PENWITH DISTRICT COUNCIL

PENWITH LOCAL DEVELOPMENT FRAMEWORK

STRATEGIC FLOOD RISK ASSESSMENT

Level 1 Coarse Assessment Part 1

August 2007

Sustainable Development and Improvement Contact

This report is published by the: Sustainable Development Policy Team Sustainable Development and Improvement Penwith District Council St Clare Penzance Cornwall TR18 3QW

For further information or advice on the contents of this report please contact: Greg Clouter Sustainable Development Policy Monitoring Officer Email; [email protected] Tel: (01736) 336828 EXECUTIVE SUMMARY

• The Strategic Flood Risk Assessment (SFRA) for Penwith District Council has been undertaken to provide a detailed and robust assessment of the extent and nature of flood risk in the district and the implications this has for land use planning. • The SFRA explains the criteria for the submission of planning applications in the future and for guiding subsequent development control decisions. • The SFRA has specific objectives to: • Provide a reference and policy document to inform in the preparation the new Local Development Framework (LDF) which will replace the adopted Penwith Local Plan; • Provide a reference and policy document to advise and inform private and commercial developers of their obligations as defined by the latest planning requirements (PPS25); • Ensure that Penwith District Council meets its obligations as outlined in the latest planning requirements (PPS25); • Enable consistent and sustainable decisions to be made by the local planning authority on issues relating to flood risk. • The principle outputs of the SFRA is provided in two parts: • This SFRA report; • A Geographic Information System (GIS) Package to provide the spatial data in electronic format for ease of access and supplying up to date information. • The spatial information provided on the GIS package consists of the following datasets: • Flood Risk and Defence Map – presents areas currently at flood risk as defined by the Environment Agency flood zone mapping and existing and proposed flood defences in the district; • Climate Change Impact Map – presents areas identified as being at future risk of flooding due to the impact of climate change. This takes into account the effect of sea level rise, fluvial flooding on Environment Agency flood zones, and fluvial flooding on potential flood risk areas which currently lie outside of the scope of the Environment Agency flood zones. • The scope of the spatial information of the SFRA covers the entire district, supplying sufficient data for an overall view of flood risk in the study area for strategic planning purposes. CONTENTS

Executive Summary

Part 1 Context and Scope of the Assessment 1-9

1. Introduction 2-4

2. Data Collection 5-6

3. Study Output 7-9

Part 2 Level 1 Coarse Assessment Part 1 10-58

Part 1 Assessment 11

1. Process 1: Problem Formulation 12-13

2. Process 2.a: Tiered Risk Assessment 14

Process 2a1: Level 1 Coarse Assessment 14-22

3. Process 2b: Stages of Risk Assessment 23

Process 2b1: Hazard Identification 23-41

4. Processes 2b2-2b5: Consequence and Significance of Flood Risk 42-47

5. Process 2a2: Prioritisation of Risk 48-51

6. Process 2a3: Level 2 Intermediate Assessment 52-54

7. Process 2a4: Level 3 Detailed Assessment 55-56

8. Process 3: Options Appraisal 57-58 Part 3 Appendices 59-78

Appendix A: Compensatory Flood Storage/Conveyance 60-61

Appendix B: Surface Water Runoff Rates 62-63

Appendix C: Flood Warning and Evacuation Planning 64

Appendix D: Organisational Responsibilities and Flood Risk 65-66

Appendix E: Flood Guidance for Planning Officers 67-68

Appendix F: Allocated Sites and Flood Risk 69

Appendix G: The Sequential and Exception Tests 70-73

Appendix H: Flood Risk Assessments 74

Appendix I: Penwith Area Profile 75-78

Glossary of Terms 79-80

References 81

PART 1

CONTEXT AND SCOPE OF THE ASSESSMENT

Page 1 1 INTRODUCTION

Context - Flood Risk and the Local Development Framework

1.1 Under the new emerging planning system, local authorities are required to undertake a Strategic Flood Risk Assessment (SFRA) to provide an evidence base to inform and guide in the preparation of Local Development Framework (LDF) documents in terms of assessing the implications of flood risk on spatial land use planning within their administrative areas. This Strategic Flood Risk Assessment is part of the evidence base for the Penwith District Council Local Development Framework process and aims to inform and provide general guidance on matters relating to flood risk within the district to development control, developers and the general public.

1.2 The Environment Agency guidance to local planning authorities on Strategic Flood Risk Assessments defines the purpose of the assessment as: 'To identify the areas within a development plan that are at risk of flooding. To identify and detail those factors that are relevant to current and future flood risks and to outline policies to be applied to such areas to minimise and manage that risk'.

