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Australian Water Resources 2005, Assessment of river and wetland health: A framework for comparative assessment of the ecological condition of Australian rivers and wetlands

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Australian Water Resources 2005
A baseline assessment of water resources for the National Water Initiative
Level 2 Assessment
River and Wetland Health Theme
Assessment of River and Wetland Health: A Framework for Comparative Assessment of
the Ecological Condition of Australian Rivers and Wetlands
Australian Water Resources 2005
A baseline assessment of water resources for the National Water Initiative
Level 2 Assessment
River and Wetland Health Theme
Assessment of River and Wetland Health: A Framework for
Comparative Assessment of the Ecological Condition of
Australian Rivers and Wetlands
May 2007
This initiative is supported through the Australian Government's
Raising National Water Standards Programme
Acknowledgements
The WRON Alliance is a group of key government, academic and industry partners who have
formed a coalition to improve the usage and value of water resources information for the
benefit of the nation. Members of the WRON Alliance involved with the development of
Australian Water Resources 2005, which is an initiative of the National Water Commission,
include: CSIRO, eWater CRC, Bureau of Rural Sciences (BRS), Australian Bureau of
Statistics (ABS), National Land and Water Resources Audit (NLWRA), and Sinclair Knight
Merz (SKM).
The River and Wetland Health theme of this report was made possible through interaction,
support and input of many organisations and individuals. In particular, thanks are due to the
jurisdictional reference group consisting of representatives of the Australian states and
Australian Government agencies. These provided important input and feedback, often at
short notice. Colin Chartres, Matt Kendall, Judy Hagan and Craig McVeigh of the National
Water Commission were closely involved with all aspects of the project and had significant
input throughout. Paul Wilson from the Victorian Department of Sustainability and
Environment and Martin Read from the Tasmanian Department of Primary Industries and
Water played a major role in supplying data and contributing to the project.
Authors: Richard H. Norris, Fiona Dyer, Peter Hairsine, Mark Kennard, Simon Linke, Linda
Merrin, Arthur Read, Wayne Robinson, Chris Ryan, Scott Wilkinson, and David Williams.
May 2007
Also available at: <http://www.water.gov.au>
This work is copyright. Apart from any use as permitted under the Copyright Act 1968, no
part may be reproduced by any process without prior written permission from the
Commonwealth. Requests and inquiries concerning reproduction and rights should be
addressed to the Commonwealth Copyright Administration, Attorney General’s Department,
Robert Garran Offices, National Circuit, Barton ACT 2600 or posted at
<http://www.ag.gov.au/cca>.
National Water Commission
95 Northbourne Ave
Canberra ACT 2600
Email: awr@water.gov.au
Phone: 02 6102 6000
© Commonwealth of Australia 2007
ISBN 13: 978-1-921107-40-5
Framework for the Assessment of River & Wetland Health
i
Contents
Page
Executive summary ...................................................................................... iii
1 Introduction ...........................................................................................1
1.1 Purpose......................................................................................... 1
1.2 The philosophy .............................................................................3
1.3 Role of the national framework ..................................................7
2 Methods .................................................................................................9
2.1 Environmental components to be represented.........................9
2.2 Assessment and reporting framework and scale ...................10
2.3 Surface water management areas ...........................................11
2.4 Reaches and wetlands ..............................................................11
2.5 The reference condition approach ...........................................14
2.6 Indices and index features ........................................................15
2.7 Integration of the framework components..............................16
2.7.1 Reach, wetland and basin scale aggregation and integration ............... 16
2.7.2 Methods to integrate indices ..................................................................... 19
2.8 Analysis of common factors determining river condition ......21
2.9 Sensitivity analysis.....................................................................21
2.9.1 Method.......................................................................................................... 21
2.9.2 Sensitivity and underlying reasons in the NLWRA I................................. 21
2.10 Range standardisation and bands of condition...................23
2.10.1 Range standardisation................................................................................ 23
2.10.2 Bands of condition ...................................................................................... 24
2.11 Missing data............................................................................ 30
2.11.1 Overall Index at various scales .................................................................. 30
2.11.2 Hydrological Disturbance Index................................................................. 31
2.11.3 Nutrient and suspended sediment load index (Water Quality and Soils
Index) 31
2.11.4 Habitat index (Physical Form Index).......................................................... 32
2.11.5 Catchment Disturbance Index ................................................................... 32
2.11.6 Aquatic Biota Index ..................................................................................... 32
2.11.7 Integrating the four environmental indices into an NLWRA I ARCE at the
reach level.................................................................................................................... 33
2.11.8 Validation of indices .................................................................................... 33
3 References........................................................................................... 34
Framework for the Assessment of River & Wetland Health
iii
Executive summary
The National Framework for the Assessment of River and Wetland Health
(FARWH) is being developed as part of the Australian Water Resources 2005
(AWR 2005) project being undertaken by the National Water Commission (the
Commission) under the National Water Initiative (NWI).
The AWR 2005 Discovery Phase, undertaken in early 2006, examined the
availability of data to undertake a national river health assessment based on
the last national assessment under the Australian Catchment, River and
Estuary Assessment 2002 (NLWRA 2002). It was determined that, although
there were significant gaps in available data in some areas of Australia, other
areas of Australia had methods and techniques that had advanced beyond
those of 2002.
For this reason, the Commission is progressing the development of a national
framework for river and wetland health assessment, with partner
governments to enable the future application of a robust national assessment
that uses existing work to the maximum extent possible.
The resulting framework, FARWH, is designed to provide the information
needed to:
establish ‘environmental and other public benefit outcomes’ (NWI
paragraph 35)
‘address currently over allocated and/or overused systems’ (NWI
paragraphs 41–45)
support ‘integrated management of environmental water’ (NWI
paragraphs 78–79).
FARWH has been developed through extensive consultation with partner
state and territory governments. Other stakeholders, such as regional
authorities that monitor natural resources, will also be increasingly involved to
better incorporate all relevant monitoring regimes.
A framework such as FARWH is seen as essential because it allows existing
work to be used for reporting the aggregate impacts of resource use on
rivers and wetlands at a national scale. In this way, long-term changes in
condition can be identified, including changes resulting from water
management regimes.
FARWH is closely linked to other major programs such as:
Victorian Index of Stream Condition
Victorian Index of Wetland Condition
Tasmanian Conservation of Freshwater Ecosystem Values Framework
Queensland Wetlands Program
Natural Resource Management Ministerial Council, National Natural
Resource Management Monitoring and Evaluation Framework
(NNRMM&EF)
Framework for the Assessment of River & Wetland Health
iv
The FARWH is based on a hierarchical model of river and wetland function,
which addresses: environmental components to be represented by a national
assessment, reporting scale, reference condition, discussion on selection of
indices, methods for integrating and aggregating indices for assessment,
sensitivity analysis, range standardisation, and managing missing data.
The FARWH proposes that six key components are appropriate for the
assessment of river and wetland health, all of which are considered to
represent ecological integrity. These are:
catchment disturbance
hydrological change and spatial extent of wetland and temporal change
water quality
physical form
fringing zone
aquatic biota.
The FARWH describes how to develop and combine indices so that
nationally comparable assessments of river and wetland health can be
achieved. This is designed to enable states and territories to include data that
are already being collected (for example, AUSRIVAS invertebrate data) and to
compare these data between regions. In some cases, such as the Victorian
Index of Stream Condition, little change is needed to incorporate specific
datasets into the national framework.
The framework presents the components of the environment to be
represented but does not prescribe which indices should be selected to
represent them. It also describes how to create the indices so that their
characteristics allow direct comparisons between jurisdictions without having
to take the same measurements in each place. For example, an index score
of 0.5 on a scale of 0–1 for biota in one place should mean the same as a 0.5
score in another place, even if different biotic groups have been used. The
index would then represent the condition of the biota considered important
for that state or territory. This is achieved by agreed range standardising,
reference conditions, validation, and sensitivity analysis.
The framework also recommends that indices should be:
relative to a reference (usually pre-European conditions)
linear and range standardised to 0–1, in increments of 0.1
divided into condition bands.
Consideration should also be given to:
the weighting of indices when aggregating from the finest scale of
measurement, which will usually be the reach or individual wetland, to
represent the surface water management area (SWMA). This weighting
would normally be by stream length, or the wetted area of individual
wetlands
Framework for the Assessment of River & Wetland Health
v
methods of integration, which may follow expert rules (e.g.such as the
CFEVF, Sustainable Rivers Audit). Where these are well thought out,
inverse ranking should be used, as in the Victorian Index of Stream
Condition. Euclidean distance is recommended where other methods
have not been well developed
sensitivity analysis to determine which indices contribute most to the
evaluations
the inevitably that there will be missing data at the finest scale of
measurement. It is recommended that three of the six components
should be present before an overall assessment can be reported
at the scale of an individual surface water management area, at least five
per cent of the recognised river reaches or wetlands should be
represented.
The Assessment of River and Wetland Health: Potential Comparative Indices
(companion document produced by the River and Wetland Health Theme,
NWC 2007), describes indices that have been developed in a way that meets
the requirements of the FARWH, largely during the first National Land and
Water Resources Audit. Indices developed as part of the Victorian Index of
Stream Condition and the Tasmanian Conservation of Freshwater Ecosystem
Values Project also conform to the FARWH. Any of these may be selected by
various jurisdictions. They may also be selected to fill gaps in the
environmental components that may not be covered in existing state or
territory programmes. Although these indices are not prescribed, some of
them such as the AUSRIVAS and hydrology indices (flow stress ranking) have
already been accepted for use by several jurisdictions and may be used quite
widely.
The Assessment of River and Wetland Health: Potential comparative indices,
(NWC 2007) therefore provides a series of methods that can be used in the
assessment of river and wetland health, including a new method that has
been developed for the fringing (riparian) zone.
Framework for the Assessment of River & Wetland Health
1
1 Introduction
1.1 Purpose
The National Framework for the Assessment of River and Wetland Health
(FARWH) is being developed as part of the Australian Water Resources 2005
project being undertaken by the National Water Commission (the
Commission) under the National Water Initiative (NWI).
Australian Water Resources 2005 (AWR 2005) reports under three headline
parameters: Water Availability, Water Use, and River and Wetland Health.
Philosophically, the term ‘river and wetland health’ is useful because it is
readily interpreted by most people and evokes societal concern about human
impacts on river and wetlands. The common goal of achieving healthy rivers
and wetlands unites scientists, in particular ecologists, and others because
the value of the scientific contributions is clear. A possible problem arises in
the choice of relevant symptoms, or indicators, because no single indicator is
likely to stand alone to reveal river and wetland health unequivocally (Boulton
1999): there is a wide variety that can be measured with varying accuracy
and at a broad range of spatial scales. Thus, the FARWH is designed to
provide a framework to guide assessment of river and wetland ‘health’.
The AWR 2005 Discovery Phase examined the availability of data relevant to
undertaking a national river health assessment based on the last national
assessment under the Australian Catchment, River and Estuary Assessment
2002. It was determined that, although there were significant gaps in
available data in some areas of Australia, other areas of Australia had access
to methods and techniques that had advanced beyond those of 2002.
For this reason, the Commission is progressing a national framework for river
and wetland health assessment. The resulting framework, FARWH, is
designed to provide the information needed to:
establish ‘environmental and other public benefit outcomes’ (NWI
paragraph 35)
‘address currently over allocated and/or overused systems’ (NWI
paragraphs 41–45)
support ‘integrated management of environmental water’ (NWI
paragraphs 78–79).
The FARWH is being developed through extensive consultation with partner
state and territory governments. Other stakeholders, such as regional
authorities that monitor natural resources, will also be increasingly involved to
better incorporate all relevant monitoring regimes into an assessment of
national river and wetland health.
A framework such as the FARWH is seen as essential because it allows
existing state and territory work to be used for reporting the aggregate
impacts of resource use on rivers and wetlands at a national scale. In this
Framework for the Assessment of River & Wetland Health
2
way, long-term changes in condition can be identified, including changes
resulting from water management regimes.
