisation by doing simple calculations such as water balances, which require information on environmental water requirements (spatially and temporally); and prioritisation of further investigations.
Within the conceptualisation stage, there should be sufficient understanding of the system to develop preliminary bounds on the major factors that restrict the combined sustainable yield of the surface and groundwater systems. Such bounds may relate to: • • • • the maximum extent to which groundwater levels could be permitted to change, based on resource, environmental or economic reasons; the minimum environmental water provision constraints; the minimum volumes that need to be diverted to maintain social and economic viability in the community; and/or others of specific interest to the catchment or community.
A predictive tool is required to guide the development of management rules (see Defining User Provisions) that allow the water resources to be put under the maximum acceptable levels of stress while still protecting the higher value uses that have a dependency on the water. Computer-based mathematical modelling is the only tool that has been identified as having this capability. Resource managers can use mathematical models to quantify the effects of trialling various management options, simulate various use and climatic variability scenarios, and demonstrate the findings to the community. The modelling methods that should be used for conjunctive resource management depend on the data available for setting up the model and for its calibration, the complexity of the
stream aquifer interaction process, the significance and environmental sensitivity of the water system, the economic importance of the area and the study resources available. For complex linked systems with high sensitivities and values, more complex models need to be used. MODFLOW is recognised as the world standard groundwater flow model, and has several surface water linkage modules that could be utilised. However, as surface water resources are of major importance, catchment models for most stream systems have been, or are being, developed. The adopted standard for the Basin (mainly for examining management scenarios) is IQQM (Integrated Quantity Quality Model). IQQM has been linked with MODFLOW, so that both surface and groundwater resources can be modelled interactively. However, only initial trials have been completed and further development and testing is needed before this integrated tool can be generally applied. There is also ongoing development of improved integrated modelling tools which do not necessarily rely on Modflow (eg. Mike-SHE, MODHMS, ZOOMQ3D, etc), and it is expected that these tools will become more commonly used in the coming years. The process of obtaining estimates of sustainable yield should be well documented, with emphasis placed on describing the conceptual model, nature of the data used, the techniques employed and the assumptions made. This reporting also should be made available publicly, and should undergo peer-review for the more significant aquifer systems.
3.6.1 Assessing Impacts from the Use of Groundwater
The framework highlights the importance of understanding the costs and benefits associated with the extraction and use of groundwater. Within an ICM framework all water using activities may have a right to access water and there will be costs and benefits associated with each use. The definition of user provisions involves consideration of the trade-offs between water users and the costs and benefits each user brings. One of the costs (or potential impacts) associated with the use of groundwater for irrigation is the change in the water and salt balance that can lead to problems such as groundwater mounding, waterlogging and salinisation of soils, and increased discharge of salt to the riverine environment. A key reason for including this analysis in the conjunctive management framework is that the use of water for irrigation may reduce the capacity of the groundwater resource (or surface water resource) to meet future demand, that is reduce the sustainable yield. For example, groundwater mounding within a shallow more saline aquifer will induce downward leakage of salt to the less saline productive aquifer. Other impacts could relate to aquifer storage depletion, and if excessive, land subsidence and infrastructure impacts. While these impacts are unlikely in most of the groundwater systems in the basin, the potential should be assessed in over allocated and over used groundwater systems.
3.6.2 Guiding Principles for Technical Assessments
Several important guiding principles have been developed that are relevant to this part of the process. Aquifer Classification The levels of effort applied to the assessment process will depend on the risk of the resource being over-exploited. The effort required to assess each system will vary according to the classification of the aquifer system. It is considered that the approach to estimation of sustainable yield can be best applied by understanding the nature of the development of a particular aquifer and the certainty in the current understanding of the groundwater system. So that aquifers with a high ratio of allocation (and use) to yield and low certainty of assessment will require the greatest effort. The classification system is summarised in Table 2.