1.3 Planning Policy Statement 1: Delivering Sustainable Development , requires local planning authorities to facilitate sustainable patterns of development by avoiding areas of flood risk and accommodating for the potential impact of climate change. Reducing the threat of flooding therefore achieves sustainable development and sustainable communities by contributing to a better quality of life.

1.4 Planning Policy Statement 12: Local Development Frameworks states; At the earliest stage in the preparation of the development plan document, and particularly for the preparation of the Core Strategy, the local planning authority should gather evidence about their area. This may include studies to be undertaken or commissioned on for example...areas of flooding... This evidence will be relied upon by the local planning authority in testing the soundness of the development plan document at independent examination.

1.5 Planning Policy Statement 25: Development and Flood Risk, requires that sites should be allocated in descending order of flood risk when reviewing development plans for the new LDF system. This constitutes a risk based approach which is determined by the application of the Sequential Flood Risk Test (SFRT). Penwith District Council is currently in the initial stages of preparing its LDF portfolio in line with the draft South West Regional Spatial Strategy (SWRSS) covering the development plan period from 2006-2026. The SFRA will guide decisions on allocating land in the new LDF system, informing in the preparation of both strategic and development control policies in enabling the application of the SFRT.

1.6 Development and Flood Risk: A Practice Guide Companion to PPS 25, Living Draft (February 2007) states: A level 1 SFRA should be sufficiently detailed to allow ` application of the Sequential Test on the basis of Table D1 of PPS25 and to identify whether application of the Exception Test is likely to be necessary. The information may be used to assess how any environmental objectives relating to flood, as defined in the Sustainability Appraisal, may be affected by additional development. This

Page 2 should principally be a desk based study making use of existing information.

1.7 Regional Spatial Strategy South West (RSS SW)

The draft RSS SW is the strategic spatial planning document proposed by the South West Regional Assembly (SWRA) covering the South West Region from 2006 to 2026 (currently under consultation until August 2006). The RSS has one specific policy regarding flood risk, Policy F1, which states:

Taking account of climate change and the increasing risk of coastal and river flooding, the priority is to: • Defend existing property and, where possible, locate new development in places with little risk of flooding; • Protect flood plains and land liable to tidal or coastal flooding from development; • Follow a sequential approach to development in flood risk areas; • Use development to reduce the risk of flooding through location, layout and design; • Relocate existing development from areas of the coast at risk, which cannot realistically be defended; and • Identify areas of opportunity for managed realignment to reduce the risk of flooding and create new wildlife areas.

SFRA Objectives

1.8 Planning Policy Statement 25: Development and Flood Risk) requires Councils to provide a detailed and robust evidence base for requesting site specific Flood Risk Assessments. These requirements will be fulfilled in the five key objectives of the SFRA.

• To prepare flood risk evidence base to inform in the preparation of the LDF. • To meet requirements of latest planning guidance (PPS25). • To provide a flood risk policy reference for developers and the general public. • To inform development control on flood risk issues relating to applications. • To provide an evidence base for requesting future site specific Flood Risk Assessments from the Environment Agency.

Status and Format of the SFRA

1.9 A SFRA is divided into two parts to reflect the two functions of planning, which is further divided into three levels of detail. Part 1 relates to spatial planning covering the entire LPA area to feed into the preparation of Development Plan Documents (DPDs). The Part 1 element consists of two levels of detail: Coarse Assessment Level 1; and an Intermediate Assessment Level 2. The Level 2 includes additional detail to the Level 1 when required. Part 2 relates to the regulation and control element of planning and will be undertaken when required to inform the preparation of Supplementary Planning Documents (SPDs) covering specific development areas. This constitutes a Detailed Assessment Level 3.

Page 3 Table 1 The LDF Process and Flood Risk Function Spatial Planning Regulation and Control Implementation Approach Local Development Supplementary Planning Documents (LDDs) Documents (SPDs) Assessment Type Strategic Flood Risk Assessment (SFRA) Part 1 Part 2 Level 1 Level 2 Level 3 Coverage Full coverage of LPA area Planned development area

1.10 This report is the level 1 Coarse Assessment, Part 1 of the SFRA for Penwith District Council

1.11 The format for this SFRA comprises of this Level 1 Coarse Assessment and a series of mapped datasets in a Geographic Information System (GIS) package. The GIS datasets covering the district will comprise of three layers to illustrate historic flood events and defences, current flood risk areas and predicted future flood risk from climate change impact. Together the GIS datasets and the report will clarify which areas of the district are suitable for sustainable development. This will allow for consistency in terms of development plan preparation (policy) and development control decisions (implementation of policy) in issues relating to flood risk.

