Australian River Assessment System: Review of Physical River Assessment Methods — A Biological Perspective

M. Parsons, M. Thomas, R. Norris
Cooperative Research Centre for Freshwater Ecology
Monitoring River Health Initiative Technical Report Number 21
Environment Australia, 2002
ISSN 1447 1280
ISBN 0 642 54887 0


3. Summary and Evaluation of River Assessment Methods

3.1 Summary of river assessment methods

The following provides a summary of the advantages and disadvantages of each of the seven river assessment methods examined in detail in the previous section. Each method was developed for a different purpose and thus, the use of the term 'advantages' and 'disadvantages' are not judgements about the relative value of each method as an individual tool for river assessment. Rather, examination of advantages and disadvantages is framed in light of the potential for each method, or components of each method, to fit the requirements of a standardised physical and chemical assessment protocol, within an AusRivAS style framework.

3.1.1 AusRivAS

Advantages
Potential disadvantages
Sampling and data collection issues

3.1.2 HABSCORE

Advantages
Potential disadvantages
Sampling and data collection issues

3.1.3 Index of Stream Condition

Advantages
Potential disadvantages
Sampling and data collection issues

3.1.4 Geomorphic River Styles

Advantages
Potential disadvantages
Sampling and data collection issues

3.1.5 State of the Rivers Survey

Advantages
Potential disadvantages
Sampling and data collection issues

3.1.6 Habitat Predictive Modelling

Advantages

Potential disadvantages

Sampling and data collection issues

3.1.7 River Habitat Survey

Advantages
Disadvantages
Sampling and data collection issues

3.2 Evaluation of river assessment methods

Each of the river assessment methods considered in this review was developed for a specific purpose and thus, the methods reflect a range of management goals and scientific approaches. However, development of a standardised protocol for the physical and chemical assessment of river condition requires consideration of the following specific qualities:

The representation of each of these qualities within the seven river assessment methods examined in this review is summarised in Table 3.2.1. Overall, the methods generally use rapid data collection and analysis methods, they have the potential for use by non-experts and their scientific outputs are presented in a form that is easily interpreted by managers (Table 3.2.1). Each of the methods also has some capacity to assess stream condition against a reference state, however, the degree to which this function is utilised in determining site condition varies among the methods. Similarly, the methods vary widely in predictive ability, applicability to a wide range of river types across Australia and scale of focus (Table 3.2.1). Differences between the dominant paradigms of stream ecology and geomorphology are reflected by two criteria: the incorporation of parameters relevant to biota and the representation of important geomorphological processes (Table 3.2.1). Geomorphic River Styles, State of the Rivers Survey and River Habitat Survey were each designed to assess physical or geomorphological aspects of streams and thus, they attempt to incorporate empirical relationships between physical parameters and biota indirectly. Conversely, AusRivAS, HABSCORE and Index of Stream Condition have a strong biological component and thus, they fail to fully consider geomorphological processes. Finding common ground between biologically and geomorphologically relevant parameters would provide a more holistic perspective on the assessment of stream condition.

 
Table 3.2.1 Evaluation of seven river assessment methods against the desired qualities of a standardised physical and chemical assessment protocol. The representation of each of the qualities by the methods is designated as yes (Y), no (N), potentially (P) or indirectly (I).
Desired qualities of the physical and chemical assessment protocol Potential methods for inclusion in the physical and chemical assessment protocol
AusRivAS HABSCORE Index of Stream Condition Geomorphic River Styles State of the Rivers Survey Habitat Predictive Modelling River Habitat Survey
Scale of focus commensurate with the AusRivAS biological monitoring protocol Y Y N P P Y P
Capacity to measure stream condition against a desirable reference state Y Y Y I Y Y I
Incorporation of parameters that are relevant to the biota, particularly macroinvertebrates Y Y Y P P Y P
Representation of important geomorphological processes that influence the formation of stream habitat N N N Y I P Y
Conformity with a rapid philosophy of data collection and analysis Y Y N N Y Y Y
Potential for use by non-experts Y Y Y N Y Y Y
Scientific outputs presented in a form that is easily interpreted by managers Y Y Y P Y Y Y
Adaptability and applicability to a wide range of river types across Australia Y P P P P Y P
Ability to predict physical stream characteristics Y N N Y N Y P

3.3 Future directions - habitat assessment workshop

As discussed in Section 1.1, development of a protocol for the physical assessment of stream condition that is complementary to AusRivAS requires simultaneous consideration of biological and geomorphological methods and approaches. This review is a first step towards merging the two approaches to stream assessment, and provides an information base that that will be built upon at the habitat assessment workshop, scheduled for 2-3 May, 2000. The habitat assessment workshop will bring together geomorphologists, hydrologists and ecologists and will involve the authors of several of the methods covered in this review. The aim of the workshop is to develop a framework for a standardised physical and chemical assessment protocol. One of the main challenges of the workshop will be to determine the physical variables that are relevant to biota, and to determine the most suitable methods for measuring these variables in a cost effective manner, and within a rapid sampling philosophy. Specifically, it is hoped that the questions posed in Section 1.1 will be answered in detail during the course of the workshop to form the basis for a standardised physical and chemical assessment protocol. The outcomes and recommendations from the habitat assessment workshop will be reported in a future document.