Evidence - Freshwater Biological Association Rivers(ii... · identifies the best methods to collect...

Standardisation of RIVPACS for deep rivers: Phase I - deriving a standard approach to deep river sampling.

Evidence

i

The Environment Agency is the leading public body protecting and improving the environment in England and Wales.

It’s our job to make sure that air, land and water are looked after by everyone in today’s society, so that tomorrow’s generations inherit a cleaner, healthier world.

Our work includes tackling flooding and pollution incidents, reducing industry’s impacts on the environment, cleaning up rivers, coastal waters and contaminated land, and improving wildlife habitats.

This report is the result of research commissioned and funded by the Environment Agency’s Science Programme.

Published by: Freshwater Biological Association August 2014 All rights reserved. This document may be reproduced with prior permission of the Environment Agency. The views and statements expressed in this report are those of the author alone. The views or statements expressed in this publication do not necessarily represent the views of the Environment Agency and the Environment Agency cannot accept any responsibility for such views or statements.

Author(s): John Davy-Bowker†, John Iwan Jones ‡ John Francis Murphy ‡ Dissemination Status: Publicly available / Restricted Keywords: Deep Rivers, bioassessment, sampling, methods, airlift, ergonomics, RIVPACS, RICT Research Contractor: †Freshwater Biological Association, The River Laboratory East Stoke Wareham BH20 6BB ‡Queen Mary University of London, Mile End Road, London, E1 4NS 01929 401892 Environment Agency’s Project Manager: David Colvill, SEPA

ii Science Report – Standardisation of RIVPACS for deep rivers: Phase 1

Science at the Environment Agency Science underpins the work of the Environment Agency. It provides an up-to-date understanding of the world about us and helps us to develop monitoring tools and techniques to manage our environment as efficiently and effectively as possible.

The work of the Environment Agency’s Science Group is a key ingredient in the partnership between research, policy and operations that enables the Environment Agency to protect and restore our environment.

The science programme focuses on five main areas of activity:

• Setting the agenda, by identifying where strategic science can inform our evidence-based policies, advisory and regulatory roles;

• Funding science, by supporting programmes, projects and people in response to long-term strategic needs, medium-term policy priorities and shorter-term operational requirements;

• Managing science, by ensuring that our programmes and projects are fit for purpose and executed according to international scientific standards;

• Carrying out science, by undertaking research – either by contracting it out to research organisations and consultancies or by doing it ourselves;

• Delivering information, advice, tools and techniques, by making appropriate products available to our policy and operations staff.

Steve Killeen

Head of Science

Science Report – Standardisation of RIVPACS for deep rivers: Phase 1 iii

Executive summary

This report addresses a lack of standardisation in the sampling methods used to collect deep river reference samples in the RIVPACS predictive models. These models are used within the River Invertebrate Prediction and Classification tool for WFD compliance monitoring across the UK. Standardisation is needed to ensure that samples are collected using the same methods, both in the RIVPACS predictive models, and in the classification samples collected by the Environment Agency, Scottish Environment Protection Agency and Northern Ireland Environment Agency. Without this, apparent differences in environmental quality may in part be due to different sampling methods rather than real changes in the environment.

In this Phase 1 project, a review has been carried out (reported separately) that identifies the best methods to collect samples from deep rivers. These are the airlift for deep rivers that are also wide, and the long-handled pond net for deep rivers that are narrow. Initial rivers width and depth thresholds were suggested between the well-standardised shallow water kick sampling method, and the point at which a deep river sampling technique should be used.

This report considers the thresholds between shallow and deep river sampling techniques in more detail and provides clear guidelines on the point at which the shallow water kick sampling technique should be changed to either airlift or long-handled pond net sampling. This report also examines the consequences of standardising deep river sampling techniques for the RIVPACS models and identifies the number of RIVPACS reference samples that would need to be replaced and the geographical coverage of deep river reference sites that the model would contain. This report also examines the consequences of using the same standardised airlift and long-handled pond net deep river sampling techniques for the WFD classification monitoring carried out by the Environment Agency, Scottish Environment Protection Agency and Northern Ireland Environment Agency. The geographical extent and numbers of classification sites affected are investigated.

An important gap in the coverage of shallow and deep water techniques is identified. At intermediate depths in wide rivers, kick samples cannot be obtained because the water it is too deep, and airlift samples cannot be obtained because the water is too shallow. A short practical field trial of modified airlift designs is suggested to see if airlift sampling devices can be shortened to quickly address this issue.

Additional items investigated include an assessment of the suitability of the two current biological classification metrics, NTAXA and ASPT, both of which are found to be fit for use in deep rivers. An investigation of the potential need for new predictive variables for deep river sites suggests that this is not necessary.

Several practical aspects of airlift sampling are also reported. Firstly, an update is provided for the Environment Agency sampling manual to bring it in line with the newly recommended deep river sampling techniques. Secondly, a standard specification of for airlift Yorkshire pattern airlift sampling device is presented. Thirdly an ergonomic assessment of airlift sampling is reported. This was based on a comprehensive field trial of airlift sampling, including all aspects of equipment handling and sampling. Fourthly, a revised safe system of work is presented. This incorporates the additional health and safety observations that emerged from the ergonomic assessment.

Finally, a specification and work programme is presented for a follow on Phase 2 project. This project would replace the non-standard deep river samples that are in RIVPACS with deep river samples collected with either an airlift or long-handled pond

iv Science Report – Standardisation of RIVPACS for deep rivers: Phase 1

net. Phase 2 would also include work to estimate the uncertainty associated with these two deep river sampling techniques, and the building of new RIVPACS models.

Incorporation of the new RIVPACS models into the RICT software would be part of a final Phase 3 project.

Science Report – Standardisation of RIVPACS for deep rivers: Phase 1 v

Acknowledgements

We would like to thank Ben McFarland1 and John Murray-Bligh of the Environment Agency for their help in developing the research proposal for this work. We would also like to thank Rachel Benstead, Chris Extence, Alice Hiley, Tim Jones, Geoff Phillips and Shelagh Wilson (Environment Agency), David Colvill (Scottish Environment Protection Agency) and Imelda O’Neill (Northern Ireland Environment Agency) for their very useful help and comments at the start up meeting and for comments on the report.

We would like to thank Cynthia Davies of the Centre for Ecology and Hydrology (Wallingford) for help extracting sampling method information from the National Invertebrate Database and also for making the CEH paper files available so that missing sampling method information for the RIVPACS sites could be found. We would also like to thank Colin Daly and Imelda O’Neill (Northern Ireland Environment Agency), and Maria Bisby, Julie Cowley, Bob Dines, Chris Extence, Nina Fielding, Claire Gladdy, Andrew Goodman, Jessy Grant, Phil Harding, Ian Humpheryes, Glen Meadows, Lucy Morris, John Murray-Bligh and John Steel (Environment Agency) for their help in confirming sampling method information for the original RIVPACS samples.

We would like to thank John Murray-Bligh (Environment Agency), David Colvill (Scottish Environment Protection Agency), and Imelda O’Neill (Northern Ireland Environment Agency) for their help in supplying recent WDF biological classification data.

In particular we would like to make a special thank you to thank Dave Barber, Barry Byatt, Paul Curry, Joanne Hood and Julie Winterbottom of the Environment Agency, Yorkshire and North East Region for their very kind help in providing a demonstration of airlift sampling, and in addition, Barry Byatt for his help in answering numerous questions about the principles of airlifting. We would like to make a special thank you to Tim Jones of the Environment Agency, Thames Region, for supplying details of the recently developed Thames airlift sampling equipment and for his help and advice on the details of this design and its new safety features.

We would also like to thank James Barker and George Green (Environment Agency), and Ross Doughty and Bernadette Fitzpatrick (Scottish Environment Protection Agency) for their help providing very useful feedback and discussion on the ergonomic, health and safety, and practical aspects of airlift sampling.

1 Now with the RSPB (Minsmere).

vi Science Report – Standardisation of RIVPACS for deep rivers: Phase 1

Contents 1 Introduction 1

2 Identification of deep river RIVPACS reference samples that need to be re-sampled 3

2.1 Collation of sampling methods for the existing RIVPACS samples 3

2.2 Deriving a standard approach to deep river sampling 4

2.3 Identification of reference sites that have been inappropriately sampled 11

2.4 Geographical coverage of deep river reference sites 14

2.5 Resolving the gap between kick/sweep and airlift coverage 20

3 Consequences of the standardised approach to deep river sampling for the UK classification network 21

4 Suitability of NTAXA and ASPT for deep rivers 26

5 Suitability of the RIVPACS environmental predictor variables for deep rivers 30

6 Updating the sampling manual for deep rivers 36

7 A specification for the Yorkshire pattern airlift 52

8 Health and safety aspects of airlift sampling 57

8.1 An ergonomic assessment of airlift sampling 57

8.2 A revised safe system of work of airlift sampling 62

9 Summary work programme for Phase 2 75

10 Conclusions 76

11 Recommendations 77

References 78

List of abbreviations 80

Appedicies 82

Science Report – Standardisation of RIVPACS for deep rivers: Phase 1 vii

Tables Table 1 Sampling methods that have been used to collect the RIVPACS reference samples. 4 Table 2 Number of RIVPACS IV reference samples needing to be re-sampled as a function of mean depth and

width using a) Long Handled Pond Net, b) Airlift, c) Kick/Sweep and d) total for all 3 methods. Based on the 2385 samples (795 reference sites) in the current RIVPACS IV GB and NI models combined. 13

Table 3 Number of airlift, long-handled pond-net, and kick/sweep samples that would need to be taken to sample the WFD classification network applying the 80cm depth and 15cm width definition of deep rivers to the recorded depths and widths (EA data cover the period 2007, 2008 and 2009; NIEA data from 2009 only). 23

Table 4 RIVPACS IV TWINSPAN end group size range, mean group size, SD of group size and percentage of RIVPACS IV sites correctly classified to end groups across the GB and NI RIVPACS IV models. 31

Table 5 GB RIVPACS IV model end group size, mean and SD depth within TWINSPAN end groups, and percentage of sites correctly classified to each group. 31

Table 6 NI RIVPACS IV model end group size, mean and SD depth within TWINSPAN end groups, and percentage of sites correctly classified to each group. 32

Table 7 The seven super-group level of classification of the 43 end groups of the GB RIVPACS IV model. 33 Table 8 Updates to Operational Instruction 018_08. 37 Table 9 Main components of the Yorkshire pattern airlift. 52 Table 10 Ergonomic assessment of video clips 1-4. Observations relate to ergonomic or health and safety issues

only. Time markers indicate the position in each video where the first example of each issue arose. 58

Figures

Figure 1 RIVPACS reference site widths (2505 reference samples). 6 Figure 2 RIVPACS reference site depths (2505 reference samples). 6 Figure 3 Plot of RIVPACS reference site widths and depths (2505 samples). 7 Figure 4 Schematic relationship between widths and depths of streams and the methods that should be used to

sample them. 7 Figure 5 Choice of sampling method for rivers with a flat riverbed cross-section. K/S = kick/sweep, LHPN = long

handled pond net, AL = airlift. All 3 methods include a 1-minute search. 9 Figure 6 Choice of sampling method for rivers with a sloped riverbed cross-section. K/S = kick/sweep, LHPN =

long handled pond net, AL = airlift. All 3 methods include a 1-minute search. 10 Figure 7 Sampling methods used to collect the existing 2505 RIVPACS reference samples compared to width

and depth data recorded when each sample was collected. Appropriate sampling methods (Kick/Sweep; Airlift; and Long-handled pond net) following Jones and Davy-Bowker (2012). Vertical and horizontal lines divide sections but precise positions are only indicative. 12

Figure 8 The 795 RIVPACS IV reference sites showing sites that should be re-sampled under different definitions of ‘wide’ and ‘deep’. Black – reference sites; red – re-sample with Kick/Sweep; green – re-sample with LHPN; blue – re-sample with Airlift. 16

Figure 9 The 795 RIVPACS IV reference sites showing sites that should be re-sampled if 80cm is regarded as ‘deep’ and 15m is regarded as ‘wide’. 18

Figure 10 A map of main rivers in the United Kingdom. Underlying map © SNIFFER, 2005 (reproduced with kind permission); river name labels added by authors. 19

Figure 11 Recent Agency WFD classification sites showing sites that would need to be sampled with a deep river method if 80cm is regarded as ‘deep’ and 15m is regarded as ‘wide’ (D80:W15). 22

Figure 12 Frequency of occurrence of recorded river depths for WFD classification biological samples collected by the EA (2007-2009), NIEA (2009), and SEPA (2009). 24

Figure 13 Observed mean and 95% confidence limits of 3-season average depth (cm) and 3-season combined NTaxa and ASPT for reference sites across the 43 Great Britain and 11 Northern Ireland RIVPACS IV TWINSPAN end groups. 27

Figure 14 Unadjusted O/E mean and 95% confidence limits of 3-season combined NTaxa and ASPT for reference sites across the 43 Great Britain and 11 Northern Ireland RIVPACS IV TWINSPAN end groups. 28

Figure 15 GB and NI percent correctly classified sites by end group. Dotted lines indicate the percent correctly classified across each whole model. Orange bars indicate end groups with mean depth >=80cm. 33

Figure 16 GB and NI percent correctly classified sites versus end group size. Orange dots indicate end groups with mean depth >=80cm (end groups 41, 42 and 43 in GB, and end group 11 in NI). 34

Figure 17 The airlift pipe of a standard Yorkshire pattern airlift. 53 Figure 18 Example of the handle-shaped shields that are suggested as additional fittings to protect the high-

pressure inlet and low-pressure outlet connections of the control box. 54 Figure 19 Airlift sampler developed by the Environment Agency, Thames Region. 56 Figure 20 Airlift control box developed by the Environment Agency, Thames Region. 56

Additional Tables and Figures are given in the suggested updates to the Environment Agency’s sampling manual (section 6) and in the revised Safe system of work for Airlift sampling. These preserve the numbering of the original Environment Agency’s documents and are not listed here.

viii Science Report – Standardisation of RIVPACS for deep rivers: Phase 1

1 Introduction

RIVPACS predictive models are well established in the UK as the primary means for setting targets against which the macroinvertebrate quality of freshwaters are assessed. In their current form, RIVPACS IV models are used by the Environment Agency, Scottish Environment Protection Agency, and the Northern Ireland Environment Agency for their Water Framework Directive compliance classifications. These models are made available to the UK Agencies, and other users, via the River Invertebrate Classification Tool. RICT is modern web based platform that ensures that all users are working from a common version of the software.

The RIVPACS IV models in RICT were developed to make RIVPACS better suited to the WFD compliance monitoring needs of the UK Agencies. These models incorporate a range of enhancements such as a broader range of biotic indices than previous versions, a screened dataset to remove non-reference state sites from their predictions, adjustments to further compensate for the likely non-reference condition of some of the stream types on which the models were built, and an expanded coverage of taxonomic predictions to better match the levels of sample analysis being carried out by the UK Agencies (Davy-Bowker et al., 2007a; Davy-Bowker et al., 2007b; Clarke and Davy-Bowker 2006; Davy-Bowker et al., 2008; Davy-Bowker et al., 2010; Clarke et al., 2011).

While the RIVPACS IV models perform well in wadeable streams, there is however a long recognised problem with the application of RIVPACS in deep rivers. RIVPACS models are based on a reference site dataset of biological samples from streams and rivers across the UK. The majority of these sites are wadeable and were therefore sampled using a standardised kick/sweep methodology. In contrast, the deep river reference samples were collected using a variety of non-standardised methods. A similar lack of standardisation also occurs in the current approach to deep river sampling within the UK Agencies.

The lack of standardisation in deep river sampling, both within the RIVPACS models and the samples currently collected by the UK Agencies is significant because three UK based sampling method comparison studies (Wright et al., 1999; Bass et al., 2001 and Jones et al., 2005) have shown that different deep river sampling methods can lead to large differences in perceived environmental quality. These method comparison studies, and others, are fully reviewed in the first report from this project (see below).

Poor standardisation of deep river biological sampling methods has the very important consequence that it makes it difficult to assess if differences between the observed macroinvertebrate community in a test sample, and the community predicted by RIVPACS are real or in part an artefact of inconsistent sampling methods. This means that the assignment of WFD quality classes in deep rivers is likely to be less reliable than those for wadeable streams. To overcome the shortcomings of the UK RIVPACS models in deep rivers, standardisation is needed in the reference samples that underpin the models. The same standardised methods should also be used for the sampling carried out by the UK Agencies for WFD classification.

There is therefore a need to review the existing method comparison studies so that the best standardised approach to deep river sampling can be identified, and also to explore the consequences of adopting this approach both for the RIVPACS models and for WFD classification monitoring.

Science Report – Standardisation of RIVPACS for deep rivers: Phase 1 1

This Phase 1 project has sought to address deep river standardisation issues in two stages.

Firstly a comprehensive review of deep river sampling has been carried. This has addressed the following issues:

i) Reviewed the results of previous deep-water methods comparison studies, including practical aspects of deep river sampling.

ii) Made recommendations on the preferred deep water sampling method(s) and the threshold between methods for sampling wadeable and deep rivers.

iii) Examined the potential discontinuities in RIVPACS predictive models that might arise from the methods used to collect reference samples.

This review is reported by Jones and Davy-Bowker (2012). Secondly, and building on the review above, this report has sought to address the following issues that need to be resolved in order to standardise deep river sampling in the UK:

iv) Finalise the threshold between methods for sampling wadeable and deep rivers.

v) Identify existing RIVPACS sites that have been inappropriately sampled (given their depth), examine the distribution of deep water reference sites in the current RIVPACS models, and suggested replacement sites.

vi) Evaluate the suitability of the classification metrics EQR ASPT and EQR NTAXA for deep rivers.

vii) Examine the potential need for additional environmental variables to adequately discriminate deep rivers in RIVPACS predictive models.

viii) Produced clear guidelines for sampling deep rivers for inclusion in future Environment Agency, Scottish Environment Protection Agency, and Northern Ireland Environment Agency sampling manuals.

ix) Established a specification for a ‘standard’ airlift sampling device. x) Provided an ergonomic assessment of airlift sampling. xi) Revised the existing safe system of work for airlift sampling. xii) Provide a specification and work programme for a Phase 2 project to collect

new deep river samples and build new RIVPACS model(s) based on samples collected using standardised deep water sampling methods.

It is anticipated that the collection of new deep river reference samples using standardised deep water sampling methods, derivation of estimates of uncertainty associated with these methods, and the building of new RIVPACS models based on these samples will be carried out in a subsequent Phase 2 project. Item xii (above) makes an important contribution to planning this Phase 2 project by identifying the tasks and activities required to deliver it, and by providing indicative costs1.

Incorporation of the new RIVPACS models into the RICT software would be delivered through a final Phase 3 project.

1 For reasons of commercial confidentiality, while a full specification and work programme has been provided to the project board, only a summary is provided in this report.

