Guiding Principles for Sustainable Groundwater Management by xld14276


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Guiding Principles for
Sustainable Groundwater

May 2004
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,
Telephone: 618 8363 1777 Facsimile: 618 8363 1477

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                                                                                                     3
    1.2 Murray-Darling Basin Context                                                                                   4
           OVERVIEW ................................................................................................... 6
    2.1 Overview of the Framework                                                                                      6
           GUIDING PRINCIPLES ............................................................................... 12
    3.1 Introduction                                                                                                 12
    3.2 Identification of Resource Management Issues                                                                 12
    3.3 Identification and Quantification of Water Users and Uses                                                    12
    3.4 Confirmation of the (External) Decision Environment                                                          13
    3.5 Technical Assessments                                                                                        13
    3.6 Surface Water and Groundwater (One-Resource) Balances                                                        14
           3.6.1 Assessing Impacts from the Use of Groundwater                                                       16
           3.6.2 Guiding Principles for Technical Assessments                                                        17
    3.7 Defining User Provisions                                                                                     20
           3.7.1 Agreed Trade-Offs                                                                                   21
           3.7.2 Integrated Modelling                                                                                21
           3.7.3 Stakeholder Consultation                                                                            22
           3.7.4 Guiding Principles for Defining User Provisions                                                     22
    3.8 Planning and Implementation                                                                                  25
           3.8.1 Operating Rules                                                                                     25
           3.8.2 Policy Framework                                                                                    25
           3.8.3 Guiding Principles for Planning and Implementation                                                  26
    3.9 Monitoring and Evaluation                                                                                    27
4         REFERENCES ............................................................................................... 29
           List of Tables, Figures, Appendices

Table 1    Key Tasks in a Conjunctive Management Framework
Table 2    Classification of Approaches to Estimating Sustainable Yield
Table 3    Classification System for Stream-Aquifer Interactions


Figure 1   Allocation Versus Yield for Groundwater Management Units Within the
           Murray-Darling Basin
Figure 2   Decision Framework for Conjunctive Resource Management Within the
           Murray-Darling Basin
Figure 3   Types of Stream-Aquifer Interactions
Figure 4   Evaluation Framework


1.1     Key Issues
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
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 Murray-
Darling 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

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.

1.2      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 Murray-
Darling 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

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.


2.1      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

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:
                              Baseflow protection (especially low flow)                    Recharge protection (instream and flood)
                              Natural flow variability (frequency, timing and duration)
                              Saline discharges

                                      IDENTIFY and QUANTIFY                           IDENTIFY and QUANTIFY
                                       WATER USES and USER                             WATER USES and USER
                                                                                 Cap and
                                     Environment          Irrigation             other policies         Water                  Policy,
                                                                                                    requirements            economic
                                     Stock                Urban                  Integrated
                                                                                                      and needs            and social
                                     Domestic             Other industry         catchment                                framework

                                                           TECHNICAL ASSESSMENTS

                         COSTS/IMPACTS                  SURFACE WATER and GROUNDWATER                                BENEFITS and
                         Ecosystem impacts                  (”One-Resource”) BALANCES                              OPPORTUNITIES
                         Salinisation                                                                               RegionalRegulation
                                                               Investigation Steps
                         Water logging                           Knowledge generation                               Social wellbeing
                         Resource depletion                      Conceptualisation                                  Ecosystem service
                         IGIM approach
                                  management                     Modelling system                                   Conservation
                         Subsidence and                          behaviour           REVIEW
                         infrastructure damage                   Reporting
                         Impact on
                         surface flows

                                                                                                                                           MONITORING AND EVALUATION
                                                 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

                                            AGREED                                                 STAKEHOLDER
                                          TRADE-OFFS                                              CONSULTATION


                                             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


                                                       PLANNING and IMPLEMENTATION

                                                              DEVELOP CONJUNCTIVE
                                                         RESOURCE MANAGEMENT PLAN
                                                        Operating rules     Policy framework