1.12 The SFRA will be constantly updated as new information becomes available. It should therefore be considered a “live” document. The principle changes will come in the form of quarterly updates to the Flood Zones provided by the Environment Agency, effecting an update of the GIS package. The data sources used in compiling the GIS mapping package are listed below (paragraphs 2.2 - 2.6).

Page 4 2 DATA COLLECTION

Data Source

2.1 The data collected for this SFRA has come from the Environment Agency, Penwith District Council and various reports relevant to specific areas of coastal and fluvial flooding within the scope of the study. This SFRA uses the most reliable data available, but due to the nature of flooding a proportion of this information will be based on estimations derived from scientifically informed predictions. It must be noted that a Level 1 Coarse Assessment SFRA is very much a planning strategic document which highlights flood risk issues in a district wide context. The data outlined below was collected to determine the baseline condition of flood risk in the district.

2.2 Data sourced from ODPM/DCLG

• Planning Policy Statement 1 – Delivering Sustainable Development, 2005; • Planning Policy Statement 12 – Local Development Frameworks, 2004; • Planning Policy Guidance 25 – Development and Flood Risk, 2001; • Planning Policy Statement 25 – Development and Flood Risk. 2006.

2.3 Data sourced from Government Office South West

• Draft South West Regional Spatial Strategy, June 2006 – April 2007; • Regional Planning Guidance 10 (SW), 2001.

2.4 Data sourced from the Environment Agency:

• Historic Floodplain Map; • Flood Zone Mapping; • Flood Map; • West Cornwall Catchment Flood Management Plan, Scoping Report 2006; • Recorded Flooding Incidents; • Data on flood defences; • Tidal Flood Extent for 2052 (based on PPS25 allowance for annual 5 mm rise in sea level to allow for climate change).

2.5 Data sourced from Penwith District Council:

• Recorded flood incidents; • Proposed and existing flood defences; • Newly En-mained Watercourses (April 2005): • Ordnance Survey mapping at 1:10000 scale; • Contour mapping; • District boundary; • Potential allocation sites for LDF affected by flooding. • Sea Defence Works In Penzance, Peter Tressider 1967 • Penwith Local Plan

Page 5 2.6 Data sourced from specific reports:

• Shoreline Management Plan, Lizard Point to Lands End; Halcrow Maritime; • Shoreline Management Plan, Lands End to Hartland Point; Halcrow Maritime; • Promenade Options Review January 2004, Hyder Consultancy Ltd; • Penzance Promenade Conditions Survey, July 2004, Hyder Consultancy; • Penzance Promenade Sea Defence Option Study, May 2005, Hyder Consultancy Ltd; • Penzance Harbour Option Review January 2004, Hyder Consultancy Ltd; • Hydrodynamic Modelling Report 2003 (Hayle Estuary). Babtie Group Ltd.

Data Accuracy

2.7 Data accuracy does not effect the actual risk of flooding to a particular site, but will determine whether an area is graded high, medium or low risk. The quality of flood data is based on recorded flood events (historic flooding) and scientific prediction determined by potential flood source and AOD of the surrounding flood plain. Historical records of flood events come from various sources and consequently vary in the accuracy of the data they provide. Flooding is an unpredictable quantum, being interrelated with meteorological conditions and extreme tidal events. Scientific prediction of potential flood risk is thus limited to hydrological modelling and contour surveys for specific sites which estimate impact scenarios for extreme weather and tidal events on the surrounding area.

2.8 The level 1 Coarse Assessment is a strategic overview of flood risk produced to a standard which conforms to the requirements of the Environment Agency, providing background information for development control in determining the need for a further detailed Flood Risk Assessments (FRA). This is especially the case in regards to the type of mitigation measures which must be undertaken to reduce the risk of flooding to the proposed site and its impact on the surrounding area.

2.9 The data used in this SFRA is the best available at time of publication. Some data may be less precise as other data due to the nature of its source. Where data is deficient or unavailable, the local authority has provided supplementary information based on informed assumptions and engineering advice.

'Don't Panic'

2.10 If the SFRA indicates that your property is either in a flood zone or in an area identified as being at future risk of flooding 'don't panic'. The annual average chance of a flood risk event occurring is low. However to be informed is to be forewarned. It is important that, if necessary, you are prepared for potential flooding before it occurs, reducing the effect it will have on you, your family and your property. Further advice on dealing with the risk of flooding is available on the Environment Agency website at www.environment-agency.gov.uk or by contacting Floodline on 0845 988 1188.