National natural resource management at broad scales requires information
at matching broad scales. Such broad-scale information on river and wetland
condition is required to assist managers to assess and develop policies,
decide on investments, evaluate program and policy performance and direct
resource management activities, particularly those of government. Thus,
broad-scale assessment that focuses on the information needs of the
Australian and state and territory governments is needed. Local government,
rural industries, community groups, and various other government and non-
government organisations will also benefit.
Water resource managers in Australia have recognised significant problems
that are associated with an increasing demand for water, declining river and
wetland health, and public pressure for changed management. For example,
dryland salinity and soil and streambank erosion are problems that affect
rivers and wetlands nation-wide. Both require management at broad scales.
More positively, the Murray-Darling Basin Cap has limited diversions in
recognition of the maintenance of environmental values as a legitimate use of
water.
The formulation of policies to manage such problems generally does not
require site-specific information but does need assessment at regional, state
or national levels. Answers are needed to questions such as:
‘What is the extent and condition of our renewable natural resources?’
‘Where and what parts of the environment are changing?’
‘What is causing the observed environmental changes?’ (Olsen et al.
1999).
The problems inherent in answering these questions have been recognised in
several countries, with the result that large-scale programmes have been
implemented. There have been national surveys of lakes and rivers in Great
Britain (Wright 1995, Raven et al. 1998), Sweden (Wiederholm and Johnson
1997), and the United States of America (Wadeable Streams Assessment. A
Collaborative Survey o f the Nation’s Streams, US EPA 2006,
<http://www.epa.gov/owow/streamsurvey/report.pdf >).
All Australian states and territories have developed white papers, strategic
plans, or policies on water that recognise shortages and the need for
management, especially in relation to the environment and achieving
sustainable water use. These policy documents lay out how water reform will
be achieved and the objectives of the relevant state and territory water Acts.
The June 2004 Intergovernmental Agreement on a National Water Initiative
(NWI)
<http://www.coag.gov.au/meetings/250604/index.htm#water_initiative>
renewed these efforts by reaffirming commitment to the 1994 agreements
and setting a new schedule of actions. All states and territories have now
Framework for the Assessment of River & Wetland Health
3
signed up to the NWI. The specific NWI objectives that relate to
environmental water provisions are:
Objective (iii) – statutory provision for environmental and other public
benefit outcomes, and improved environmental management practices
Objective (iv) – complete the return of all currently overallocated or
overused systems to environmentally sustainable levels of extraction.
Furthermore, paragraph 79 (f) of the NWI requires ‘management and
institutional arrangements to ensure the achievement of environmental and
public benefit outcomes including any special requirements needed for the
environmental values and water management arrangements necessary to
sustain high conservation value rivers, reaches and groundwater area’.
The aim of the FARWH is to develop an approach that can be used by all
Australian states and territories to provide assessments of river and wetland
health that are comparable nationally. It is intended to incorporate a range of
river and wetland attributes that indicate key ecological processes. The
attributes measured and method of reporting also will be designed to aid in
interpretation of the causes of observed environmental degradation.
1.2 The philosophy
FARWH is based on the premise that ecological integrity is represented by all
the major components of the environment that comprise an ecosystem.
Damage to biota is usually the final point of environmental degradation and
pollution. Thus, the aquatic biota are a fundamental indicator of disturbance
to rivers and wetlands and their catchments, including groundwater. Aquatic
biota should therefore be included in any assessment of river and wetland
health. The biota are also components of, or critical to, the goods and
services provided by rivers and wetlands that are valued by society.
The function of the FARWH is to bring together in an assessment a number
of related elements of river and wetland condition. The approach that has
been adopted has been informed by our understanding of the links between
catchments, river and wetland habitats, and their aquatic biota. The
conceptual model and components of the FARWH are summarised in Figures
1 and 2.
Framework for the Assessment of River & Wetland Health
Figure 1: Conceptual model of scales of factors related to river and
wetland condition.
This hierarchical model demonstrates catchment features such as
longitudinal and lateral connectivity (dams and levees) and land use, which
in turn have an effect on habitat features (riparian vegetation, snags,
channel geomorphology), and these together affect the biotic components
of the system (algae, aquatic vegetation, insects, fish, water birds). The
model includes floodplain wetlands but groundwater will be more
important for coastal plain and other wetlands and connectivity between
rivers and their floodplains less so.
4
Framework for the Assessment of River & Wetland Health
Figure 2: Generalised models of wetlands, their main features and their
interactions with groundwater and surrounding catchments
(source: Queensland wetlands project)
Elements other than the aquatic biota need to be included in a
comprehensive FARWH for several reasons.
5
Framework for the Assessment of River & Wetland Health
6
other features of the environment have value in their own right
the available or selected group of biological indicators may not be
sensitive to all forms of river or wetland degradation
there may be a time lag between environmental disturbance and
observable biotic response
monitoring only the biota may tell us that the biota are damaged, but not
why. A comprehensive assessment that includes measurements of the
key stressors will provide information about the probable causes of
degradation, and therefore guide management decisions and actions
Unless monitoring is continuous and includes all types of biota, certain
types of disturbance may go undetected, or be detected only after severe
impairment has occurred, because the chosen group of biological
indicators are insensitive, or there is a time lag between environmental
disturbance and biotic response.
The framework proposed here is based on a hierarchical model of river and
wetland function (Figs 1 and 2) in which broad-scale catchment
characteristics affect local hydrology (water regimes), hydraulics, habitat
features, and water and soil quality. These influence the river and wetland
biota, an ultimate indicator of river and wetland health. This model is a
refinement of the model underpinning the assessments made in the Snowy
Water Inquiry (Young et al. 1998) and similar models that have been adopted
in other major state programmes such as:
the Victorian Index of Stream Condition
<http://www.vicwaterdata.net/vicwaterdata/data_warehouse_content.asp
x?option=5>
the Victorian Index of Wetland Condition
<http://www.dse.vic.gov.au/DSE/nrence.nsf/LinkView/3EA5B6AEFB53EE
3DCA25708B00145F44522C816829EBF3F7CA25700C00240E63>
the Tasmanian Conservation of Freshwater Ecosystem Values Project
<http://www.dpiw.tas.gov.au/inter.nsf/WebPages/JMUY-5QF35H?open>
the Queensland Wetlands Program
<http://www.epa.qld.gov.au/publications/p01948aa.pdf/Monitoring_wetla
nd_extent_and_condition.pdf>.
At the broad scale, catchment character influences a river or wetland through
large-scale controls on hydrology, sediment delivery, and chemistry (Allan
and Johnson 1997, Johnson and Gage 1997, Mitsch and Gosselink 2000).
Therefore, if catchments are disturbed or in degraded ecological condition,
then associated rivers and wetlands will also be unhealthy. Much of the
degradation in Australia’s rivers and wetlands results from land-use practices
in surrounding catchments (Boulton and Brock 1999). Assessing catchment
condition may therefore provide information about the ultimate causes of any
observed biological impoverishment, and highlight potential impacts that
have not yet caused biological degradation within rivers but that are likely to
do so.
Framework for the Assessment of River & Wetland Health
7
At the local scale, available habitat and the local physical, chemical and
biological features that provide living space and resources determine the
types and numbers of plants and animals that can potentially live at a site.
The quantity and quality of available habitat affects the structure and
composition of resident biological communities (Hynes 1968, Meffe and
Sheldon 1988, Boulton and Brock 1999, Maddock 1999), and are thus critical
elements of ecological condition. Habitat assessment provides information
about the likely proximal causes of impoverished biological states, and may
be used as a surrogate for biological condition (including biodiversity) where
these latter data are unavailable. Aspects of habitat assessed in the FARWH
include water quantity and quality, soils of wetlands, geomorphology, fringing
zone vegetation structure, and the connectedness, longitudinal of rivers and
lateral of rivers to their floodplain (including wetlands), and wetlands to their
catchments and groundwater.
1.3 Role of the national framework
The FARWH is designed to use data from existing programmes such as:
the Victorian Index of Stream Condition
<http://www.vicwaterdata.net/vicwaterdata/data_warehouse_content.asp
x?option=5>
the Victorian Index of Wetland Condition
<http://www.dse.vic.gov.au/DSE/nrence.nsf/LinkView/3EA5B6AEFB53EE
3DCA25708B00145F44522C816829EBF3F7CA25700C00240E63>
the Tasmanian Conservation of Freshwater Ecosystem Values Project
<http://www.dpiw.tas.gov.au/inter.nsf/WebPages/JMUY-5QF35H?open>
the Lake Eyre Basin Rivers assessment (Sheldon et al. 2005) and the
Queensland Wetlands Program
<http://www.epa.qld.gov.au/publications/p01948aa.pdf/Monitoring_wetla
nd_extent_and_condition.pdf>.
The FARWH is also designed to provide the basis for choosing and managing
reporting measures from the Natural Resource Management Ministerial
Council, National Natural Resource Management Monitoring and Evaluation
Framework (NNRMM&EF) <http://www.nrm.gov.au/monitoring/>. The
relationship between the two frameworks is shown in Figure 3 While the two
are closely related in some ways, the NNRMM&EF is more targeted to
assessing particular issues of relevance to the National Action Plan, rather
than overall river and wetland health.
Framework for the Assessment of River & Wetland Health
National Water Initiative NHT / NAP
Australia’s Water Resources 2005 National Monitoring & Evaluation Framework
National River & Wetland
Health Assessment Framework 4. Inland Aquatic Ecosystem Integrity
River
Condition Wetland
Condition
Wetland
Extent &
Distribution
Nationally Agreed
Recommended
Indicators
10 Matters for Target
Catchment
Disturbance
Index
Water Quality
& Soils
Index
Aquatic Biota
Index Physical Form
Index
Hydrological
Disturbance
Index
Nationally Agreed
Recommended
Indicators
Nationally Agreed
Recommended
Indicators
Jurisdictional / Basin Programs
(eg MDBC SRA, Vic ISC, Tas CVEF)
Fringing
Vegetation
Index
Figure 3: Relationship between the Framework for the Assessment of
River and Wetland Health and the Natural Resource
Management Monitoring and Evaluation Framework (source
Edgar et al. 2006)
A primary function of the FAWRH is to provide the approach for locally
relevant, comprehensive assessments of river and wetland health that are
comparable across jurisdictions. In this context, there is no need for the
same measures to be made in each place, but the indices derived from the
various measures must be directly comparable. For example, salinity could
be an important water quality measure in one place, and nutrients could be
important in another. The indices representing the various measures of water
quality should be equivalent, so a score of 0.8/1.0 based on salinity is
equivalent to the same score based on nutrients.
8
Framework for the Assessment of River & Wetland Health
9
2 Methods
2.1 Environmental components to be represented
Catchment and habitat conditions are not the sole determinants of the
richness and abundance of aquatic biota. Biological processes such as
primary production, trophic relationships, competition, predation,
immigration, emigration and recruitment also influence the composition and
structure of running water communities. Some states and territories already
have well-developed methods for assessing ecological processes that may
be incorporated as biological measures.
In many places, these ecological processes can be too complex and poorly
understood to be explicitly included in an assessment method, but they
should be considered for inclusion anyway. Interactions among chemical and
physical process create conditions at a range of scales that strongly
influence biological processes (Boulton and Brock 1999). For example, the
level of photosynthetic activity is heavily influenced by light, temperature and
nutrient regimes—aspects of habitat that could be covered in the
assessments of nutrient and suspended sediment loads and riparian
condition. Similarly, hydrology, connectedness, and riparian vegetation all
affect carbon fluxes, and therefore trophic structure, in rivers. Thus, while
ecological processes might not be measured directly, structural variables that
affect, or are affected by, those processes would be assessed.
It is proposed that the following environmental components be assessed as
part of the FARWH:
Catchment Disturbance Index incorporates the effects of land use, change
in vegetation cover and infrastructure (for example, roads and railway lines)
on the likely runoff of sediments, nutrients and other contaminants to rivers
and wetlands. The index should incorporate the effects of large-scale, non-
point source impacts.