                                                              GUIDING PRINCIPLES FOR
                                                         PLANNING and IMPLEMENTATION                                                                                   FIGURE
                                                       Access and trading  Precautionary approach

PIRSA 202294_006
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

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
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                         KEY TASKS                                           INPUTS                                         OUTCOMES

                  • Determine key sustainability and
Identify Issues   conjunctive management issues (in                  • Knowledge of the stresses within the           • A focus for the assessment and planning
                  consultation with all stakeholders) for the        biophysical, social and economic setting         process
                  catchment and/or operating environment

Identify and                                                         • Records of groundwater use, identification
                                                                                                                      • A clear understanding of the stakeholders
Quantify Water    • Determine the volume and quality of water        of groundwater dependent ecosystems and
                                                                                                                      and the relative magnitude of potential water
                  required by consumers and the environment          quantification of environmental water use,
Users and Uses                                                       land use data, location of production wells

                                                                                                                      • An understanding of the constraints and
Confirm                                                              • Legislation, policy and management plans       opportunities available from external
External          • Review existing legislation, policy and          (water, environmental and land)                  processes.
                  management plans to confirm the scope of the
Decision          decision making environment.                       • Social and economic studies for different      • A clearer understanding of the
Environment                                                          land uses and scenarios                          environmental, social and economic
                                                                                                                      consequences and risks
                                                                                                                      • Characterisation of stream-aquifer linkages
                                                                                                                      and environmental water requirements
                                                                                                                      • Characterisation and quantification of key
                  • Literature and information review to identify                                                     processes for recharge/discharge, flow, water
                  data sources and collate data                      • Multi-disciplinary technical team, including   quality and ecosystem dependence
                  • Analyse data to quantify data quality and        hydrogeologists, hydrologists, ecologists        • Identification of planning timeframe(s) and
                  site-specific linkages (fluxes, levels, temporal   • Groundwater and surface water data,            data deficiencies
                  and spatial variability, etc.)                     topography, geology, ecology, water use          • Development of conceptual model
Technical         • Assess Robustness of system to help
                                                                     • Robustness estimate and characterisation       • Stream-aquifer linkage classification, and
                  prioritise further investigations (next stage)
Assessments                                                          of hydrogeology/hydrology from stage 1           indication of potential impacts on quality or
                  • Classify stream-aquifer linkages                 • Water planning input on allocation & water     beneficial use category, and quantity
                  • Develop conceptualised model of water            use strategies; operating environment            • Prioritisation of further investigations
                  resource system and undertake system water
                                                                     • Ecological input on environmental water        • Selected modelling approach to investigate
                  balance to check model validity
                                                                     needs (notably GDE and/or riparian needs)        key issues
                                                                                                                      • Improved water efficiency, and potential
                                                                                                                      farm productivity
                                                                                                                      • Economic rationalisation

    Stage                         KEY TASKS                                          INPUTS                                            OUTCOMES
                 • Agree on the conceptual model across all
                 • Develop/update/calibrate modelling tools       • Outcomes of previous two stages
                                                                                                                      • Quantify effects in terms of water balances,
                 • Scenario modelling of conjunctive              • Data/analysis for model development and           water levels & quality and EWPs
Define User      management and sustainability issues             calibration, and statistical/probability analysis
                                                                                                                      • Quantify spatial/temporal variations
Provisions       • Analyse results for scenario modelling and     • Site-specific detailed features for stream-
                                                                                                                      • Quantify probability of depletion/recovery
                 formulate scenarios to better meet targets       aquifer interaction and GDEs
                                                                                                                      • Find balance between extraction & EWPs
                 • Provide feedback to all stakeholders on the    • Stakeholder constraints
                 modelling of the key issues

