Aquatic and Riparian Plant Management: Controls for Vegetation in Watercourses

Aquatic and riparian plant management: controls for vegetation in watercourses Technical guide Project: SC120008/R2 The Environment Agency is the leading public body protecting and improving the environment in England. 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 by the Environment Agency’s Evidence Directorate and funded by the joint Environment Agency/ Defra Flood and Coastal Erosion Risk Management Research and Development Programme. Published by: Author(s): Environment Agency, Horison House, Deanery Road, Sebastian Bentley, Rachael Brady, Jonathan Cooper, Bristol, BS1 9AH Krista Davies, Matthew Hemsworth, Peter Robinson www.environment-agency.gov.uk and Laura Thomas ISBN: 978-1-84911-326-7 Dissemination Status: Publicly available © Environment Agency – July 2014 Keywords: All rights reserved. This document may be reproduced Aquatic vegetation, riparian, management, control, with prior permission of the Environment Agency. flood risk management, physical, chemical, environmental, biological, biosecurity The views and statements expressed in this report are those of the author alone. The views or statements Research Contractor: expressed in this publication do not necessarily JBA Consulting, Epsom House, Chase Park, represent the views of the Environment Agency and the Redhouse Interchange, South Yorkshire, DN6 7FE Environment Agency cannot accept any responsibility for Tel: 01302 337798 such views or statements. Environment Agency’s Project Manager: Email: [email protected]. Lydia Burgess-Gamble, Evidence Directorate E: [email protected]. Theme Manager: Adrian Rushworth, FCRM Manager Collaborator(s): Lydia Burgess-Gamble (Environment Agency), Jacky Carroll (Penny Anderson Associates, Helen Hamilton (Penny Anderson Associates), Jonathan Newman (Centre for Ecology and Hydrology) and Christine Orchard (Penny Anderson Associates) Project Number: SC120008/R2 ii Aquatic and riparian plant management – technical guide Evidence at the Environment Agency Evidence underpins the work of the Environment Agency. It provides an up-to-date understanding of the world about us, helps us to develop tools and techniques to monitor and manage our environment as efficiently and effectively as possible. It also helps us to understand how the environment is changing and to identify what the future pressures may be. The work of the Environment Agency’s Evidence Directorate is a key ingredient in the partnership between research, guidance and operations that enables the Environment Agency to protect and restore our environment. This report was produced by the Scientific and Evidence Services team within Evidence. The team focuses on four main areas of activity: Setting the agenda, by providing the evidence for decisions; Maintaining scientific credibility, by ensuring that our programmes and projects are fit for purpose and executed according to international standards; Carrying out 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. Miranda Kavanagh Director of Evidence Aquatic and riparian plant management – technical guide iii Executive summary This guidance provides watercourse managers in flood risk management operating authorities (both technical staff and field operatives) with a framework to help inform decisions on when and how to manage vegetation, taking into account the species present and the watercourse type. It updates previous aquatic and riparian vegetation management publications to take account of these changes. This technical guide provides detailed information on the most important aquatic and riparian species in the UK. It describes the different types of watercourse and the range of management techniques (physical, chemical, biological, environmental and novel) available. Information is also given on the broad-scale impacts of aquatic and riparian plant management and the issues and factors to consider when planning any aquatic and riparian vegetation management operation. It is designed to be read and used together with: Decision-making spreadsheet tool – a tool to help inform selection of the most appropriate technique(s) to manage a particular watercourse type, with a specific species problem Field guide – a concise guide to help collect the information needed to use the decision-making spreadsheet tool The evidence on which this guidance is based is presented in an accompanying case study report and a literature review report. iv Aquatic and riparian plant management – technical guide Acknowledgements We