2 Science Report – Standardisation of RIVPACS for deep rivers: Phase 1

2 Identification of deep river reference samples that need to be re-sampled

The existing deep river reference sites within the RIVPACS database have been sampled with a variety of different sampling techniques. This makes building RIVPACS models that work well in deep rivers difficult because some of the variability that is currently assumed to represent genuine differences between sites, is likely to be due in some part to the various methods used to obtain the samples.

To pave the way for a future RIVPACS deep rivers Phase 2 project that will replace these deep river samples with samples collected by standardised methods, three key issues will first need to be addressed:

• Accurate information will need to be collated on the deep river sampling methods used to collect the existing RIVPACS samples were taken

• A standard rule will need to be developed that guides the choice of deep river sampling technique that should be used under a wide range of environmental conditions.

• The existing RIVPACS reference sites that have been inappropriately sampled will need to be identified and earmarked for replacement.

These three topics are addressed in the sections that follow.

2.1 Collation of sampling methods for the existing RIVPACS samples

As a first step towards standardising the sampling methods used for the RIVPACS deep river samples, information on the sampling methods that were used to collect the existing RIVPACS reference samples needed to be collated. Unfortunately, this information was not readily available in the RIVPACS database and needed to be gathered from a number of sources.

The majority (80%) of the sampling method information was obtained from the CEH ‘National Invertebrate Database’, from which the RIVPACS database was originally created. However, there were still several hundred samples for which this sampling method information was not available. To help obtain the sampling methods for these samples, Cynthia Davies (CEH, Wallingford) kindly made the original archived paper field sheets available so that the missing data could be searched for.

After a detailed search of the original paper files at CEH Wallingford, some gaps still existed. A number of alternative methods had to be used to fill the gaps including:

• Searching the 1990 National Rivers Authority (now Environment Agency), national biological ‘River Quality Survey’ database, as some of the RIVPACS reference sites had originally been collected as part of that survey.


• Searching RIVPACS research and development contract reports that described the development of earlier versions of RIVPACS

• Consultation with the Environment Agency, Scottish Environment Protection Agency, and the Northern Ireland Environment Agency as many of the RIVPACS reference samples had actually been collected by staff of these organisations.

• Examining Ordnance Survey maps to see if streams and rivers would have been too small to have been sampled by any of the potential deep river sampling methods.

This process was successful and the missing RIVPACS reference site sampling method information was found. The completed sampling method dataset was then added to the RIVPACS database.

2.2 Deriving a standard approach to deep river sampling

As a second step towards standardising the sampling methods used for the RIVPACS deep river samples, a standard approach needed to be developed that would address the question of how to make a clear and consistent choice of the most appropriate sampling method for deep rivers.

RIVPACS has evolved over a long series of separate development stages. The oldest reference samples were collected in 1978 and most recent in 2002. During this extended period of development, while the kick/sweep methodology for wadeable streams has been relatively standardised as a 3-minute kick/sweep with a 1-minute search, the sampling methods used for deep river have been more varied (Table 1).

Table 1. Sampling methods that have been used to collect the RIVPACS reference samples.

Sampling method All 835 RIVPACS sites 795 sites in RIVPACS IV Kick/Sweep + Search 2431 2317 Airlift (non-standardised) 22 22 Dredge 49 43 Grab 2 2 Dry 1 1 Total 2505 2385

Some of the deep river reference samples have been collected using an airlift, others with a dredge, and some samples have been collected with a grab. Within the deep river sampling methods, there are also further problems due to weak standardisation of sampling time/effort. Other deep river sites may also have been sampled with the Kick/Sweep method, possibly by gaining access only to the shallowest parts of the river. When viewed across the whole dataset, there has been a varied approach to the methods used to collect the RIVPACS deep river reference samples, and the need for a standardisation is clear. It is also noteworthy that when viewed nationally, a similar


variety of approaches to deep-river sampling almost certainly exist in the samples that are currently being collected for WFD classification monitoring by the UK Agencies.

The need for a standardised approach to deep river sampling that can be applied to both the RIVPACS reference samples, and to current WFD classification monitoring, is therefore clear.

This need for standardisation is even more apparent when the effects on RIVPACS observed/expected ratios are considered. The current variety of deep river sampling methods, both for the RIVPACS reference samples and for the data being collected by the Agencies, means that a test (observed) sample collected by one method, might be compared to an expectation based on samples that have collected by quite different methods. The non-standardisation of deep river sampling methods is therefore probably compromising the ability of RIVPACS IV to properly classify deep river sites.

Any standard rule to address the question of how to make a clear and consistent choice of the most appropriate sampling method for deep rivers must be easy to use, and not be reliant upon difficult to obtain measurements or data. The simplest approach is probably one that only takes water depth into account and works by setting a simple threshold at which any site deeper than a certain depth is regarded as deep, and is therefore sampled by a given deep river method. Any site that is shallower would then still be sampled by the very well established and proven kick/sweep plus search sampling method.

While this approach is appealing for its simplicity and ease of practical use, the first report from this Phase 1 project has recommended that a strategy should be developed where mid-channel samples are collected with a Yorkshire pattern airlift and combined with sweep samples from the margin collected with a pond net. This recommendation was reached after a very detailed review of a wide range of deep river sampling methods that compared the quality of data they produce, their efficiency in capturing macroinvertebrates and their cost-effectiveness (Jones and Davy-Bowker, 2012). The same review also recommended that for deep but narrow rivers, a long-handled pond net could be used, but that this would not be appropriate for rivers that are both deep and wide as the mid-channel fauna would be so under-represented as to result is miss-classification of sites.

Implementing the recommendations of (Jones and Davy-Bowker, 2012) into a standard rule for deciding upon deep river sampling methods, results in a simple algorithm based on just stream depth and stream width. Rivers that are shallow should be sampled with a kick/sweep plus search; deep narrow rivers should be sampled with a long-handled pond net plus search; and deep wide rivers should be sampled with an airlift plus search.

The review by Jones and Davy-Bowker made the decision process for identifying the correct sampling method for a deep river clear, but only set provisional criteria for how deep a river should be before it is classed as ‘deep’ and how wide a river must be before it is classed as ‘wide’. A provisional suggestion of 40% of the streambed being wadeable, or 75cm average depth was suggested as the cut off for depth, while a suggestion of 10m was suggested as the distinction between narrow and wide. An examination of the width and depth characteristics of the RIVPACS reference sites (Fig. 1 and 2) is needed to help in the definition of the criteria of what constitutes a deep river and what constitutes and a wide river. In addition, an estimate of the consequences for the number of RIVPACS reference sites that would need to be re-sampled is also important (Section 2.3)


Figure 1. RIVPACS reference site widths (2505 reference samples).

Figure 2. RIVPACS reference site depths (2505 reference samples).

Figure 1 shows that the commonest stream width across the UK-wide RIVPACS dataset is approximately 5-10 metres. The frequency distribution tails off gradually towards some rarely occurring but extremely wide rivers up to 120 metres in width. Figure 2 shows that river depth follows a similar pattern, with the commonest depth being about 20 cm, and deeper rivers becoming less and less frequent up to a maximum recorded depth of about 3 metres. It is also important to see how the two variables width and depth relate to each other (Fig. 3).

300250200150100500

800

700

600

500

400

300

200

100

0

Mean Depth (cm)

Freq

uenc

y


140120100806040200

800

700

600

500

400

300

200

100

0

Width (m)

Freq

uenc

y

Figure 3. Plot of RIVPACS reference site widths and depths (2505 samples)

Figure 3 shows that the majority of RIVPACS reference samples were obtained from streams and rivers that were both shallow and narrow. A smaller number of samples were taken from sites that were shallow and wide, and from sites that were narrow and deep. Fewest of all were samples from rivers that were both wide and deep. Related to this, the stream width and depth algorithm suggested in Jones and Davy-Bowker (2012) can also be expressed in diagrammatic form (Figure 4).

Figure 4. Schematic relationship between widths and depths of streams and the methods that should be used to sample them


Figures 3 and 4 show that implementing a rule to choose a sampling method based on width and depth would appear to be logical. In most cases, sampling sites that are shallow, regardless of width, (Figure 4, box A) should be wadeable and can therefore be sampled by the RIVPACS kick/sweep (plus 1-minute search) method. Deep rivers cannot be waded and should be sampled either by long-handled pond net (B. in Figure 4) or airlift (C. in Figure 4) depending on their width.

For both narrow and wide deep rivers, a (non-optional) 1-minute search at the margins is also required to make these methods comparable to the RIVPACS kick/sweep (plus 1-minute search) method used in shallow (wadeable) streams.

Before moving on to identifying the reference sites that might need to be replaced as a result of implementing a rule to choose sampling methods based on width and depth alone, it is also important to consider how depth itself is measured. In the data presented so far, mean depth has been used, where this is the average of the three separate depths recorded at ¼, ½ and ¾ channel width when each RIVPACS reference sample was taken. However, it could have been more meaningful to have considered the minimum or maximum recorded depth as these values might correspond more closely to the maximum wadeable depth from which a kick/sweep sample could be obtained.

Mean, minimum and maximum depth will only differ where a riverbed profile is not flat. If a rule is going to be established that determines the choice of sampling method using mean depth as one of its components, the influence of different riverbed profiles must also be considered as this might influence the proportion of a site that could be effectively sampled using kick/sweep methodology where the river is close to the point of becoming too deep to kick sample.

2.2.1 Flat riverbed cross-section

Firstly the simple situation of a relatively flat-bottomed river should be considered (Figure 5). In a flat-bottomed river, the three depth measurements at width ¼, ½, and ¾ are all, by definition, the same as the mean depth. If the mean depth is less than or equal to what is defined as ‘deep’ (and therefore wadeable), all 3 depths, and therefore, all three locations at which the depth were measured will also be wadeable. In this situation a kick/sweep sample is appropriate.

Where mean depth is non-wadeable, all 3 depths, and therefore, all three locations at which the depth were measured will also be non-wadeable. In this situation a deep-water sampling technique must be used. If the width is less than or equal to what is defined as 'wide', a long-handled pond net is appropriate. If the width is greater than what is defined as 'wide', an airlift must be used.

2.2.2 Sloped riverbed cross-section

In a sloped river channel, the three depth measurements at width ¼, ½, and ¾ will all be different. Some or all of the three locations at which depth measurements were made or estimated may therefore be wadeable, while some or all may not.

In Figure 6 a sloped riverbed is depicted. In the table inset into Figure 6, an arbitrary maximum wadeable depth of 85cm has been chosen. Four mean depths (70, 80, 90 and 100cm) that cover the transition across wadeable to non-wadeable depths are examined. Given the fact that the channel is sloped, this dictates that for each mean, one of the measured depths must be less than the mean, and one greater than the mean. For example, in the case of the mean depth being 70cm, we have chosen one depth equal to the mean (70cm), one less than the mean (60cm) and one greater than the mean (80cm). In this first example, none of the depths exceed the wadeable depth (85cm) so all locations at which the depth was measured can be kick/sweep sampled, and a kick/sweep sample is therefore deemed appropriate for the site.

If the channel was the same depth but was more strongly sloped, (e.g. 40, 70, 100cm), the mean still equals 70cm but one location at which the depth was measured would


Figure 5. Choice of sampling method for rivers with a flat riverbed cross-section. K/S = kick/sweep, LHPN = long handled pond net, AL = airlift. All 3 methods include a 1-minute search.

now be too deep to kick/sweep sample. In this case, because at least half of the total river width can still be kick/sweep sampled, we consider that river should still be kick/sweep sampled. A decision based on the mean depth is therefore still appropriate.

In Figure 6 the effect of increasing water depth is also explored. At a mean depth of 80cm, half the river width is still accessible for kick/sweep sampling (85cm is the arbitrary limit) so this method remains appropriate for the site. Again, if we increase the slope (e.g. 50, 80, 110cm), half of the river width still remains accessible so a decision based on the mean depth is still appropriate.

As the mean depth increases further, for example 90cm, the mean depth is now greater than the 85cm is the arbitrary wadeable limit. In this situation, only one of the individual depths is wadeable. This means that at best, only a quarter of the site is shallow enough for kick/sweep sampling. In this case, a deep-water method should be used. At mean depth 100cm, none of the separate measured depth locations are accessible for kick/sweep and again, a deep-water method should be used.


Figure 6. Choice of sampling method for rivers with a sloped riverbed cross-section. K/S = kick/sweep, LHPN = long handled pond net, AL = airlift. All 3 methods include a 1-minute search.

Finally, a situation can be envisaged where the mean depth is considerably deeper than the wadeable depth (e.g. 100cm) but the channel is so sloped that one depth location is accessible for kick/sweep sampling (e.g. 80, 100, 120, mean = 100). In this situation again, the choice of sampling method should still be based on the mean depth because at best, only a quarter of the site is shallow enough for kick/sweep sampling so a deep-water method should be used.


In all the sloped riverbed, wadeable to non-wadeable transitions above, for both shallow and steeply sloped streambeds, it can be concluded that the choice of sampling method should still be based on the mean depth. Once the mean depth exceeds that which can be regarded as ‘deep’ then a deep-water technique should be used. The choice between long-handled pond net and airlift is then same as in the case of a flat-bottomed river and is simply based on width (if the width is less than or equal to what we define as 'wide', a long-handled pond net is appropriate, if the width is greater than what we define as 'wide' an airlift must be used).

For all three methods, kick/sweep, long-handled pond net, or airlift, a 1-minute search (using a standard pond net rather than long-handled pond net) must also be included.

2.2.3 U-shaped riverbed cross-section

Streambeds can take many forms other than the simple flat or sloped channels considered above. One of the commonest is a U-shaped channel where the depth is greatest in the middle (½ width depth measurement) and shallowest at the edges (¼ and ¾ width measurements). For example, if the maximum wadeable depth is 85cm, and a channel has a mean depth of 80cm, this might comprise three measured depths of 70 (¼), 100 (½) and 70 (¾). In this example the two edges are wadeable out to one quarter of the river width respectively, while the middle of the channel is non-wadeable. In this case a kick/sweep sample is still acceptable although this must comprise material from both sides of the river so a crossing point must be found. In total, half of the streambed is accessible for kick/sweep sampling and a deep river technique is not necessary. As in the case of the sloped riverbed, because half of the river width still accessible, a decision based on the mean river depth is still acceptable.

2.2.4 Confounding factors – soft sediment and fast flow

Several factors can make the straightforward application of a rule based on river depth and river width to determine sampling method more complicated. Two of the most notable are soft sediments and fast flowing water. While these are probably both encountered on very different types of river, they both produce the same end result in that they both reduce the ability to wade over streambed that (based on water depth alone) should be accessible. In these cases, again the application of the mean river depth and river width approach to determining sampling method should still be used. However if this results in a decision to take a kick/sweep sample that a cannot practically be obtained, consideration should be given to moving the sampling site to a more accessible location or shifting over to the appropriate deep river technique depending on the width.

2.3 Identification of reference sites that have been inappropriately sampled

A major consequence of adopting a restrictive rule for determining the sampling method to be used for deep rivers is that some existing RIVPACS reference samples that don’t comply will have to be replaced.

Information on the sampling methods used to obtain each of the 2505 RIVPACS reference samples has been combined with data on the mean width and depth of the RIVPACS sampling sites (section 2.2) in Figure 7.


Figure 7. Sampling methods used to collect the existing 2505 RIVPACS reference samples compared to width and depth data recorded when each sample was collected. Appropriate sampling methods (Kick/Sweep; Airlift; and Long-handled pond net) following Jones and Davy-Bowker (2012). Vertical and horizontal lines divide sections but precise positions are only indicative.

Figure 7 shows that when strict rules over the choice of sampling method are imposed, many of the existing reference sites fail to meet these criteria. The deviations from the width and depth rules are summarised below:

• For shallow streams the method should be a kick/sweep plus search. Several samples have been taken with methods other than this (grab, dredge, and airlift). These would need to be re-sampled with RIVPACS kick/sweep plus 1-minute search.

• For deep narrow streams, the method should be a long-handled pond net sample plus search. The existing samples have been sampled by kick/sweep, dredge, grab and airlift. None of the existing samples comply with the new width and depth rule and all of them would need to be re-sampled.

• For deep wide rivers the method should be a 3-minute standardised airlift sample plus search. The existing samples have been sampled by kick/sweep, dredge and airlift. None of the existing samples comply with the new width and depth rule and all of them would need to be re-sampled.

Estimates can now be made of the number of RIVPACS reference samples that need to be re-sampled by combing the information on a range of possible mean depth and width settings that define rivers as ‘deep’ and ‘wide’, with information on how the sites were originally sampled. This analysis (Table 2) is restricted to the 2385 reference samples that are used in RIVPACS IV, rather than the full 2505 samples in the database.


Table 2. Number of RIVPACS IV reference samples needing to be re-sampled as a function of mean depth and width using a) Long Handled Pond Net, b) Airlift, c) Kick/Sweep and d) total for all 3 methods. Based on the 2385 samples (795 reference sites) in the current RIVPACS IV GB and NI models combined.

a) Airlift

b) Long Handled Pond Net

c) Kick/Sweep d) Total number of new samples

Width (m)

>5 >10 >15 >20 >25 >30 >35

Mea

n de

pth

(cm

) > 50 386 318 250 194 160 134 111 > 60 285 235 194 152 125 107 88 > 70 233 197 166 131 107 90 77 > 80 193 165 139 109 90 73 62 > 90 167 144 119 96 81 64 55

> 100 114 101 88 70 60 50 45 > 110 108 95 82 67 57 47 42

Width (m)

≤5 ≤10 ≤15 ≤20 ≤25 ≤30 ≤35

Mea

n de

pth

(cm

) > 50 32 100 168 224 258 284 307 > 60 23 73 114 156 183 201 220 > 70 17 53 84 119 143 160 173 > 80 12 40 66 96 115 132 143 > 90 5 28 53 76 91 108 117

> 100 3 16 29 47 57 67 72 > 110 3 16 29 44 54 64 69

Total (AL+LHPN+KS)

Mea

n de

pth

(cm

) ≤ 50 1

Mea

n de

pth

(cm

) 50 419 ≤ 60 2 60 310 ≤ 70 2 70 252 ≤ 80 2 80 207 ≤ 90 6 90 178

≤ 100 18 100 135 ≤ 110 18 110 129

Example - The numbers of samples that need to be re-sampled if ‘deep’ is defined as mean depth >80cm and ‘wide’ defined as width >15m:

Airlift 139 Long handled pond net 66 Kick/Sweep 2 Total 207


The analysis above (Table 2) clearly shows the number of RIVPACS IV reference samples that should be replaced with new samples using alternative sampling methods, using any scenario of the point at which a river is regarded as deep and wide.

However, in this analysis each sample was treated independently and no account was taken for the fact that the same site that might have been classed as deep in one season (e.g. spring), might subsequently be regarded as shallow in another season (e.g. summer or autumn). It is therefore suggested that each sample that requires replacement should, in the first instance be re-sampled at the same location and season as it was originally sampled. This time however, making sure that a sampling methodology is selected that is compliant with the rules that have been established for choosing sampling techniques based on stream width and stream depth.

