Hertfordshire Local Flood Risk Management Strategy

Appendix C Hertfordshire Local Flood Risk Management Strategy Strategic Environmental Assessment Scoping Report Prepared by LUC April 2016 Project Title: Strategic Environmental Assessment of Hertfordshire Local Flood Risk Management Strategy Client: Hertfordshire County Council Version Date Version Details Prepared by Checked by Approved by 1 14/9/15 First draft for client Susanne Juliette Juliette Young review Underwood Young 2 22/04/16 Final version for Susanne Taran Taran consultation Underwood Livingston Livingston Kate Nicholls Hertfordshire Local Flood Risk Management Strategy Strategic Environmental Assessment Scoping Report Prepared by LUC April 2016 Planning & EIA LUC LONDON Offices also in: Land Use Consultants Ltd Registered in England Design 43 Chalton Street Bristol Registered number: 2549296 Landscape Planning London Glasgow Registered Office: Landscape Management NW1 1JD Edinburgh 43 Chalton Street Ecology T +44 (0)20 7383 5784 London NW1 1JD Mapping & Visualisation [email protected] FS 566056 EMS 566057 LUC uses 100% recycled paper Contents 1 Introduction 1 The study area and key characteristics 1 Hertfordshire’s LFRMS 2 Strategic Environmental Assessment 3 Equalities Impact Assessment 4 Structure of the Scoping Report 4 2 SEA Process and Methodology 5 Stages in the SEA Process 5 How will the Scoping Report be used? 6 3 Relevant Plans and Policies 7 Summary of Review of Plans, Policies and Programmes 11 4 Baseline Information and Key Environmental Issues 12 Baseline Information 12 Hertfordshire County Geographical Context 12 Environmental Baseline Data 12 Key Environmental Issues and Likely Evolution without the Strategy 24 5 SEA Framework and Approach to the SEA 27 SEA Framework and Approach to the SEA 27 Approach to the later stages of the SEA 27 Assessment of Alternatives 28 Draft Environmental Report 28 6 Next Steps 30 Consultation 30 Appendix 1 31 Review of Plans, Policies and Programmes of relevance to the SEA of the LFRMS 31 1 Introduction LUC was appointed by Hertfordshire County Council in August 2015 to prepare the Strategic Environmental Assessment (SEA) Scoping Report for the review of the Local Flood Risk Management Strategy (hereafter referred to as the LFRMS). The purpose of this Scoping Report is to outline the framework for undertaking the later stages of the SEA of the emerging LFRMS. This involves reviewing other relevant plans and programmes, considering the current state of the environment in Hertfordshire, identifying any key environmental issues or problems which may be affected by the LFRMS and developing an ‘SEA framework’ comprising specific objectives against which the measures included in the LFRMS will be assessed. The study area and key characteristics Hertfordshire is located immediately to the north of London, adjoining the counties of Buckinghamshire, Cambridgeshire and Essex and the unitary authorities of Central Bedfordshire and Luton. Hertfordshire covers an area of 1,642 km2. Hertfordshire has a distinctive mix of small to medium sized urban settlements juxtaposed with many smaller villages. All of Hertfordshire’s towns and villages are of archaeological significance. Many of them date from the medieval period although the ‘new’ towns of the twentieth century should equally be considered as important cultural assets (the latter include Letchworth and Welwyn Garden City). The largest towns are Watford, Hemel Hempstead, Stevenage and St. Albans. Overall, there is no single dominant urban centre, but a dense network of towns. Hertfordshire’s dispersed settlement pattern is a major contributor to increased car traffic. The East and West Coast Mainline railways both pass through the county, with stations at Stevenage, Watford Junction and Hemel Hempstead. These routes are part of the trans- European transport network (TEN-T)) and provide connections to the Continent via the Channel Tunnel and the high speed links onwards to Paris, Brussels and elsewhere. The main freight route to Europe is via Felixstowe and Harwich, to which there is easy road access from Hertfordshire via the A120. Over half of the Hertfordshire land area is designated as Green Belt, and also includes the Chiltern Hills to the west and north west, designated as an area of outstanding natural beauty (AONB). However, both the natural environment and the built environment are subject to pressures, particularly from development and congestion linked to increased levels of traffic. Parts of the east of the county fall within the London–Stansted–Peterborough Corridor Growth Area. Proposals for additional development around Luton and Dunstable could affect North Hertfordshire. Hertfordshire is served by the Grand Union Canal and the Lee/Stort Navigations, which are navigable to narrow boats. Although