Physical Form Index uses measures of sediment inputs, riparian vegetation
structure and connectedness (dams, weirs, levee banks, groundwater
abstraction) to assess the state of local habitat and its likely ability to support
aquatic life.
Hydrological Disturbance Index recognises the importance to aquatic
ecosystem function of the water regime, both surface flow and groundwater,
depending on the ecosystem.
Water Quality and Soils Index considers the effects on biota of long-term
changes in water quality characteristics (rivers and wetlands) and soil quality
(wetlands), such as changes in suspended sediment and total nutrient
concentrations or loads, and the effects of short-term changes in salinity and
toxicant levels.
Fringing Zone Index represents structural and condition features of the
streamside zone, or the zone surrounding a wetland. While this index could
contain features relevant to the Physical Form and Aquatic Biota indices, the
Framework for the Assessment of River & Wetland Health
10
zone is seen as such an important focus of management that it requires its
own category.
Aquatic Biota Index represents the response of biota to changes in the
environment. This index can be based on extensive national sampling of
invertebrates sensitive to disturbance. Other components of the biota (for
example, fish, water plants, algae, and riparian vegetation condition) would
give a fuller picture of the response of ecosystems to change.
2.2 Assessment and reporting framework and scale
Australia’s land area is just under 7.7 million square kilometres with a
population of around 21 million people (about 2.5 people per square
kilometre). The island continent has large regional variations in climate and,
after Antarctica, is the driest continent on earth. Compared with most other
continents, Australia has few lakes, and the country is heavily reliant on water
from rivers for economic, agricultural, industrial and domestic activity.
Indeed, 95 per cent of the population lives within 10 kilometres of a river
channel (Thoms et al. 2000), which is high compared to other countries.
River and wetland health assessments should be conducted at the scale of
river reaches, or individual wetlands. Reaches should be specified within the
region assessed (usually surface water management area). A method for
reach specification that was used in the National Land and Water Resources
Audit I (NLWRA I) is described below (section 2.4). The scale of the NLWRA I
reaches can be changed depending on the resolution of the digital elevation
models used and it is recognised that some states (such as Victoria) already
have their own methods based on on-ground or other assessment methods.
Wetlands will be specified according to a minimum area when wet. Two
outstanding issues are the number of wetlands required to adequately
represent a surface water management area and whether their assessment
scores should be weighted by their relative size to provide . Numbers of
wetlands to be sampled has been discussed in the Lake Eyre Basin Rivers
Assessment <http://www.deh.gov.au/water/basins/lake-
eyre/publications/assessment.html>. Both issues are being addressed in the
National Indicators for Wetland Ecosystem Extent, Distribution and Condition
project <http://www.nrm.gov.au/monitoring/indicators/index.html>.
Assessments at the reach scale may be reported at that scale to meet local
needs but also can be aggregated to broader spatial scales to provide
assessments for surface water management areas, an entire state or territory,
and at the national level. It is intended that assessment for the NWI will be
undertaken at the scale of a surface water management area. State-based
assessment programmes that conform to FARWH (such as the Victorian
Index of Stream Condition, the Tasmanian Conservation of Freshwater
Ecosystem Values Framework, and eventually the Murray-Darling Basin
Sustainable Rivers Audit) could also be reported at scales that meet
jurisdictional needs.
Framework for the Assessment of River & Wetland Health
11
2.3 Surface water management areas
The river basins used for the framework will be the surface water
management areas provided by each of the states and territories to the
National Water Commission. In some cases, these are groups of small river
basins. In New South Wales they have been divided into regulated and
unregulated sections.
2.4 Reaches and wetlands
River basins are large areas with a considerable diversity of river and wetland
condition, necessitating a finer basic unit for calculation of the framework
indices. Wetlands will usually be discreet units of measurement and the
number of individual wetlands assessed may constitute the sample size
representing the surface water management area (see Sheldon et al. 2005).
Wetlands may need to be weighted by their area when aggregated to provide
an assessment of a surface water management area.
River links, the stretches of river between tributary junctions, are an easily
defined, fine-scale unit within a river network. There may be many thousands
of river links (depending on the mapping resolution used) in any assessment
area, making reporting and modelling cumbersome. For example, the
Tasmanian Conservation of Freshwater Ecosystem Values Framework has
about 400,000 river links at a 25-metre resolution. Many of these links do not
differ very much in their physical character. A large river is unlikely to change
its physical character in response to being joined by a small tributary stream.
Consequently, river links may be aggregated into reaches of similar character
to reduce unnecessary duplication of calculations and results.
Geomorphologists have many ways of defining river reaches that often
depend on intensive surveys (Rosgen 1996, Brierley et al. 1999). Intensive
on-ground surveys are unlikely to be possible for reporting on all surface
water management areas in a state or territory (or perhaps even one).
Consequently, an automated system based on geomorphological principles
was developed in NLWRA I and is available for use in this assessment,
although other approaches can be used if they are available. The headwaters
of catchments contain many small stream sections that could numerically
overwhelm all other sections of a surface water management area, and for
which little information is available for broad-scale surveys. To avoid this
problem, and to ensure that the reporting scale represents most of the
surface water management area in the reporting area, a reach was defined in
the NLWRA I as having a minimum contributing catchment area of 50 square
kilometres (this could be changed depending on state and territory needs).
The physical character of a river is likely to change from one link to another
as a result of major changes in catchment area that determine the flow and
other fluxes such as sediments and nutrients. Changes in slope between
links influence the velocity of flow and hence the shear stress and the stream
power or sediment transport capacity, leading to changes in channel and bed
morphology. Flow and material loads are also influenced by catchment areas,
and hence the product of catchment area and slope (a simple surrogate
Framework for the Assessment of River & Wetland Health
12
measure for stream power) is often used by geomorphologists as a primary
indicator of geomorphic form (Montgomery and Buffington 1997; Dietrich et
al. 1993). Entry to, or exit from, reservoirs and lakes must also be considered,
and it was ensured that river links and reaches were broken at these points.
The above principles were used to aggregate river links into reaches.
A branching network of river links joined by nodes was defined in the NLWRA
I from the AUSLIG 9-second digital elevation model (DEM) of Australia. This
data set is available for the framework, however, finer scale DEMs are
available in some places and there may be benefits in using them. An
alternative method of defining river networks from mapped streams was
dismissed in the NLWRA I because, in places, the position of the mapped
streams does not coincide exactly with valleys in the DEM. The DEM is
required to generate topographic attributes of catchment area and the slope
of each river link, and errors in positioning produce many spurious results.
However, some states with extensive on-ground measurement programmes,
such as Victoria, may have reaches defined by direct observation.
The NLWRA I used the ARCInfo flow accumulation algorithm to define the
catchment area of all cells in the DEM. The river network was defined as
beginning at a catchment area of 50 square kilometres. Short links, where the
catchment area had reached less than 75 square kilometres by the
downstream node, were removed. This data set is available for use but could
also be modified using the same algorithm with finer resolution DEMs.
In the NLWRA I, links were further separated by nodes at the entry to and exit
from reservoirs and lakes. The presence of lakes and reservoirs was derived
from an AUSLIG waterbody database mapped from 1:2.5 million topographic
maps. This database was found to unreliably distinguish natural lakes from
waterbodies created or regulated by dams. A separate AUSLIG point
coverage of flow control structures was obtained to define regulated
waterbodies from natural lakes. Lakes were defined as those waterbodies
that did not intersect an associated structure in the dam database.
Reservoirs were defined as water bodies that intersected structures of
10 metres height or greater. All river links downstream of reservoirs were
defined as having regulated flow.
Reaches used for the NLWRA I were formed by concatenating one or more
network links and joined according to the following rules:
all first order links (those with no tributary) were assigned as separate
reaches
for links downstream, the product of link slope and drainage area (a
stream power surrogate) was compared to that of the two tributary links
if one tributary link provided 90 per cent or more of the area of the link,
then the tributary reach was continued downstream unless the area slope
product differed by a factor of two or more. In that case a new reach was
started
if no tributary link dominated the area of the downstream link, then the
tributary reach of closest area and slope product was continued
Framework for the Assessment of River & Wetland Health
downstream. If the product of area and slope for the link differed by more
than twofold from both tributaries a new reach was started
new reaches were initiated at the entrance and exit from lakes and
reservoirs.
Each reach has an internal contributing area (called a subcatchment area in
this project). The subcatchment area is the catchment area added to the
reach between its upper and lower limits (Fig. 4). The subcatchment area of
first order streams is the entire catchment area of the river link.
Subcatchment areas for each reach were determined from the flow
accumulation grid. The slope of the link was defined as the elevation
difference between the upper and lower ends of the link divided by the length
of the link.
The total catchment area of a river reach is the spatial extent of land that
drains to the most downstream point of a reach. That means that the
catchment of a reach has nested within it the catchments of all upstream
reaches. The catchment area was determined by merging the subcatchment
of the reach with all upstream sub-catchments (Fig. 4).
A unique seven or eight digit identifier was given to each reach, composed of
the three or four-digit Australian Water Resources Council basin identifier
followed by an arbitrarily assigned four-digit code.
13
Framework for the Assessment of River & Wetland Health
14
Figure 4: Relationships between reaches, subcatchments and
catchments
As a check, DEM-derived river networks were compared with named
streamlines recorded on the AUSLIG 1:250,000 topographic map series. A
close match was found in all upland areas (areas with ridge and valley
topography). If links did not coincide with a named stream they were
excluded from the database. This process was necessary in the drier and
flatter regions to remove DEM-generated flow accumulations that are not
expressed on the ground as streams for reasons such as transmission
losses, dispersion of flow, terminal lakes, or lack of flow through dune
systems and depressions. The Murray-Darling Basin stream network was
also manually checked and edited against the 72 1:250,000 topographic map
sheets that cover the basin. The lowland rivers of the Murray-Darling Basin
were not well represented by the link network because of problems of
anabranching streams, distributary channels, and flow through very flat areas
that were not well represented by the DEM. Accurate representation of this
type of system requires further development, and reaches identified in
lowland parts of the Murray-Darling Basin used in the NLWRA I should be
treated with caution.
The derivation of the river reach network in the NLWRA I was time
consuming, and it has not been verified. To improve reporting, knowledge of
the types of rivers in the area assessed would be useful and could be
considered by each state and territory. There have been attempts to classify
the rivers of specific regions within Australia but there has no attempt to do
this at broader scales.
2.5 The reference condition approach
When conducting a financial audit it is not sufficient to know merely how
much is in the till. Crucial to any audit is knowing how much is in the till in
relation to how much should be there. Using a health analogy, a
measurement of blood pressure by itself is insufficient to interpret the health
of the patient. Information is also needed on what a healthy blood pressure
would be and the patient’s measurement is compared with that reference.
This referential approach has been adopted for the framework. That is, an
assessment of river health relative to what the river or wetland would have
been like if it had not been changed by human activities.
Assessments for each element of the framework are based on departures
from reference conditions. Where ecological integrity is the criterion for
health, reference conditions are usually defined as the presumed natural
state of a site, determined by physically and chemically similar undisturbed
sites. Typically it is impossible to find completely undisturbed sites with
which to compare test sites, in which case minimally disturbed or best
available sites are often used to define reference conditions (Wright et al.
1983, Simpson et al. 1996, Reynoldson et al. 1997). Reference conditions
Framework for the Assessment of River & Wetland Health
15
can also be set by professional judgement (Ladson et al. 1999), modelling of
past conditions, historical records, or palaeoecological evidence (Thoms et
al. 1999). Reference conditions for the FARWH have been set by a
combination of minimally disturbed sites, historical data, modelling of past
conditions, and professional judgement; the guiding principle is that
reference conditions should be as close to natural (pre-European settlement
or pre-1750) as possible.