Table 2. Classification of Approaches to Estimating Sustainable Yield
Allocation : Sustainable Yield Ratio <50% Error in Sustainable Yield >±50% <±50% II I 50 – 75% III II 75 – 100% >100% IV III V IV
In addition, aquifers can be assigned a status as follows: Groundwater Status
Where Allocation to Sustainable Yield ratio is less than 50%. Generally, some further development may be possible. Where Allocation to Sustainable Yield ratio is between 50 and 75%. Some limited scope for further groundwater development is possible, but may rely on an increased planning effort to properly define the available resource. Where Allocation to Sustainable Yield ratio is between 75 and 100%. Generally, the groundwater resource is approaching full allocation, and using a conservative approach, further development is unlikely or only possible in areas with available resources and minimal development. Where Allocation to Sustainable Yield ratio is greater than 100%. No groundwater is available, and steps to limit or reduce current allocations are warranted. Where the ratio of Usage to Sustainable Yield is greater than 100%. This is a special case where usage, as opposed to allocation, has already exceeded Sustainable Yield, and calls for immediate intervention to reduce both allocations and usage as effects from pumping may be causing irreversible damage.
The five classification approaches defined in Table 2 each have specific knowledge requirements demanding different levels of investment and different (incremental) technical approaches in estimating sustainable yield. Moving to higher levels of integrity within the table generally involves: • • • More detailed and complex conceptual models; Greater understanding and estimation of recharge and discharge fluxes; More information (spatial and temporal data related to water levels, groundwater quality, groundwater abstraction and rainfall; aquifer distribution and hydraulic properties); Better understanding of surface water/groundwater interactions; Better understanding of groundwater dependent ecosystem requirements and provisions; Greater emphasis on quantification, particularly predictive modelling (for instance, numerical modelling); Better land use and land management data; Greater emphasis on quality assurance/peer review; and More intensive monitoring and reporting of trends to stakeholders.
• • • • • •
As an aquifer increases in its development status, a predictive capacity should be developed to support sustainable yield estimation. The use of a high-complexity numerical model is strongly advised for all developed and overdeveloped aquifers (i.e. those with a >100% allocation: sustainable yield ratio). System Robustness The classification of an aquifer can also be modified by aquifer robustness, which is the ratio between aquifer storage and recharge (for largely undeveloped systems), and the ratio of aquifer storage to sustainable yield (for developed systems). It is a useful concept because it provides a good indication of aquifer capability after taking into account all the system requirements (recharge, discharge, ecology, etc), and can help prioritise investigations. In aquifers with a large robustness (that is, a large storage compared to yield or recharge), there may be opportunities to use the aquifer storage to buffer natural variations in climate, provided aquifer recovery is likely within specified timeframes. The threshold levels that define high and low robustness have not yet been defined, but the following key findings from case studies described in a recent paper by Middlemis et al (2004) proposes some Robustness thresholds. In this case, the sustainable yield has not yet been defined exactly, but a default value of 1.6 GL/year (the existing abstraction regime) has been adopted for the purposes of this exercise. However, it could eventually be set at a higher level, as the long term average recharge is around 5 GL/year. The aquifer storage was estimated as the product of the aquifer volume and an assumed porosity of 15 %, giving 562 GL. Note that this estimate does not take account of the range of salinity from fresh to sub-potable.
Thus, the developed Robustness is estimated at 350, although more detailed assessment could devise Robustness indices for the various ranges of water quality that imply suitability for beneficial use classes. The undeveloped Robustness value may be estimated as the 562 GL aquifer storage divided by the 5 GL long term average recharge estimate, giving a Robustness of 75. Intuitively, one might expect the undeveloped robustness index to be higher than developed robustness, but that simply depends on the ratio of long term recharge to sustainable yield, and it might be that that ratio itself could be a better indicator of developed robustness (in this case, the value would be about 3; suggesting that a value greater than about 3 may indicate a robust aquifer if the definition of long term recharge to sustainable yield were to be adopted for Robustness). While the definitions and threshold levels that define high and low robustness have not yet been comprehensively agreed, based on the above case studies, the following threshold levels are suggested: • • an index of 100 or higher indicates high Robustness index of less than 10 or 20 indicates low Robustness.
Further investigation of this issue, including the definitions, ratios and indices, and the threshold values in particular, is considered warranted to help devise and communicate sustainable resource management strategies. Stream-Aquifer Interaction A simple classification system based on the primary connection between groundwater and adjacent surface water drainage has been developed (refer Table 3) which distinguishes between systems that are hydraulically connected and those where the water table is separated from the stream (Figure 3). The system further classifies the linkages into gaining or losing (to or from the stream), and the likely impact of one resource on the quality and quantity of the other. Once the water resource components have been classified, investigation and management priorities can be determined and further analysis of the interaction between streams and aquifers undertaken.