Page 6 3 STUDY OUTPUT

3.1 Scope

This SFRA comprises of two parts, this report and a Geographic Information System (GIS) package providing digital map data depicting areas of flood risk of the district for public access. The two components of the SFRA provides the basis for a consistent approach to flood risk and land use to inform decisions at both a: strategic level, when drawing up policies for the new Local Development Framework; and at a functional level, to guide development control in the processing of applications.

3.2 Geographic Information System

The map data provided by this study is in a GIS package. Geographical Information System (GIS) is a means of displaying spatial information (maps) in an electronic format on computer based systems. The main advantages of providing data on the GIS is that new information can easily be updated on to the system whenever it becomes available, and that this information can be supplied to the public on the council website and development control on the in house system. This allows for quick and easy access to the data package to all interested parties. The datasets contained on the GIS will comprise of two layers:

3.3 Flood Risk and Defence Map

This dataset identifies areas of current and historic flood risk based on the Environment Agency Flood Zone Map. The flood zones shown on the map refer to areas identified by the Environment Agency at high risk (zone 3) and low-to-medium risk (zone 2) of flooding by coastal or fluvial flooding. All land not incorporated into zones 3 or 2 are in flood zone 1 which is regarded as little to no risk of flooding. This layer records existing and proposed flood defences maintained by the Environment Agency and the district authority. Privately maintained defences are not recorded on the dataset. Flood defences comprise of a single or system of structure(s) to protect against flooding up to a specific level. This is known as the 'standard of protection'. The standard of protection of a flood defence may change over time due to the affects of climate change and the impact of subsequent development on the flood plain since the development of the defence. Demarcation of flood defences on the layer helps to inform on development proposals by:

These maps:

• Identify areas where flood risk could be reduced due to the presence of defences; • Identify areas of defended flood plain for development considerations. Flood plains without defences are often classified as functional flood plains. PPG25 recommends the maintenance of a constant supply of functional flood plain to alleviate flood risk. Functional flood plains naturally store floodwater during times of flooding prior to releasing the surplus safely into adjacent watercourses.

Page 7 Climate Change Impact Map

3.4 To meet the requirements of PPS25, this SFRA has to consider the long term impact of climate change on all types of flood risk. The impact of climate change on the severity and frequency of flood events is ultimately uncertain. In order to assist local and regional planning authorities to assess appropriate strategies to accommodate against climate change, the Government established the UK Climate Impacts Programme (UKCIP). Consequently future climate change scenarios were produced by UKCIP in 2002. PPS25 states: The climate changes already seen in the UK are consistent with the UKCIP02 scenarios. This suggests that winters will become wetter over the whole of the UK, by as much as 20 per cent by the 2050s. A shift in the seasonal pattern of rainfall is also expected, with summers and autumns becoming much drier than at present. Snowfall amounts will decrease significantly throughout the UK, but the number of rain-days and the average intensity of rainfall are expected to increase. Although average seasonal wind speeds could increase over most of the country, there is currently much less certainty regarding the potential for greater storminess and the consequences for sea surges or extreme wave activity on coasts.

3.5 For climate change impact mapping the SFRA uses the 1 in 1000 year flood zone 2 to give an indication of how flooding may increase due to climate change and increased flows on fluvial floodplains. For tidal floodplains the current flood zone 2 may is also used as an approximation of the climate change flood extent. It is to be noted that the flood zone maps are due to be updated and that accuracy in relation to predicted increases in sea level from 2080 – 2110 is questionable.

Allowance for Climate Change

3.6 Allowances for predicted climate change impact are based on the recommended contingency allowances for net sea level rise (See Table 2) and the recommended national precautionary sensitivity ranges for peak rainfall intensities, peak river flows, offshore wind speeds and wave heights (See Table 3) as outlined in Tables B.1 and B.2 in Annex B of PPS25.

Table 2: Recommended contingency allowances for net sea level rise Administrative Region Net Sea Level Rise (mm/yr) Relative to 1990 1990-2025 2025-2055 2055-2085 2085-2115 South West 3.5 8.0 11.5 14.5 Source: PPS25, Annex B, Table B.1

Table 3: Recommended national precautionary sensitivity ranges for peak rainfall intensities, peak river flows, offshore wind speeds and wave heights Parameter 1990-2025 2025-2055 2055-2085 2085-2115 Peak rainfall intensity +5% +10% +20% +30% Peak river flow +10% +20%

Page 8 Offshore wind speed +5% +10% Extreme wave height +5% +10% Source PPS25, Annex B, Table B.2

Sea Level Rise

3.7 For calculating sea level rise up to 2025 the 3.5mm rate in Table 1 is applied back to the 1990 base sea level year, that is by adding the number of years from 1990 and multiplying by a factor of 3.5. The same formula is applied in calculating sea level rise in the other three periods of Table 1 using the base dates of 2025, 2055 and 2085, adding the number of years from the relevant base date and multiplying by their respective predicted rate.