To re-sample at the same location, it will be important to establish if the watercourse will still pass the WFD screening criteria that should apply to all new reference samples (Davy-Bowker et al., 2007b). Any locations that would now fail these criteria would result in that site being rejected from RIVPACS and a need for a comparable new site to be found.

Given that there has been a general trend for river quality improvement over the past 30 years, it is anticipated that the quality of most sites requiring re-sampling would tend to have improved rather than deteriorated so it is not deemed necessary (or efficient) to explore the quality of these sites at this time. Rather, it is recommended to wait until the width and depth settings are finalised and agreed across the UK Agencies so that the current quality of just those sites that are earmarked for replacement can be investigated.

2.4 Geographical coverage of deep river reference sites

A final step in identifying the reference samples that need to be re-sampled is to consider whether the geographical coverage of the proposed replacement reference sites properly represents the geographical coverage of deep rivers in the UK.

To examine the geographical coverage of UK RIVPACS deep river sites, it was decided that several scenarios of what might be defined as ’deep’ and ‘wide’ would be investigated so that the consequences of these choices could be shown for the geographical coverage of RIVPACS sites that would need to be re-sampled. Three average depths (60cm, 80cm and 100cm) and 3 widths (10m, 15m and 20m) were investigated.

The choice of these settings was guided by considering sensible limits on depth and width in relation to the following factors:

1. Deeper than a certain depth, a river cannot be kick/sweep sampled (both in terms of practical issues and operator safety). After some consideration we have chosen 1m as the deepest that a river can be kick/sweep sampled. This depth may vary to some extent depending on water velocity and substrate type (for example, it is easier to kick/sweep deep water when that water is slow flowing or the water body has a with hard substrate, versus a situation where a river is fast flowing or has a soft deep substrate that effectively makes the river deeper than the measured depth). 1m may also be deeper than some people consider


possible or safe to kick/sweep sample so this has been set as the upper limit of the analysis.

2. Shallower than a certain depth, a river should be kick/sweep sampled. A river shallower than about 60cm average depth should probably always be kick/sweep sampled (unless the substrate is extremely soft and deep so that the realised depth is much greater than this).

3. In terms of width, defining a deep river of less than 10m width as ‘wide’ presents considerable logistical problems. This is because any river that is both deep, and over 10m wide, would then therefore have to be sampled using an airlift. This probably has unrealistic resource implications for the UK Agencies in the overly large number of sites they would then have to airlift for their routine monitoring.

4. Defining a (deep) river as wide with a width of greater than about 25 metres is also unrealistic because anything narrower that this would therefore only be sampled by a long-handled pond net which would seriously under-represent the benthic fauna of very wide rivers (Jones and Davy-Bowker, 2012).

The nine maps in Figure 8 show the distribution of RIVPACS reference sites that would need to be re-sampled with a deep river technique under three definitions of ‘deep’, and three definitions of ‘wide’ that are considered to cover a sensible range of these settings.

The depth settings in Figure 8 were chosen to cover the threshold depth at which a kick sample becomes less-and-less possible (and less safe) and should therefore give way to a deep river sampling method. Deep is defined as 60cm, 80cm or 100cm average depth to cover the range of firstly, definitely wadeable for most biologists (60cm); secondly, borderline wadeable (80cm); and thirdly, probably not wadeable by most biologists under routine conditions (depth 100cm) i.e. without a dry suit. The upper limit of 100cm depth is supported by the responses to a questionnaire circulated to EA, SEPA, NIEA biologists (and others) given in Wright et al. (1999), where a deep river was most commonly defined as one in which the site was too deep to take a reliable kick sample, and the main channel or whole river width was deeper than 100cm.

Wide was defined in Figure 8 as 10m, 15m and 20m. The wider a deep river is before it is defined as ‘wide’, (e.g. 20m as opposed to 10m) the more of these deep rivers can be sampled with a long-handled pond-net and the fewer need to be sampled with an airlift. In deciding these three width settings, two opposing factors had to be balanced out. Firstly, in terms of practicality and manpower resources, airlift samples are more difficult to collect than long-handled pond-net samples. Sorting airlift samples also takes longer than long-handled pond net samples (Neale et al., 2006). Practicality therefore creates a pressure to choose as wide as possible definition of the width threshold (e.g. 20m+) although the threshold point arising from this consideration is somewhat arbitrary. Secondly, wide rivers cannot be effectively sampled from the edge alone as the high scoring mid-channel fauna are underrepresented. This issue is examined in Neale et al. (2006) where the ASPT of samples collected with an airlift increased with river width whilst those associated with margin samples decreased, resulting in increasing separation of ASPT for these two techniques with river width. Neale et al. concluded that in wider rivers there was more spatial segregation between the margins and channel. These two methods therefore collect different aspects of the whole community, so if a river is only defined as wide at a very wide setting of say 50m width, any sites less than 50m wide will therefore be sampled by a techniques (long-handled pond-net) that does not adequately represent the mid channel community. This separation of ASPT scores obtained by airlift and margin samples as a function of river width was indistinct at 10m river width but complete by 20m river width hence the decision to use the width settings 10m, 15m and 20m in Figure 8.


Figure 8. The 795 RIVPACS IV reference sites showing sites that should be re-sampled under different definitions of ‘wide’ and ‘deep’. Black – reference sites; red – re-sample with Kick/Sweep; green – re-sample with LHPN; blue – re-sample with Airlift.


Looking firstly at Figure 8 in terms river depth; if a river is defined as deep where its mean depth is 60cm, there are considerably more RIVPACS reference samples that need to be replaced than if a river is defined as deep if it has a mean depth of 100cm. Again this has resource implications for the RIVPACS dataset, since a definition of a deep river of 60cm would mean that many more samples would need to be replaced. In considering river width, the total number of samples that would need to be replaced does not change with river width, but rather the balance between how those samples are replaced shifts. Defining a wide river as 10m wide means that many of the replacement samples would have to be airlift samples (since only those less than 10m in width could be sampled by long-handled pond net). Conversely, defining a river as wide when it has a width of 20m would mean that there are fewer replacement airlift samples and more replacement long-handled pond-net samples. The same principles apply to the WFD classification network (see section 3).

While any final decision on exactly what the definitions of a deep and a wide river should be are subject to review by the UK Agencies, the authors have recommended that the compromise settings of 80cm for depth, and 15m for width probably represent a reasonable compromise between the various scientific and practical considerations involved. The geographical distribution of reference sites requiring re-sampling using this 80cm deep, 15m wide definition (henceforth denoted D80:W15) is examined in further detail in Figure 9.

Figure 9 shows the consequences of defining a river as 'deep' if its depth is >80cm, and wide if its width is >15m. This figure shows the sites that need to be re-sampled in more detail to identify the main river systems affected. This should be viewed in conjunction with Figure 10, which gives the names of the major large rivers in the UK.

Figure 9 can also be view in combination with Table 2, which gives the total numbers of samples that need to be re-sampled by each method. In this definition of 'deep' as >80cm deep and 'wide' as >15m wide scenario, 139 samples need to be re-sampled by Airlift, 66 by long-handled pond net and 2 replacement kick/sweep samples need to be taken.

Geographically, there are sites where existing RIVPACS IV sites would need to re-sampled using either and airlift or long-handled pond net throughout the United Kingdom. However, these are unevenly distributed with most in England and Scotland, a few in Northern Ireland, and very few in Wales.

The rivers in Scotland that would need replacement reference samples (mainly using the airlift) are principally on the large eastern Scottish rivers Tweed, Tay, Dee, and Spey. There are also sites on the rivers Thurso and Halladale on the northern Scottish coast, various rivers on the northwestern Scottish mainland, and also along the southwest Scottish Dumfries and Galloway coast. Almost all the replacement sites in Scotland would need to be airlift sampled.

In England, starting along the east coast, new reference samples would be needed on the River Derwent and the River Ouse/Ure (mainly by airlifting). A considerable number of replacement samples would also be needed in East Anglia including sites on the River Welland and numerous sites on the Great Ouse river system including some of the larger lowland drains, although roughly half of these would be re-sampled using a long-handled pond net rather than an airlift. In the Thames catchment, the River Thames itself would require replacement samples (almost all by airlift), along with some of its larger tributaries. In the south east of England new samples would also be needed from the River Stour.

Along the south coast and south west of England, new airlift samples would be needed from the Rivers Test and Exe and new long-handled pond net samples from the Moors River and the River Cale. Along the Bristol Channel, new long-handled pond-net


Figure 9. The 795 RIVPACS IV reference sites showing sites that should be re-sampled if 80cm is regarded as ‘deep’ and 15m is regarded as ‘wide’.


Figure 10. A map of main rivers in the United Kingdom. Underlying map © SNIFFER, 2005 (reproduced with kind permission); river name labels added by authors.


samples would be needed from the River Parret system. In Wales and the English midlands, new airlift samples would be needed from the Rivers Wye and Severn, and new long-handled pod net samples would be needed from the Teifi and several sites in the English midlands.

Finally, Northern Ireland would need new deep river reference samples collected primarily by airlift, but also by long-handled pond-net, from the Bush River and in the north, a number of rivers on the Bann system including the Killagan Water, Moyola River and the Blackwater, and also from the Finn River and Sillees River in the south west.

While Scotland and Northern Ireland appear to have a sufficient coverage of deep-river reference sites (with the possible exception of the west coast Scottish mainland) it is interesting to note that there are no deep river RIVPACS reference sites in the far north of England despite the presence of a number of large river systems as the Coquet, Tyne, Wear and Tees in the east, and the Eden, Lune and Ribble in the west. This might be because these are high gradient rivers that have closely spaced riffle-pool sequences all the way down to the sea. However, if the lower reaches of these rivers are both deep (with few riffles) and are of sufficiently high quality, there may be some merit in gathering new reference samples to address this potential gap in geographical coverage. A similar weakness in geographical coverage exists in North Wales where the River Dee has the potential to provide high quality deep river reference sites.

2.5 Resolving the gap between kick/sweep and airlift coverage

In section 2.4 a rule was recommended that suggested that the compromise settings of 80cm for depth, and 15m for width should be chosen to define the point at which wadeable streams are kick/sweep sampled, while deep rivers should be either long-handled pond net or airlift sampled, depending on river width. However, later in this report, the specification for the Yorkshire pattern airlift identifies that the overall length of this device is currently 140cm (section 7). There is therefore a gap between the maximum depth for kick/sweep sampling and the minimum working depth that an airlift sampler can operate. This gap exists at river depths between 80 and 140cm deep.

Unfortunately it has not been possible to identify a sampling strategy that could be used in rivers that are between 80-140cm deep. Possible solutions that have been considered include kick/sweep sampling rivers deeper than 80cm, although this has been ruled out, as it would pose unacceptable health and safety risks to sampling staff. Another possible solution considered was to choose shallower parts of these rivers and take kick/sweep samples. However this is not acceptable because these sampling locations would not be representative of the general river reach.

The best solution would be to close the gap by modifying the Yorkshire pattern airlift so that it can work at water depths as shallow as 80cm. To the best of the authors’ knowledge, no data exists on the performance of airlift sampling devices that use shorter airlift pipes. It is the therefore recommended that a short practical study should be undertaken to test this. This should take the form of a field trial of five lengths of airlift pipe that cover the depth range in question and beyond (e.g. 40, 70, 100, 120, 140), to measure the recovery substrate seeded with coloured beads, from rivers with three different depths, and at 3 different air-pressure settings. Assuming that recovery of coloured beads is a reasonable surrogate for recovery of benthic fauna, this study would be relatively quick to perform, as the samples would only need to be dried and weighed to assess the performance of the various pipes under different depths and pressures. It is suggested that this could be carried out via the Environment Agency Framework Contract so the results could be forthcoming quickly without delaying the main RIVPACS deep rivers Phase 2 project.


3 Consequences of the standardised approach to deep river sampling for the UK classification network

In section 2.4 the impact of establishing a standard width and depth based rule for determining the correct macroinvertebrate sampling method was examined for the RIVPACS reference samples. However it is also extremely important to consider how adopting such a standardised approach to determining the sampling method would impact upon the WFD classification currently being carried out in the UK by the Environment Agency, Scottish Environment Protection Agency, and the Northern Ireland Environment Agency

Figure 11 shows the distribution of current (2007, 2008 or 2009) Water Framework Directive biological classification sites across the United Kingdom (black dots), with rivers defined as deep if the recorded depth was >80cm, and wide if the recorded width was >15m. Sites that would need to be sampled using an airlift are indicated by blue dots while sites that would need to be sampled with a long-handled pond net are indicated by green dots (as previously used in Figures 8 and 9).

Throughout England and Wales the areas in which a deep river technique would be required are broadly similar to those found by examining the RIVPACS reference sites (Figure 9), although there are clearly many more sites because the classification network is considerably larger than the reference site database. As with the RIVPACS reference sites, most sites where a deep river technique would be required are in central, southern and eastern England, and there are fewer sites in the south west of England, Wales and the North of England. The balance between airlift and long-handled pond net samples also appears to be broadly similar between the RIVPACS sites and the WFD classification sites, although a strict numerical comparison is not possible.

In Northern Ireland the number of WFD classification sites that would need a deep river technique also seems to be broadly comparable with the number RIVPACS sites that would need to be re-sampled, although deep rivers may be under represented to some extent. The geographical distribution of these deep sites within Northern Ireland differs between the two datasets but this is probably just due to the selection of different sites from which to gather samples.

In Scotland however, there are fewer WFD classification sites that would need to be sampled with a deep river technique than there were reference sites that would need a deep river technique. This suggests that deep river sites are strongly under-represented in the sampling carried out by SEPA.

This issue was further investigated in Figure 12 where the proportion of samples where the recorded depth exceeded 80cm was investigated for both the WFD classification samples and the RIVPACS reference samples. Figure 12 shows that in England and Wales 10.2% of the entire WFD classification network was based on samples collected from sites with recorded depths >80cm. In Northern Ireland 5.25% of samples were collected from sites with recorded depths greater than 80cm. However, in Scotland only 0.43% of samples were collected from sites where the recorded water depth was greater than 80cm (only 17 samples out of 3968 analysed between 2007 and 2009) compared to the RIVPACS reference samples where 5.72% had depths greater than 80cm.


Figure 11. Recent Agency WFD classification sites showing sites that would need to be sampled with a deep river method if 80cm is regarded as ‘deep’ and 15m is regarded as ‘wide’ (D80:W15).


There can only be two possible reasons for the differences observed in the water depths recorded by the EA and NIEA compared to those recorded by SEPA:

1) Scottish rivers are not deep

Samples collected for RIVPACS bioassessment should be collected from sampling sites that reflect the general character of the stretch upon which they are intended to report. In England, rivers are likely to have lower gradients and therefore widely spaced riffles. This means that a representative sample must be taken from a more commonly occurring feature such as a deep run or glide as opposed to from a riffle, since this is a rare feature and therefore not representative of the stretch. In Scotland, rivers tend to have higher gradients than those in England so that these rivers will have riffle-pool sequences extending further down towards the sea than rivers of comparable discharge in England. A sample from a riffle is therefore more likely to be representative of a deep river in Scotland than it would be in England.

Further evidence to support this conclusion comes from the rareness of deep rivers also observed in both the classification network and the RIVPACS dataset in northern England, Wales and the south west of England where rivers will also have higher gradients than those in central, southern and eastern England.

It therefore seems likely that the apparent shallowness of Scottish rivers could be at least in part because of higher gradients of these rivers and the greater availability of riffles from which to take samples. It is however unlikely that this is the sole cause of the apparent under representation of deep rivers in the Scottish WFD classification network given the apparent commonness of deep rivers in Scotland in the RIVPACS database.

2) SEPA are under representing the deep rivers

It is also possible that sampling from deep rivers has been avoided to a greater extent than in the England and Wales.

In conclusion, it is not possible to assess the consequences of the 80cm depth and 15m width definition of deep rivers for the WFD classification network for Scotland because of the under representation of deep rivers in the monitoring network. As it stands, the consequences would be negligible with almost no Scottish rivers requiring a deep river technique, however, this conclusion would be unsafe without first understanding why the WFD classification network in Scotland appears to have so few deep rivers compared to the classification network for England and Wales and the numbers of sites that the RIVPACS database suggests should be present.

An assessment of the consequences of the 80cm depth and 15m width definition of deep rivers for the Water Framework Directive biological classification sites of the England and Wales, and Northern Ireland classification networks is possible, and is given in Table 3 below.

Table 3. Number of airlift, long-handled pond-net, and kick/sweep samples that would need to be taken to sample the WFD classification network applying the 80cm depth and 15cm width definition of deep rivers to the recorded depths and widths (EA data cover the period 2007, 2008 and 2009; NIEA data from 2009 only). Number of airlift

samples Number of long-

handled pond-net samples

Number of kick/sweep

samples

Total number of samples

EA 184 210 4377 4771 NIEA 2 5 229 236 SEPA not known not known not known 835


Figure 12. Frequency of occurrence of recorded river depths for WFD classification biological samples collected by the EA (2007-2009), NIEA (2009), and SEPA (2009).


By far the biggest effect on resources would be in England and Wales, where over a 3-year period approximately 184 airlift samples (61 per year) would need to be taken (the vast majority of which would be in England). In Northern Ireland a very small number of airlift and long-handled pond-net samples would need to be taken in any one given year (although this may be higher than Table 3 suggests given the slight under-representation of deep rivers in the Northern Ireland classification samples).


4 Suitability of NTAXA and ASPT for deep rivers

EQR ASPT and EQR NTaxa are currently the only metrics used for the UK’s WFD river quality classifications. Despite the recent availability of other metrics (e.g. LIFE, WHPT, AWIC, PSI), ASPT and NTaxa have remained the primary means of river quality bioassessment used by the UK agencies to assess and report biological river quality at a national scale. This section examined the suitability of EQR ASPT and EQR NTaxa for deep rivers.

ASPT (average score per taxon) is the derived from the sum of all BMWP scoring taxa divided by the number of BMWP scoring taxa and is known to respond well to organic pollution stress. NTaxa (number of taxa) is simply the number of BMWP scoring taxa, and while it also responds to organic pollution stress it also gives an indication of general taxonomic richness that might also be affected by stressors that are not organic in nature. Observed and expected ASPT and NTaxa are used in their EQR forms through RICT to report river classes. The lower of the two EQR classes is used as the overall assessment. This ‘minimum of NTaxa or ASPT’ EQR approach is referred to by the acronym MINTA.

While EQR ASPT and EQR NTaxa are well established as indices for reporting the quality of UK rivers, their suitability for assessing the quality of deep rivers as opposed to shallower, i.e. wadeable streams has not been specifically tested. This section therefore examines EQR ASPT and EQR NTaxa values (and also simple observed ASPT and NTaxa) across the RIVPACS reference site dataset to see if systematic differences exist in these indices between wadeable streams and deep rivers.