Table 3. Classification System for Stream-Aquifer Interactions Hydraulic Connection StreamAquifer Interaction Process Gaining Stream Losing Stream Variable Gaining and/or Losing Stream Losing Stream Potential Impacts on Surface Water Resources of Groundwater Abstraction* High Medium Medium to High No Impact** Potential Impacts on Surface Water Quality of Poor Groundwater Quality High No Impact Low Potential Impacts on Groundwater of Changes to Surface Water Flows or Quality Low High Medium to High High
Connected Connected Connected
* the potential for impacts needs to be considered in relation to the status of groundwater development or opportunities for development before priorities can be determined ** no impacts at the local scale due to groundwater abstraction in disconnected systems. 19
Gaining or effluent streams which receive water through their bed from groundwater
Losing of influent streams which lose water to the aquifer through their bed
Connected to the groundwater system by a continuoues saturated zone
Connected to the groundwater system by an unsaturated zone.
Underflow dominated streams where most groundwater flows parallel to the stream but does not discharge into the stream
Throughflow dominated streams which are gaining on one reach but losing on the other.
Adapted from Woessner (1995)
TYPES OF STREAM-AQUIFER INTERACTIONS
e:\projects\MDBC (AR)\Conj Use (03)\Figures\Fig 2_revb.mxd
With knowledge of these linkages and acceptance of the environment as a legitimate water user, conjunctive (or integrated) resources management would appear to be a necessary component in any resource management plan irrespective of whether the plan is integrated, surface water alone or groundwater alone. Minimum Datasets A minimum dataset should be constructed for each aquifer in order to determine sustainable yield or to implement a monitoring and evaluation strategy. This dataset should meet agreed quality criteria related to both spatial and temporal variability and uncertainty for the key aquifer parameters. Catchment Site Specifics are Crucial Scenario modelling has shown that catchment site-specifics determine the nature, extent and magnitude of stream-aquifer interaction processes. The timing of these interactions can substantially affect the magnitude and direction of the flow processes. Therefore, policies for conjunctive management and ecosystem protection need to be determined on a sub-catchment or stream reach basis, as this would provide the greatest level of certainty for both decision makers and users. Quality Assurance In an environment of higher levels of scrutiny, which will be brought about by the desire to provide certainty in the form of property rights, quality outputs from any sustainable yield estimation process will not only be required, but will be expected. How does one ensure that outputs from the sustainable yield approach are of an acceptable quality, and do all sustainable yield estimates have to be of the same quality ? There are no standards for the estimation of sustainable yield in many countries. Any need to ensure that outputs from the sustainable yield estimation process meet the highest standards, needs to be tempered by the need to retain flexibility of approach and to acknowledge that quality of output is directly linked to the data availability and the level of resources provided. With a clear move to a ‘beneficiary pays’ approach to funding natural resource management, there may be times in the future when the beneficiary does not have the capacity to pay for the highest standard.
Defining User Provisions
Definition of user provisions is the next part of the process, which is an exercise that involves taking information from the technical assessments (with an integrated modelling tool) to inform stakeholders about the costs and benefits of various trade-offs between high value water uses. Figure 2 shows that the process iterates between integrated modelling, agreeing to the trade-offs and consulting with stakeholders. This section briefly describes the process of defining user provisions and summarises the relevant guiding principles. This paper does not explore the issue of stakeholder consultation. Consequently, there is no detailed description of this part of the process in this report.
3.6.3 Agreed Trade-Offs
There are two main user provision issues to resolve: 1. 2. The proportion of the available consumptive water that is to be extracted from the groundwater and surface water resources; and The allocation of the water amongst the various user groups, including urban and domestic, industrial, mining, stock, irrigation, environmental and downstream requirements.
This division of water resources is the basis of any management plan. Often the volume of water that is allocated is based on an acceptable impact to the aquifer and the users of water within the aquifer. It is possible that the term “sustainable yield” could be replaced by “acceptable yield” where the difference is based on a set of negotiated trade-offs between the resource condition and the requirements of high-value water users such as the environment and irrigators. It is critical in this process that the technical information that underpins the trade-off negotiations is communicated in the most appropriate manner – that is, it includes statements regarding certainty and variability, and it has been independently peer reviewed. Likewise potential uses, especially for the environment, need also to be carefully evaluated. Most of these issues regarding the process of formulating a water management plan fall outside the scope of work reported in this paper, but nevertheless, are highly dependent on the successful conclusion to activities that estimate sustainable yield, and reviews of these estimates over time. One of the key questions will be whether groundwater users will accept part of the risk in the capacity of the resource to provide water (both from a quantity and quality perspective) in the future. It may become more common that groundwater users accept a “share of the available resource”. Implicit in any water-sharing plan is water quality. As the quality of both groundwater and surface water can vary over time, and groundwater in particular can have large quality differences spatially, this may play a major role in resource allocation and long-term sustainability.