3.8 In calculating the impact of tidal and coastal flooding, wave height and wind speed sensitivity ranges outlined in Table 2 need to be taken into consideration to make allowance for the affects of storminess on the predicted increased rates of high water sea level rise given in Table 1. Table 2 shows that an allowance of +5% for offshore wind speed and +5% for extreme wave height need to be added to the predicted increase in sea level rate between 1990 and 2055. These percentages increase to +10% for both factors during the period 2055 to 2115.

Fluvial and Surface Run-off Flooding

3.9 The impact of climate change on flooding inland (fluvial and surface run-off) will take the form of increased levels of rainfall both in terms of the overall number of rain-days per year and rate of intensity. The overall affect of increase rainfall is the anticipated rise in the rate of peak river flow.

3.10 Table 2 outlines the anticipated increase rates for peak rainfall intensity in terms of adding a percentage increase to the rainfall measurement (in mm/hr). From the base dates 1990 and 2025 the increase is calculated to be +5% and +10% respectively, rising to +20% from 2055 and +30% from 2085.

3.11 The figures given for peak river flow rate estimates are taken from the mean river flow rates of 27 river catchments. Table 2 shows that the anticipated increased rate varies from between +10% from 1990 to +20% from 2025 onwards. This percentage is added to the peak flow measurement at cubic metre per second (cm/s).

3.12 PPS25 comments that: Sensitivity testing of the Flood Map produced by the Environment Agency, using the 20 per cent from 2025 to 2115 allowance for peak flows, suggests that changes in the extent of inundation are negligible in well-defined floodplains, but can be dramatic in very flat areas. However, changes in the depth of flooding under the same allowance will reduce the return period of a given flood. This means that a site currently located within a lower risk zone could in future be re- classified as lying within a higher risk zone. This will have land use implications in respect to the appropriate type of development to be considered according to its vulnerability to flooding (See Table 4).

Page 9 PART 2

LEVEL 1 COARSE ASSESSMENT PART 1

Page 10 PART 1 ASSESSMENT

Processes

The template for the format of this Level 1 Coarse Assessment is taken from the DEFRA/EA R & D Technical report FD2320/TR: Flood Risk Assessment Guidance for Assessing New Development (Phase 2); Framework and Guidance for Assessing and Managing Flood Risk for New Development - Full Development and Tools – Section 26: Strategic Flood Risk Assessments – Processes and Procedures. The processes for this assessment are summarised below:

• Process 1: Problem Formulation • Process 2: Tiered Risk Assessments • Process 2a.1: Level 1 Coarse Assessments • Process 2b: Stages of Risk Assessments • Process 2a.2: Prioritisation of Risk • Process 2a.3: Assess need for a Part 1 Level 2 Intermediate Assessments • Process 2a.4: Assess need for a Part 2 Level 3 Detailed Assessments • Process 3: Options Appraisal

Each of the process is further subdivided into key activities or process parts which are given a specific reference number. This SFRA will follow the reference system outlined in FD2320 as closely as is practical for the remit of this assessment.

Page 11 1 Process 1: Problem Formulation

1.1 Objectives of the Local Development Framework Core Strategy

The Penwith District Core Strategy sets out the spatial strategy objectives of planning policy for the district up to 2026. It is the key document in the new LDF system which provides the policy framework to guide and inform in the preparation of all subsequent Local Development Documents (LDDs) concerning the appropriate location of new housing development allocations in the towns and villages of the district for the next 20 years.

1.2 Objectives of the SFRA

This Level 1 Coarse Assessment is required by PPS25 to identify the extent of flood risk in the administrative area of the district in order to enable the local planning authority to identify appropriate sites for allocated development following the Sequential Test. This evidence base will inform in the preparation of the LDF and identify areas where future requests to the Environment Agency for site specific Flood Risk Assessments (FRAs) may be required. This assessment takes account of current flood risk and the possible future risk on development using evidence from the latest forecasts of the impact of climate change on increased sea levels, peak rainfall and peak river flows in the district.