The indices calculated in the framework all assess the condition of a river
reach using a referential approach. The Aquatic Biota Index could use a
modified reference approach, but the reference for some biotic indices may
be straightforward. The approach is dictated by the way sites are compared
statistically and the absence of unchanged reference sites in some parts of
the country. For example, the reference for exotic plants and fish would be
zero. Most of the other indices could use a simpler comparative approach
and take as their reference point a completely unchanged condition. Both of
these approaches are valid and can be used jointly to assess the overall
condition of a river. Nevertheless, differences in the way reference condition
is determined in relation to the different indices should be kept in mind when
interpreting the condition of a reach or surface water management area.
2.6 Indices and index features
Initially, reaches and individual wetlands should be assessed, and the results
should then be aggregated to generate assessments of surface water
management areas. Directly measured data will not be available for every
river reach, with the result that a variety of approaches could be adopted,
including direct site measurements, remotely sensed data and modelled data
that can be combined to provide assessments for all of the reaches in an
area of interest.
Ideally, several biological measures would be included in the assessment as
components of the Aquatic Biota Index (for example, fish, water plants and
algae). The most extensive dataset that will be available is that for aquatic
invertebrates from the National River Health Program. Methods for fish have
been developed by the Murray-Darling Basin Sustainable Rivers Audit and
are being applied across the basin.
The extensive datasets compiled for the Wild Rivers Project—including land
uses, infrastructure, levee banks, and dams—are also useful, and they are
available from the NLWRA I. Data on sediment transport, nutrients and
hydrology could be provided in some cases by process models that were
used extensively in the NLWRA I. Water quality data are spatially sparse (see
testing in Victoria and Tasmania below) when considered at the scale of
reaches and surface water management areas and, apart from nutrients, are
difficult to model for the extensive areas without them.
Framework for the Assessment of River & Wetland Health
16
2.7 Integration of the framework components
2.7.1 Reach, wetland and basin scale aggregation and integration
In the FARWH the term ‘aggregation’ is used to denote assembling measures
of the same index in different places into a measure at a larger spatial scale,
for example, aggregating measures of the Aquatic Biota Index for a group of
reaches, or a group of wetlands to provide a measure of the Aquatic Biota
Index for a basin (for either the rivers, or the wetlands). The term ‘integration’
denotes assembling measures of different indices at a given scale to
generate a combined assessment at the same scale, for example, reach-
scale indices of flow regulation, nutrient and suspended sediment loads
integrated for a reach. These issues have been considered in more detail for
reaches representing a river within a surface water management area than
they have for individual wetlands that represent a surface water management
area.
At the reach or wetland level, an assessment will usually be provided for each
index and individually these provide most information. These indices can be
integrated to produce an assessment for each reach, or each wetland.
Similarly, an assessment will usually be required for each individual index at
the scale of an entire surface water management area. In turn, these may be
integrated to produce an overall assessment at the surface water
management area. A summary of the decisions taken to integrate indices and
sub-indices, and to aggregate from reach to basin scale can be found in
Table 1. Normally, the surface water management area assessments for
wetlands and rivers would be separate because they represent the condition
of different waterbody types, namely rivers or wetlands.
In calculating the assessment for a surface water management area, a
decision is needed whether to aggregate the individual reach or individual
wetland scores or to integrate the individual indices across the surface water
management area. It is considered appropriate to produce the basin-scale
assessment by integration rather than aggregation because of the nature of
the two processes involved. Aggregation is more appropriate when crossing
spatial scales, and integration is more appropriate for combining different
indices. When aggregating indices up to the basin scale, different weighting
approaches are likely to be chosen for different indices.
Framework for the Assessment of River & Wetland Health
17
Table 1: Summary of integration and aggregation procedures for
different sub-indices and indices.
Index – reach
scale
Integration approach
and weighting
Aggregation
approach and
weighting
Index
Hydrological
Disturbance Index
As per Index of Stream
Condition framework
Arithmetic average with
double weighting to
change in seasonal
periodicity
Reach index
aggregated to
basin index by
calculating length
weighted average
of all reach scores
Surface water
management area
(SWMA)
Hydrological
Disturbance Index
Water Quality
Index (e.g.
nutrient and
suspended
sediment loads)
Worst measure in reach
taken as nutrient and
suspended sediment
load assessment
Components
unweighted
Reach index
aggregated to
basin index by
calculating length
weighted average
of all reach scores
SWMA Nutrient
and Suspended
Sediment Load
Index
Physical Form
Index
Standardised Euclidean
distance
Components
unweighted
Reach index
aggregated to
basin index by
calculating length
weighted average
of all reach scores
SWMA physical
index
Catchment
Disturbance Index
Impacts summed
Components
unweighted
Indices for each
reach
aggregated to
give a basin
score
Reach index
aggregated to
basin index by
calculating area
weighted average
of all reach scores
SWMA Catchment
Disturbance Index
Aquatic Biota
Index
Reach index
aggregated to
basin index by
calculating area
weighted average
of all reach scores
SWMA Fringe
Index
Fringing Zone
Index
Unweighted reach
average
Reach index
aggregated to
basin index by
calculating area
weighted average
of all reach scores
SWMA Fringe
Index
Overall Index Above six indices
integrated to give
FARWH for reach
Standardised Euclidean
distance Components
unweighted or inverse
weighted rankings
Above six indices
integrated to
make FARWH for
SWMA
Standardised
Euclidean
distance
Components
unweighted or
inverse weighted
rankings
Framework for the Assessment of River & Wetland Health
18
For example, reach length or wetland area weighting might be used for a
Water Quality and Soils Index, and contributing catchment area weighting
would be more appropriate for a Catchment Disturbance Index. If the reach-
or wetland-scale assessment scores were to be aggregated to the scale of
an entire surface water management area, weighting would be limited to one
weighting approach that may not be entirely suitable for all the indices.
Where the weighting is different for some indices, then they SHOULD be
weighted to the basin scale FIRST. Even more relevant, there are bound to
be many reaches that do not have all indices available, hence reach- or
wetland-scale integrations could be biased away from some indices and
aggregation will enhance this bias. Regardless of the balance of the
individual sub-indices, the basin scale (weighted) averages are unbiased. For
example, an effect of aggregating all indices by reach then to surface water
management area, or by index and then to surface water management area
is shown in Table 2.
Table 2: Example of weighting by either reach or index for all reaches
Reach
Length of
reach Index1 Index2 Index3 Index4
Reach standardised
Euclidean distance
1 162 6 4 6 9 0.58
2 192 1 4 7 8 0.43
3 114 2 3 5 2 0.29
4 14 3 3 1 0.23
5 88 4 9 4 0.51
6 19 3 8 4 0.45
7 22 4 7 6 0.55
8 34 8 5 7 9 0.69
9 116 3 3 8 0.42
10 95 8 0 2 0.25
BASIN weighted average standardised Euclidean distance 10.44
Weighted BASIN
mean 23.89 3.82 5.39 6.10 0.47
1 Used in NLWRA1
2 Recommended by FARWH
Furthermore, aggregation of each index to the basin scale allows flexibility in
the effect of scale and basin-wide reporting for the component indices. For
example, there could be indices that apply at different scales to FARWH
reaches: certainly hydrology acts at different scales from macroinvertebrates.
Reporting at the basin level using independent aggregation makes more
sense.
There might be a shortcoming to this approach where reporting is desired at
individual reaches or wetlands, and they are represented by different subsets
Framework for the Assessment of River & Wetland Health
of the full set of assessment components. For example, water quality could
be missing from one and hydrology from another. Where initial reporting is
desired at the individual reach or wetland, methods may need to be
employed that allow this. The inverse ranking system used by the Index of
Stream Condition in Victoria is applied at the reach scale and then integrated
measures are aggregated to broader scales.
2.7.2 Methods to integrate indices
Indices can be integrated at the reach, wetland or basin level in different
ways to produce an assessment of river and wetland condition (Table 3). The
standardised Euclidean distance approach provides a measure of how
different a reach is from the reference condition using information from the
measures comprising an index or sub-index. It has an advantage over a
mean value in that it can be used to represent the location of reaches in the
n-dimensional space defined by the measures. An example of the calculation
of an index using the standardised Euclidean distance is given below where
I = index score, and A, B, C and D are the sub-indices that comprise the
index. The denominator is the square root of the number of indices, in this
case 4).
()()()( )
4
1111
12222 DCBA
I+++
=
A second type of integration approach is to take the worst of the component
sub-indices. This follows the precautionary principle and is useful for water
quality indices such as nutrient and suspended sediment loads. For instance,
if a reach had very low total phosphorus and total nitrogen measures, but the
suspended solids load was enormous, then the condition of the reach should
be assessed as poor as a result of the suspended solids condition. Similarly,
a toxicant that exceeds lethal limits should be the one that drives the overall
assessment, regardless of the levels of other water quality measures.
A third type of integration approach that is used is to sum the impacts of the
sub-indices. This approach was used for the Catchment Disturbance Index in
the NLWRA I, for which three sub-indices each contributed very similar types
of impact though from different activities. The sum returns a value that is
dependent in magnitude on the number of component indices, and so it
should be avoided or standardised where possible. The average of the
component indices is simple and is recommended in some situations where
equal weighting is intuitive.
In an adaptation of the precautionary principle, the Index of Stream Condition
uses an inverse ranking method that gives more weight to lower scores. For
example, if five indices are used and they are all on a standard scale, they are
ranked in order of lowest to highest score. The first ranked index (the lowest
score) is multiplied by five, then the next ranked score is multiplied by four,
and so on. All weighted scores are then summed and divided by 15 (that
is, 5 + 4 + 3 + 2 + 1). The same principle can be used for any number of
19
Framework for the Assessment of River & Wetland Health
20
indices but the denominator (the sum of the ranks) varies accordingly. This
method tends to moderate the effect that one large value may have on a
simple arithmetic mean or sum.
The Tasmanian Conservation of Freshwater Ecosystem Values Framework
and the Murray-Darling Basin Sustainable Rivers Audit employ expert rules to
integrate the subcomponents and components. These are weightings
determined by expert knowledge about the environmental importance of
components (see
http://www.mdbc.gov.au/__data/page/64/summary_macroinvert_theme.pdf).
For example, the rules developed for the Sustainable Rivers Audit
macroinvertebrate index give highest importance to biodiversity—richness
(SR-MIr) followed by presence of pollution sensitive taxa (SIGNAL or SR-
MIs)—and least importance to the presence of expected taxa (AUSRIVAS OE
or SR-MIoe). The AUSRIVAS OE was allowed to affect only the overall
macroinvertebrate index where the score was low. This was because of the
lack of confidence in higher scores due to the lack of suitable reference sites.
Table 3: Integration techniques recommended for use in the framework
Note: other methods may be appropriate but the underlying philosophy and
their effects on the final index should be made explicit
Integration technique Rationale Proposed use
Standardised Euclidean
distance
The measures comprising an index are
different but complementary ways of
estimating the overall status
Integrating the flow regulation
sub-indices
Integrating the Physical Form
sub-indices
Integrating the indices into the
overall score
The worst of a group of
measures is taken as the
overall measure
Used where the overall measure is best
estimated by the lowest common
denominator, not an average type measure
Integrating the water quality
sub-indices
The impacts of the
measures in the group are
added to arrive at an
overall measure
Used where measures are estimates of the
same type of impact, though derived from
different origins. As a consequence, the
impacts should be added
Integrating the Catchment
Disturbance sub-indices where
individually they may have
similar effects
Expert rules based on
knowledge of the relative
importance of possible
combinations of
components
Used where the scientific understanding of
components can be applied to enhance the
overall score and aid interpretation
May be especially important of
biological measures that can
be affected by scale, or any
features with varying level of
confidence
Not all indices will be available for all reaches or wetlands. In such instances
it is possible to calculate the standardised Euclidean distance, the
precautionary principle method (using, or weighting to the lowest scores) and
the sum of the component indices just from those that are available.
However, the number of missing values may influence the integration and
aggregation chosen for broader scales of reporting (Table 2).