The first step in this analysis was to distinguish wadeable streams from deep rivers. The simplest way to do this was to use the existing biological classification that underpins the current RIVPACS IV GB and NI models (Davy-Bowker et al., 2008). These classifications contain 43 biological end groups in GB and the 11 end groups in NI, with each classification representing the natural gradient in physical variables that exists across the GB and NI stream types. Figure 13 shows these end groups arranged in sequence across the x-axis. The y-axis of Figure 13 shows the mean and 95% confidence limits of water depth across all sites in each end group. The individual water depths are themselves the mean of the nine separate water depth measurements; three each from the spring; summer and autumn reference sampling occasions.

Earlier in this report it was suggested that rivers with an average depth greater than 80cm should be regarded as deep rivers (section 2.4). Figure 13 shows that in GB only end groups 41, 42 and 43 have average depths with a mean greater than 80cm (dotted line in Figure 13). In Northern Ireland only end group 11 has an average depth with a mean greater than 80cm. These end groups (containing 32, 12, 13 and 7 sites respectively) therefore contain the majority of the RIVPACS reference sites where the average depth would be classified as deep using the D80:W15 rule (see section 2.4). While the 95% confidence limits of depth in Figure 13 show that some sites in the deep end groups are shallower than 80cm, and that some sites in the other end groups have mean depths greater than 80cm, the biological end groups still constitute a reasonable method of distinguishing the deer river reference sites from the wadeable ones.


Figure 13. Observed mean and 95% confidence limits of 3-season average depth (cm) and 3-season combined NTaxa and ASPT for reference sites across the 43 Great Britain and 11 Northern Ireland RIVPACS IV TWINSPAN end groups.

1110987654321

7.0

6.5

6.0

5.5

5.0

4.5

1110987654321

40

30

20

10

0

1110987654321

200

150

100

80

50

0

43424140393837363534333231302928272625242322212019181716151413121110987654321

7.0

6.5

6.0

5.5

5.0

4.5

43424140393837363534333231302928272625242322212019181716151413121110987654321

40

30

20

10

0

43424140393837363534333231302928272625242322212019181716151413121110987654321

200

150

100

80

50

0

GB Depth (cm) NI Depth (cm)

GB Obs NTaxa NI Obs NTaxa

GB Obs ASPT NI Obs ASPT


43424140393837363534333231302928272625242322212019181716151413121110987654321

1.4

1.3

1.2

1.1

1.0

0.9

0.8

0.7

0.6

Figure 13 also shows the mean and 95% confidence limits of the 3 season combined NTaxa and ASPT across the 43 GB and 11 NI RIVPACS IV biological end groups. In Great Britain NTAXA gradually increases between end group 1 and end group 43, with a peak somewhere between groups 31 and 40. The ‘deepest’ end groups (41, 42 and 43) have a high mean NTAXA but this is not the highest across all end groups. It is possible that had the deepest rivers been sampled by airlift that the mean NTAXA would peak in the deepest rivers. Overall the relationship is one in which observed NTAXA increases with water depth up to the maximum mean water depth reached in the GB biological end groups of about 150cm.

A similar pattern in observed in Northern Ireland where NTAXA increases across end groups with progressively deeper mean water depth. The deepest end group, end group 11, has a high NTAXA, although it also appears to have wider NTAXA confidence limits than of the other end groups.

Figure 14. Unadjusted O/E mean and 95% confidence limits of 3-season combined NTaxa and ASPT for reference sites across the 43 Great Britain and 11 Northern Ireland RIVPACS IV TWINSPAN end groups.

1110987654321

1.4

1.3

1.2

1.1

1.0

0.9

0.8

0.7

0.6

43424140393837363534333231302928272625242322212019181716151413121110987654321

1.2

1.1

1.0

0.9

0.8

1110987654321

1.2

1.1

1.0

0.9

0.8

GB O/E NTaxa NI O/E NTaxa

GB O/E ASPT NI O/E ASPT


In contrast, mean observed ASPT scores follow a clearly decreasing trend across the GB end groups, with the 3 deepest end groups having mean ASPT scores of 5.15 (group 41), 5.47 (group 42) and 4.79 (groups 43). These are among the six lowest mean ASPT scores across all 43 GB end groups. In NI the same effect is observed, with the deepest end group, end group 11, having the single lowest mean observed ASPT (5.17) across the 11 NI end groups.

Looking at observed/expected scores (Figure 14), if the RIVPACS IV GB and NI models are working correctly, it would be appropriate to expect that mean NTAXA O/E scores, and mean ASPT O/E scores, across all of the end groups should approach unity (a value of 1), with no trend towards higher or lower values in deeper or shallow waters. Figure 14 shows that this assumption is broadly true. In GB and NI, mean O/E NTAXA are both close to 1 and no trend across the end groups is discernible. Mean O/E ASPT is also close to unity in GB, with no trend due to water depth apparent.

In Northern Ireland, a slight trend towards lower O/E ASPT in deeper sites does appear to exist. This may however be due to the methods used to sample deep waters. In NI, of the 330 reference samples, all but three were sampled using the Kick/Sweep method. The Kick/Sweep methodology will sample wadeable streams efficiently, but deeper rivers less efficiently. Observed scores in the deep end group 11 will therefore tend to be lower than the expected scores because the expected scores are a weighted average across end groups that include contributions from shallower waters that will have been sampled more efficiently. Had the efficiency of deep and shallow water sampling been the same, it is likely that the O/E values would have been close to unity across all end groups with no trend towards lower O/E ASPT scores in deeper sites.

In summary, in both GB and NI, there is a trend for deep river reference sites to have higher observed NTAXA scores and lower observed ASPT scores compared to shallower streams. This trend is completely normal and represents a natural difference in community composition that exists between shallow streams and deeper rivers. As required by any effective RIVPACS model, that trend is removed in the O/E scores produced by the RIVPACS IV models, so that the O/E scores for both NTAXA and ASPT are close to 1 regardless of water depth. The only exception to this, O/E ASPT in Northern Ireland, may be entirely due to the relative inefficiency (under-sampling) of deep river sites compared to wadeable streams, which were almost all sampled with the same Kick/Sweep sampling technique. There does not therefore appear to be any reason to suspect that NTAXA or ASPT may be any less suitable for use in deep rivers than they are in wadeable streams.

Furthermore, there are considerable difficulties that would arise from using different indices for deep rivers than those for wadeable streams. For example, any new deep river reporting indices would need their own biases and EQR correction factors. The uncertainty estimates in RIVPACS may also need to be adjusted for any new deep river indices. Furthermore, additional difficulties would arise due to the fact that separate wadeable stream and deep river indices would also need to be inter-calibrated to provide a continuous scale without discontinuities.

Given the apparent absence of any evidence to suggest that separate deep river reporting indices are needed, and the potential disruption and discontinuities that their introduction would create, the introduction of specific deep river reporting indices is not recommended.


5 Suitability of the RIVPACS environmental predictor variables for deep rivers

The current RIVPACS IV GB and NI models use a range of environmental predictor variables. These variables have proven highly effective as predictors of biological reference communities, both in RIVPACS IV and in earlier versions. However, there is a concern that while the current predictor variables work well across whole-models, they may not be as good at predicting reference communities in deep rivers as they are in wadeable streams.

Any future version of RIVPACS that includes new deep river reference samples would need to produce predictions for deep rivers that are broadly as accurate as those produced for wadeable streams. In this section the suitability of the current RIVPACS environmental predictor variables for deep rivers versus wadeable streams is compared to see if new predictor variables might be needed.

Any such new variables would need to be easily derivable, independent from the existing variables, and would also need to be obtained for the existing samples in the RIVPACS dataset. Given the potential difficulty in finding new variables, it is important to ascertain whether new variables to better predict reference communities in deep rivers are really needed.

Since the current RIVPACS IV model uses all of the current predictor variables, the effectiveness of these variables in deep versus wadeable streams could be investigated by testing model performance, i.e. the accuracy of predictions, for test sites that deep versus test sites that are wadeable.

One of the standard approaches for testing RIVPACS model performance is to put the reference samples back through the model and calculate the percentage of reference samples correctly classified (re-assigned) to the same end group as the original biological classification from which the model was derived (e.g. Moss et al., 1999). For example, a percent correctly classified of say 55% would mean that 55% of the reference samples had been correctly re-assigned to their original biological end group.

The percentage of reference samples correctly classified (re-assigned) has commonly been used to compare the performance of different candidate models. Moss et al., (1999) used the percentage of sites correctly allocated to screen seventeen potential procedures for developing a classification and prediction system based on an earlier 410-site reference site database. Clarke et al., (2011) also used the same technique more recently in developing models that avoid the use of the variables width, depth, substrate and alkalinity. In this work, the percentage of sites correctly allocated to end group is denoted ‘ReSub’, meaning re-substitution to distinguish it from a similar but alternative cross validation or ‘leave-one-out’ approach (denoted ‘XVal’) where the fit of each site is tested in turn against models based on all of the other sites.

Moss et al., (1999) noted that the percentage of sites correctly allocated to their end group is a very severe test of model performance, and that sites allocated to the wrong end groups may have close affinities to the correct group, and the therefore predictions may still be reliable. In addition, RIVPACS models draw their predictions from a weighted average contribution from all end groups, not just the one to which they are most probably related. It should therefore not be of great concern to find that some groups of sites are not correctly allocated to their single original TWINSPAN end group, as this does not undermine the prediction system.


The equivalent analysis of percentage of reference samples correctly classified for the GB and NI RIVPACS IV models is given in Table 4. Table 4 shows that in GB and NI the percentage of sites correctly allocated across all end groups were 51.8 and 66.4% respectively. This acts as a useful benchmark of overall model performance, and when compared to the models developed in Clarke et al., (2011) shows that the RIVPACS IV models have comparable performance.

Table 4. RIVPACS IV TWINSPAN end group size range, mean group size, SD of group size and percentage of RIVPACS IV sites correctly classified to end groups across the GB and NI RIVPACS IV models.

Model Range of end group size

Mean end group size

S.D. end group size

% of sites correctly classified to end group

GB 6-32 15.93 6.31 51.8 NI 7-17 10.00 3.35 66.4

Here however, the issue is model performance in deep rivers versus wadeable streams. The percentage of reference samples correctly classified has therefore been used to compare the effectiveness of different regions within a single model to investigate the effectiveness of the predictor variables in deep versus wadeable streams (Tables 5 and 6).

Table 5. GB RIVPACS IV model end group size, mean and SD depth within TWINSPAN end groups, and percentage of sites correctly classified to each group.

End Group

End group size

Mean depth of sites in end group (cm)

S.D. of depth of sites in end group


1 9 13.09 3.3 100.0 2 11 16.63 4.96 81.8 3 11 22.59 6.51 90.9 4 9 18.88 3.93 55.6 5 10 35.87 16.05 90.0 6 8 35.23 17.11 50.0 7 6 19.9 2.92 50.0 8 17 21.82 11.06 17.6 9 12 53.14 44.32 25.0 10 18 37.24 15.23 44.4 11 21 39.38 21.24 42.9 12 14 33.29 12.96 21.4 13 17 25.44 5.7 58.8 14 21 25.09 6.98 42.9 15 11 26.43 8.66 36.4 16 17 21.95 9.53 52.9 17 15 36.59 17.07 60.0 18 22 51.18 28.89 36.4 19 18 32.21 15.76 50.0 20 10 33.65 17.23 10.0 21 13 20.45 7.73 7.7 22 20 38.94 15.83 30.0 23 10 19.49 8.47 50.0


24 11 23.17 8.81 45.5 25 23 25.81 10.85 73.9 26 27 20.03 8.91 44.4 27 16 16.61 10.85 43.8 28 9 10.66 3.4 44.4 29 9 15.47 7.63 66.7 30 14 7.16 4.39 92.9 31 15 36.24 23.76 46.7 32 32 34.96 32.51 62.5 33 10 54.66 18.81 70.0 34 17 51.79 25.25 76.5 35 21 23.98 12.18 66.7 36 20 57.14 51.86 35.0 37 20 32.64 11.78 45.0 38 23 24.3 15.09 52.2 39 30 22.65 12.72 56.7 40 11 24.15 11.23 45.5 41 32 88.86 60.87 40.6 42 12 154.61 56.79 66.7 43 13 138.9 62.11 100.0

Table 6. NI RIVPACS IV model end group size, mean and SD depth within TWINSPAN end groups, and percentage of sites correctly classified to each group.

End Group

End group size

Mean depth of sites in end group (cm)

S.D. of depth of sites in end group


1 8 24.88 7.06 25.0 2 7 31.43 13.21 42.9 3 12 23.75 5.22 58.3 4 7 23.29 6.13 71.4 5 13 23.77 6.91 84.6 6 13 26.69 19.4 76.9 7 17 29.21 6.92 70.6 8 10 57.2 31.21 70.0 9 9 32.89 11.91 77.8 10 7 58 20.95 71.4 11 7 96.14 60.55 57.1

Tables 5 and 6 show the percentages of sites allocated to each of the 43 GB and 11 NI end groups. It is also useful to see the descriptions of combined ‘super-groups’ at the 7-group hierarchical TWINSPAN classification level in GB (Table 7) when interpreting the GB results.


Table 7. The seven super-group level of classification of the 43 end groups of the GB RIVPACS IV model.

Super-group

N sites

Mean TAXA

Mean

ASPT Dominant characteristics

1-7 64 23.0 6.27 All in Scotland mostly islands 8-16 148 25.2 6.79 Upland streams, mainly in Scotland and N England 17-26 169 31.7 6.42 Intermediate rivers, SE Scotland, Wales, N & SW England 27-30 48 27.1 6.25 Small steeper streams, with 13km of source, discharge1/2 31-36 115 34.8 5.84 Intermediate size lowland streams, including chalk, SE 37-40 84 32.7 5.58 Small lowland streams, including chalk, SE Britain 41-43 57 32.7 5.14 Lowland streams, SE England, larger, fine sediments

The percentage of sites correctly classified is also displayed graphically in Figure 15.

Figure 15. GB and NI percent correctly classified sites by end group. Dotted lines indicate the percent correctly classified across each whole model. Orange bars indicate end groups with mean depth >=80cm.

In GB, end groups 1, 2, 3 and 5 all have very high percentages of sites correctly allocated to end groups. These end groups include Scottish island reference sites that discriminate well from the other GB reference sites. Moving along the GB end groups, the percentages of sites correctly allocated to end groups vary around the mean. The percentage of sites correctly allocated to the deep (mean depth >= 80cm) reference site end groups 41, 42 and 43 (shown in orange in Figure 15), is fairly typical of the average, with end groups 41 and 42 a little below and a little above average respectively, and end groups 43 well above the average. These data suggest that the deep river end groups are distinguished at least as well as, if not better than the other end groups in the GB model. Given that the percentage correctly classified reflects the performance of the whole set of environmental variables in the RIVPACS model, this suggests that the combination of predictor variables already used in RIVPACS IV are at least as good at discriminating the deep rivers as they are at discriminating wadeable streams and rivers from the continuum of river types present in GB.

51.8%

66.4%

NI % Correctly Classified

GB % Correctly Classified


0

20

40

60

80

100

1 2 3 4 5 6 7 8 9 10 11

0

20

40

60

80

100

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43

Figure 16. GB and NI percent correctly classified sites versus end group size. Orange dots indicate end groups with mean depth >=80cm (end groups 41, 42 and 43 in GB, and end group 11 in NI).

In NI the average percentage of correctly classified sites across the whole model is higher (66.4%) than that in GB (Table 4). As with GB, the percentages of sites correctly allocated to end groups vary around the mean. The percentage of sites correctly allocated to the single deep (mean depth >= 80cm) reference site end group 11 (shown in orange in Figure 15), is a little below the average at 57.1%. The percentage of sites correctly allocated to end group 11 is well within the range of percentages of sites correctly allocated for the other end groups in NI, and again suggests no weakness in the predictor variables used in the NI model in terms of their ability to discriminate deep river sites.

However, a further possibility exists. It could be the case that the percentage of sites correctly allocated to end groups may be related to the relative sizes of the end groups. The larger end groups might tend to have a higher percentage of sites correctly allocated compared to a smaller end groups. Given that the GB deep river end group 41 contains 32 sites this might have affected the conclusions reached above. This issue is examined in Figure 16 where the percent correctly classified is plotted against end group size. In both GB and NI there is no relationship is apparent between the percent correctly classified and end group size suggesting that the large size of end group 41 has not led to a falsely high proportion of sites correctly allocated to that group.

The analysis of model performance above suggests that the current predictor variables work as well for deep rivers as they do for wadeable streams. Despite these results, there remains the possibility that a requirement for new predictor variables might only emerge after building and testing new models incorporating replacement deep river reference sites sampled with standardised methods. If this proves to be the case, it would probably be necessary to choose new variables that could be derived from maps or GIS datasets. These could then be gathered after the new reference samples had been collected and would not need to be chosen prior to the collection of the new reference samples. They could also be derived for the rest of the reference sites in the RIVPACS dataset at the same time.

NI GB


0

20

40

60

80

100

0 5 10 15 200

20

40

60

80

100

0 10 20 30

In conclusion, the existing deep river reference sites appear to be discriminated as well as wadeable streams and rivers by the combination of variables used within the current RIVPACS IV GB and NI models. There therefore appears to be no requirement for new predictor variables to distinguish the current deep river reference samples.


6 Updating the sampling manual for deep rivers

The Environment Agency and the Institute of Freshwater Ecology first published a comprehensive manual for the collection of RIVPACS compatible freshwater macroinvertebrate samples in 1997. This document, known as BT001, (Murray-Bligh et al., 1997) was intended to describe the entire process of site selection, sampling (by kick/sweep, dredge and airlift methodologies), transporting and storing samples, sample preservation, quality assurance, and various other issues such as data archiving, equipment specifications and appropriate levels of taxonomic resolution for sample analysis. This methods manual has recently been updated (Environment Agency, 2009). Now known as Operational Instruction 018_08, the methods manual now deals more exclusively with the field based aspects of sampling and data collection, whilst a separate series of supporting operation instructions now cover issues such as fixing and preserving samples, laboratory analysis and quality control.

Given that the aim of this project is to pave the way for standardisation of deep river sampling methods in RIVPACS and the monitoring carried out by the UK agencies, it is now necessary to provide an update to Operational Instruction 018_08 for deep river sampling. This updated material is necessary to enable field staff in SEPA, the EA, and the NIEA to be able to collect reference biological samples and associated environmental data in a manner that will be fully consistent with the collection of new reference samples and variables that is proposed for Phase 2 of this project.

Whilst the update to Operational Instruction 018_08 is primarily concerned with replacing the existing sections on deep river sampling, recommendations are also made for alterations to other sections of the manual where this is necessary to ensure that the whole document remains consistent with the new deep river section. The various updates to Operational Instruction 018_08 are provided in two forms. Firstly, where the updates are only minor, these are given in the form of brief notes in Table 8 below. Secondly, where the updates to Operational Instruction 018_08 are more substantial, these are noted in Table 8, and then a subsequent re-written section of Operational Instruction 018_08 is provided following Table 8.