1.3 Boundaries of the Assessment

The development plan period for the LDF covers the next 20 years from 2007 -2026. The SFRA covers the whole administrative area of the district from 2007 – 2026. The SFRA is to inform on the preparation of the LDF at a strategic level on issues relating to flood risk and proposed development, identifying where specific proposals will require further intermediate or detailed assessment. An overview of district wide flood risk indicators are outlined below (See Table 4).

1.4 Controlling Factors of the SFRA

The principal controlling factors of the SFRA include a number of issues relating to sustainable flood and coastal erosion management which can be applied to spatial planning:

• the location of existing and proposed development outlined in the emerging LDF; • the legislative requirements of planning guidance PPS1, PPS12 and PPS25; • delivering the objectives of Sustainability Appraisal for risk management in considering the economic costs and benefits of proposals in terms of reducing flood risk to people and assets, the economy and the environment. • the impact of climate change and the location of development; • the protection and enhancement of the natural environment and BAP priority habitats, identifying existing risk and possible opportunities for biodiversity gain; • the integration of objectives in existing catchment and coastal management plans (CFMPs and SMPs) with the objectives of the SFRA; • engagement with stakeholders affected by the SFRA: Penwith District Council as the Local Planning Authority and as the Local Drainage Authority; the

Page 12 Environment Agency as the principal advisory authority on flood risk issues; businesses and members of the public located in the district area.

1.5 Conceptual Model

Within the authority area all forms of flooding have occurred at varying degrees depending on location of site in regards to identified Source/Pathway/Receptor components. The S-P-R component refers to: Sources of a flood, such as rain, river, surge or wave; Pathway, the flood extent in terms of fluvial or coastal floodplain or overland flow; and the Receptor, the identified recipient of the flood hazard which includes people, assets or habitat. The baseline conditions for the SFRA will comprise of the current flood zones 1, 2 and 3 and a projected forecast of the potential impact of climate change. The SFRA will identify potential consequences of flooding in terms of area vulnerability to the following flood risk components:

• Fluvial floodplains • Tidal floodplains • Fluvial and tidal operating in combination • Estuaries and beaches • Flood defences and alleviation schemes (coastal and fluvial) • Surface water runoff from existing and proposed developments • Surface water runoff from rural sources (field runoff) • Local sewage system deficiencies • Flooding from artificial drainage systems • Groundwater flooding

Page 13 2 Process 2a: Tiered Risk Assessment

The risk based approach of applying the sequential test requires a strategic understanding of current flood risk across the authority area. For a Level 1 Coarse Assessment this analysis will usually take the form of a qualitative assessment of identified risk components based on existing information.

2.1 Process 2a.1 Level 1 Coarse Assessment

The Level 1 Coarse Assessment of flood risk in the towns and villages of Penwith is provided in tables 5 below with accompanying maps in Appendix A. The level of detail required of this assessment, to determine whether a flood risk screening study of the district or a qualitative assessment is appropriate, is dependent on the answers to the following questions:

• What is the probability of flooding in the absence of defences across the Local Planning Authority area (high/medium or low)? • What proportion of area with high flood probability is already taken up by development, which is therefore at risk ? • What is the probability of inundation with existing flood defences across the Local Planning Authority area (significant, moderate or low)/ • How much new development is required in the Local Planning Authority area?

2.2 Guidance from the R & D report FD2320/TR2 advises that the above questions can be answered for a Level 1 assessment in the form of the following table (4):

Table 4. Flood Risk Indicators for Penwith District No Question Area (km2) % of Area 1 Size of district 304 2 Area in Zone 3 (High flood risk) 8.6 2.82% of total area 3 Area in Zone 2 (Moderate flood risk) 9.5 3.13% of total area 4 Existing development in Zone 3 0.7 8.13% of Zone 3 5 Existing development in Zone 2 0.9 9.47% of Zone 2 6 Area of Zone 3 that is protected N/A % of Zone 3 7 Total developed area 12.5 5.6% of total area 8 Required new development 2.5 0.82% of total area 9 Likely new development in Zones 3 N/A % of Zones 3 and 2 and 2 10 Area affected by drainage problems 6.5 2.1% of total area 11 Area affected by groundwater flooding N/A % of total area 12 Area affected by overland flows 6.5 2.1% of total area Source: GIS desktop survey

2.3 Flood Risk Indicators (FRIs) are measurable attributes to help determine levels of overall flood risk in the study area including: the identification of existing and

Page 14 predicted sources of flood hazard; exposure of existing and proposed development in pathway areas; and the vulnerability or receptor status of such development. The FRIs suggest that the Coarse 1 Assessment only requires a screening study