3.6.4 Integrated Modelling
To explore a wide range of alternative trade-offs in any catchment, an integrated modelling tool is required. The tool must incorporate surface-groundwater interaction features (preferably site-specific) and must be able to at least quantify the flow and (preferably) water quality processes associated with land and water management change. This study has concluded that the ideal technical solution for improved conjunctive management involves an integrated modelling approach, where the stream and aquifer systems are simulated in detail, along with their mutual interaction. Resource managers can then investigate and quantify surface-groundwater and flow-quality interactions due to alternative management strategies or climatic regimes (through scenario modelling). The effects of alternative management strategies can then be demonstrated to communities during the consultation process. For complex systems, a detailed approach is warranted, requiring modelling studies with quite complex models that are accurately calibrated, in order to investigate the details of the interaction processes and explore opportunities for improved conjunctive management.
Deleted because further discussion of generic approaches is not included in this draft – do we want to include it?
3.6.5 Stakeholder Consultation
The role of the stakeholders in the development of the water allocation component of a management plan is paramount. A plan developed by water managers in conjunction with the community, based on sound technical advice and considering all environmental, economic and social concerns would have widespread acceptance. In reality, individual expectations usually make such an agreement in water resource plan development very difficult. Failure to fully engage the major stakeholders or to treat all stakeholders equally often creates conflict between consumers and regulators resulting in mistrust, litigation and unwillingness of existing consumers to accept that water is needed for other uses such as the environment. Working closely and cooperatively with the main consumers will create a partnership to the issue of sustainable groundwater management. This approach has been shown to lead to an effective resolution of the required trade-offs.
3.6.6 Guiding Principles for Defining User Provisions
Guiding principles were developed in this papert around selected issues that may be encountered during the development of user provisions for a conjunctive resource management. Provision for Groundwater Dependent Ecosystems and Riparian Zone Management Adequate provision should be made for the high-value Groundwater Dependent Ecosystems (GDEs) associated with any aquifer. The provision can be either based on a specific volume across the Groundwater Management Unit (GMU) or local area water level or water quality triggers. The quantum of the provision should be based on an explicit set of environmental objectives and actual requirements for the identified GDEs. Riparian zone management is a combination of land, water and ecosystem management within a specified zone aligned with surface water features. The objective in any such management is to reduce the impacts of abstractions on ecosystems, while maintaining sustainable groundwater-surface water interaction processes, and maximising opportunities to use aquifer storage attributes to buffer seasonal or drought period variability. Groundwater development in riparian buffer zones may need to be restricted in connected stream environments, but restrictions are generally less critical in disconnected stream environments, unless there are significant groundwater-dependent ecosystems in the riparian zone. In principle, restrictions to groundwater use are more likely to be required in connected stream situations to maintain stream baseflows, to maintain natural water tables close to streams, and to protect riparian vegetation ecosystems. This could be achieved by reducing the impact of groundwater pumping on inducing leakage from the stream and/or maintaining groundwater conditions that can provide baseflow support when required, over a specified time frame (eg. at least one normal irrigation period). This means that groundwater users need to contribute to the provision of environmental flows for surface water. Appropriate buffer distances would need to be developed for each water source based on the stream-aquifer interaction type and the extent of riparian vegetation and any GDEs on
the floodplain. This is very dependent on the hydraulic characteristics of individual aquifers, and site-specific integrated modelling would be required to set distances. Conversely additional resource utilisation is possible in a disconnected system, along with riparian zone management. Storage Depletion, Recharge and Beneficial Use Short term aquifer storage depletion may be accepted as an explicit goal for conjunctive resource management, provided there is a high probability of recovery within an appropriate planning timeframe, adequate provision of environmental water needs, no damage to the aquifer matrix, and no long term change in the beneficial use (water quality) status. Floods should also be recognised for their important role in groundwater recharge, and, where possible, used to maximise recharge and to improve conjunctive use opportunities. The beneficial use of water should be retained at its existing level for both groundwater and surface water. Some deterioration of quality has to be expected over a long period of time, as water use tends to concentrate salts within systems and/or reduce the outflow of salts from the systems. Water quality monitoring is essential, and when changes are identified through monitoring, adaptive management plans should be invoked to address the