Some additional alterations that not related to deep river sampling or the correction of inconsistencies that would arise from updating the deep river sampling sections, are also provided in Table 8. These primarily address areas of Operational Instruction 018_08 where some simplification or clarification was considered desirable.

One of the most significant additions to the sampling manual is the inclusion of clear rules for choosing the sampling method (kick/sweep, long-handled pond-net, or airlift) based on the D80:W15 rule discussed in section 2.3. This D80:W15 rule should help to ensure that a standard approach is taken when field staff are choosing the most appropriate sampling methods for streams and rivers in the UK.

Following a meeting between John Murray-Bligh and Tim Jones (EA) and John Davy-Bowker (FBA) at the FBA River Laboratory on 9th September 2013, and a follow on telephone meeting on 13th September 2013, between John Murray-Bligh, John Davy-Bowker and Iwan Jones (QMUL), a decision was made to include a 1 marginal minute sample in the long-handled pond net and airlift sampling procedures. This is instead of the manual search that accompanies kick/sweep sampling. A summary of the complete methods for all three types of sample (kick/sweep, long-handled pond net, and airlift) is given in the flow chart on page 41 and discussed in more detail in the pages that follow.


Table 8. Updates to Operational Instruction 018_08

Pg Section Updates 4 Essential a pond net, long-handled pond net or airlift sampler; 4 Extras for

dredge sampling

Remove this section

12 Discharge category

A suggested simplification of the discharge category:

14 to 15

Choosing the sampling method

Section replaced – see sections following from Table 1.

17 Manual search for one minute

Pond net samples need a manual search, which is in two parts: [rather than all three sampling methods need a search]


...time spent moving around the site. The manual search (both parts) is performed by seeking and collecting individual animals from the watercourse. [clarification on individual animals from BT001, Fig. 2.8]


... if you suspect nothing will be found. The search may be fruitless, either... [clarification of wording from BT001, section 2.7.2]

18 Sampling method

For the details of each sampling method refer to: Three minute pond net sampling method, on page 24; Long-handled pond net sampling method, on page 29; Airlift sampling method, on page 34.

18 Keeping your net clear

Step 1: Do this at least after every minute of sampling with a pond net or long-handled pond net.

19 Keeping your net clear

Step 2: Step 2 should be removed.

20 Removing from the collecting net

Step 2: The easiest way to remove a sample from the pond net or long-handled pond net …

Discharge category

Mean annual discharge (cubic metres per second) Min Max

1 <0.31

2 0.31 0.62

3 0.62 1.25

4 1.25 2.50

5 2.50 5.00

6 5.00 10.00

7 10.00 20.00

8 20.00 40.00

9 40.00 80.00

10 >80.00


Table 8. Continued.

23 Transporting samples

Live sorting is not acceptable for RIVPACS bioassessment. The following recommendations are made: Paragraph 4 – remove. Paragraph 5 – reword as below: Return samples to the laboratory and preserve or fix them, ideally no more than 10 hours after collection.

24 Contents Topics should be updated: Three minute pond net sampling method Long-handled pond net sampling method Airlift sampling method

24 Selecting a net

Use a standard FBA-pattern pond net for kick and sweep sampling.

24 Selecting a net

Last bullet point: A long-handled pond net is used for sampling narrow deep rivers, but

they are not recommended for general kick and sweep sampling. 28 To 39

From and including the section titled ‘In deep waters’, up to the end of the section on airlifting from boats, this entire section is replaced – see sections following from Table 1.

43 Stream width

Step 1, Paragraph 4: For narrow rivers the use of a metre rule, marked pond net handle or river crossing pole is acceptable. For rivers with a width greater than 5 metres a measuring tape or calibrated range finder should be used.

43 Stream width

Step 2: Step 2 should be removed.

44 Stream depth

Step 3: Use a marked pond net handle or a metre rule. When using a rule, ensure that the narrow edge is facing the current to avoid distortion, and that the rule does not dig deeply into the substrate making the river appear to be deeper than it really is.

44 Stream depth

Step 4: If the stream is wadeable, record the depth to the nearest centimetre. If the depth cannot be directly measured, estimate it as follows:

<1 metre to the nearest 10 cm; >1 metre to the nearest 20 cm.

44 Stream depth

New Step between 4 and 5: If airlift sampling, measure the river depth in the sampling area from the boat. Use either a graduated long-handled pond net, or a graduated depth measuring rope fitted with a rounded weight that cannot act as an anchor.

45 Substrate composition

Table 2. The boulders/cobbles category often leads to confusion as the terms ‘boulder’ and ‘cobble’ suggest quite large objects and the size of ‘half a fist’ is difficult to envisage. An alternative might be a tennis ball. This typically has a diameter of 67mm which is very close to the 64mm distinction between the categories.

45 Substrate composition

Step 3: It is difficult to judge the composition of the river bed in deep or turbid water. Use the substratum visible at the water's edge, the feel of the stream bed under foot, the contents of the sampling net, previously recorded data and local knowledge to help. When airlift sampling, the estimate of substrate composition may have to be based on the contents of the net bag and the feel of the airlift as it is bounced over the river bed whilst sampling.


Table 8. Continued.

51 Glossary, long-handled pond net

A hand held sampler comprising a square framed collecting net on the end of a long multi-sectional handle. Often abbreviated as a LHPN.

51 Glossary, pond net

A hand held sampler comprising a square framed collecting net on the end of a handle. Also known as a kick sampling net, hand net or FBA-net.

54 Related documents

Additional documents to be listed in the river sampling section: Yorkshire pattern airlift specification Yorkshire pattern airlift safe system of work

Re-written sections for the current Environment Agency sampling manual, Operational Instruction 018_08, are provided on the pages that follow. These cover areas of the manual where the updates relating to deep river sampling were more substantial than those noted in Table 8 above.


Choosing the sampling method

Preferred method

On the first visit to a site, follow the instructions in Figure 4 to choose the appropriate sampling method. Once a site is established, the usual method should be detailed in the site file.

The preferred method for macro-invertebrate sampling is the three minute pond net sample, described on page 24, plus a one minute manual search for individual animals. This is often referred to as simply a pond net sample or a kick sample, though it will often include sweep sampling.

For deep rivers there are two sampling techniques, either:

Long-handled pond net sampling

or airlift sampling.

The two deep river techniques do not include the one minute manual search. Instead, an additional one minute marginal sample is included. This incorporates elements of the manual search, but is one minute of active sampling rather than one minute of searching for individual animals.

Do not combine any of the three distinct sampling techniques (pond net, long-handled pond net or airlift) within a single sample.

Dredge samples are not compatible with the reference samples in the RIVPACS models in RICT, and for this reason dredge samples should no longer be taken for WFD or GQA classification surveys.

Recording the method

Record the sample method on BIOSYS. See Store data on BIOSYS for more information.

Figure 4 The diagram on the next page illustrates how to select the appropriate sample method.


Figure 4

Pond net Use a combination of kicking and sweeping depending on the substratum, current and habitat conditions.

Sample all habitats in proportion to their cover.

3-minutes of active sampling.

Long-handled pond net Reach out as far as safely possible with the LHPN from the channel or bank to sample the benthos.



Is the width of the watercourse > 15m? (measured across the sampling area)

No

Airlift Sample using a Yorkshire pattern airlift deployed from a boat covering all habitats.



Manual Search Part 1

Is the mean depth of the watercourse > 80cm? (averaged across the 3 depth measurements at ¼, ½, and ¾ channel width in the sampling area)

No Yes

Yes

Manual Search Part 2 1-Minute Marginal Sample 1-Minute Marginal Sample

Science Report – S

tandardisation of RIV

PA

CS

for deep rivers: Phase 1

41

In deep waters

If the watercourse is too deep for a conventional kick sample, you will need to select the appropriate deep river sampling method using the flow diagram in Figure 4.

There are two allowable deep river sampling techniques, long-handled pond net samples and airlift samples. Dredge samples are no longer permitted for samples that may get used for RIVPACS/RICT assessments.

The choice of sampling techniques for deep rivers is determined solely by two measurements, the river depth, and the average river width, both taken from within the sampling area. The table below describes the decision process summarised in Figure 4 in more detail.

Step Action

1 Measure the river depth. If the river depth, averaged across 3 depth measurements taken at ¼, ½ and ¾ river width, is less than or equal to 80cm, a reasonable proportion, generally at least half, of the sampling area is deemed to be wadeable, and a standard pond net sample is appropriate.

2 Secondly, if the average river depth is greater than 80cm, a second measurement is needed, the river width.

3 If the river width is less than or equal to 15 metres, the river is deemed to be deep but narrow and a long-handled pond net sample is appropriate.

4 If the river is greater than 15m wide, the river is deemed to be deep and wide, and an airlift sample must be taken using a boat, as this is the only way to properly represent the benthic fauna of rivers that are both deep and wide, and therefore very difficult to properly sample by any other means.

5 This approach, termed the 80:15 rule should be the sole basis for determining the choice of sampling method for deep rivers. It is the same rule that is used to choose the sampling methods for additions to the deep river dataset underpinning the RIVPACS predictive models in RICT.

6 The width and average depth measurements can be spot measurements taken on the day of sampling, although where possible it is better to use, long-term averages that lead to a fixed approach to the choice of sampling technique used at the same site on repeated visits.

7 You must read the 426_05 Generic Risk Assessment on working in or near water and should generally take two people to these sites. Much of the health and safety advice given in the 116_04 Safe system of work for using dredges is still applicable to long-handled pond net and airlift sampling.


http://intranet.ea.gov/ams_document_library/04/4_07_health_and_safety/hs_risk_assessments/426_05.doc

http://intranet.ea.gov/ams_document_library/icontent/DocDir51/116_04.doc

http://intranet.ea.gov/ams_document_library/icontent/DocDir51/116_04.doc

With long-handled pond net and airlift samples

As part of any long-handled pond net or airlift sample, you must also carry out a one minute marginal sample. This typically involves using a standard length pond net to actively sweep the marginal areas and shallows close to the banks.

The marginal sample comprises 1 minute of active sampling and should seek to represent the fauna of the margins of the watercourse that are poorly represented by long-handled pond net or airlift samples alone. It can incorporate elements of the manual search, for example capture of surface dwelling animals or those attached to solid substrates, but it is one minute of active sampling rather than one minute of searching for individual animals.

Long-handled pond net sampling

What to use Use a long-handled pond net with handles in 3 separate sections and an overall length including the net frame of 4 metres.

The long-handled pond net is essentially the same design of net as the FBA-pattern pond net for kick and sweep sampling, except that it has a much longer handle in 3 separate screw together sections, with an overall length including the net frame of 4 metres.

the frame must have a straight lower edge of 20 - 25 cm and straight, vertical sides of 19 - 22 cm;

regularly check that the bottom edge of the frame is not bent, because this reduces its sampling efficiency; Thin gauge aluminium frames are prone to this type of damage.

use nets 50 cm deep; They are less easily blocked because of their greater mesh surface.

the pond net handle including frame should be 4 metres long and graduated to assist in measuring river depth.

Staffing levels Long-handled pond net sampling must always be carried out by at least two people.

Preparing the long-handled pond net

Attach the three sections of the long-handled pond net together tightly to avoid the handles working loose during sampling.


Figure 7 Photo of a long-handled pond net.

Standard long-handled pond net sampling

A standard long-handled pond net sample comprises two different sampling strategies:

3-minutes of active long-handled pond net sampling of the main channel; 1-minute of active marginal sampling. The 3-minute long-handled pond net sample is typically carried out first, followed by the 1-minute marginal sample. This allows the sampler to first ascertain the best positions from which to perform a long-handled pond net sample. A good position permits a long reach out into the watercourse, access to all habitat types, and ease of recovery of the sample over the river bank.

Sometimes, long-handled pond net sampling can overly disrupt the margins. If this is the case take the 1-minute marginal sample first, and then the 3-minute long-handled pond net sample.

The table below describes the procedure for the 3-minutes of active long-handled pond net sampling of the main channel.

Both the 3-minute long-handled pond net component and the 1-minute marginal component are pooled to form the complete long-handled pond net sample.

Step Action

1 A long-handled pond net sample should be taken by standing on the river bank. This avoids the need to wade into water with a mean depth greater than 80cm deep (see Figure 4).

2 The long-handled pond net should be pushed out into the channel with the net opening facing down, and then drawn back to the operator applying down force to sweep the net though the top of the benthic substrate on the return stroke.

Stream beds in narrow deep rivers tend to be composed of medium sized to fine substrates. These can usually be dislodged relatively easily using a long handled pond net.

Table continued on next page


Step Action

3 At the end of the sampling stroke, the net should then be rotated so that the opening faces upwards and then pushed outwards again towards the mid channel with the net lifted up, so that it is close to the water surface. The net should then be rotated to face downwards and pushed down again for the next sampling stroke.

4 Each sampling stroke across the streambed should sample a new area of previously un-sampled river bed to avoid repeatedly sampling the same area. This is easiest to achieve by moving upstream one or two steps between each sampling stoke.

5 Take care not to lose any of the sample by moving the net through the water column with it facing downwards whilst not actually sampling.

6 The aim is to include as many separate sweeps of the river bed as possible in the 3 minutes. This should simulate the effect of taking a kick sample in shallower water, where a large number of separate ‘kicks’ are performed.

7 The long-handled pond net sweeps should sample all of the habitats discernible in the river channel in proportion to their occurrence.

8 The 3-minutes of active sampling includes both the sampling stokes, and the return stokes where the net is pushed out towards the mid channel again for the next sampling stoke. If you need to reposition yourself on a different area of river bank, or empty the net, the stopwatch should be stopped as you are no longer actively sampling.

9 Empty the net bag once it becomes too heavy to easily move through the water, or at least after every minute of sampling.

10 Try to avoid lifting the fully assembled long-handled pond net from the very far end of the extension handles, especially when laden with a sample. This places considerable stress on the handles. When recovering samples from the river it is better to feed the handles back through the hands until the net is close to your body so that the weight is evenly distributed

Once the 3-minutes of active long-handled pond net sampling of the main channel are finished, the 1-minute of active marginal sampling should be carried out. The one minute marginal sample is essential and should be carried out using a standard pond net. It can also be carried out using the long-handled pond net with the extension poles removed. The marginal sample comprises 1 minute of active sampling and should seek to represent the fauna of the margins of the watercourse that are poorly represented by long-handled pond net sampling. It can incorporate elements of the manual search, for example capture of surface dwelling animals or those attached to solid substrates, but it is one minute of active sampling rather than one minute of searching for individual animals.


The marginal sample should seek to represent the habitats available in proportion to their occurrence. For example, it will often take the form of a sweep of marginal vegetation, but in some cases it might include kicking/sweep sampling of a shallow marginal shelf, working the surfaces of hard artificial banks or sampling tree roots. Where it is practical and safe to do so, the margins of both banks should be included in the marginal sample.

Other relevant procedures for long-handled pond net samples

The following previously described procedures for pond net samples should also be adhered to for long-handled pond net samples and their associated marginal samples: Keeping your net clear, described on page 18 What you must not keep, described on page 19 What to collect and keep, described on page 19 Removing from the collecting net, described on page 20


Airlift sampling

What to use You must use a Yorkshire pattern airlift sampler or similar from a boat if you wish to take samples for use with RIVPACS/RICT.

Other airlift designs with different tube diameters, different equipment weight, or additional quantitative sampling devices should not be used.

Yorkshire pattern airlift sampler

Figure 8 below shows a photo of a Yorkshire pattern airlift sampler.

It includes the following:

a 1.4 metre long, 10 cm diameter plastic pipe, with a right-angle and a 45 degree angle bend, a net collar at the top and a weight at the bottom;

guide ropes, to move the airlift over the river bed and to retrieve it; a collecting net fixed to the collar at the top of the pipe with a Jubilee clip;

the end of the net is closed by tying a knot in it so that it can be emptied without removing it from the pipe.

an air supply cylinder, typically standard 232 bar scuba diving cylinders fitted with a DIN (screw) connection and hose reel. Inlet pressure of 232 bar (3365 psi), regulated at the outlet to 7 bar (0 - 100 psi), with a separate on/off lever.

an air hose, to supply air from the regulator to the base of the airlift pipe; a tool kit with a screwdriver, pliers, wrenches, Allen keys, and spares; three spare collecting nets; a gas cylinder carrier. Further technical details of the Yorkshire pattern airlift sampler can be found in A specification for the Yorkshire pattern airlift sampler.

Usage We recommend using two 15 litre air cylinders, giving you three samples with each cylinder. You can conserve air by regulating both the pressure and volume regulators.

Figure 8 Figure 8 below shows a Yorkshire pattern airlift sampler.


A standard airlift sample

A standard airlift sample includes two different sampling strategies:

3-minutes of active airlift sampling of the main channel; 1 minute of active marginal sampling. The 3-minute airlift sample is typically carried out first, followed by the 1-minute marginal sample.

The airlift sample can be either a single transect across the river (where the river is very wide) or a number of smaller transects, covering the range of habitats at the site in proportion to their occurrence. If the stream bed and its associated habitats cannot be observed from the boat, and the habitats cannot therefore be sampled in proportion to their occurrence, the airlift sample should cover as many separate areas of river as is possible within the sampling area.

Use at least two people for the airlift, one to control the air supply and boat, another to control the sampler itself.

Each airlift sample takes an absolute minimum of three minutes to collect, but often takes longer due to the need to bring the boat around to re-position for another sampling transect. The amount of time spent actively airlift sampling should be 3 minutes. This should be measured using a stopwatch. The time spent both sampling and bouncing the airlift between sampling patches is included within the active sampling period. Time spent re-positioning the boat should not be included in the 3 minutes and the stopwatch should be stopped whilst this is being done.

Both the 3-minute airlift component and the 1-minute marginal component are pooled to form the complete airlift sample.


Choosing a site

The amount of material lifted by the sampler depends on the nature of the substratum.

Airlifts work best on gravel or stony river beds. Airlifts can raise large items such as half bricks. On sandy or silty river beds the airlift may bury itself in the sediment. This can clog the net bag and impede the airflow. You may need to bounce it gently on the river bed to prevent it digging in too deeply.

As with pond net and long-handled pond net sampling, airlift sampling becomes less efficient on large boulders. If the airlift fails to recover any material for a period of sampling, for whatever reason, you should add additional time onto the 3 minutes to ensure that a full three minutes of effective active sampling has been achieved.

The table below describes how to deploy and take the airlift sample.

Step Action Before you start sampling

1 Check the air pressure to ensure the cylinder is full enough to complete the sample. Check that the on/off lever on the air supply panel is 'off’.

2 Turn the air 'on' at the cylinder. Check the high pressure inlet gauge.

If the reading is… then… 200 and 240 bar (2900 – 3480 psi)

the cylinder is full.

less than 35 bar (510 psi) the cylinder is nearing empty, and should not be used.

Using the airlift 3 Either standing in the boat (if the river flow is slow), or kneeling (if the

river flow is fast), lower the airlift into the water. Use the control ropes to maintain the tube between vertical and 40 degrees. Do not allow it to lie horizontally on the bed.