originally built as commercial waterways they are now predominantly used by leisure craft. The length of major navigable waterways in Hertfordshire is approximately 55 km. The geology of Hertfordshire ranges from the claylands of the London Basin to extensive chalklands, and is the major factor determining the county’s topography and its soils. Gault clay outcrops are found only at the north western extremity of the county. Elsewhere it is overlain by up to 205 metres of chalk, which forms the Chiltern Hills in the north west with their chalk scarp and dip slope cut by valleys. The Reading Beds clays and gravels which were deposited over the chalk have largely been eroded apart from some outlying hills, such as that on which St. Albans is built. Glacial clays and gravels overlie much of the north east of Hertfordshire, and river gravels occupy the Vale of St Albans and many of the river valleys. The chalk which underlies most of Hertfordshire forms an important water aquifer which provides water from wells and pumped SEA of Hertfordshire’s LFRMS SEA Scoping Report 1 April 2016 boreholes, a vital source of public drinking water and water for industry and agriculture. It also forms a part of the natural environment providing, in particular, water for the chalk streams which flow across the county. A summary of flood risk in Hertfordshire is provided in the Local Flood Risk Management Strategy for Hertfordshire 2013-20161. Hertfordshire is at risk from a variety of sources of flooding which are known to interact with each other. The main sources of flood risk include surface water, groundwater, rivers and other watercourses. As well as events caused by a single source there may be in combination effects, for example, elevated river levels impeding surface water drainage which then results in flooding, where the state of the river and volumes of surface water in isolation would not have been problematic. Flooding from all these sources is expected to increase in frequency or severity as a result of climate change. The potential for surface water flooding is predicted in most of Hertfordshire’s major settlements, with approximately 53,400 dwellings at risk2. In relation to fluvial flooding in Hertfordshire, 8,017 dwellings fall in Flood Zone 2 (1 in 1000 chance of flooding in any year) and 4,879 in Flood Zone 3 (1 in 100 chance in any year). Significant levels of fluvial flood risk are seen in the south and south eastern parts of the county in particular. The presence of the chalk aquifer in Hertfordshire and other underground water bearing areas such as the river gravel deposits mean that there is potential for groundwater flooding in Hertfordshire. There are confirmed cases, both widespread and in settlements known to be at particular risk. The mapping of Areas Susceptible to Groundwater Flooding is based on 1 kilometre squares where the percentage of the area where there is the potential for groundwater emergence is above 25%. The majority of Hertfordshire is not shown to be at risk above this level, with very few kilometre squares with a percentage greater than 50%. Hertfordshire’s LFRMS The Flood and Water Management Act 2010 (‘the Act’) requires Lead Local Flood Authorities (LLFAs) to produce a Local Flood Risk Management Strategy (LFRMS). These strategies must be consistent with the National Flood and Coastal Erosion Risk Management Strategy. They will set out a vision for the management of flood risk and although the Act specifies some of the key elements that must be included in the LFRMS, it is intended that they will be locally specific, reflecting key local issues and enabling communities to be more involved in decision-making regarding flood risk management. The Act defines local flood risk as flood risk from: Surface runoff. Groundwater. Ordinary watercourses (those that do not form part of a ‘main river’). It requires LFRMSs to specify: The risk management authorities within the LLFA’s area. The flood and coastal erosion risk management functions that may be exercised by those authorities in relation to the area. The assessment of local flood risk for the purpose of the strategy. The objectives for managing local flood risk (including any objectives included in the authority’s flood risk management plan prepared in accordance with the Flood Risk Regulations 2009). The measures proposed to achieve those objectives. How and when the measures are expected to be implemented. 1Local Flood Risk Management Strategy for Hertfordshire 2013-2016 http://www.hertsdirect.org/docs/pdf/f/hertslfrmsall.pdf 2 Hertfordshire County Council Preliminary Flood Risk Assessment (June 2011) SEA of Hertfordshire’s LFRMS SEA Scoping Report 2 April 2016 The costs and benefits of those measures, and how they are to be

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