Summary of emerging evidence from the Demonstration Test Catchments (DTC) Platform 1 Contents 1 Introduction ............................................................................................................................ 7 1.1 The Context ............................................................................................................... 7 1.2 The Challenge ............................................................................................................ 7 1.3 Demonstration Test Catchments ............................................................................... 9 1.4 Beneficiaries and Impacts ........................................................................................ 11 1.4.1 Informing and Supporting Policy ................................................................................11 1.4.2 Supporting Policy Delivery ............................................................................................11 1.4.3 Demonstrating to Industry and Stakeholders .......................................................11 1.4.4 Researchers and Research Funders ...........................................................................12 2 Understanding the Issues ................................................................................................. 12 2.1 Introduction ............................................................................................................. 12 2.2 Catchment Characteristics ....................................................................................... 12 2.2.1 Hampshire Avon .................................................................................................................14 2.2.2 Tamar ......................................................................................................................................15 2.2.3 Eden .........................................................................................................................................16 2.2.4 Wensum .................................................................................................................................17 2.3 Catchment Monitoring ............................................................................................ 19 2.3.1 Sub-Catchment Approach...............................................................................................19 2.3.2 Hydrological and Water Quality Monitoring ..........................................................26 2.3.3 Ecological Monitoring ......................................................................................................28 2.3.4 Other Monitoring and Assessment Approaches ...................................................29 2.4 Results and Interpretation....................................................................................... 35 2.4.1 Hydrology and Water Quality across the DTC Platform ....................................36 2.4.1.1 Differences in Hydrological and Hydrochemical Behaviours and Chemistries in the DTC Sub-Catchments .....................................................................................................................46 2.4.1.2 Nutrient and Sediment Delivery to Streams in the DTC Sub-Catchments: the Relative Importance of Flow Conditions under Different Geoclimatic Conditions ..........52 2.4.1.3 Seasonal Pollutant Transfers .............................................................................................55 2.4.1.4 Hydrology and Water Quality Conclusions ..................................................................60 2.4.2 Ecology ...................................................................................................................................61 2.4.3 Specific Groundwater Investigations ........................................................................72 3 Measures ................................................................................................................................ 84 3.1 Background .............................................................................................................. 84 3.2 Selection of Measures ............................................................................................. 85 3.3 Mitigation Measures Development Plans ............................................................... 89 3.3.1 Avon ........................................................................................................................................89 3.3.2 Tamar Catchment, Caudworthy Water .....................................................................92 3.3.3 Development of a Mitigation Measures Plan in the Eden .................................94 3.3.4 Development of Mitigation Measures Plan in the Wensum .............................96 3.4 Implementation of Measures across the Catchments ............................................ 98 3.4.1 Avon ........................................................................................................................................98 3.4.2 Tamar ................................................................................................................................... 106 3.4.3 Eden ...................................................................................................................................... 111 3.4.4 Wensum .............................................................................................................................. 113 3.5 Rationale of Monitoring Approach ........................................................................ 118 2 3.5.1 Sub-Catchment Monitoring ........................................................................................ 118 3.5.2 Avon Measures Monitoring Plan .............................................................................. 119 3.5.3 Eden Measures Monitoring Plan .............................................................................. 121 3.5.4 Wensum Measures Monitoring Plan ....................................................................... 124 4 Working with Stakeholders: Knowledge Exchange and Understanding Farmer Behaviour .................................................................................................................... 126 4.1 Introduction ........................................................................................................... 126 4.2 An Overview of Local Knowledge Transfer and Knowledge Exchange Activities .. 126 4.3 Media Activity and Dissemination ......................................................................... 128 4.4 Stakeholder Events ................................................................................................ 129 4.4.1 EdenDTC Catchment Bus Tour .................................................................................. 130 4.4.2 Avon DTC Farm Advisor Workshop, May 2012 ................................................. 131 4.4.3 Wensum DTC Farmer Presentations and Field Visits, 2014 ......................... 133 4.4.4 Farmer-Led Monitoring in the Wensum DTC ..................................................... 135 4.5 Supporting the Catchment-Based Approach ......................................................... 137 4.6 The Baseline Farm Survey...................................................................................... 137 4.6.1 Understanding Farmer Behaviour ........................................................................... 137 4.6.2 Implementing the Survey ............................................................................................ 138 4.6.3 Current Adoption of Mitigation Measures ............................................................ 138 4.6.4 Attitudes to Future Adoption of Measures ........................................................... 139 4.6.5 Farmer Priority Measures ........................................................................................... 143 4.7 Farm Diaries ........................................................................................................... 143 4.8 Assessment of Progress and Future Priorities ....................................................... 144 4.8.1 Future Priorities .............................................................................................................. 144 5 Monitoring and Evaluation of On-Farm Interventions for Informing Water Quality Policy ............................................................................................................................. 145 5.1 Introduction ........................................................................................................... 145 5.2 The General Challenge Driving DTC ....................................................................... 145 5.2.1 The Specific Challenge Driving DTC ........................................................................ 146 5.2.2 A Twin-Track Approach to Iterative Science ...................................................... 146 5.2.3 Developing a ‘Catchment Science Toolkit’ ............................................................ 147 5.2.4 Lumped Descriptive Metrics for Characterising and Comparing Hydrochemical Response ............................................................................................................... 149 5.2.5 Detecting Change with Conventional Hydrochemical Time Series Data . 150 5.2.6 Detecting Change with Nutrient Speciation and Fractionation Data ........ 153 5.2.7 Detecting Change using Hysteretic