4 Turn the air supply on for two to five seconds. If functioning properly, air bubbles should surface in a cloud of silt. The airlift should now be almost vertical, buoyed up by the air in the collecting net and the upper part of the pipe.

5 Pull in any excess rope. Check by the feel of the rope that the lower end is on the river bed.

Table continued on next page


6 Use one of the following methods to control the air flow: leave the air flowing and move the airlift across the river bed; or sample in a series of short bursts in different locations by

turning the air supply on and off. Whichever method you use, you must aim to sample the habitats present in proportion to their occurrence.

7 It is important to keep the ropes and the airline away from the boat's propeller. In slow to moderate flow conditions, the boat should be moved upstream in reverse. Airlift sampling is carried out with the airlift and ropes over the bow downstream.

8 In faster rivers, if the helmsman tries to reverse upstream, the speed of the water makes it difficult to keep the airlift vertical. In these situations, the boat should be moved upstream of the sampling site with the airlift out of the water. The engine power should then be reduced so that the boat floats downstream through the site with the river flow. During this time, the airlift can be deployed and a series of sampling bounces can be obtained. Several such manoeuvres will normally be required to complete 3-minutes of active sampling. Airlift sampling requires good communication between the sampler and the helmsman who need to closely coordinate their actions.

9 Make sure that the airlift is in contact with the stream bed and not suspended from the boat when sampling. A cloud of disturbed sediment appears in the water when the airlift is working correctly.

10 Recover the airlift bottom end first, by pulling it upwards with the bottom rope. This will wash the material into the collecting net, see Figure 9, below.

From a bridge or the shore

Airlift sampling must be carried out using a boat so that the whole stream bed can be sampled. Sites under bridges are not suitable. Airlifting should not be attempted by throwing the airlift from the bank.

Figure 9 Figure 9 is an illustration showing how to use a Yorkshire pattern airlift.


Boat work Additional procedures must be followed for the use of airlift samplers from small boats.

You must follow the guidance in Yorkshire pattern airlift safe system of work;

You must refer to the 767_06 Safe Management of Boatwork guidance; You must follow the procedures in the generic risk assessments for

32_04 Boatwork; You must follow the procedures in 83_04 Sampling from a boat.

Once the 3-minutes of active airlift sampling of the main channel are finished, the 1-minute of active marginal sampling can be carried out. The one minute marginal sample is essential and should be carried out using a standard pond net. It can also be carried out using a long-handled pond net with the extension poles removed. The marginal sample comprises 1 minute of active sampling and should seek to represent the fauna of the margins of the watercourse that are poorly represented by airlift sampling. It can incorporate elements of the manual search, for example capture of surface dwelling animals or those attached to solid substrates, but it is one minute of active sampling rather than one minute of searching for individual animals. The marginal sample should seek to represent the habitats available in proportion to their occurrence. For example, it will often take the form of a sweep of marginal vegetation, but in some cases it might include kicking/sweep sampling of a shallow marginal shelf, working the surfaces of hard artificial banks or sampling tree roots. Where it is safe to do so, ideally the margins of both banks should be included in the marginal sample. This is often easiest to achieve by sampling from the boat.

Other relevant procedures for airlift samples

The following previously described procedures for pond net samples should also be adhered to for airlift samples and their associated marginal samples:

Keeping your net clear, described on page 18 What you must not keep, described on page 19 What to collect and keep, described on page 19 Removing from the collecting net, described on page 20




7 A specification for the Yorkshire pattern airlift

In order to standardise deep river sampling techniques more closely, there is a need to standardise the design of the airlift sampling apparatus itself. In the previous sections of this report, and in the review given in Jones and Davy-Bowker (2012), the Yorkshire pattern airlift has been selected as the standard design for future airlift sampling. This design, originating from the former Yorkshire Region of the Environment Agency (now Yorkshire and North East Region), has been the basis for several of the recent method comparison studies, and the conclusions from those studies therefore remain most relevant if this design is retained with as few modifications as possible as the basis for standardising the airlift. All technical details have been kindly provided by Barry Byatt, Environment Agency, Yorkshire and North East Region.

A specification for a Yorkshire pattern airlift is given below. While the exact dimensions may vary slightly between manufacturers, this Yorkshire pattern airlift specification should form the basis for future airlift sampling equipment that is used both for collecting new reference samples, and for subsequent Water Framework Directive classification monitoring. Once new RIVPACS models have been constructed using samples collected with a Yorkshire pattern airlift, airlift designs that deviate markedly from the Yorkshire pattern will no longer be compatible with the RIVPACS predictive models used in RICT. These could make RIVPACS observed/expected ratios invalid and potentially cause differences in assessments of environmental quality due to sampling equipment design alone.

The standard Yorkshire pattern airlift design specified below is intended to form a standard in the same way as the FBA pond net is the recognised standard design for use in wadeable streams. The main components of the Yorkshire pattern airlift are given in Table 9. The main dimensions of the airlift pipe are also shown in Figure 17. Table 9. Main components of the Yorkshire pattern airlift.

1 Airlift pipe, 1.28 m long, made from 110 mm external diameter plastic pipe. Attached to this at the top are a 90º right-angled elbow bend, a 45º-angled bend, and a net attachment collar. The 90º right-angled bend and 45º-angled bend are made from off-the-shelf rainwater down pipe fittings that incorporate O-rings to form a seal. Each joint is further strengthened by 4 stainless steel non-slip nuts and bolts through the sidewalls to prevent the joints working loose during use (see Figure 17).

2 1mm mesh collecting net fixed to the collar at the top of the airlift pipe with a stainless steel Jubilee clip. The end of the net is closed by simply tying a knot so that it can be emptied without removing it from the pipe.

3 10 Kg ring-shaped lead weight attached at the bottom of the airlift pipe using 4 stainless steel non-slip nuts and bolts through the sidewalls.

4 Two guide ropes, to move the airlift pipe over the riverbed and retrieve it. 5 At least two compressed air cylinders, typically standard 232 bar scuba diving cylinders

fitted with a DIN (screw) connection and tested to IDEST standards. These give on average three airlift samples per cylinder (but see the note at the end of this section).

6 High-pressure hose to connect a compressed air cylinder DIN (screw) connection to the high-pressure inlet of the airlift control panel/regulator.

7 Airlift control panel/regulator comprising a high-pressure inlet (peak inlet pressure 232 bar = 3365 psi), a low-pressure outlet (regulated to between 0 and 7 bar = 100 psi), and appropriately scaled needle gauges for each. This should be of sturdy metal


construction with a strong lid to prevent damaged when in transit. The high-pressure inlet and low-pressure outlet connections should be protected from mechanical damage by the addition of handle-shaped shields that protrude beyond the connections (Fig 18).

8 Wheel mounted hose reel, with 15 metres of air hose with an on/off gas lever valve for connecting to the low-pressure outlet of the control panel/regulator.

9 Short length of approximately 2 metres of air hose permanently attached to the airlift pipe with a reinforcing sleeve at the top to prevent crimping. The top of the air hose should be connectable to the main hose reel (with low pressure hose connections), the bottom should pass through the side of the airlift pipe using brass or stainless steel fittings to form a air outlet inside the airlift pipe.

10 Tool kit with a screwdriver, pliers, wrenches, Allen keys, and spares. 11 Three spare collecting nets. 12 Wheeled gas cylinder carrier.

Figure 17. The airlift pipe of a standard Yorkshire pattern airlift.

1.4 m

Knot

1mm mesh bag

Jubilee clip

45° angle

90° angle

Stainless steel bolts

Eye ring

Low-pressure hose

Stainless steel handles

10 Kg lead weight

Airlift pipe (110mm)

Reinforcing sleeve


Figure 18. Example of the handle-shaped shields that are suggested as additional fittings to protect the high-pressure inlet and low-pressure outlet connections of the control box.

While several of the components of the Yorkshire pattern airlift can be purchased from a diving supplier, the manufacture of the airlift pipe and airlift control panel/regulator is best done by a specialist contractor. The Environment Agency, Yorkshire and North East Region, have previously used the following contractor to construct airlifts:

Address: Commercial Diving and Marine Services Malt Kiln Lane Appleton Roebuck York YO23 7DT

Telephone: 01904 744424

Contact: Steve Fila

Commercial Diving and Marine Services have retained design drawings and have designed and made tools necessary to build Yorkshire pattern airlifts. All pressurised components should also be independently inspected to ensure that they are fit for purpose.

Further details of the Yorkshire pattern airlift, including photographs of many of the components described in Table 9 can be found in the Safe System of Work (see section 8.2). It should be noted this Safe System of Work is based very closely upon the one in use by the Environment Agency, Yorkshire and North East Region at the time this report was written (see Appendix I) with modifications arising from the ergonomic assessment in the next section.

Note

As a further note (Barry Byatt, EA Yorkshire and North East Region, pers. comm.), the weight of the air cylinders could be reduced if the system was designed to operate at 300 bar as opposed to the existing 232 bar. The 232 bar, 15-litre cylinders that are currently used by EA Yorkshire and North East Region contain about 3000 litres of air, and together with the valve, weigh about 18Kg. Given that a typical airlift sample uses approximately 900 litres of air, these therefore allow about three samples to be taken, with a small reserve.


If 300 bar, 7-litre cylinders were used instead, these would store 2100 litres of air, weigh 8.7 kg with the valve, and give two samples, again with a small reserve.

The reduction in weight of each cylinder from 18Kg to 8.7 Kg is considerable, and while more cylinders would need to be taken, especially on long sampling runs, the reduction in manual handling weight would be considerable.

It is therefore recommended that the airlift and control panel should be designed and rated to operate using 300 bar cylinders.

The Thames Airlift

Following the specification of the Yorkshire pattern airlift above, a description of a new airlift sampler recently developed by Tim Jones of the Environment Agency, Thames Region is given below (also see Figures 19 and 20). This shares many similarities with the Yorkshire pattern airlift and has also addressed many of the safety issues that existed with other (older) airlift designs. A number of important features that make this device particularly safe to use are summarised below.

1) Two separate stages of air flow regulation. One directly on the bottle, reducing pressure from 232 to 10 bar (3365 to 145 psi). This means all air lines are at a safe pressure should one of them become damaged. Earlier designs had a potentially dangerous full pressure air line. The second stage of regulation is variable from 0 to 10 bar (145 psi). This is similar to final pressure of the Yorkshire pattern airlift (regulated to between 0 and 7 bar = 100 psi)

2) All air lines are made to commercial airline standards and can take pressure far and above those generated by the equipment. Consequently the risks from a damaged airline are minimal.

3) The pressure control equipment is contained within a tough, almost indestructible Peli case (www.peliproducts.co.uk) to protect the regulator and make for easy transportation. The panel is clearly labelled to ensure the air ‘in’ and ‘out’ are correctly connected. There is an emergency ‘on-off’ leaver to allow for emergency shut off. This has an associated pressure release valve.

4) Pressure-in and pressure-out gauges are incorporated into the design so that exact air pressure control can be achieved.

5) The airlift itself has a stout handle for easy lifting and carrying as well as removable stainless weights on the lower end to allow adjustment as necessary.

6) This design has been tested by EA Thames Region and ir reported to work very well. It uses very little air and so only requires the small 'pony' 5 litre air cylinders which makes manual handling much safer (see the note at the bottom of page 53 for a similar observation in relation to the Yorkshire airlift).

The company that engineered the Thames airlift have indicated that they could produce a batch of airlift units, or further one off examples for testing as required. Approximate costs are around £2000 per unit (excluding air cylinder). Thames Region have also experimented with 'Mini' version which can be thrown from a bank a good distance and dragged back, although this would probably not be a design that would meet the standardised approach to sampling described in section 6.

In summary, whilst it is appropriate not to deviate too far from the Yorkshire pattern airlift to maintain relevance with previous deep river sampling method comparison studies, the Thames airlift incorporates a number of important safety features that merit inclusion in any new units purchased for the collection of new reference samples or by the Agencies for their monitoring.


http://www.peliproducts.co.uk/

Figure 19. Airlift sampler developed by the Environment Agency, Thames Region.

Figure 20. Airlift control box developed by the Environment Agency, Thames Region.


8 Health and safety aspects of airlift sampling

One of the factors that have hindered the adoption of airlift sampling devices beyond the EA Yorkshire and North East Region has been the concern that there may be significant health and safety issues associated with airlift sampling. These issues are examined in this section.

In order to assess the health and safety aspects of airlift sampling an ergonomic assessment of airlift sampling has been undertaken (section 8.1). This assessment has covered all aspects of the process of boat deployed airlift sampling, including the storage of equipment, routine transport to the field survey site, assembly and deployment, airlift sampling, marginal sweep or search sampling, and the recovery of the sample and the equipment from the river that users will be expected to undertake. The ergonomic assessment has not covered safety aspects involved in specialist maintenance, such as disassembly of pressure cylinders and valves for testing as this is a specialist task beyond that required to be undertaken by field sampling teams.

The ergonomic assessment was then used to update the safe system of work that is currently used by the EA Yorkshire and North East Region to include any new safety issues that had not already been addressed (section 8.2).

8.1 An ergonomic assessment of airlift sampling The ergonomic assessment was carried out by firstly holding a field-based demonstration of airlift sampling. This demonstration that was carried out on the 21st May 2010 with the very kind help of the following people from the Environment Agency, Yorkshire and North East Region:

Barry Byatt Dave Barber Julie Winterbottom Joanne Hood Paul Curry

The assessment of storage and loading was performed at Coverdale House (Environment Agency, Yorkshire and North East Region), while the river-based assessment was carried out on the River Derwent at Barmby Barrage, Yorkshire.

Several other Environment Agency, Scottish Environment Protection Agency, and Northern Ireland Environment Agency members of staff, including health and safety advisers, from the were also invited to attend the demonstration so that their observations and feedback could be incorporated into the assessment. The following people either kindly attended the demonstration or provided subsequent feedback on the ergonomic assessment and the revised safe system of work that has been written as a result (section 8.2):

James Barker Health, Safety and Wellbeing Advisor, South East (EA) George Green Analysis and Reporting Team Leader (EA) Ben McFarland Senior Scientist, SW Region (EA) John Murray-Bligh National Ecology Technical Advisor (EA) Ross Doughty Ecology Unit Manager, SW Region (SEPA)


Bernadette Fitzpatrick Health and Safety Manager, Corporate Office (SEPA) David Colvill Senior Freshwater Ecologist (SEPA)

A short film of the demonstration was also made to assist the subsequent review of ergonomics and also to enable other people who are not familiar with airlift sampling to see the technique. The film has been edited into four short video clips as shown below, all of which are available to view from the FBA web site:

Part 1 – Loading the equipment prior to sampling (07 min, 53 sec)

http://www.fba.org.uk/sites/default/files/airlift-ergonomics-part1.wmv

Part 2 – Loading and launching the boat (13 min, 34 sec) http://www.fba.org.uk/sites/default/files/airlift-ergonomics-part2.wmv

Part 3 – Airlift sampling (11 min, 11 sec) http://www.fba.org.uk/sites/default/files/airlift-ergonomics-part3.wmv

Part 4 – Unloading and recovering the boat (08 min, 33 sec) http://www.fba.org.uk/sites/default/files/airlift-ergonomics-part4.wmv

The second stage of the ergonomic assessment was carried out by reviewing each of the movie clips described above. The ergonomic and health and safety aspects of each separate activity were considered and all of the observations made are detailed in Table 10 below. Table 10 is split into four parts (one for each video clip). Time markers are also provided for quick reference to the relevant part of each video. Where there were multiple occurrences of the same ergonomic or health and safety issue, only the time of the first occurrence is noted.

Table 10. Ergonomic assessment of video clips 1-4. Observations relate to ergonomic or health and safety issues only. Time markers indicate the position in each video where the first example of each issue arose.

Part 1 – Loading the equipment prior to sampling

Item Time Ergonomic or health and safety issues 1 00:19 Boat fuel containers – use approved lockable fuel can storage

container. Take care not to trap hands or fingers when accessing fuel can storage container.

2 00:27 Boat fuel containers – lift carefully avoiding straining back 3 00:27 Boat fuel containers – avoid any naked flames when handling boat fuel,

including transport for refilling. Avoid use of metal cans that can spark against a concrete floor – plastic cans are safer. Take special care not to be too rough or to drop fuel containers as this could result in a potentially fatal explosion.

4 01.03 Boats – need to adhere to operational instructions relating to boats. These may include items such as boat stability tests to determine maximum working load for any given boat with a given engine size. Boats should be inspected annually.

5 00.55 Make sure the boat is securely strapped or fixed to the trailer.






Table 10. Continued.

6 00.55 Make sure any equipment that is going to be transported in the boat whilst on the road, e.g. fuel tanks or oars, are securely attached to the boat so that they cannot fall out of the boat whilst in transit to the sampling site.

7 01:02 Boat – a rigid hull is best as it gives a solid, non-deformable base on which to stand. Inflatable boats are acceptable but these should be fitted with walking boards otherwise it is difficult to deploy and sample with an airlift.

8 02.00 Boats – also need to carry an anchor, bailer in case the boat were to develop a leak whilst on the water, a fire extinguisher, a first aid kit, and an alternative method of propulsion (e.g. oars or a smaller back up out board motor depending on the size and speed of the rivers from which samples are being taken).

9 02:25 Store items that might be rendered unsafe if they were damaged, e.g. the compressed air control box, in a location where they are unlikely to be accidentally damaged in storage.

10 02:35 Airlift storage – good practice to store the heavier items in an upright position, strapped flat against a wall in the store, e.g. the airlift tube itself and the compressed air cylinders.

11 02:48 Larger/heavier items should, where possible, be moved on wheeled trolleys with long pulling handles to prevent excessive manual lifting. For example, the coil of compressed air hose and the compressed air cylinders. Particular care should be taken when moving compressed air cylinders as damage to the regulator could result in an uncontrolled release of air, which if the cylinder is full, could result in injury.

12 02:48 Operators should use safety gloves and steel toecap boots/shoes for moving the heavier items of equipment to reduce the risks of injury.

13 03:38 When doing manual lifting, use a good manual lifting technique to avoid back injuries. Where possible, break down the heavier components into smaller individual loads. For heavier items such as compressed air cylinders and out-board engines two people should lift these objects together.

14 04:12 Load larger, heavier items first. Compressed air cylinders should be securely strapped into the vehicle for transit. Smaller, lighter items should be loaded last. Ensure that any vehicle being used to transport airlift sampling equipment has a suitable bulkhead to prevent the load from moving forwards in the event of a road accident.

15 06:21 When hitching the boat to the vehicle, use two or more people to move the trailer to spread the load. Avoid trapping hands/fingers when bringing the trailer hitch towards the tow bar. Do not attempt to manually lift the boat up from the trailer hitch, use the adjustable dolly wheel to raise the trailer hitch to the appropriate height. If the trailer has a brake, use the brake to prevent it rolling away whenever possible. Make sure the trailer it fully clicked down over the tow bar. Make sure the dolly wheel is fully raised and securely clamped. Make sure the safety cable is properly attached. Make sure the lighting cable is connected and that the lights are all functioning correctly on each occasion that the trailer is hitched to the vehicle.