implications. Conjunctive management approaches need to consider water quality implications. Planning Timeframe The planning timeframe or accounting period for the use of storage as a conjunctive management practice is critical. With robust aquifers, it may not be quite as urgent to undertake investigations to improve the accuracy of parameter values, as there may be little risk of over-exploitation if inappropriate decisions are made. An aquifer with smaller robustness, however, is generally at a higher risk of depletion and/or degradation, and is therefore an obvious candidate for more detailed investigations and management focus. The investigations need to quantify the key system processes and parameters and thereby reduce the risk of inaccurately estimating the sustainable yield, or of not quantifying in detail the volumes and timing of flows associated with a stream-aquifer interaction. A specific planning timeframe should be agreed for all aquifers that are managed via a sustainable yield – consideration should be given to a 5-year timeframe for high priority aquifers (i.e. those categorised as developed or over developed), though very responsive (or less robust) aquifers may also require a shorter planning timeframe. Uncertainty, Variability and Risk The definition of sustainable yield implies a "volume per annum" approach, and indeed this is the approach utilised by most management authorities. Allocations are usually fixed as a volume per annum which has been calculated from system estimates of recharge and discharge and then environmental, economic, social considerations to arrive at sustainable yield. This allocation is usually only varied when management policies allow "carry over" of unused allocation from one year to the next. This is an extremely conservative method of management and usually results in use remaining well under the allocated volume for all years. In contrast, the calculation of yield from surface water storages usually involves a detailed hydrological analysis that results in a long-term simulation of the storage behaviour based on the runoff that the historical rainfall would have produced. In most cases, the volume
that could have been supplied from the storage during a "critical period" of below average rainfall is the limiting factor on the storage yield if the simulation requires a constant annual volume to be supplied. However, if a managed failure is permitted to occur in the analysis, a much larger volume can be supplied for perhaps 90% of the time, with restrictions on use implemented when the storage volume is low to protect the environment from any adverse effects while accepting the economic consequences (which over the planning timeframe, are usually positive). Such a system of risk management should be considered in groundwater management and in fact may have a more beneficial role here than with surface water storages. The ability to build robust simulation models of groundwater systems is now available, and with the use of these models, allocations could be set to allow system failure for a small percentage of time, with the failure system prevented in real life by the implementation of a system of pumping or access restrictions. System “failure” for groundwater systems could be considered in terms of unacceptable drawdowns, degrading water quality, or irreversible aquifer compaction. Uncertainty and variability of the sustainable yield estimate also occur due to lack of information and because of error in analytical approaches. Uncertainty and variability should be quantified wherever possible and communicated to all stakeholders. Over time, there may be a need to reduce the level of uncertainty and understand the effect of variability to increase the reliability of sustainable yield estimates. Managed Aquifer Response Aquifer performance management should be adopted as a means of defining sustainable yield wherever possible, but especially in terms of defining GDE requirements and managing systems where there is a poor amount of information about the aquifer system. Aquifer response management can be used to control local area impacts (quantity, quality and ecosystem attributes) that result from local overuse, even though the sustainable yield for the GMU may not be exceeded. This is a sustainable yield concept that is not necessarily reflected in the volume or share of the resource assigned to users. However it does have implications for access and use on a year-to-year basis. In some cases, aquifer sustainable yield will not be the key quantity that determines operational rules for groundwater abstraction. Rather, the key operational rules will relate more to:
drawdown limits or bore separation distances linked back to individual or local area abstraction rates (for quantity issues); changes in salinity or other important quality parameters linked back to individual or local area abstraction rates (for quality issues); ecosystem health, baseflows or similar environmental consequence linked back to individual or local area abstraction rates (for GDE issues).
Reporting Regular updates and transparency in all the work that is being undertaken needs to be in place. Stakeholders could be engaged at certain agreed milestones as outlined in a communication plan. This communication process with resource users should commence early in the management process. At a minimum, information on available datasets, current estimates
of recharge and discharge, the degree of uncertainty and variability, and the timetable for future data collection and analysis should be communicated for all areas that are more than 50% developed. Technical studies may also need to be supported by socio-economic studies to determine likely impacts and constraints on development, communities and local economies.
