Melissa Parsons, Martin Thoms and Richard Norris
Cooperative Research Centre for Freshwater Ecology
University of Canberra
Monitoring River Health Initiative Technical Report Number 22
Environment Australia, 2002
ISSN 1447-1280
ISBN 0 642 54888 9
The physical assessment of stream condition lies within a broad framework of environmental restoration. Most river rehabilitation methods recommend the use of a pre and post-restoration assessment of condition. For example, the 12-Step rehabilitation process of Rutherfurd et al. (2000) includes description of present stream condition and evaluation of the success of the rehabilitation process. Similarly, Kondolf (1995) recommends the collection of baseline data that can be used to evaluate change caused by rehabilitation projects and Hobbs and Norton (1996) stress the importance of identifying the processes leading to degradation or decline, and of developing easily observable measures of the success of restoration interventions. The assessment protocol described in this document addresses these aspects of river rehabilitation by providing a quantitative approach to the physical assessment of river condition.
The Australian River Assessment System (AusRivAS) is a nationally standardised approach to biological assessment of stream condition using macroinvertebrates, that was developed under the auspices of the National River Health Program (NRHP). Within the AusRivAS component of the NRHP a suite of 'toolbox' projects have been commissioned with the aim of either refining the existing assessment techniques, or developing additional aspects of river health assessment. One of these toolbox projects is the physical assessment module, which involves development of a standardised protocol for the assessment of stream physical condition. Construction of such a protocol requires simultaneous consideration of stream condition from a physical and a biological 'habitat' perspective. While there would seem to be obvious interdependencies between the physical and biological components of streams, merging them is a complex task because of the different paradigms that exist in the disciplines of fluvial geomorphology and stream ecology. However, it is envisaged that the incorporation of a physical assessment module into AusRivAS will provide a tool for evaluating and understanding the physical condition of streams that is complementary to measures of stream condition that are made using the biota (Maddock, 1999). This tool can be used to enhance the AusRivAS assessments of stream condition, and also to evaluate physical condition within a stream restoration framework.
The AusRivAS physical assessment protocol is a method for assessing the physical condition of streams and rivers. The protocol is a 'stand alone' method of physical and geomorphological assessment, however, it also has the capability to complement the biological assessments of stream condition that are made using AusRivAS.
This document is essentially a 'field manual' that presents the background information to the method and instructions for the selection of reference sites and collection of physical data. Full implementation of the protocol involves collection of reference site information from both the field and the office, and subsequent development of predictive models. This document describes methods for reference site selection and field and office data collection only. It does not describe methods for the construction of predictive models, because these closely follow the AusRivAS procedures described in Simpson and Norris (2000). To make an assessment of physical stream condition using the protocol, a large number of reference sites must be sampled and predictive models generated. Then, the condition of test sites can be determined using these models. This is the same process that was used in the National River Health Program to develop AusRivAS.
The protocol follows the Habitat Predictive Modelling approach of Davies et al. (2000) that in turn, is similar to AusRivAS in both data collection and analytical procedure (Simpson and Norris, 2000). This approach has advantages over other physical assessment methods in use in Australia because it allows prediction of the stream features expected to occur at a sampling site and generates quantitative assessments of physical condition (ie. observed/expected ratios). However, achievement of robust predictions relies on the inclusion of a wide range of physical and geomorphological factors. Thus, the Habitat Predictive Modelling approach of Davies et al. (2000) will be strengthened with sampling design, data collection and analytical components derived from other physical and geomorphological stream assessment methods presently in use in Australia.
Additionally, it should be noted that this protocol is for use in freshwater rivers and streams only and NOT for use in estuaries or tidal sections of lowland rivers.
This document is divided into seven parts. This section, Part 1, describes the background and derivation of the protocol and also gives an overview of how the protocol works. Part 2 provides information and instruction on the procedure that will be used to select reference sites. These reference sites are then used in the construction of predictive models. Part 3 gives an overview of the requirements for collecting field and office based data and Part 4 contains the data sheets for use in the field. Part 5 is used in conjunction with Parts 3 and 4 and gives detailed technical instructions for the collection or measurement of each field based and office based variable used in the protocol. Part 6 is the reference list and Part 7 contains various appendices to the text.