16 07:45 When connecting and removing regulators and pressure testing gauges from compressed air cylinders, make sure that regulators and gauges are screwed down tightly so that they do not work loose when in transit or being used for sampling.



Part 2 – Loading and launching the boat

Item Time Ergonomic or health and safety issues 1 00:00 All staff involved in the deployment of the boat, loading of the boat, and

the sampling itself should wear safety foot wear, protective gloves and life jackets that are regularly checked.

2 00:45 When reversing the boat towards the water, another person should give clear instructions to ensure that the trailer is not accidentally reversed too far. Where a slipway is used, another person should give clear instructions to ensure that the trailer is not reversed off the side of the slipway.

3 00:55 All ropes should be properly coiled to reduce the risk of anyone becoming entangled as the boat is being launched.

4 01:28 When launching the boat off the trailer, the boat may accelerate suddenly and may collide with persons standing nearby. Care should be taken to avoid hands or loose clothing becoming trapped and dragging anyone into the water. The painter line should be slack enough to reduce the risk of someone being dragged into the water.

5 03:29 Make sure that the painter line to the boat is securely attached to a solid object before stepping into the boat.

6 03:40 When doing manual lifting, use a good manual lifting technique to avoid back injuries. Where possible, break down the heavier components into smaller individual loads. For heavier items such as compressed air cylinders and out-board engines two people should lift these objects together.

7 04:05 When moving heavy objects into the boat, use two people where necessary and move the object in small steps to avoid overstraining.

8 04:36 Make sure the dead-man cut out is fitted to the engine to ensure that the engine cuts out should the helmsman fall overboard.

9 04:40 Ensure that the pressure release valve on the fuel tank is raised to prevent negative fuel tank pressure causing engine failure due to fuel starvation.

10 05:25 Load large or heavy items into the boat first, ensuring that they cannot roll around. Fit smaller items into the remaining space ensuring that there is adequate room for the crew.

11 06:28 Ensure that the secondary means of propulsion (e.g. oars or back up engine) is not forgotten.

12 07:26 Connect and pressurise the 6 components of the airlift in the correct sequence (as described in section 8.2).

Part 3 – Airlift sampling

Item Time Ergonomic or health and safety issues 1 00:12 Ensure that all loose equipment that might get caught up in the airlift

equipment is stowed away. 2 00:30 Ensure that the airlift air hose and airlift ropes are not tangled prior to

sampling and that no loose coils become entangled around the crew. 3 01:00 Make sure that the distribution of weigh in the boat is not adversely

affected when airlift sampling from the side of the boat and avoid leaning too far out when holding operating the ropes.



4 01:00 Staff taking an airlift sample should employ a good lifting technique to reduce the risk of back injury whilst deploying the airlift over the side of the boat and whilst sampling.

5 01:00 The crew should have a procedure in place to release the airlift should it become snagged and held fast on an underwater obstacle. This should involve depressurisation of first the high and then the low-pressure sides of the control panel, disconnection or cutting of the low-pressure hose and release of the control ropes to release the airlift from the boat. A knife capable of cutting air hose and rope should therefore be carried as part of the airlift equipment.

6 04:30 To ensure safety, the skipper (helmsman) should remain in charge of the overall sampling operation. If for example, if the skipper needs to urgently move the boat, perhaps to avoid the river bank or a collision with another boat, the other crew members must, on the skipper’s command, suspend the sampling until the skipper is happy for it to re-start.

7 07:05 When using the pond net for the marginal sweep or search (or adding an extension pole to elongate the net), care should be taken not to hit another crewmember with either the net or the pole.

8 07:26 When taking a marginal sample with a pond net, care should be take not to over balance and fall into the water.

9 07:30 When taking a marginal sample with a pond net, care should be take not become overstretched or strained in an attempt to obtain the sample.

10 08:12 An extension pole should be used where necessary to reduce the risk of the engine propeller becoming entangled in the streambed.

Part 4 – Unloading and recovering the boat

Item Time Ergonomic or health and safety issues 1 00:10 When stepping out of the boat, take care to avoid falling due to the

boat pushing away from the riverbank. 2 00:25 Secure the boat firmly before unloading large or heavy items. 3 00:33 Depressurise the airlift components before dismantling. 4 01:08 Untangle and properly coil and bag the ropes and air hose in the boat

to reduce the risk of tripping. 5 02:55 Use two or more people to recover large or heavy items from the boat. 6 03:30 Disconnect the fuel supply from the engine and run the engine until it

cuts out so that no fuel is left which might later escape into the vehicle. 7 04:45 Where possible, use a vehicle-mounted winch to haul the boat from the

water to reduce manual handling. The winch operator should not stand over or in-line with the winch in case the wire or strap breaks, potentially causing injury. Where a slipway has been used to recover the boat, another person should give clear instructions to ensure that the trailer is not reversed off the side of the slipway. Care should be taken using hand operated winces to avoid trapping fingers.

8 06:26 When reversing the boat trailer another person should give clear instructions to the driver.

9 06:54 Care should be taken using hand operated winces to avoid trapping fingers



10 07:30 Heavy items such as outboard engines should be lifted and carried using good manual handling techniques, and where possible, by two people.

11 07:55 Guiding a boat onto a trailer on land should be done by teamwork using good manual handling techniques. Good communication is essential to avoid the boat slipping off the side.

The ergonomic assessment given in Table 10 above covers all of the observed ergonomic or health and safety issues that were apparent from the demonstration of airlift sampling, including the entire process of storage and loading of equipment, loading and launching the boat, airlift sampling itself and unloading and recovering the boat.

This ergonomic assessment was then used to review the existing airlift safe system of work that is currently in place in the Environment Agency, Yorkshire and North East Region (Appendix I) and to write a revised safe system of work that recommends actions to address any previously unidentified issues. This revised airlift safe system of work, integrating all aspects of the ergonomic assessment, health and safety issues and airlift specification alterations is presented below.

While the ergonomic assessment has covered the entire process recorded on the videos, many of the tasks associated with boat work are more generic and the health and safety aspects of these should already be covered in existing boat handling safe systems of work. The existing safe system of work has not therefore been extended to cover these aspects, but has instead focussed on issues that are unique to airlift sampling.

In general, whilst the ergonomic assessment listed a large number of issues, all of these appear to all lend themselves well to risk reduction through a good safe system of work.

Of particular note was the process of airlifting sampling itself. In the video the operators were handling the airlift on ropes from the side of the boat. Given the relatively light weight of the Yorkshire pattern airlift compared to some other designs, the buoyancy in use, the sharing of effort between two operators, and the good posture adopted by the staff involved, this task which is unique to airlift sampling, appeared to well within an acceptable level of ergonomic risk. The risks associated with this activity appear to be no greater than those associated with normal manual handling tasks.

8.2 A revised safe system of work of airlift sampling The ergonomic assessment above was used to update the safe system of work that is currently used by the EA Yorkshire and North East Region. The revised safe system of work is given on the following pages.


Safe system of work for Airlift sampling This safe system of work (SSOW) relates to airlift sampling undertaken using the ‘Yorkshire’ design of airlift as illustrated in Fig 1. Fig 1. Yorkshire pattern airlift equipment. 1. PERSONNEL The following personnel issues must be satisfied before undertaking airlifting: Airlift sampling must be carried out by at least two people. If deployed from a boat it would be normal to use a third person but depending on the layout of the boat and the experience of the staff this may also be double manned. One person must be designated as person in charge of airlift operation and it must be clear to all staff who this is. All persons involved in airlift sampling must be familiar with the safety issues associated with working with compressed gases. The task should be divided between staff as follows: - At each site one person acts as the Sampler and one as an ‘Air supply regulator’. The role of the Air supply regulator is to monitor the sampler, control the flow of air, continually assess hazards in relation to the activity, consider the safety of members of the public and be prepared to act if something goes wrong. They must have on them all necessary ancillary safety equipment, such as a mobile phone, throwing line etc. Whilst the designated person in charge remains the same it is recommended that staff swap roles during the course of

(Revised following the ergonomic assessment)


the day to reduce fatigue, ensuring that they exchange all the relevant safety equipment. All staff involved in airlift sampling must have attended the following training courses:

• Water Safety,

• Emergency First Aid and

• Manual Handling.

In addition they must receive practical instruction in the different stages of the SSOW from a competent sampler / Team Leader.

The following PPE must be worn:

• Gloves,

• Lifejacket

• Safety boots

Airlifting is only to be conducted by individuals who are physically capable and happy and competent to use the equipment. 2. RISK ASSESSMENT The following guidance is also available for the legal aspects of working with compressed gases:

• Safe use of compressed gases • Carriage of dangerous goods • Written scheme of examination

This work is subject to the following risk assessments:

• Boat work • Generic airlift risk assesment • Manual handling

In all cases undertake a Dynamic (site specific) Risk Assessment, which takes account of the prevailing conditions before taking the sample. Above all, if in any doubt do not take the sample and consult your Team Leader. 3. EQUIPMENT The Yorkshire pattern airlift is based around a purpose designed 300 bar control panel/ regulator that is designed to take high pressure air and supply suitable volumes of low pressure air (Fig 2). The regulator is designed to be connected to a breathing air cylinder using a DIN (screw) connection. The air pressure is then reduced via the internal pressure reduction valve from the cylinder pressure to a design pressure of 12


bar. If a working pressure of 12 bar is exceeded the integral pressure relief valve will operate within the panel. There are six components to the system;

1. Cylinder. This is a standard 300 bar scuba diving cylinder fitted with a DIN (screw) connection tested to IDEST standards for filling with breathing air.

2. High-pressure connecting hose with purge system. The connector has an ‘o’ ring on the end and a small screw on the purge system. Care should be taken not to lose this.

3. Regulator / Control Panel 4. Low-pressure connecting hose with flow valve connector. 5. Hose reel 6. Airlift pipe

This equipment, excluding the cylinders, should only be used for airlift sampling. Air cylinders must only be filled with breathing air and and must filled at a recognised breathing air filling station. Cylinders must only be filled by a trained authorised filling technician. Fig 2. Yorkshire pattern airlift components 4. STORAGE The equipment should be stored in a clean dry place away from oil, grease and fuel. The area should be well ventilated and should not be prone to excessive heat. The store should be marked to show that compressed gases are stored there.


Heavier items such as the airlift pipe and the compressed air cylinders should be stored upright, strapped to a wall. The regulator / control panel should be stored in a position where it cannot be knocked or otherwise damaged whilst in storage. Particular attention should be paid to protecting the high-pressure inlet and low-pressure outlet connections from damage. Before leaving base the designated person in charge must ensure all of the equipment is within its current test date and is fit for use (see for example Fig 3). All connections should be keep free of debris and the high pressure connections should be kept free of oil, grease and fuel to reduce the risk of explosion. ‘o’ rings should be checked to ensure they are in good condition. The regulator should also be within its test date. When connecting and removing regulators and pressure testing gauges from compressed air cylinders, make sure that regulators and gauges are screwed down tightly so that they do not work loose when in transit or being used for sampling. Fig 3. Cylinder neck showing the last test stamp and the next inspection due sticker. 5. LOADING Large/heavy items should, where possible, be moved on wheeled trolleys with long pulling handles to reduce manual handling, e.g. the coil of compressed air hose and the compressed air cylinders. Particular care should be taken when moving compressed air cylinders. Cylinders should be handled using the attached handles and not the valves as damage to the regulator could result in an uncontrolled release of air which could result in injury. Whilst loading and unloading the equipment, care should be taken to ensure good manual handling practices are followed following the relevent risk assessment. Where possible, break down the heavier components into smaller individual loads. For heavier items such as compressed air cylinders and out-board engines two people should lift these objects together. Load larger, heavier items first. Compressed air cylinders should be securely strapped into the vehicle in an upright position, away from the rear doors. This will give the


cylinders better protection in the event of a rear shunt accident. Smaller, lighter items should be loaded last. 5. TRANSPORT TO SITE The equipment must be transported to site in a suitable vehicle with a bulkhead to prevent the load from moving forwards in the event of a road accident. Inert compressed gas labels (green diamond type, Fig. 4) must be attached and visble at the rear of the vehicle to clearly indicate that the vehicle is carrying compressed gas. Fig 4. Inert compressed gas label 6. LOADING THE BOAT All staff involved in the deployment of the boat, loading of the boat, and the sampling itself should wear life jackets that are regularly checked. When reversing the boat towards the water, another person should give clear instructions to ensure that the trailer is not accidentally reversed too far. Where a slipway is used, clear instuctions should be given to ensure that the trailer is not reversed off the side of the slipway. When launching the boat off the trailer, the boat may accelerate suddenly and may collide with persons standing nearby. Care should be taken to avoid hands or loose clothing becoming trapped and dragging anyone into the water. The painter line should be slack enough to reduce the risk of someone being dragged into the water. All other ropes should be properly coiled to reduce the risk of anyone becoming entangled as the boat is being launched. Make sure that the painter line to the boat is securely attached to a solid object before stepping into the boat. When lifting items into the boat, proper manual lifting techniques should be used, and where possible break down the heavier components into smaller individual loads. For heavier items such as compressed air cylinders and out-board engines two people should lift these objects together. Load large or heavy items into the boat first, ensuring that they cannot roll around. Fit smaller items into the remaining space ensuring that there is adequate room for the crew. Make sure the dead-man cut out is fitted to the engine to ensure that the engine cuts out should the helmsman fall overboard. Ensure that the pressure release valve on the fuel tank is raised to prevent negative fuel tank pressure causing engine failure due to fuel starvation. Ensure that the secondary means of propulsion (e.g. oars or back up engine) is also loaded.


7. CONNECTION AND PRESSURISATION OF THE SYSTEM FOR USE Once the equipment is in place the components can be connected in the following order. All componets should be deemed to be in good conditon before any connections are made. If there is any sign of defect the system should not be pressurised.

1. Snift (open the cylinder a small amount to release a short blast of air) the cylinder valve open quickly to clear any dust or debris from the cylinder valve (failure to do so can result in the damage of internal valve seats).

2. Connect the high pressure hose to the cylinder using the DIN (screw) connector. Fig 5, 6, 7 and 8.

3. Remove high pressure cap from the control panel/regulator (Fig 5) and connect the high presssure hose to the panel/regulator. Never exceed 300 bar inlet pressure.

4. Open the control panel/regulator lid using the key provided and lock it into position (as directed in control panel/regulator operator manual).

5. Ensure the control panel/regulator control valve (Fig 5) is turned fully anti clockwise.

6. Remove the low pressure cap from the control panel/regulator (Fig 5) and connect the low pressure hose (blue) via the valve (Fig 9).

7. Unwind the appropriate amount of hose from the hose reel (Fig 2). 8. Attach the bayonet connection from the control panel/regulator to the reel (Fig

10). 9. Attach the loose end of the cable reel to the bayonet connection on the airlift

pipe. 10. Attach the control ropes to the top and bottom of the airlift pipe using the eye

bolts. 11. If working from a boat make sure the system is stable and that the boat is on an

even keel. Where possible prevent the system components from moving around.

12. Turn on the air supply at the cylinder, ensuring the the air supply lever on the low pressure outlet (Fig 9) is turned to the closed position.

Fig 5. Airlft control panel / regulator


Fig 6. High pressure hose DIN connector Fig 7. DIN fitting on cylinder pillar valve Fig 8. High pressure hose connected to cylinder Fig 9. Low pressure hose and valve Fig 10. Low pressure hose bayonet connection Once the system is pressurised, if there is a hissing sound then there is a bad connection. In this event, turn off the air at the cylinder, open the low pressure valve to release any pressure, and explore the reason for the poor connection. Tighten the connection and re test the system. The control panel/regulator is fitted with a positive pressure bleed system and there will be a very slight hissing sound from the back of the regulator valve, this is normal. Once there is a good connection check the volume of air in the cylinder on the high pressure gauge (full will read approximatly 275-300 bar). If pressure is below 50 bar be aware that you may need to change the cylinder to complete the survey. (see section 10 - disconnecting the airlift).

13. Turn the control panel/regulator valve until the low pressure gauge reads 6 bar. Adjustment can be made, to ensure a suitable flow of gas whilst the sample is being collected. Turn the valve clockise to increase the flow.


14. Coil and position the ropes, air supply hose and any other equipment carefully to ensure they do not become entangled around your feet – check they will not snag anything else either.

15. Ensure that the weight distribution within the boat is safe with respect to the positioning of equipment. The equipment should also be set up in such a way as to take up the minimum space whilst achieving maximum stability for the boat.

16. Tie a knot into narrow end of sample net. 17. Using good manual handling technique, and taking care not to lean too far over

the side of the boat, lower the airlift tube into water using ropes (NOT the air supply hose) to position tube onto the river bed. The sampling can be performed by one person, but is better done with two.

18. When airlift tube is in position on the river bed, lift the safety catch and turn on the air supply lever to allow air to flow down to the airlift . A stream of bubbles and a cloud of silt emerging from the airlift net bag will indicate that the system is working correctly.

To obtain the sample move the airlift tube across the river bed by pulling on the ropes. Once the sample has been collected recover the airlift (see section 9). Never fully empty a cylinder. It is best practice is to ensure there is at least 20 bar left in the cylinder to prevent water entering the system which will speed up corrosion. 8. DEPLOYING FROM THE BOAT Remember that when deploying from the boat, the skipper (generally the helmsman) should remain in charge of the overall sampling operation. The skipper has the responsibility of operating the boat safely and any instructions given by the skipper should be followed immediately. For example, if the skipper instructs the crew that sampling should stop and the airlift should be retrieved, this should be done immediately as the skipper may need to make an emergency manouver that has not been anticipated by the other crew members. Once the sample is collected the operators should inform the skipper who will give the all clear to lift the equipment back into the boat. Once all of the equipment is back on the boat the operators should inform the skipper that all equipment is out of the water. Use one of the following methods to control the air flow:

• leave the air flowing and move the airlift across the river bed; • or sample in a series of short bursts in different locations by turning the air

supply on and off. Whichever method you use, the air flow can only be turned on once the skipper is happy. In slow to moderate flow conditions, the boat should be moved upstream in reverse. The boat should be nosed in towards one bank and the engine reversed so that the engine is moving upstream. Once the skipper is happy the airlift can be lowered over the side of the boat. The air supply can then be turned on. Airlift sampling is carried out with the airlift and ropes over the bow downstream. The boat should be reversed across the river with the airlift trailed downstream moving with the boat. The engine should always be kept upstream of the airlift whilst in the


water and good systems of communication should be kept between the skipper and the person controlling the airlift. Only the amount of rope and air hose needed for the depth of water should be payed out as it is vital to keep the ropes and the airline away from the boat's propeller. If the for any reason the boat drifts towards the air pipe or the ropes the following decisions need to be made to prevent the ropes fouling the propeller and rendering the vessel immobile: a) Move the boat into neutral and let the boat swing round on the airlift and then

decide how to proceed. b) Tighten the ropes and recover the airlift, hose and ropes into the boat. See

section 9 recovering airlift. The decision will be made by the skipper who will give clear signals as to the course of action to be taken. If there is a concern that equipment has fouled the propellor, the sampling should be stopped until all the equipment has been checked for damage. The operators will be in a standing position and care should be given by the skipper not to move the boat suddenly. Airlift operators should ensure they maintain their balance. In faster rivers, if the helmsman tries to reverse upstream, the speed of the water makes it difficult to keep the airlift vertical. In these situations, the boat should be moved upstream of the sampling site with the airlift out of the water. The engine should then be run on idle so that the boat floats downstream through the site with the river. During this time, the airlift can be deployed and a series of sampling bounces can be obtained. Several such manoeuvres will normally be required to complete a full sample. If the airlift becomes snagged operators should loosen their grip to prevent themselves being pulled out of the boat or over balancing when the pipe comes free. The crew should have a procedure in place to release the airlift should it become permanently snagged and held fast on an underwater obstacle. This should involve depressurisation of first the high and then the low-pressure sides of the control panel, disconnection or cutting of the low-pressure hose and release of the control ropes to release the airlift from the boat. A knife capable of cutting air hose and rope should therefore also be carried as part of the airlift kit. Airlift sampling requires good communication between the sampler and the helmsman who need to closely coordinate their actions. When using the pond net for the marginal sweep or search component of the sample (or adding an extension pole to elongate the net), care should be taken not to hit another crewmember with either the net or the pole. Care should be take not to over balance and fall into the water, or to overstretch in an attempt to obtain the sample. An extension pole should be used where necessary to reduce the risk of the engine propeller becoming entangled in the streambed. 9. RETRIEVING THE AIRLIFT 1. Slowly pull in the Airlift using the rope and apply a hand over hand action.