Planning and Implementation
A conjunctive resource management plan can be prepared once the user provisions (i.e. sustainable yield) have been defined. The main elements of the plan are the operating rules, a policy framework and a monitoring and evaluation strategy. This section describes issues around the development of the operating rules and policy framework. This paper did not focus on the detail of development and implementation of plans (other than the development of a monitoring and evaluation strategy), but there are two guiding principles presented; access and trading, and the precautionary approach to implementation of conjunctive management principles.
3.6.7 Operating Rules
An essential component of the planning process is the development of operating rules (provided within water plans) that will allocate the water to users in such a way that the principles of sustainable yield and conjunctive resource management are achieved, along with achieving economic and social benefits. Historically, a wide variety of methods have been used to allocate water, but by far the most common approach in the past has been based on promoting development of irrigation and industrial development. Most allocations were issued before systems were comprehensively understood, and usually well before the sustainable yield was calculated. The allocations were issued virtually on demand, on a “first in, first served” basis. Distribution of extraction of water has little meaning for most surface water sources, but the “first in, first served” policy has, in many areas, resulted in a very poor spatial distribution of pumping from an aquifer, leading to the development of “hot spots” with excessive local pumping causing severe drawdown. A fundamental principle of improved groundwater management is that the withdrawal must be spread out over the aquifer (i.e. areas of concentrated development must be avoided). The optimum distribution of pumping can be calculated by a well calibrated model, and depends on aquifer transmissivity, water quality and recharge sources as well as competition for pumping entitlements. Very few systems would, at this stage, have even a reasonable distribution of yield. Operating principles should also consider such factors as set back distances from streams to protect riparian vegetation, drought management, water requirements of groundwater dependent ecosystems, base flow in streams, and the requirements of any other water users (e.g. high-value town water supplies).
3.6.8 Policy Framework
Policy mechanisms and market-based initiatives to control water use also have to be considered as part of the operating principles. There are many that have been used as a component of water management, such as:
allocations being issued up to the sustainable yield;
penalties (usually monetary charges) put in place for use in excess of allocation; allocations managed on an annual basis, and annual allocations announced based on the volume in storage; under-use in one year can be carried over for use in the next year; and/or advance draw can be made on allocations from the following year.
Risk management approaches are commonly used in surface water management, but rarely in groundwater. In surface water systems, allocations are usually set at a level that the modelling indicates would be achievable for a percentage of time (say, 90%), with restrictions put in place to control use when water is not available (or is reaching the minimum targets developed for sustainable yield). As demonstrated in scenario modelling, the application of risk management approaches such as considering the probability of aquifer depletion and recovery within specified timeframes is readily achievable, and is strongly recommended in conjunctive resource management.
3.6.9 Guiding Principles for Planning and Implementation
Access and Trading In the implementation of any conjunctive management initiative that relies on the preferential use of one resource over the other at certain times, consideration of individuals’ access to each resource is of paramount importance. One particular example is where properties have access to surface water, but do not overlie an aquifer. Conjunctive resource management policies need to ensure that preferential use of one resource does not discriminate against those who face access challenges. Detailed consideration of these issues is outside the scope of this project. There should be consistency in regulation of the use of surface and groundwater systems to allow for water trading (as separate sources or between sources) to make effective/efficient use of the one resource. If we regulate one part of the system (eg. surface water), effectively creating property rights, and then the other part of the system (eg. groundwater) should also be regulated. Otherwise, systematic inequities can develop that will disturb water trading and resources management.
Uncertainty and variability of the sustainable yield estimate should be quantified wherever possible and communicated to all stakeholders. Over time, there may be a need to reduce the level of uncertainty and understand the effect of variability to increase the reliability of sustainable yield estimates. Aquifer systems may be subjected to more explicit risk management approaches, as is the case with surface water systems, when sustainable yield estimates are derived.