                                                                                                                      • Sustainable water resource system yield,
                                                                                                                      allocation and EWP strategy/policy
                 • Use modelling tool to quantify water                                                               • Share of the water resource
                 balance and quality components (including                                                            • Conjunctive resource management options
                 EWPs) in an allocation planning process
                 applied to specified timeframe, accounting for   • Modelling tool (not necessarily numerical)        • Stakeholders informed re water balance
Planning and                                                                                                          components, quality and risk/probability
                 hydrological variability                         • Water planning policies
Implementation                                                                                                        •   Drought management (and recovery) rules
                 • Use modelling tool to investigate and set      • Stakeholder engagement
                 operating rules for resource management,                                                             •   EWP’s for GDEs
                 consistent with allocation policy                                                                    •   Hotspot management rules
                                                                                                                      •   Maximising the effectiveness of high stream
                                                                                                                      flow/flood flow conditions

                 • Identify monitoring targets to assess
                                                                                                                      • Report on assessment of performance in
                 • Optimise monitoring network/data                                                                   relation to targets
                 requirements                                     • Outcomes from previous stages                     • Optimal monitoring network/system
Monitoring and   • Identify data gaps or weak data areas          • Monitoring data                                       Status reports to stakeholders
Evaluation       where improved information and knowledge is
                                                                                                                      • Report on assessment of performance in
                                                                                                                      relation to targets
                                                                                                                      •   Prioritise further work
                 • Review performance and identify any need
                 for further investigation/monitoring/modelling


3.1      Introduction
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.

3.2      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.

3.3      Identification and Quantification of Water Users and                              Uses
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 over-
development 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.

3.4      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 re-
vegetation 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.

3.5      Technical Assessments
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

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.

3.6      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.


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 post-
water 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

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%         50 – 75%      75 – 100% >100%

 Error in        >±50%          II           III            IV            V
                 <±50%           I            II            III          IV

In addition, aquifers can be assigned a status as follows:

 Groundwater               Definition
    Under-               Where Allocation to Sustainable Yield ratio is less than 50%.
    developed            Generally, some further development may be possible.
    Developing           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.
    Developed            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.
   Over-developed        Where Allocation to Sustainable Yield ratio is greater than
                         100%. No groundwater is available, and steps to limit or reduce
                         current allocations are warranted.
    Over-used            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

•        Better understanding of surface water/groundwater interactions;

•        Better understanding of groundwater dependent ecosystem requirements and

•        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

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

Table 3. Classification System for Stream-Aquifer Interactions

Hydraulic             Stream-                Potential Impacts      Potential Impacts         Potential Impacts
Connection            Aquifer                on Surface Water       on Surface Water          on Groundwater
                      Interaction            Resources of           Quality of Poor           of Changes to
                      Process                Groundwater            Groundwater               Surface Water
                                             Abstraction*           Quality                   Flows or Quality
Connected             Gaining                 High                     High                    Low
Connected             Losing Stream           Medium                   No Impact               High
Connected             Variable                Medium to                Low                     Medium to
                      Gaining and/or          High                                             High
                      Losing Stream
Disconnected          Losing Stream           No Impact**              No Impact**             High
* 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.

                                 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                                             Connected to the groundwater system
  by a continuoues saturated zone                                                     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

                   e:\projects\MDBC (AR)\Conj Use (03)\Figures\Fig 2_revb.mxd

                                                                                                  Project: AR-03
                                                                                                                        November 2002
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.

3.7      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.      The proportion of the available consumptive water that is to be extracted from the
        groundwater and surface water resources; and

2.      The allocation of the water amongst the various user groups, including urban and
        domestic, industrial, mining, stock, irrigation, environmental and downstream

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

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

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

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

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

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

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

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).


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.

3.8      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

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.

3.9     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

•       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



          Refine                              Target
          management                          setting


          (against                                          Report
          objectives)                                       (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.


                                                          FRAMEWORK                      4
GeoTech Graphics 595-2968
                                                                                 December 2003
The evaluation framework adopts a contemporary business approach by applying
benchmarking principles that involve:

(a)     The establishment of baseline assessments against which progress can be

(b)     A predictive framework that provides for the forecasting of outcomes under the
        various intervention options;

(c)     A planning process that realises management responses;

(d)     Target setting for each resource management objective;

(e)     Setting indicators that support reporting against targets; and

(f)     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

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,

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.


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