Minimise leaning forward or sideways whilst pulling. 2. When retrieving the Airlift and its contents raise the lower (weighted) end of the

tube first to allow water and any remaining sample to wash down into the net.


3. Throughout the course of this operation safe lifting / manual handling techniques must be used.

4. Turn off the air supply at the low-pressure valve. 5. Wash the sample to the knotted end of the net by dipping the net into the water

then rock the net end of the tube in the water to wash silt out of the net and allow the sample to fully enter the sample net.

10. DISCONNECTING THE AIRLIFT 1. Turn off the air supply at the cylinder. NEVER try to remove the connection

whilst the cylinder is turned on or whilst there is any pressure registering on the gauges.

2. Open the red low pressure air supply lever to empty the system of any remaining pressure. Ensure that both pressure gauges read zero. Alternatively the pressure can be released by unscrewing the purge valve next to the cylinder connection.

3. It is now safe to uncouple the air supply hoses. 4. It is now safe to remove the connection from the cylinder Pillar Valve. Caution

should be taken because this connection may be very cold and there may be ice formed due to the expansion of the gas leaving the cylinder. (Charles’s Law)

5. Ensure all connections are kept clean and dry. Replace all connection covers. 11. RECOVERING THE AIRLIFT EQUIPMENT FROM THE BOAT Depressurise the airlift components before dismantling (see section 10). When stepping out of the boat, take care to avoid falling due to the boat pushing away from the riverbank. Secure the boat firmly before unloading it. Untangle and properly coil and bag the ropes and air hose in the boat to reduce the risk of tripping. Use two or more people to recover larger or heavier items from the boat. Disconnect the fuel supply from the engine and run the engine until it cuts out so that no fuel is left which might later escape into the vehicle. Where possible, use a vehicle-mounted winch to haul the boat from the water to reduce manual handling. The winch operator should not stand over or in-line with the winch in case the wire breaks potentially causing injury. Care should be taken using hand operated winces to avoid trapping fingers. When reversing the boat trailer another person should give clear instructions to the driver. Where a slipway has been used to recover the boat, another person should give clear instructions to ensure that the trailer is not reversed off the side of the slipway 11. PROBLEMS The regulator is fitted with a safety valve and the low pressure outlet is set at a maximum of 12 bar pressure. If the valve is opened too much excess air will be vented from the back of the regulator. If this occurs decrease the regulator setting.


In the event of a gas leak turn off the air cylinder valve, if it is safe to do so. Then open the purge valve to depressurise the system. If it is not safe to turn off the system retreat and wait for the cylinder to empty. The system should then be taken out of service and returned to the supplier for inspection and repair. The equipment should be monitored at all times and if any operator has any concerns about the system it should be depressurised and taken out of service until it has been inspected by the supplier. 12. MAINTENANCE Under the Pressure Systems Safety Regulations a Written Scheme of Examination is required for the control panel / regulator used for airlifting. 12.1 MAINTENANCE AND EXAMINATION: ROUTINE CHECKS (EACH TIME THE EQUIPMENT IS USED) • External, visual safety check to determine:

- Suitability for service (e.g. gas inlet pressure rating, damage) - Condition of threads and sealing surfaces, absence of oil or grease contamination

• condition of hoses • seal on connectors 12.2 MAINTENANCE AND EXAMINATION: ANNUAL CHECKS The control panel/regulator should be inspected and serviced annually by the supplier, which in the case of the equipment depicted here was:

Commercial Diving and Marine Services, Malt Kiln Lane, Appleton Roebuck, York, North Yorkshire, England, YO23 7DT. Contact: Steve Fila Telephone: 01904 744424

• the control panel/regulator should be marked after its annual inspection to indicate

its suitability for continued use. • regulator O-ring failure results in a sudden release of high pressure air. O-rings

should be replaced routinely as part of the annual inspection and service. • If the regulator requires maintenance it should be labelled and not used until the

maintenance has been carried out. • If the system needs repair or servicing it should be labelled and returned to the

supplier. • Regulators that are uneconomical to repair should be removed from use

immediately and replaced if required. Details of the service history should be retained in your local filing system. Cylinders that are owned should be tested in accordance with the pressure vessel test requirements and all relevant paperwork should be retained in your local filing system. Cylinders that are hired are inspected to The Inspectorate for Diving Equipment Servicing and Testing (IDEST) standards. This currently means that cylinders are inspected every 2.5 years as required by the law. Details of the inspection will be stamped on the cylinder.


Fig 11. Summary airlift safe system of work flow chart


9 Summary work programme for Phase 2

Following this Phase 1 ‘Standardisation of RIVPACS for Deep Rivers’ project, a follow on Phase 2 project will be needed to replace the RIVPACS deep river reference samples that have been inappropriately sampled. This will involve the collection of new reference samples with either long-handled pond net or airlift sampling techniques and the incorporation of the updated dataset into new RIVPACS models. Prior to this, a short practical field trial should be undertaken to measure the effectiveness of airlift pipes at shallows depths (see section 2.5).

A summary of the tasks that the Phase 2 work programme will include is given below:

i) Screening of the existing sites to be re-sampled to ensure that they are still of WFD reference quality.

ii) Identification of any new sites that are needed [subject to the outcome of i) above].

iii) Re-sampling of sites across the UK using the appropriate standardised methodology at each site over three seasons [where necessary]. To ensure consistency in sample collection, this should be undertaken by a team experienced in the use of standardised long-handled pond net and airlift sampling techniques covering the full range of environmental conditions encountered in deep rivers across the UK.

iv) Field exercise to assess replicate sampling uncertainty associated with standardised long-handled pond net and airlift sampling.

v) Field exercise to assess [and if necessary correct for] any discontinuities arising from the choice of sampling method.

vi) Sorting and identification of samples to RIVPACS species level (RIVPACS taxonomic level 4; see Davy-Bowker et al., 2010).

vii) Data entry and validation.

viii) Modification of the RIVPACS database to incorporate data from sites re-sampled and any new sites [subject to the outcome of i) above].

ix) Construction of new RIVPACS models where deep rivers have been sampled with an appropriate standard method. This includes testing of candidate models, re-calculation of biotic indices, creation of taxonomic output files, and incorporation of estimates of uncertainty.

x) Reporting

A fully costed work programme for Phase 2 has also been circulated to the Phase 1 project board. For reasons of commercial confidentiality, the fully costed programme is not included in this report.

Incorporation of the new RIVPACS models into the RICT software and training of staff in standardised deep river sampling would be part of a final Phase 3 project.


10 Conclusions

This project has addressed a number of important issued that are prerequisites to the future standardisation of RIVPACS for deep rivers. Firstly, a comprehensive review of deep river sampling techniques has been carried out both in the UK and internationally (Jones and Davy-Bowker 2012). This review has identified clear and straightforward approach for determining the appropriate choice of sampling method using a simple algorithm based on stream width and depth. The review has also recommended that deep river sampling methods should be standardised with the long-handled pond net sampling for deep rivers that are narrow, and airlift sampling from a boat as the standard method for deep rivers that are also wide. In this report the operation thresholds for the definitions of depth and width are clarified. These should be adopted to guide the appropriate choice of standardised sampling method for all future RIVPACS and WFD classification samples across the UK.

This report has also identified the existing RIVPACS reference sites that need to be replaced to make the RIVPACS dataset compliant with the algorithm for governing the choice of sampling method.

While a gap has been identified between the maximum wadeable depth at which kick/sweep samples can be safety recovered, and the shallowest depth at which current Yorkshire pattern airlift samples can be obtained, a short practical field trial of shortened Yorkshire pattern airlifts is proposed to quickly address this problem without delaying the RIVPACS deep rivers Phase 2 project

Based on the analysis in this project the introduction of specific deep river reporting indices does not seem necessary and is not recommended.

New material has been provided to make amendments to the Environment Agency sampling manual (Operational Instruction 018_08) to update the material on deep river sampling methods. This can also be used to update comparable sampling manuals used by the Scottish Environment protection Agency and the Northern Ireland Environment Agency.

Following the ergonomic assessment of airlift sampling that was carried out as part of this project; updates have been suggested for the existing Environment Agency airlift safe system of work that would ensure that airlift sampling is carried out in a way that is ergonomically safe and that does not pose any significant health and safety risks.

The necessary prerequisite knowledge is now in place for a Phase 2 project to be started. This would collect new deep river reference samples using standardised deep water sampling methods, derive estimates of uncertainty associated with these methods, and build new RIVPACS models based on these samples. A specification and work programme for Phase 2, including indicative costs, has been supplied to the project board and is summarised in this report.


11 Recommendations

1. Recommendations are made for the replacement of existing RIVPACS deep river reference samples with newly collected samples that have been obtained using the standardised sampling methods of either long-handled pond net from the bank, or airlift samples from a boat. The choice of method should be determined by the use of a simple algorithm of stream width and depth. The same standard approach for determining the choice of sampling technique for deep river samples should be applied to all WFD classification monitoring by the Environment Agency, Scottish Environment Protection Agency, and the Northern Ireland Environment Agency.

2. There is a gap between the likely maximum wadeable depth at which kick/sweep samples can safely be obtained (80cm), and the minimum operating depth at which a Yorkshire pattern airlift can operate when fully submerged (140cm). It is recommended that a short practical field trial of five lengths of airlift pipe that cover the depth range in question is undertaken to measure the effectiveness of airlift pipes at shallows depths. It is suggested that this could be carried out via the Environment Agency Framework Contract so the results could be forthcoming quickly without delaying the main RIVPACS deep rivers Phase 2 project.

3. Given the apparent absence of any evidence to suggest that specific deep river reporting indices are needed, and the potential disruption and discontinuities that their introduction would create, the introduction of specific deep river reporting indices is not recommended.

4. Recommendations are made for alterations to the Environment Agency sampling manual (Operational Instruction 018_08) to update the material on deep river sampling methods.

5. In the light of an ergonomic assessment of airlift sampling, recommendations are made for alterations to the existing Environment Agency airlift safe system of work.

6. It is recommended that airlift sampler regulators/control panels should be modified to operate using higher pressure. The use of 300 bar cylinders would reduce manual lifting for sampling staff as these cylinders are smaller and lighter.

7. The necessary prerequisite evidence is now in place for a Phase 2 project to collect new deep river reference samples using standardised deep water sampling methods, derive estimates of uncertainty associated with these methods, and build new RIVPACS models based on these samples.


References

BASS J. A. B., WRIGHT J. F., CLARKE R. T., GUNN R. J. M. & DAVY-BOWKER J. (2000) Assessment of sampling methods for macroinvertebrates (RIVPACS) in deep watercourses. Environment Agency R&D Technical Report E134.

CLARKE R. & DAVY-BOWKER J. (2006) Development of the scientific rationale and formulae for altering RIVPACS predicted indices for WFD Reference Condition. Scotland and Northern Ireland Forum for Environmental Research, Edinburgh, UK. (SNIFFER project WFD72B).

CLARKE R., DAVY-BOWKER J., DUNBAR M., LAIZE C., SCARLETT P. & MURPHY J. (2011) Enhancement of the River Invertebrate Classification Tool. Scotland & Northern Ireland Forum for Environmental Research, Edinburgh, UK. (SNIFFER project WFD119).

DAVY-BOWKER J., ARNOTT S., CLOSE R., DOBSON M., DUNBAR M., JOFRE G., MORTON D., MURPHY J., WAREHAM W., SMITH S. & GORDON V. (2010) Further Development of River Invertebrate Classification Tool. Scotland & Northern Ireland Forum for Environmental Research, Edinburgh, UK. (SNIFFER project WFD100).

DAVY-BOWKER J., CLARKE R., CORBIN T., VINCENT H., PRETTY J., HAWCZAK A., BLACKBURN J., MURPHY J. & JONES I. (2008) River Invertebrate Classification Tool. Scotland and Northern Ireland Forum for Environmental Research, Edinburgh, UK. (SNIFFER project WFD72C).

DAVY-BOWKER J., CLARKE R.T., FURSE M., DAVIES C., CORBIN T., MURPHY J. & KNEEBONE N. (2007a) Database Documentation. Scotland and Northern Ireland Forum for Environmental Research, Edinburgh, UK. (SNIFFER Project WFD46).

DAVY-BOWKER J., CLARKE R.T., FURSE M., DAVIES C., CORBIN T., MURPHY J. & KNEEBONE N. (2007b) RIVPACS Pressure Data Analysis. Scotland and Northern Ireland Forum for Environmental Research, Edinburgh, UK. (SNIFFER Project WFD46).

ENVIRONMENT AGENCY (2009) Freshwater macro-invertebrate sampling in rivers. Operational Instruction 018_08. Issued 16/06/09. Environment Agency, Bristol.

JONES J.I., BASS J.A.B. & DAVY-BOWKER J. (2005) Review of methods for sampling invertebrates in deep rivers. North South Shared Aquatic Resource (NS Share).

JONES J.I. & DAVY-BOWKER J. (2012) Standardisation of RIVPACS for deep rivers: Phase I - review of techniques for sampling benthic macro-invertebrates in deep rivers. Environment Agency, Bristol.

MOSS D., WRIGHT J.F., FURSE M.T & CLARKE R.T. (1999) A comparison of alternative techniques for prediction of the fauna of running-water sites in Great Britain. Freshwater Biology 41: 167-181.

MURRAY-BLIGH J. A. D., FURSE M. T., JONES F. H., GUNN R. J. M., DINES R. A. & WRIGHT J. F. (1997) Procedure for collecting and analysing macroinvertebrate samples for RIVPACS. BT001. Institute of Freshwater Ecology & Environment Agency.

NEALE M.W., KNEEBONE N.T., BASS J.A.B., BLACKBURN J.H., CLARKE R.T., CORBIN T.A., DAVY-BOWKER J., GUNN R.J.M., FURSE M.T. & JONES J.I. (2006) Assessment of the Effectiveness and Suitability of Available Techniques for Sampling


Invertebrates in Deep Rivers. North South Shared Aquatic Resource (NS Share) Final Report T1(A5.8) – 1.1.

WRIGHT J. F., CLARKE R. T., GUNN R. J. M., BLACKBURN J. H. & DAVY-BOWKER J. (1999) Testing and further development of RIVPACS – Phase 3. Development of new RIVPACS methodologies . Stage 1. Environment Agency.


List of abbreviations

AL Airlift invertebrate sampling method or device

ASPT Average Biological Monitoring Working Party Score Per Taxon

AWIC Acid Water Indicator Community (a macro-invertebrate biotic index)

BMWP Biological Monitoring Working Party

CEH Centre for Ecology and Hydrology

DIN Deutsches Institut für Normung e.V. (the German Institute for Standardization)

D80:W15 80cm deep and 15m wide definition of depth and width

EA Environment Agency

EQR Environmental Quality Ratio

FBA Freshwater Biological Association

GB Great Britain

GIS Geographical Information System

GQA General Quality Assessment.

IDEST Inspectorate for Diving Equipment Servicing & Testing

KS or K/S Kick/Sweep invertebrate sampling method

LHPN Long-handled pond net: a standard FBA pond net with a 1.5m long handle (referred to as a standard FBA long-handled pond net in Murray-Bligh et al. 1997), modified so that extensions can be fitted to increase the length to 4 m

LIFE Lotic-invertebrate Index for Flow Evaluation (a macro-invertebrate biotic index)

MINTA Minimum of NTaxa or ASPT

NI Northern Ireland

NIEA Northern Ireland Environment Agency

NTAXA Number of Biological Monitoring Working Party scoring Taxa

Obs Observed (e.g. observed NTaxa or observed ASPT)

O/E Observed/expected ratio (e.g. observed NTaxa divided by expected NTaxa)

psi Pounds per square inch

PSI Proportion of Sediment sensitive Invertebrates (a macro-invertebrate biotic index)

ReSub Re-substitution. A method of testing RIVPACS model performance by measuring the percentage of sites correctly classified (re-assigned) to their original biological end group


RICT River Invertebrate Classification Tool

RIVPACS River Invertebrate Prediction and Classification System

S.D. or SD Standard deviation

SEPA Scottish Environmental Protection Agency

SNIFFER Scotland and Northern Ireland Forum for Environmental Research

SSOW Safe system of work

TWINSPAN Two-Way INdicator SPecies ANalysis

UK United Kingdom

WFD Water Framework Directive

WHPT Walley Hawkes Paisley Trigg (a macro-invertebrate biotic index)

XVal Cross validation or ‘leave-one-out’. A method of testing RIVPACS model performance where the fit of each site is tested in turn against models based on all of the other sites


Appendices

Appendix I – Original safe system of work for Airlift sampling

Reproduced with the kind permission of Environment Agency, Yorkshire and North East Region

Authors: Barry Byatt and Dave Barber, Environment Agency, Yorkshire and North East Region


This page intentionally blank

We are The Environment Agency. It's our job to look after your environment and make it a better place – for you, and for future generations.

Your environment is the air you breathe, the water you drink and the ground you walk on. Working with business, Government and society as a whole, we are making your environment cleaner and healthier.

The Environment Agency. Out there, making your environment a better place.

Evidence - Freshwater Biological Association Rivers(ii... · identifies the best methods to collect...

Documents

Transcript of Evidence - Freshwater Biological Association Rivers(ii... · identifies the best methods to collect...