Precautionary Approach Given that there will be variations in the accuracy and reliability of the assessment of resources (caused mainly by data deficiencies); there are limitations to the implementation of conjunctive management principles. Thus, the precautionary approach should be applied in the implementation of conjunctive management principles, within an adaptive management framework where there is limited knowledge, sensitive ecosystems or where there is a high risk of depletion or degradation of the resource. Incremental decisions
should be allowed regarding policy, allocation and management plans, provided there are also strategies for:
Monitoring and performance assessment, leading to improved understanding and conceptualisation, and application of updated analytical and modelling tools; Devising methods to cope with variability, based on probability analyses and risk assessments within specified timeframes; and Making adequate provision for high value water-dependent ecosystems, and implementing research and monitoring programmes to improve understanding of EWRs and EWPs.
Monitoring and Evaluation
The evaluation framework is constructed around the water balance of catchments and groundwater systems, and accordingly, appreciates that groundwater resources are often intimately linked to surface water resources in ways that call for the management of one to be aware of influences on the other. This is particularly significant, for example where streams are highly connected to aquifers and groundwater systems, or where important groundwater resources also sustain natural ecosystems. The evaluation framework also recognises that contemporary groundwater management must be nested within the overall framework of the Integrated Catchment Management. In this sense the approach adopted sets firm natural resource management objectives together with a hierarchy of targets, indicators, and monitoring protocols. Each of these are chosen to inform the performance of strategies, and whether implementation of management responses are indeed realising the objectives or whether there is a need to further refine strategies and the predictive framework (Fig. 4) The natural resource management objectives selected within the evaluation framework includes:
Maintenance of the condition of groundwater dependent ecosystems; Maintenance of in-stream hydrology for river health initiatives and for maintenance of aquifer recharge; Maintenance of groundwater supply relative to irrigation demand; Compatibility with broader natural resource management issues related to reducing the impacts of development; and Compatibility with broader natural resource management issues related to reducing the impact on irrigation development.
The evaluation framework developed in this paper acknowledges two levels of assessment. It appreciates that evaluation applies to both the overall process of assessing the sustainability of groundwater resources through consideration of the component processes influencing the water balance, along with the demands made upon the resource by a the range of users and uses. It also recognises that evaluation also applies to specific activities that relate to performance monitoring and reporting.
BENCHMARKING FRAMEWORK FOR NATURAL RESOURCE MANAGEMENT
Baseline assessment Predictive analyses Refine management response Target setting Management response Monitor (performance) Review (against objectives) Report (against targets)
The elements of a generic benchmarking approach to natural resource management with application to the future management and evaluation of groundwater resources and irrigation impacts.
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The evaluation framework adopts a contemporary business approach by applying benchmarking principles that involve: (a) (b) (c) (d) (e) (f) The establishment of baseline assessments against which progress can be measured; A predictive framework that provides for the forecasting of outcomes under the various intervention options; A planning process that realises management responses; Target setting for each resource management objective; Setting indicators that support reporting against targets; and Monitoring systems and protocols for each indicator that inform progress in realising targets and objectives.
For each objective the framework describes a target, indicator and monitoring protocols (methods, location, frequency, duration, units of measurement and presentation). The framework also recognises that there will be modifications to a standard approach across different groundwater flow systems, between systems with different types of the surface water – groundwater interaction and with different levels of resource development. Monitoring data needs to be evaluated, and aquifer performance reviewed, within a timeframe that is much shorter than the planning timeframe. It is suggested that this timeframe could be at least twice as often during the planning period, but more likely four times. This review and evaluation could be used as a trigger to reassess the estimation of sustainable yield. Over time, any monitoring program should be aimed at increasing data quality. With the trend towards more community-based decision making in relation to groundwater management, there will be a need to implement structured approaches to evaluation such as that described in this section.
Clifton, C. and Evans, R. (2001) Environmental Water Requirements of Groundwater Dependent Vegetation. Technical Report Number 2. Environment Australia National River Health Program. Commonwealth of Australia, Canberra. Middlemis, H., Bonte, M., and Yan, W. (2004). Watermark Project: Conjunctive Resource Management: Scenario Modelling of Linked Stream-Aquifer Systems. In Proceedings Murray-Darling Groundwater Workshop, Bendigo, February 17-19, 2004. Sinclair Knight Merz 2001. Survey of Baseflow in Un-regulated Catchments within the Murray-Darling Basin. Report to the Murray-Darling Basin Commission, Canberra. Resource and Environmental Management (REM) 2003. Watermark: Sustainable Groundwater Use Within Irrigated Regions. Guiding Principles for Sustainable Groundwater Management in the Murray-Darling Basin. Final Report for Stage 1. Prepared for the Murray-Darling Basin Commission. November, 2003.