Framework for the Assessment of River & Wetland Health
21
2.8 Analysis of common factors determining river condition
An overview of categories of major river management issues, and their scale
of impact can be provided by statistical analysis of the suite of indices, rather
than individual indices, since actual condition is usually determined by
several factors. Groups of reaches or wetlands with common issues can be
identified systematically using a multivariate statistical approach. The
NLWRA I calculated the Euclidean distance between each pair of reaches,
based on the environmental measures for each reach. Reaches were then
grouped using Ward’s Clustering method (SAS Institute 2000), which is an
efficient method for large data sets. The groups formed in this way may be
particularly useful for avoiding the information loss that is inherent in
integration, providing additional information on the spatial distribution of
combinations of issues.
2.9 Sensitivity analysis
2.9.1 Method
The overall assessment will change because of changes in selected indices,
their sub-indices, and the methods used for integration and aggregation.
Interpretation of the scores to some extent will be dependent on
understanding the sensitivity of the overall assessment to changes in the
sub-components. Two methods of sensitivity assessment used in the
NLWRA I were found to yield similar results and the computationally simpler
one was recommended. This recommended method is analogous to the
‘jackknife’, a commonly used statistical technique whereby one sub-index at
a time is removed from the dataset, and the mean absolute change in overall
assessment is then calculated (Norris et al. 2001).
This analysis should be performed in two ways:
on reaches or individual wetlands with complete data sets of all selected
indices and sub-indices
on all reaches or wetlands in the reporting region where many will have
one or more indices missing.
Sensitivity in this second dataset mirrors the effect on the overall assessment
for a jurisdiction, because it depends not only on impact gradients and
integration techniques, but also on data availability. Consequently, sub-
indices with data in many reaches have more effect on the overall
assessment than sub-indices with fewer data points. An example of the
components of sensitivity testing from the NLWRA I follows.
2.9.2 Sensitivity and underlying reasons in the NLWRA I
The main reasons for the differences in influence between the sub-indices in
the NLWRA I were identified as:
the method of aggregation of the indices representing each
environmental component
the range and distribution of the scores
Framework for the Assessment of River & Wetland Health
the number of observations (in case of the national data).
In the ideal sensitivity analysis testing in the NLWRA I for reaches having all
indices (Figure 5), five factors played an equally important role: land use, the
three habitat sub-indices, and total phosphorus. The three habitat
components each had a wide range of sub-index values, and ranked roughly
equally because they were aggregated to the habitat index by the
standardised Euclidean distance method. Although the range of total
phosphorus values was not wide, the sub-index ranked highly because of the
integration approach used for the nutrient and suspended sediment load
index. The nutrient and suspended sediment load sub-index was determined
by taking the value of the lowest component; in most reaches this was total
phosphorus. The land use sub-index was ranked more highly than the
infrastructure sub-index because of the smaller range of values of the latter
sub-index.
The Hydrological Disturbance Index consisted of four components, none of
which had a major influence on the NLWRA I Assessment of River Condition
(environment) (ARCE) score because they were not as variable as other sub-
indices, and each sub-index contributed only 25 per cent to the Hydrological
Disturbance Index.
Change in ARC
0.00
0.02
0.04
0.06
0.08
0.10
Infrastructure
LCC
Landuse
Mean Annual Flow
Flow Duration
Seasonal Amplitude
Seasonal Period
Connectivity
Bedload
Riparian Vegetation
Suspended Sediments
Total Phosphorus
Total Nitrogen
Hydrology
CDI Habitat Water
Quality
Figure 5: Influence of each sub-index on the ARCE using only reaches
for which there was a complete dataset.
The sensitivity analysis using all reaches assessed in the NLWRA I, including
those with missing data (Figure 6), showed that the contribution of the sub-
indices to the national assessment differed slightly from the ideal situation.
22
Framework for the Assessment of River & Wetland Health
The strong influence of the three habitat components remained, but the
influence of the total phosphorus sub-index was slightly greater. This results
from the near complete dataset for the nutrient measures based on modelled
data compared to some other indices. The effects of land use and
infrastructure in the Catchment Disturbance Index are now identical in this
example, because the integration rules required both to be present to
calculate the Catchment Disturbance Index. With few hydrological data
available, the hydrological disturbance sub-indices had relatively little
influence on the ARCE at the national level.
Figure 1.6 Influence of each sub-index on the ARCE using data
from all reaches
Change in ARC E
0.00
0.02
0.04
0.06
Infrastructure
LCC
Landuse
Mean Annual Flow
Flow Duration
Seasonal Amplitude
Seasonal Period
Connectivity
Bedload
Riparian Vegetation
Suspended Sediments
Total Phosphorus
Total Nitrogen
Hydrology
CDI Habitat Water
Quality
2.10 Range standardisation and bands of condition
2.10.1 Range standardisation
It is proposed that assessments of river and wetland health be range
standardised to 0–1 with increments of 0.1 for each of the indices
representing the major environmental components (biota, catchment
disturbance, hydrological disturbance, physical form, fringing zone and water
quality). This is necessary so that assessments from different jurisdictions are
immediately comparable. Range standardisation also renders the scores
dimensionless, thus accounting for different types of measurements that will
inevitably be required for various indices selected both within and among
jurisdictions.
23
Framework for the Assessment of River & Wetland Health
24
A score of 1 corresponds to the best attainable or pristine condition, and a
score of 0 to a totally degraded condition. Each of the indices should be
examined to ensure that it is theoretically possible to arrive at index values
ranging from 0 to 1. Each of the index values should also be examined to
ensure that the reach conditions that produce values of 0, 0.5 and 1 could be
appropriately described as totally degraded, halfway between degraded and
pristine, and pristine (as the scores imply). This evaluation can be based on
professional judgment because the composition of each index of a number of
sub-indices means that different combinations of sub-index scores could
produce the same index score. It is unlikely to be possible to develop a more
objective link between index scores and the described condition.
2.10.2 Bands of condition
Prior extensive consultation with states and territories in the National River
Health Program (NRHP) and the NLWRA I has confirmed the desire for the
assessments to be divided into bands of condition as an aid to mapping and
interpretation. It is proposed that the range of scores be divided into five
bands to produce five categories. Values of 0–0.2 are accorded a condition
of severely modified, 0.2–0.4 substantially modified, 0.4–0.6 moderately
modified, 0.6–0.8 slightly modified, and 0.8–1.0 largely unmodified. The
categories in the NLWRA I ARCB (Aquatic Biota Index) had different labels
and used slightly different cutoff points, depending on the distribution of the
values for the AUSRIVAS reference sites on which it was based. The
derivation of the ARC
B
BB bands is described in more detail in the proposed
possible Aquatc Biota Index section of the potential comparative indices
document (NWC 2007).
The purpose of this section is to provide further interpretation of the
framework categories: largely unmodified, slightly modified, moderately
unmodified, substantially modified and severely unmodified.
Largely unmodified condition: 0.8–1
Rivers and wetlands that are largely unmodified considered to be in pristine,
or near pristine condition should have some or all of the following:
catchment land uses that minimally disturb the river, such as
conservation, some types of forestry, low levels of grazing or cropping
at most, limited changes to the hydrological regime
at most, limited changes to the physical form (for example, fringing
vegetation structure reasonably intact, no dams or levees and very little
sediment deposition)
loads of suspended sediment, total nitrogen and total phosphorus close
to natural
stream plants and animals should be in similar numbers and of similar
types to those at unimpacted reference sites.
Framework for the Assessment of River & Wetland Health
A healthy Murray River wetland with
a mosaic of wetland plants that
provide diverse habitat for a range of
species
(Source: Andrew Tatnall for CRC for
Freshwater Ecology)
A Healthy Murray River wetland
with a mosaic of plants that dries
out during summer (fore ground:
Moira Grass, Milfoil, Primrose;
background: Giant Rush,
Phragmites, Red Gum
(Source: Andrew Tatnall for CRC for
Freshwater Ecology)
Slightly modified condition: 0.6–0.8
Rivers and wetlands that are slightly moderately modified and considered to
be in good condition should have some or all of the following:
25
Framework for the Assessment of River & Wetland Health
a catchment dominated by land uses that have little effect on
waterbodies such as state forest or protected recreation areas
some minor changes to the hydrological regime as a result of diversion or
abstraction
some minor changes to the physical form; for example, fringing
vegetation reduced to 60–80 per cent of original coverage, diversions or
abstraction upstream but not in the reach, and some little or no sediment
deposition
water quality close to natural but with occasional minor short-term events
possible
plants and animals with noticeable slight loss in variety and numbers or
condition. Few, if any, exotic species present.
Mostly native well vegetated riparian
zone, some encroachment into the
channel (Source: Institute of Applied
Ecology, University of Canberra)
Good flow, natural channel, some
clearing for a picnic area (Source:
Institute of Applied Ecology,
University of Canberra)
Wetland with slightly modified
riparian vegetation but still with a
variety of aquatic plants (Source:
Institute of Applied Ecology,
University of Canberra)
Protected catchment but with low
flows modified by a road crossing
(Source: Institute of Applied
Ecology, University of Canberra)
Moderately modified condition: 0.4–0.6
26
Framework for the Assessment of River & Wetland Health
Rivers and wetlands that are moderately modified and considered to be in
fair condition should have some or all of the following:
a catchment dominated by land uses that disturb the river to some
extent, such as dryland cropping and grazing
some changes to the hydrological regime as a result of impoundments or
abstraction
some changes to the habitat, for example, fringing vegetation reduced to
40–60 per cent of original coverage, dams upstream but not in the reach,
and some sediment deposition
loads of suspended sediment, total nitrogen and total phosphorus above
natural
plants and animals with substantial loss of condition, variety and
numbers. For AUSRIVAS, 20–50 per cent of the expected animals have
been lost.
Little catchment disturbance, riparian
zone intact but extensive sediment
deposition (Source: Institute of
Applied Ecology, University of
Canberra)
Some loss of riparian vegetation,
some catchment disturbance from
cropping, and some sediment
deposition (Source: Institute of
Applied Ecology, University of
Canberra)
Extensive change to riparian
vegetation, reduced flow as a result
Riparian vegetation intact, minimal
disturbance to the surrounding
27
Framework for the Assessment of River & Wetland Health
of abstraction (Source: Institute of
Applied Ecology, University of
Canberra)
catchment, mine upstream causing
impaired water quality (Source:
Institute of Applied Ecology,
University of Canberra)
Substantially Modified Condition: 0.2–0.4
Rivers and wetlands that are substantially modified and considered to be in
poor condition may have some or all of the following:
catchment land uses with moderate to severe disturbance such as
intensive cropping and irrigated land uses
moderate to severe changes to the hydrological regime as a result of
impoundments, diversions or abstractions
moderate to severe changes to the physical form, including loss of 50–75
per cent of riparian vegetation, connectivity affected by nearby dams or
levees, and substantial sediment deposition
poor water quality, possibly with moderate to high loads of suspended
sediment, total nitrogen and total phosphorus
plants and animals that show substantial change possibly with obvious
invasion of exotic species (for example, fringing plants, aquatic plants
and fish such as carp). For AUSRIVAS, 50–80 per cent of the expected
animals have been lost.
Very little riparian vegetation,
catchment heavily disturbed by
cropping and grazing, some
sedimentation (Source: Institute for
Applied Ecology, University of
Canberra)
Reduced riparian vegetation,
catchment disturbed by cropping,
altered hydrological regime
(Source: Institute of Applied
Ecology, University of Canberra)
28
Framework for the Assessment of River & Wetland Health
Horse Park Wetland, ACT. A wetland
of national significance. A bird
breeding site that has been grazed
for decades and is subject to urban
encroachment (Source: Institute of
Applied Ecology, University of
Canberra)
Substantial loss of riparian
vegetation, catchment disturbed by
grazing, high levels of
sedimentation (Source: Institute of
Applied Ecology, University of
Canberra)
Severely Modified Condition: 0–0.2
Rivers and wetlands that have been severely modified and considered to be
in very poor condition may have some or all of the following:
catchment land uses that cause significant disturbance to rivers and
wetlands such as intensive agriculture or urbanisation
significant changes to the hydrological regime, for example, large
reductions in flow, extended wetting or drying of wetlands, and changes
in the seasonality of flow and inundation events
extensive changes to the physical form, including loss of riparian
vegetation, loss of connectivity, and extensive sediment deposition
poor water quality possibly including high loads of suspended sediment,
total nitrogen and total phosphorus
major invasion of weeds and other exotic organisms, little regeneration of
riparian species, and likely dominance of a few taxa. For AUSRIVAS,
80–100 percent of the expected animals have been lost (this is possible
with some toxic effluents such as mine wastes).