Flood Risk Screening Study

Table 5 – Flood Risk Screening Study Settlement Flood Identified areas Source of Where new Allocated Zone & of flood risk: flood risk: windfall development Drainage Receptors Primary and development requiring a Strategy Secondary will add to Level 2 Catchment Hazards flood risk Assessment Main Towns Penzance Zone 2 & 3 Wherrytown, High tide and Proposals in Local Plan Morrab Road , storm surge low lying Proposal H- Brighton Terrace, areas of tidal C allocated Abbey Slipway , catchment site at Jennings Street , (Western Jewsons, the Harbour Quay, Promenade Old Coal Yard the Harbour Car and the and the Park, Chyandour harbour area) Builders Yard Square Zone 2 & 3 Love Lane, Overtopping Proposals in Alexandra of River low lying Gardens, Lariggan areas of the - Mennaye fields, Lariggan & Castle catchment Horneck Road Zone 2 & 3 Chyandour Overtopping Proposals in Square, of Chyandour low lying - Chyandour Brook areas of Coombe, catchment Newlyn Zone 2 & 3 Newlyn Harbour, High tide and Proposals in Penpons Close, storm surge low lying The Strand, Jack areas of tidal - Lane, Tolcarne catchment and Newlyn Sea Front Zone 2 & 3 Stable Hobba Overtopping Proposals in and Newlyn of Newlyn low lying area - Coombe Coombe River Zone 1. No Church Street, Surface Proposals in Local Plan significant Chywoone Hill water field low lying area Proposal H-E, flood risk Road, Tredavoe runoff and Chywoone identified and Chyvellas sewer Hill Close surcharge

Page 15 Settlement Flood Identified areas Source of Where new Allocated Zone & of flood risk: flood risk: windfall development Drainage Receptors Primary and development requiring a Strategy Secondary will add to Level 2 Catchment Hazards flood risk Assessment Hayle Zone 2 & 3 Loggans Cross, Overtopping Proposals in Yellow Penmare, Love of Angarrack low lying area Lane, Marsh Stream and of Angarrack - Lane, Guildford Loggan's Mill catchment Road and Leat Beatrice Terrace Zone 2 & 3 Commercial Pluvial Proposals in Road Surface low lying - Water runoff areas Zone 2 & 3 Foundry Square Combined Proposals in tidal and low lying area fluvial and of Mellenear overtopping Stream and - from the tidal Mellanear catchment Stream Zone 2 & 3 North Quay, East Tidal and Proposals in Allocation in Quay & South Storm Surge low lying area Local Plan Quay of tidal Proposal TV- catchment D St Ives Zone 2 & 3 Wharf Road, Tidal and Proposals in High Street & St Storm Surge low lying area Yellow - Andrews Street of tidal catchment Zone 2 & 3 Hellesveor Moor, Overtopping Proposals in Local Plan Yellow Higher Stennack, of Stennack low lying area Proposal H-J The Stennack, Stream and of the Housing Chaple Street, Surface Stennack Allocation at Gabriel Street, Water Runoff catchment Old Stennack Bedford Place, Drill Ground St Andrews Street and Tregenna Place Carbis Bay Zone 2 & 3 Carninney Lane, Overtopping Proposals in Polwithen Drive of Carbis low lying area and St Ives Road Water of Carbis - Stream Water catchment Zone 1. No St Ives Road, Pluvial, Proposals in significant bottom of surface low lying - flood risk Longstone Hill water runoff areas identified and ponding

Page 16 Settlement Flood Identified areas Source of Where new Allocated Zone & of flood risk: flood risk: windfall development Drainage Receptors Primary and development requiring a Strategy Secondary will add to Level 2 Catchment Hazards flood risk Assessment St Just Zone 1. No Fore Street and Pluvial Proposals in significant Bosorne Road surface low lying flood risk water runoff, areas - identified sewage surcharge Village with a range of facilities Madron Zone 1. No Frogmoor, significant property flooded, - - - flood risk cause identified undisclosed Heamoor Zone 2 & 3 Parc Mellan, Overtopping Proposals in Treneere Lane & of Chyandour low lying area - Joseph Lane Brook of Chyandour catchment Gulval Zone 2 & 3 Trevarrack Overtopping Proposals in (Trevarrack) Place, Pendrea, of low lying area Chycornick Ponsandane of Terrace, Brook, tidal Ponsandane Trythogga Road, and Storm catchment - Branwell Lane & Surge and Eastern Green Surface Roundabout Water Runoff (A30) Ludgvan Zone 2 & 3 B3309 and 4 Overtopping Proposals in (Lower properties of Ludgvan low lying area - Quarter) Stream of Ludgvan catchment Crowlas Zone 2 & 3 A30, Church Overtopping Proposals in Square, Chapel of Red River, low lying area Road and surface of Red River - Rospeath water and catchment field runoff Long Rock Zone 2 & 3 A30, Long Rock Overtopping Proposals in Roundabout, of Long Rock low lying area Safeway, the Stream and of Long Rock Mini Roundabout Tidal and Stream and - , Riverside and Storm Surge tidal Sea View and Surface catchments Cottages Water Runoff