The protocol has been written with the assumption that the reader is familiar with AusRivAS sampling procedures, model development and model outputs. General information on AusRivAS can be obtained at http://ausrivas.canberra.edu.au/ and technical information can be found in the papers collected together in Wright et al. (2000).
Development of the physical assessment protocol involved three stages: evaluation of physical stream assessment methods currently in use in Australia, a habitat assessment workshop and derivation of final recommendations for a standardised assessment protocol. Each of these stages will be discussed briefly in the following sections.
The Index of Stream Condition (Ladson and White, 1999; Ladson et al., 1999; White and Ladson, 1999), River Habitat Audit Procedure (Anderson, 1993a; Anderson, 1993b; Anderson, 1993c; Anderson, 1999), River Styles (Brierley et al., 1996; Cohen et al., 1996; Fryirs et al., 1996; Brierley et al., 1999; Brierley and Fryirs, 2000) and Habitat Predictive Modelling (Davies, 1999; Davies et al., 2000) methods were evaluated against a set of criteria that represent the desirable requirements of a standardised physical assessment protocol (Table 1.1).
The Index of Stream Condition, the River Habitat Audit Procedure, River Styles and Habitat Predictive Modelling were designed for slightly different purposes and subsequently, each of these methods differ in their compatibility with the requirements of a standardised physical assessment protocol (Table 1.1). Each method performed equally well against criteria such as 'ability to assess stream condition against a desirable reference state', and 'applicability to all stream types within Australia'. However, only one or two methods performed well against criteria such as 'ability to predict physical stream features that should occur in disturbed rivers and streams' and 'outputs of physical condition that are comparable to AusRivAS outputs of biological condition' (Table 1.1). Overall, no one method met all the requirements for a stand-alone stream assessment protocol. However, each method contains important individual components that will be combined into a comprehensive protocol for assessing stream physical condition (see Section 1.2.3).
Twenty-two leading ecologists, geomorphologists and hydrologists attended a workshop titled "Stream Habitat Assessment: Integrating Physical and Biological Approaches", that was held at the University of Canberra on May 2-3, 2000. Broadly, the workshop was designed to provide the rationale and background information upon which to build a standardised physical assessment module. Several critical areas of the development of the physical assessment protocol were identified at the workshop. These were:
In addition, the Habitat Assessment Workshop also examined the types of physical variables that would be useful for inclusion in the protocol.
| Criteria required for the physical assessment protocol | Existing physical assessment methods | |||
|---|---|---|---|---|
| River Habitat Audit Procedure | Index of Stream Condition | River Styles |
Habitat Predictive Modelling | |
| Ability to predict the physical features that should occur in disturbed rivers and streams | N | N | P1 | Y |
| Ability to assess stream condition relative to a desirable reference state | Y | Y | Y | Y |
| Use of a 'rapid' data collection philosophy | Y | Y | N | Y |
| Use of physical variables that do not require a high level of expertise to measure and interpret | Y | Y | P2 | Y |
| Use of variables that represent the fluvial processes that influence physical stream condition | Y | Y | Y | P3 |
| Outputs that are easily interpreted by a range of users | Y | Y | N | Y |
| Applicability to all stream types within Australia | P4 | P4 | P4 | P4 |
| Incorporation of a scale of focus that matches the scale of biological collection within AusRivAS | Y | Y | P5 | Y |
| Collection of physical parameters that are relevant to macroinvertebrates | P | P | P | Y |
| Outputs of physical condition that are comparable to AusRivAS outputs of biological condition | N | N | N | Y |
1Predictive ability relies on expert knowledge of the geomorphological
behaviour of river systems.
2Variables may not require a high level of expertise to measure,
but a high level of expertise to interpret
3Currently uses physical data collected in AusRivAS, but can
be modified to incorporate other types of variables
4There is no existing Australia wide system for assessing the
physical condition of rivers. All methods are potentially modifiable for use
in different river types across Australia.
5River Styles uses a multi-scale approach to characterise and
assess river systems.
The areas of concern identified at the Habitat Assessment Workshop were considered alongside the evaluation of existing stream assessment methods to make a final set of recommendations for the content and philosophy of the physical assessment protocol. These recommendations were:
These recommendations were then used to formulate the content of the physical assessment protocol (see Section 1.3), including the reference site selection procedure (Part 2) and the methods for field and office based data collection (Part 3).