29
Framework for the Assessment of River & Wetland Health
Total loss of riparian vegetation,
catchment impacts from clearing and
grazing, dam immediately
downstream, poor water quality
(Source: Institute of Applied Ecology,
University of Canberra)
Major loss of riparian vegetation,
intensive cropping in catchment,
hydrological regime altered by
abstractions (Source: Institute of
Applied Ecology, University of
Canberra)
Extensive changes to hydrological
regime as a result of multiple dams
upstream (Source: Institute of
Applied Ecology, University of
Canberra)
Mine waste polluted creek,
deposition of ferric hydroxide and
high trace metals, poor water
quality (Source: Institute of Applied
Ecology, University of Canberra)
2.11 Missing data
2.11.1 Overall Index at various scales
It is inevitable that many reaches and wetlands will have missing data for
several possible reasons. It is necessary that protocols for dealing with
missing data are determined at the outset. There are six components, each
of which is represented by an index. At least three of these indices must be
present before an overall assessment can be reported. There could be a
marked effect on the final score where this is done at the reach or individual
wetland scale before aggregating to the surface water management area.
Many reaches within a surface water management area will have different
30
Framework for the Assessment of River & Wetland Health
31
indices missing but there will still be enough to provide an overall
assessment. Therefore, although this may be acceptable, it means that the
overall score for a surface water management area could include errors
introduced because of variability in the component indices that have been
incorporated for individual reaches or wetlands.
The Victorian Index of Stream Condition also suggests handling missing data
on a pro rata basis at the reach scale
(http://www.vicwaterdata.net/vicwaterdata/isc2004/download/doc/2ISC%20
FACTSHEET%20DR03.pdf). Where indices for individual reaches or wetlands
are aggregated first, and then integrated at the scale of a surface water
management area, each component should be represented by a minimum
number of reaches or wetlands. This should be five per cent of the
recognised reaches or wetlands (minimum wetted area) in the surface water
management area. Thus, the sample size will be proportional to the number
in the surface water management area.
The following examples were developed during the NLWRA I for each of the
major environmental components represented. The approaches described
here could form the basis for rules that can be adopted in FARWH.
2.11.2 Hydrological Disturbance Index
The Hydrological Disturbance Index of the NLWRA I consists of four sub-
indices, similar to the ‘flow stress ranking’ used in the Victorian Index of
Stream Condition and proposed for the Tasmanian Conservation of
Freshwater Ecosystem Values Framework and the Murray-Darling Basin
Sustainable Rivers Audit. For reaches that had adequate hydrology data, all
four measures could be calculated and then used to calculate the
Hydrological Disturbance Index. However, the majority of reaches in the area
assessed did not have hydrological data, and protocols had to be developed
for managing those places. In some cases, such as remote areas with little or
no development, the assumption could be made that there was no
hydrological change, thus providing a score of 1. A similar approach may be
adopted in many areas for wetlands, depending on the nature and scale of
development.
2.11.3 Nutrient and suspended sediment load index (Water Quality and
Soils Index)
At the reach scale, the nutrient and suspended sediment load index consists
of three sub-indices: the suspended solids sub-index, total nitrogen sub-
index, and total phosphorus sub-index. These sub-indices were derived from
modelled data and so reaches had either a full set of nutrient and suspended
sediment load results, or none if the models could not be run. The relative
completeness of the data is a major advantage of modelled data over
measured data. Salinity data were not used to calculate the water quality
reach-scale water quality index.
The reach-scale nutrient and suspended sediment load index was
aggregated to give a basin-scale (surface water management area)
Framework for the Assessment of River & Wetland Health
32
assessment if the data in the basin were from reaches whose total catchment
area represented at least 50 per cent of the basin. If less than 50 per cent of
the basin was represented by data, the basin was not assessed.
2.11.4 Habitat index (Physical Form Index)
The habitat index of the NLWRA I (Physical Form Index in this framework)
consists of three sub-indices: bedload condition, riparian vegetation, and
connectivity. There were a number of reaches for which either the bedload
condition or riparian sub-indices were missing. The connectedness sub-
index was calculated for all reaches.
These three measures were integrated using the standardised Euclidean
distance. In theory, the loss of one or more components does not introduce a
bias with this integration approach, although it does result in a loss of
information. That is, if all three measures were identical, the loss of one
would not affect the resulting Physical Form Index. As a result, a decision
was taken to require a minimum of two measures for calculation of the
Physical Form Index.
The reach-scale Physical Form Index was aggregated to give a basin-scale
assessment if the data in the basin were from reaches for which the total
catchment area represented at least 50 per cent of the basin. If the reaches
with data represented less than 50 per cent of the basin area, the basin was
not assessed.
2.11.5 Catchment Disturbance Index
The Catchment Disturbance Index used in the NLWRA I consists of three
sub-indices: land use, land cover change, and infrastructure. Most reaches
had sufficient data to determine the land use and infrastructure sub-indices.
Data required to calculate the land cover change sub-index were missing for
a number of reaches.
These sub-indices were integrated to generate the Catchment Disturbance
Index by summing their impacts. Loss of any measure will result in a positive
bias to the score; however, for most reaches the land cover change sub-
index was close to one and varied little. Given this situation, it was decided
that the Catchment Disturbance Index required a minimum of the land use
and infrastructure sub-indices to be calculated.
The reach-scale Catchment Disturbance Index was aggregated to give a
basin-scale (surface water management area) assessment if the data in the
basin were from reaches whose total catchment area represented at least 50
per cent of the basin. If the reaches with data represented less than 50 per
cent of the basin area, the basin was not assessed.
2.11.6 Aquatic Biota Index
The AUSRIVAS data from the National River Health Program represents a
large data set of many thousands of sites. Some states have continued to
sample intensively using the same methods and increased the database
substantially since the NLWRA I. With large datasets such as this, which are
Framework for the Assessment of River & Wetland Health
33
based on individual site measurements, there is an opportunity to model the
gaps where strong relationships can be established. This approach was
adopted in the NLWRA I, and rules were set for when a model was deemed
of sufficient quality to accept the outputs.
Thus, the function of the ANNA models used in the NLWRA I (Linke et al.
2005) was to enable prediction of the biotic condition of a reach that had not
been sampled (Norris et al. 2001). The AUSRIVAS modelling approach uses
two measures for each site: a list of taxa predicted to occur if the site is in
good condition (E value), and the taxa observed to occur at the site (O value).
Together these two values give the O/E score.
For reaches that had not been sampled, there was a need to predict the taxa
expected at the site if it were in good condition (E value), and to also predict
taxa that occurred at the site under current conditions (modelled observed
value MO). Together these values provide the MO/E score, a measure of
condition and a surrogate for the AUSRIVAS O/E score. The ANNA modelling
approach was judged more suitable for the needs of the NLWRA than the
AUSRIVAS modelling approach because, while it produces similar outputs, it
avoids the classification step and is computationally more efficient.
2.11.7 Integrating the four environmental indices into an NLWRA I
ARCE at the reach level
The nutrient and suspended sediment load sub-index and Catchment
Disturbance Index could be calculated for most reaches given the rules
above. The Physical Form Index was missing for several reaches, and the
Hydrological Disturbance Index was not assessed for many reaches.
These four measures were integrated into the ARCE using the standardised
Euclidean distance approach. A decision was needed on whether to require
the full complement of four indices to calculate the ARCE, or whether this
requirement could be relaxed to base the ARCE on a subset of the four
indices. As outlined above, this index is relatively unbiased by the loss of
measures, but all four indices are important. This has already been argued in
relation to the conceptual understanding of the processes determining river
condition.
The decision taken was to require a minimum of three indices to calculate the
ARCE. While not a satisfactory situation, this approach is preferable to
calculating the ARCE for that small subset of the reaches for which a
complete dataset was available. A comprehensive monitoring programme by
states and territories would enable more rigorous data standards to be set
than those described here. This should be possible in Tasmania, Victoria and
the Murray-Darling Basin.
2.11.8 Validation of indices
With the measures selected by jurisdictions within this framework, it is
important to show that they accurately represent the true river or wetland
condition. This requires independent, accurate information on the state of
river or wetland condition against which the data can be compared.
Framework for the Assessment of River & Wetland Health
34
For components of the sub-indices used in the NLWRA I, and the ARCB
based on AUSRIVAS, there are various additional data that can be used for
this purpose. The detailed validation of these components used in the
NLWRA is dealt with in the following methods sections for the different
indices. A useful approach is to compare the selected indices to datasets
that have similar measures at a similar spatial scale. This is one of the
objectives of the testing of this framework but that should also remain an
important step for individual states and territories.
Several states and territories have conducted river condition assessments;
usually they differ from the NLWRA I in the spatial scale at which the
assessment is conducted, and in the measures used. The river condition
assessment with which the Assessment of River Condition 2000 has the
greatest similarity in terms of measures and spatial scale is the Victorian
Index of Stream Condition. The Index of Stream Condition has been
completed for the entire state, has measures most similar to those in the
Assessment of River Condition 2000, and has detailed documentation of the
methods used. Index of Stream Condition data were used to validate
components of the ARC used in the NLWRA I.
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... The national recommendation in wetland condition assessment works with six themes, each of which cover one part of the physical and biological components and processes, that contribute to the ecological integrity of the wetland (Conrick et al. 2007, Norris et al. 2007b • Change in algae (as a measure of primary productivity rather than water quality) As part of the project, one or two indicators per theme were selected and trialed for the Darwin region lagoons. Data availability was reviewed and indicator values were calculated and discussed with respect to their utility. ...
... The selection of indicators for trial was guided firstly by the proposed national indicators in the final report from Conrick et al. (2007) and secondly by the National Water Initiative report 'Assessment of River and Wetland Health: Potential Comparative Indices' (Norris et al. 2007a). As the NT currently does not engage in regular and comprehensive wetland condition monitoring, it was decided to set up indicators as in the Framework for Comparative Assessment of the Ecological Condition of Australian Rivers and Wetlands (Norris et al. 2007b). ...
... As stated above, it was attempted to design the indictor setting such that it is compatible with the Framework for Comparative Assessment of the Ecological Condition of Australian Rivers and Wetlands (Norris et al. 2007b) with respect to range standardisation and bands of condition. ...