would like to thank those who have been worked on the development of this guide through their involvement on the Project Board and Project Advisory Group. We would also like to thank all those who attended the workshop testing the decision-making spreadsheet tool in September 2013. Additionally, we would like to thank all those who have provided information, case studies and photographs for inclusion in this guide. Unless stated otherwise, all photographs included in this guide are the copyright of the Environment Agency. Aquatic and riparian plant management – technical guide v Contents 1. Introduction 1 1.1 Scope of the guidance 1 1.2 Target audience 2 1.3 Content of the guidance 3 1.4 Structure of this technical guide 4 2. Ecology and management of aquatic and riparian vegetation 5 2.1 Importance of aquatic and riparian vegetation 5 2.3 Types of aquatic and riparian plants 5 2.4 Reasons for aquatic and riparian plant management 7 2.5 Watercourse management 10 2.6 Factors contributing to aquatic and riparian plant problems 13 2.7 Future changes to aquatic and riparian plant problems 14 3. Impacts of vegetation management 17 3.1 Environmental impacts 17 3.2 Impacts on vegetation communities 18 3.3 Geomorphological impacts 18 4. Planning aquatic and riparian plant management 19 4.1 Planning management 19 4.2 Problem identification 22 4.3 Develop baseline understanding 22 4.4 Management considerations 22 4.5 Management objectives 43 4.6 Management plan 43 5. Species 45 5.1 Introduction 45 5.2 Submerged species 46 5.3 Floating-leaved plants – free-floating plants 62 5.4 Floating-leaved plants – rooted floating-leaved plants 67 5.5 Emergent species – tall emergent species 83 5.6 Emergent species – broad-leaved emergent species 98 5.7 Algae 108 5.8 Non-native invasive bank species 114 6. Watercourse type classification 122 6.1 Introduction 122 6.2 Background to watercourse type classification 122 6.3 Defining geomorphic watercourse types 127 6.4 Selecting geomorphic watercourse type 133 vi Aquatic and riparian plant management – technical guide 7. Techniques 135 7.1 Introduction 135 7.2 Techniques considered 135 7.3 Physical techniques 137 7.4 Chemical techniques 158 7.5 Environmental techniques 169 7.6 Biological techniques 188 7.7 Novel techniques 197 7.8 Integrated management 200 8. Decision-making spreadsheet tool 201 8.1 Introduction 201 8.2 How to use the spreadsheet tool 201 9. Case studies 208 9.1 River Mole, Surrey 209 9.2 Nafferton Beck, East Yorkshire 213 9.3 Moretons Leam, Cambridgeshire 216 9.4 River Lee, Luton 221 9.5 Boating Dike, South Yorkshire 225 10. Monitoring 228 10.1 Adaptive management 228 10.2 Existing watercourse monitoring programmes and methods 230 10.3 Developing a monitoring protocol 233 10.4 Proposed monitoring protocol 236 References 239 List of abbreviations 242 Glossary 243 Appendix A Legislative review 248 A.1 Legislation driving aquatic and riparian plant management 248 A.2 Legislation with regard to the implementation of vegetation management techniques 257 A.3 Environmental considerations 264 A.4 Other permissions and consents 270 Appendix B Impacts of aquatic and riparian vegetation on flow conveyance 272 B.1 Introduction 272 B.2 Conveyance estimation system 272 B.3 Assessment of the hydraulic impacts of vegetation removal 275 Appendix C Linking watercourse type classifications 282 Appendix D Background to decision-making spreadsheet tool 283 Aquatic and riparian plant management – technical guide vii Table 2.1 Types of aquatic and riparian plants 6 Table 2.2 Possible techniques for vegetation management 12 Table 2.3 Non-native invasive aquatic plant species in the UK 15 Table 4.1 Planning checklist 19 Table 4.2 Relevant exemptions 36 Table 6.1 JNCC river types 123 Table 6.2 UKTAG river classification 124 Table 6.3 Summary of geomorphic watercourse type 126 Table 7.1 Possible techniques for vegetation management 136 Table 7.2 Required water depths to limit growth 179 Table 9.1 Data inputs to spreadsheet tool for River Mole 211 Table 9.2 Data inputs to spreadsheet tool for Nafferton Beck 214 Table 9.3 Data inputs to spreadsheet tool for Moretons Leam 217 Table 9.4 Data outputs for three problem species at Moretons Leam 218 Table 9.5 Data inputs to spreadsheet tool for River Lee 222 Table 9.6 Data outputs for two problem species in the River Lee 223 Table 9.7 Data inputs to spreadsheet tool for Boating Dike 226 Table 10.1 Existing watercourse monitoring methodologies 230 Table 10.2 Generic monitoring protocol 236 Table

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