Isbourne Catchment Project Scoping Study
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Isbourne Catchment Project: Scoping Study (Final Report) Isbourne Catchment Project Scoping Study (Final Report) To Isbourne Catchment Partnership & Environment Agency By School of Natural and Social Sciences, University of Gloucestershire & The Countryside and Community Research Institute Isbourne Catchment Project: Scoping Study (Final Report) Project Title: Isbourne Catchment Project: Scoping Study (Final Report) Client Reference: Start Date: January 2016 Finish Date: October 2016 Duration: 10 months Project Manager (Research Team) Chris Short Research Team: Lucy Clarke, Rob Berry Date of Report: 27 October 2016 University of Gloucestershire Francis Close Hall Campus Swindon Road Cheltenham, GL50 4AZ www.ccri.ac.uk www.glos.ac.uk/sciences When quoting this report use the following citation: Clarke L, Short C and Berry R (2016) Isbourne Catchment Project: Scoping Study (Final Report), Report to Isbourne Catchment Partnership & Environment Agency. School of Natural and Social Sciences & CCRI, University of GloucestershireI: Gloucestershire, UK. Isbourne Catchment Project: Scoping Study (Final Report) Table of Contents List of Tables ......................................................................................... 4 List of Figures ....................................................................................... 4 Glossary ................................................................................................ 6 Key terms & definitions ........................................................................ 7 Executive Summary .............................................................................. 8 1. Introduction ................................................................................ 14 1.1 Study Brief ......................................................................................................... 14 1.2 Study Approach ................................................................................................. 15 1.3 Consultations .................................................................................................... 16 1.4 Report Structure ................................................................................................ 16 2. What are natural flood management options? ......................... 17 2.1 Introduction to natural flood management options ............................................. 17 2.2 Rural Sustainable Drainage Systems (RSuDS) ................................................. 18 2.3 Land management changes .............................................................................. 20 3. River Isbourne Catchment Characterisation ............................ 23 3.1 The Catchment .................................................................................................. 23 3.1.1 Main river .......................................................................................................... 24 3.1.2 Ordinary watercourses ...................................................................................... 24 3.1.3 Lakes and reservoirs ......................................................................................... 24 3.1.4 Groundwater bodies .......................................................................................... 24 3.2 Topography ....................................................................................................... 24 3.2.1 Upland Areas .................................................................................................... 24 3.2.2 Upper River Valleys ........................................................................................... 25 3.2.3 Floodplain River Valleys .................................................................................... 25 3.2.4 Proportion of landscape type within the Isbourne Catchment ............................ 25 3.3 Geology & Soils ................................................................................................. 25 3.4 Hydrology and hydrogeology ............................................................................. 27 3.4.1 Flow monitoring data ......................................................................................... 28 3.5 Flood events in the Isbourne Catchment ........................................................... 32 3.6 Land and water use (past and present) ............................................................. 32 3.6.1 Water use .......................................................................................................... 32 3.6.2 Land use ........................................................................................................... 33 2 | P a g e Isbourne Catchment Project: Scoping Study (Final Report) 3.6.2.1 Implications of land use change ........................................................................ 34 3.6.3 Designated sites and wildlife areas.................................................................... 35 3.7 Current governance and institutional framework ................................................ 36 4. Natural flood management options for the Isbourne ............... 37 4.1 Defining the NFM drivers within the Isbourne Catchment .................................. 37 4.1.1 Flood risk ........................................................................................................... 37 4.1.2 Sediment ........................................................................................................... 38 4.1.3 Water quality ..................................................................................................... 38 4.1.4 Other WFD impacts and considerations ............................................................ 39 4.2 NFM application to water courses in the Isbourne ............................................. 40 4.3 Water body reviews for applicable NFM ............................................................ 40 4.4 Potential measurable benefit factors .................................................................. 45 4.5 Suggested governance arrangements (local and institutional) ........................... 46 4.6 Other potential flood risk solutions ..................................................................... 47 5. Summary, natural flood management opportunities & recommendations ............................................................................... 48 5.1 Summary of main findings ................................................................................. 48 5.1.1 Key catchment drivers ....................................................................................... 48 5.1.2 Catchment character ......................................................................................... 49 5.2 Opportunities for NFM ....................................................................................... 50 5.3 Principles for the use of NFM ............................................................................ 51 5.3.1 Applicability factors ............................................................................................ 51 5.3.2 Measurability factors ......................................................................................... 52 5.4 Recommendations ............................................................................................ 52 5.5 Next steps ......................................................................................................... 54 5.6 Suggested further reading ................................................................................. 54 6. References .................................................................................. 55 7. Appendices ................................................................................. 58 3 | P a g e Isbourne Catchment Project: Scoping Study (Final Report) List of Tables Table 1. Typical locations for RSuDS designs (adapted from Atkins, 2013 & SEPA 2015) .. 18 Table 2. Typical locations for land management options (SEPA 2015, EA 2016) ................ 21 Table 3. River Isbourne catchment WFD water body summary ........................................... 23 Table 4. Proportion of area within Isbourne catchment that falls within the three main landscape types used for this study .................................................................................... 25 Table 5. Soils of the Isbourne catchment and their characteristics (Data source: Cranfield University, 2016) ................................................................................................................. 26 Table 6. Peaks over Threshold analysis for the Hinton on the Green gauging station (1973- 2007) – the data was split into 8 year sets. Taken from Haycock, 2010. ............................. 29 Table 6. Water quality/chemistry results for the Isbourne catchment (2015 WFD) ............... 39 Table 7. Possible NFM options for the water courses in the Isbourne catchment ................ 43 Tables in the Appendices: Table A1. Summary of the 2015 WFD status of the River Isbourne (ID GB109054039631).60 Table D1. Summary of the RSuDS designs and general applications (based on data in Avery, 2012)…………………………………………………………………………………………68 List of Figures Figure 1: Map showing the location of springs in the headwaters of the River Isbourne, the fourteen springs which contribute directly or indirectly to the River Isbourne are marked. Source: Murray 2016 27 Figure 2: Mean annual flow at Hinton-on-Green gauging station between 1973-2014 (data sourced from the NRFA