Technical Report
Full-text available
The ecological importance of wetlands has now been widely acknowledged, but the knowledge about the assessment of wetland condition still lags far behind that on rivers and streams (Norris et al. 2007a, Finlayson et al. 2005, Finlayson & Davidson 2001, Finlayson & Spiers 1999). The National Wetland Indicators Project aimed at reviewing wetland condition indicators used for environmental and natural resource management projects with the goal to stream line them and provide national recommendations on the types of indicators to be used (Conrick et al. 2007). The National Wetland Indicators Project was carried out through a National Wetland Indicator Review as a collaborative project between the National Land & Water Resources Audit (NLWRA), the Department of the Environment and Water Resources (DEW), and the Wetlands & Waterbirds Taskforce (WWTF) (Conrick et al. 2007). The project presented in this report trials the framework and indicators for wetland extent, distribution and condition on the lagoons in the Darwin region. The extent and distribution of the lagoons in the Darwin region is presented as mapping based on Quickbird Imagery. As the mapping process took more time than anticipated, the final mapping of all lagoons in the study area will be presented in the Final Milestone Report. This report presents the extent and distribution of 31 selected lagoons. Wetland condition indicators are selected based on data availability for the nationally recommended indicators. Of the six indicator themes used for wetland condition assessment, five are reported on here, namely catchment disturbance, physical disturbance, hydrological disturbance, the fringing zone and water quality. The indicators calculated for catchment disturbance and fringing zone condition are assessed as meaningful and suitable and could be used without modification. Land use and vegetation or clearing data are likely to be readily available for all of the Northern Territory. However, as the wetland mapping including mapping of catchments is not comprehensively available in the NT, the indices can not simply be calculated. The Hydrological Disturbance Index calculated on water extraction is assessed as meaningful with the limitation of only using licensed water extraction information with data on domestic use and unlicensed water extraction not available. The impervious area indicator does provide meaningful results, but is not assessed as adequate to fully represent hydrological disturbance of a lagoon or wetland. The Physical Disturbance and Water Quality Indices require further work. As discussed in the relevant chapters, the Physical Disturbance Index will require additional testing, however, more information is needed from other parts of the NT to adjust and finalise the scoring system for the area and proximity to closest wetland sub indices, if they are to be used in the way trialed. The Water Quality Index was trialed using six water quality parameters and provides meaningful results. It is however suggested to reduce the number of water quality parameters required from six to three or so including turbidity and nitrogen. It is suggested to sample in the late wet / early dry season. At this stage it is recommended to sample more than once for a Water Quality Index calculation. None of the ten lagoons, for which there was data for all of the five indicators to be calculated, achieved the unmodified score in all of them, and neither had a similar band placing for all of the five indices. So far the best ratings were obtained for Korebum Lagoon and Kurrabam 1 Lagoon, both scoring four times the reference condition and obtaining one score as slightly modified. The worst scores were obtained by Knuckey’s, McMinns and Edwin Creek 2 Lagoons. The catchment disturbance index provided the lowest average scoring of moderately modified for the 23 catchments of the 31 lagoons. The average fringing zone and physical disturbance scores were also moderately modified with the scores for the fringing zone ranging from undisturbed to 8 Milestone Report 1: NT wetland indicator trials severely modified, whereas the physical disturbance being mainly slightly to substantially modified. The average water quality index was 0.8, just being classed as largely unmodified and the hydrological disturbance obtained the highest score of 1.0 throughout. This report also provides protocols for the calculation of these five indices and maps displaying the results of the indices per individual wetland.
... The national recommendation on wetland condition assessment works with six themes, each of which covers one part of the physical and biological components and processes that contribute to the ecological integrity of the wetland (Conrick et al. 2007, Norris et al. 2007b). The six themes and the currently proposed indicators are (Conrick et al. 2007 • Change in algae (as a measure of primary productivity rather than water quality). ...
... As stated in Milestone Report 1 it was attempted to design the indicator setting such that it is compatible with the Framework for Comparative Assessment of the Ecological Condition of Australian Rivers and Wetlands (Norris et al. 2007b) with respect to range standardisation and bands of condition. Therefore the indicator values range from 1 to 0 with 1 being in excellent and undisturbed condition and 0 being severely modified and unhealthy. ...
... Therefore the indicator values range from 1 to 0 with 1 being in excellent and undisturbed condition and 0 being severely modified and unhealthy. The bands as in Norris et al. (2007b) are listed in Table 1. The colour coding is applied according to Norris et al. (2007c). ...
Technical Report
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The project presented in this Final Milestone Report is part of the National Wetland Indicators Project regional trials, trialing the National framework and indicators for wetland extent, distribution and condition on the lagoons in the Darwin region. Indicator Themes 1-5 (catchment disturbance, physical disturbance, hydrological disturbance and the fringing zone) were reported on in detail in Milestone Report 2 for all of the lagoons in the study area. This report contains the final data, guidelines and protocols for Theme 6 (Biota) for six selected lagoons in the Darwin Region as well as updated versions of the aggregation and integration of indices. It also contains an evaluation of the Australian Government Wetland Classification Scheme for the lagoons of the Darwin Region. Five indicators were trialled for the biota theme: fish (taxon number), amphibians (taxon number), macrophytes (taxon number) and two sub-indices for weed species: the number of exotic species present and the number of declared weeds. The Biota Index was calculated for the six selected lagoons in which trials were carried out. Taxon numbers for fish were low and a score could only be calculated for one lagoon (Girraween Lagoon) for which a larger amount of data was available. Girraween Lagoon was classed as largely unmodified when surveyed in the dry season. Due to a lack of available baseline data, the current data collection of macrophyte diversity served to establish reference conditions for the selected lagoons. Due to this fact, all the lagoons were classed as largely unmodified for this indicator. The two measures of weeds proved to be the most useful and distinguished the lagoons well. The data collation for the amphibian index found that there were virtually no existing data on amphibians in the trial lagoons. Surveys revealed low taxon numbers at all of the lagoons. It was not possible to establish a meaningful amphibian index due to a number of factors. Further data collections using a mixture of methods are required to establish a useful amphibian index. The late start of this aspect of the project and the early onset of the dry season further confounded the establishment of the amphibian index. The integration of wetland condition indices was updated with the Biota Index for the six trial lagoons as was the aggregation of indices for the entire region. Only McMinn’s Lagoon received a WCI score that differed from that reported in Milestone Report 2. The lagoon received a slightly higher WCI and moved from category D to C, moderately modified, due to a high Biota Index. The aggregation of indices for all the lagoons of the study area was updated but did not change since new data were only available for six of the lagoons. The overall condition of all lagoon complexes in the study area scored 0.71, which is classed as slightly modified. The overall condition of all natural lagoon complexes scored a little higher with 0.76, which is also in the slightly modified category. The overall condition of man-made lagoon complexes scored considerably lower with 0.56, which places them into the moderately modified band. This was assessed as representing the current situation. When comparing wetland scores on a broader scale across the country, it appears that a large amount of work remains to be done. Validation and sensitivity analysis of the indicator system trialed for the Darwin region are required to enable comparison of scores between regions, and within the country. The evaluation of the Australian Government Wetland Classification Scheme found that it could be applied to the Darwin Region lagoons without modification but limited data availability did not allow full classification of all the lagoons. The Queensland Wetland Classification Methodology (Environment Protection Agency 2005) was also trialed and was found to be more useful because it allows for some uncertainty and later updates as more information becomes available.
... Another river health assessment approach considers a hierarchical model, which combines catchment, habitat and biota, assuming that the components at higher levels of hierarchy affect components at lower levels (i.e., catchment health affects river health). In other words, this methodology chooses variables on the assumption that ecological integrity is represented by all the major components of the environment that comprise an ecosystem (Norris et al., 2007). Thus, a package of representative variables on catchment disturbance, hydrological changes, water quality, soil, physical form, fringing zone and aquatic biota are included to assess the overall health of river. ...
... The river health assessment approaches which are heavily dependent on condition of reference sites (Observed versus Expected commonly known as O/E ratio) have a tendency to misinterpret the true state of rivers. In Australia, many composite river health approaches such as AUSRIVAS (National River Health Assessment Program), FARWH (National Framework for the Assessment of River and Wetland Health), IRC (Tasmanian Index of River Condition) and SRA (Sustainable River Audit, systematic river health assessment for the Murray Darling Basin) consider the state of pristine condition or pre-European reference conditions to assess the health of river systems at state and national levels (Barmuta et al., 2002, Norris et al., 2007, Askey-Doran et al., 2009, Peter et al., 2008. However, if the reference sites are already impacted, the river health assessment becomes erroneous. ...
Thesis
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The main objectives of this thesis are to: (i) examine the concept of river health through views and expectations of stakeholders; (ii) identify and evaluate the key river health indicators related to the main functions and uses of the river system and, (iii) develop a flexible river health assessment framework which can be adapted to other river systems. The Hawkesbury-Nepean River system (HNR), a complex river in peri-urban landscape in south-eastern Australia, is used as a case study to achieve the objectives of this thesis. The first three chapters of this thesis are dedicated to understanding the social implications of river health including its meaning while the remaining chapters progressively explore the key indicators of river health assessment and attempt to develop a simple framework and tools for sustainable management of river health. The analysis of the primary and secondary data collected in this study indicated that water temperature has an important influence on phytoplankton community structure and downstream prawn harvesting (M. macleayi). The community patterns of benthic macroinvertebrates were influenced by water pH. The historical records revealed how the water temperature has significantly increased since the 1980s and it is expected that future rising temperatures due to climate change may have a significant influence on the phytoplanktons and commercially viable fisheries industry in the river system. Aphanocapsa holsatica and Chironomid larvae appeared as the important indicators for upstream and downstream site differences in water quality. A seasonal succession of phytoplanktons indicated that summer, autumn and winter samples were dominated by Cyanophyta, Chlorophyta and a mix of species respectively. As the final stage of this study, a four-step framework (understand, identify, develop and apply) was proposed to assess river systems based on the key findings of this study. The framework starts by understanding the social and environment aspects related to river health. This is further evaluated in conjunction with multivariate statistical methods to identify key indicators to assess river health. Particular attention is given to retain variables that are cost effective, easy to measure and less labour intensive for routine monitoring purposes while providing valuable information on the condition of the river system. Finally, this information is utilised to develop reach specific river health assessment tools addressing the key services of the river system (i.e., irrigation, recreation). The framework developed in this thesis indicates a higher degree of flexibility, as it does not advocate a single method of assessment for rivers in different landscapes, considers local knowledge in great detail and attempts to develop tools for key river uses. Overall, the river water quality data analysed during this study helped in identifying a number of key indicators for routine and rapid monitoring purposes. In particular, selected key indicators were incorporated into a framework and predictive tools for assessing eutrophication and microbial risk for recreational activities.
... Assessing river condition can help identify pressures affecting rivers, and with the appropriate assessment steps in place, may allow the determination if a river has changed or improved (Whittington 2002). In Australia, a number of river condition assessment programs have occurred at a national scale (NLWRA 2002, Norris et al 2007 and the state or basin scale (Wittington 2002;Gippel 2007). A National Framework for the Assessment of River and Wetland Health (FARWH) was developed to support the baseline Australian Water Resources 2005 assessment, and focused on six key indicators of riverine health (Norris et al 2007). ...
... In Australia, a number of river condition assessment programs have occurred at a national scale (NLWRA 2002, Norris et al 2007 and the state or basin scale (Wittington 2002;Gippel 2007). A National Framework for the Assessment of River and Wetland Health (FARWH) was developed to support the baseline Australian Water Resources 2005 assessment, and focused on six key indicators of riverine health (Norris et al 2007). Many river condition assessments have either used a few or many indicators, with a common set of indicators frequently used across assessments (Wittington 2002;Gippel 2007). ...
... the Framework for Assessment of River and Wetland Health (FARWH) (see Dixon et al., 2011;Norris et al., 2007;Senior et al., 2011;Storer et al., 2011;Turak et al., 2011), the Sustainable Rivers Audit ) and the South-east Queensland Ecosystem Health Monitoring Program (EHMP) . ...
... The development of a detailed monitoring framework for HCVAEs in northern Australia was well beyond the scope of the project -previous experience has shown that it takes years of scientific development and community engagement before the monitoring framework can be finalised. Examples of the detailed work required include: the development of a National framework for the Assessment of River and Wetland Health (FARWH - Norris et al. 2007); the trial of the FARWH in the wet/dry tropics of northern Australia (Dixon et al. 2010); and, the development of a water quality monitoring framework for the Katherine and Daly River catchment (Risby et al. 2009). ...
... The RCI uses a standardised Euclidean distance formula to integrate input indices. The standardised Euclidean distance formula was chosen in accordance with the recommended FARWH approach (Norris et al., 2007a): RCI ¼ 1 À ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi ð1 À GCIÞ 2 þð1 À NRVIÞ 2 þð1 À HSIÞ 2 þð1 À RBCIÞ 2 q ffiffiffi 4 p This approach enables data collected from disparate methods to be combined into a single score of overall condition. Application of the method produces a score (range 0e1), where a higher score indicates better condition, such that: 0.8e1 ¼ Very Good (equivalent to FARWH "Largely Unmodified") 0.6e0.8 ...
River managers in Australia are managing in the face of extremes to provide security of water supply for people, production and the environment. Balancing the water requirements of people, environments and economies requires that water security is viewed holistically, not just in terms of the water available for human consumption. Common definitions of water security focus on the needs of both humans and ecosystems for purposes such as drinking, agriculture and industrial use, and to maintain ecological values. Information about achieving water security for the environment or ecological purposes can be a challenge to interpret because the watering requirements of key ecological processes or assets are not well understood, and the links between ecological and human values are often not obvious to water users. Yet the concepts surrounding river health are inherently linked to holistic concepts of water security. The measurement of aquatic biota provides a valuable tool for managers to understand progress toward achieving ecological water security objectives. This paper provides a comprehensive review of the reference condition approach to river health assessment, using the development of the Australian River Assessment System (AUSRIVAS) as a case study. We make the link between the biological assessment of river health and assessment of ecological water security, and suggest that such an approach provides a way of reporting that is relevant to the contribution made by ecosystems to water security. The reference condition approach, which is the condition representative of minimally disturbed sites organized by selected physical, chemical, and biological characteristics, is most important for assessing ecological water security objectives.
Technical Report
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Deakin University was engaged by the Department of Sustainability and Environment to develop an Index of Estuary Condition (IEC) for evaluating the environmental condition of Victorian estuaries. The Index will ultimately complement the existing Index of Stream Condition (ISC) by providing a consistent statewide assessment of the environmental condition of estuaries. This will better enable: • Estuarine condition to be reported at regional, state and national levels. • Prioritisation of resource allocation. • Strategic evaluation of management interventions in estuaries. Workshops involving participants with expertise in a variety of disciplines were convened to integrate learnings from assessment programs currently being developed interstate and overseas. This report synthesises and builds on the output from those workshops which: • Identified key components (themes) of estuaries that contribute to estuarine condition. • Contributed to development of a broad conceptual model for Victorian estuaries • Identified possible measures of each theme In keeping with the sub-indices of the ISC, six themes were identified for use in the IEC: Physical form, Hydrology, Water quality, Sediment, Flora and Fauna. Several measures within each theme are recommended to assess estuary condition (Table A). Implementation of particular measures in the IEC partly depends on the investment required to both collect and interpret the required data. With regard to data collection, each measure was assessed according to whether there is an established sampling procedure, how frequently data need to be collected and the level of expertise required for collection and processing. For interpreting the data, measures were scored on whether baseline condition is established and whether descriptions and scores are developed which reflect the extent of deviation from that condition. These scores were used to indicate which measures are feasible to implement immediately and which require further investigation (Table 8). A trial of the recommended IEC measures in a selection of estuaries is recommended as it would provide an opportunity to test the measures and their suitability for application statewide. It is suggested that the trial is conducted in estuaries subject to various levels of threats within each of the four estuary classes described by Barton et al. (2008)
Article
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Exchanges of water, sediment and associated nutrients between river channels and flood plains are important for the ecological functioning of large flood-plain river ecosystems. The deposition of sediment and associated nutrients was measured on four different flood-plain surfaces along a 15 km reach of the lower River Murray, southeastern Australia, during a controlled flood event. Discharge peaked at 80 000 megalitres per day (MLd), resulting in the entire flood plain being inundated for at least 114 days. During this period, 81 944 t of sediment or 13% of the suspended load was retained within the study reach. Of this, 23 202.5 t was deposited on the various flood-plain surfaces. The sediments were mainly silty loams and contained large amounts of nutrients: the equivalent of 950 t of total organic carbon (TOC), 50 t of total Kjeldahl nitrogen and 2.3 t of total Kjeldahl phosphorus was deposited on the flood plain during this flood event. The spatial distribution of the deposited sediment and associated nutrients was found to be variable. The highest rates of sediment deposition were recorded nearest to the river channel, but the highest concentrations of nutrients were found in distal areas. Flood-plain topography, surface roughness and the timing of sediment input and associated nutrient input were considered to be the main factors influencing the highly variable spatial distribution of this exchange between the river channel and its flood plain.
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We quantitatively sampled fish assemblages and measured habitat structure in upper coastal plain streams of the central Savannah River drainage, South Carolina. Fish species abundances ordinated in principal component space based on 15 habitat variables were arrayed along gradients of velocity and stream size (depth and width) and their covariates such as substrate and cover. The majority of species' centroids oriented toward slower, deeper habitats with depositional substrates and cover. Size classes within some species were well separated, indicating change in habitat use with age, whereas others clustered closely, indicating consistent habitat use through ontogeny. In an ordination based on species distributions and abundances (detrended correspondence analysis) species again oriented along velocity and stream size gradients. Although taxonomically related species had distinct optima, most genera and families clumped into similar regions, indicating a phylogenetic component to assemblage composition. A Mantel comparison of species ordinations on PCA and DCA axes resulted in high and significant concordance, indicating that these independent techniques produce the same conclusion regarding response of fishes to habitat parameters. Much site-to-site variation in composition of coastal plain fish assemblages can be attributed to variation in habitat structure, primarily current velocity and stream size.
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Traditional methods of establishing control sites in field-oriented biomonitoring studies of water quality are limited. The reference-condition approach offers a powerful alternative because sites serve as replicates rather than the multiple collections within sites that are the replicates in traditional designs using inferential statistics. With the reference-condition approach, an array of reference sites characterises the biological condition of a region; a test site is then compared to an appropriate subset of the reference sites, or to all the reference sites with probability weightings. This paper compares the procedures for establishing reference conditions, and assesses the strengths and deficiencies of multimetric (as used in the USA) and multivariate methods (as used in the UK, Canada, and Australia) for establishing water-quality status. A data set of environmental measurements and macroinvertebrate collections from the Fraser River, British Columbia, was used in the comparison. Precision and accuracy of the 2 multivariate methods tested (AUStralian RIVer Assessment Scheme: AusRivAS, Benthic Assessment of SedimenT: BEAST) were consistently higher than for the multimetric assessment. Classification by ecoregion, stream order, and biotic group yielded precisions of 100% for the AusRivAS, 80-100% for the BEAST, and 40-80% for multimetrics; and accuracies of 100%, 100%, and 38-88%, respectively. Multimetrics are attractive because they produce a single score that is comparable to a target value and they include ecological information. However, not all information collected is used, metrics are often redundant in a combination index, errors can be compounded, and it is difficult to acquire current procedures. Multivariate methods are attractive because they require no prior assumptions either in creating groups out of reference sites or in comparing test sites with reference groups. However, potential users may be discouraged by the complexity of initial model construction. The complementary emphases in the multivariate methods examined (presence/absence in AusRivAS cf. abundance in BEAST) lead us to recommend that they be used together, and in conjunction with, multimetric studies.
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1. In the mid-1970s, Hynes (1975) wrote eloquently about the complex interactions between aquatic and terrestrial systems. Central theories in stream ecology developed thereafter have dealt with the longitudinal flow of energy, materials and organisms in streams, and, with the exception of the flood pulse concept (Junk, Bayley & Sparks, 1989), have largely ignored areas outside the riparian zone. The structure of the upland and activities occurring there play a more important part than previously recognized in regulating community structure and ecosystem processes in streams.2. These new perspectives are made possible by developments in hierarchy theory, patch dynamics, and the refinement of tools used to quantify spatial and temporal heterogeneity.3. Geographical information systems (GIS), image processing technology and spatial statistical techniques allow quantitative assessment of lateral, longitudinal and vertical components of the landscape that interact at several spatial and temporal scales to influence streams. When GIS is used in concert with geostatistics, multivariate statistics, or landscape models, complex relationships can be elucidated and predicted.4. To a certain extent, the tools discussed above have only automated functions that were previously performed manually. This suite of tools has improved the ability of aquatic ecologists to examine relationships and test theories over larger, more heterogeneous regions than were previously possible.5. At the local, state and federal level, management and regulatory frameworks are currently being re-evaluated to incorporate this new perspective in resource management and policy decision making.6. We will discuss current and future trends in technologies and tools used for aquatic ecosystem research, and the use of techniques as they are applied in these regional assessments are also discussed.
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To investigate the linkage between erosion process and channel network extent, we develop two simple erosion threshold theories driven by a steady state runoff model that are used in the digital terrain model TOPOG to predict the pattern of channelization. TOPOG divides the land surface into elements defined by topographic contours and flow lines, which can be classified as divergent, convergent and planar elements. The calibration parameter for the runoff model is determined using empirical evidence that the divergent elements which comprise the ridges in our study area do not experience saturation overland flow, where as the convergent elements in the valleys do during significant runoff events. A threshold theory for shallow landsliding predicts a pattern of instability consistent with the distribution of landslide scars in our 1.2 km2 study site and confirms the interpretation, based on field observations, that indicate the steeper channel heads to be at least partially controlled by slope instability. Most sites of predicted and observed slope instability do not, however, support a channel head, hence landslide instability alone is not sufficient for channelization. In contrast, most elements predicted to be eroded by saturation overland flow coincided with the observed location of the channel network. In addition, areas of predicted downslope decrease in relative sediment transport capacity were found to correspond to locations where channels became discontinuous. -from Authors
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Abstract River InVertebrate Prediction And Classification System (rivpacs) is a software package developed by the Institute of Freshwater Ecology (IFE) for assessing the biological quality of rivers in the United Kingdom. The system can be used to generate site-specific predictions of the macroinvertebrate fauna to be expected in the absence of major environmental stress. Each prediction is based on a small number of environmental features that are used to characterize the site. The fauna predicted can then be compared with the fauna observed at the same site. This offers a procedure for evaluating biological quality with application in river management both at the local level and for national surveys. Close collaboration between the IFE team and biologists in the water industry during the project had a beneficial influence on the operational development of the system.A second feature of RIVPACS is the national classification of sites, based on the macro-invertebrate fauna. Although the classification is currently a pre-requisite for the prediction system, it also has intrinsic value because newly sampled sites of high biological quality can be placed within the national framework, based on their macroinvertebrate fauna. This facility is of interest to the statutory nature conservation bodies as an element in their site appraisal procedures.The predictive component of the current version of the system (RIVPACS n) was used in the 1990 River Quality Survey to assess the biological quality of almost 9000 sites throughout the United Kingdom. Further developmental work is now under way to provide a more comprehensive version of the system for the 1995 survey.
Article
Summary1. Physical habitat is the living space of instream biota; it is a spatially and temporally dynamic entity determined by the interaction of the structural features of the channel and the hydrological regime.2. This paper reviews the need for physical habitat assessment and the range of physical habitat assessment methods that have been developed in recent years. These methods are needed for assessing improvements made by fishery enhancement and river restoration procedures, and as an intrinsic element of setting environmental flows using instream flow methods. Consequently, the assessment methods must be able to evaluate physical habitat over a range of scales varying from the broad river segment scale (up to hundreds of kilometres) down to the microhabitat level (a few centimetres).3. Rapid assessment methods involve reconnaissance level surveys (such as the habitat mapping approach) identifying, mapping and measuring key habitat features over long stretches of river in a relatively short space of time. More complex appraisals, such as the Physical Habitat Simulation System (PHABSIM), require more detailed information on microhabitat variations with flow.4. Key research issues relating to physical habitat evaluation lie in deciding which levels of detail are appropriate for worthwhile yet cost-effective assessment, and in determining those features that are biologically important and hence can be considered habitat features rather than simple geomorphic features.5. The development of new technologies particularly relating to survey methods should help improve the speed and level of detail attainable by physical habitat assessments. These methods will provide the necessary information required for the development of the two-and three-dimensional physical and hydraulic habitat models.6. A better understanding of the ways in which the spatial and temporal dynamics of physical habitat determine stream health, and how these elements can be incorporated into assessment methods, remains a key research goal.