Page 17 Settlement Flood Identified areas Source of Where new Allocated Zone & of flood risk: flood risk: windfall development Drainage Receptors Primary and development requiring a Strategy Secondary will add to Level 2 Catchment Hazards flood risk Assessment Marazion Zone 2 & 3 Green Lane to Tidal and Proposals in Car Park and Storm Surge low lying area Marazion sea and of Marazion - front Overtopping River and of Marazion tidal River catchments Goldsithney Zone 1. No Primrose Hill Field runoff significant - - flood risk identified St Buryan Zone 1. No significant - - - - flood risk identified Pendeen Zone 1. No significant - - - - flood risk identified Lelant Zone 2 & 3 Old Court House, Overtopping Proposals in Waterside of Lelant and low lying area Cottage access Nance of Lelant bridge, Streams Stream and Trevarrack, the Nance - Old Pottery, Stream Trevacroft Wood, catchments Lelant Roundabout and Griggs Quay St Erth Zone 2 & 3 Church Street, Overtopping Proposals in Little Mill Lane of Hayle low lying area and Chenhals River, of Hayle River - Lane surface and catchment field runoff Connor Zone 1. No A30 and Overtopping Proposals in Downs significant Blacksmiths of stream low lying area - flood risk Lane (outside and field of river identified settlement area) runoff catchment Nancledra Zone 2 & 3 Nancledra Bridge Overtopping Proposals in of Red River low lying area - of Red River catchment

Page 18 Settlement Flood Identified areas Source of Where new Allocated Zone & of flood risk: flood risk: windfall development Drainage Receptors Primary and development requiring a Strategy Secondary will add to Level 2 Catchment Hazards flood risk Assessment Village with limited - facilities Mousehole Zone 2 & 3 Sea front (tidal), Tidal and Proposals in Mousehole Lane, Storm Surge, low lying area Duck Street, Surface of Paul North Street and Water runoff, Stream, - Fore Street overtopping Tumble Tyn (fluvial) of Paul and Stream and Tumble Tyn the tidal Streams catchments Paul Zone 2 & 3 Bryher Barn, Paul Stream Proposals in Trevithal Farm Overtopping, low lying area Cottage field runoff of the Paul - and sewer Stream system catchment surcharge Newbridge Zone 2 & 3 Properties Overtopping Proposals in adjacent to of Bosullow low lying area - stream Stream of stream catchment Trewellard Zone 1. No significant - - - - flood risk identified Sennen Cove Zone 2 & 3 Sea front (tidal) Tidal and Proposals in & Old Success Storm Surge, low lying area - Inn (drainage Surface surcharge) Water runoff Sennen Zone 1. No Churchtown significant - - - - flood risk identified Porthcurno Zone 2 & 3 Various Overtopping Proposals in properties of low lying area - Porthcurno Stream Phillack Zone 1. No significant - - - - flood risk identified

Page 19 Settlement Flood Identified areas Source of Where new Allocated Zone & of flood risk: flood risk: windfall development Drainage Receptors Primary and development requiring a Strategy Secondary will add to Level 2 Catchment Hazards flood risk Assessment Relubbus Zone 2 & 3 Stonehouse, the Overtopping Proposals in Old Post Office, of Hayle low lying area Chy-an-Dowr River , of the Hayle and Oatley Surface River - water runoff catchment from B3280 and groundwater Perranuthnoe Zone 1. No Village Pluvial Field Proposals in significant runoff low lying - flood risk areas identified Rosudgeon – Zone 1. No Perran significant - - - - Downs flood risk identified Cannonstown Zone 2 & 3 Rose-an-Grouse Overtopping Proposals in of St Erth low lying area Stream of St Erth - Stream catchment Angarrack Zone 2 & 3 Nanpusker Overtopping Proposals in Bridge, Hatches of Angarrack low lying area Hill and WWTW Stream of Angarrack - Stream catchment Carnhell Zone 1. No Village Surface Proposals in Green significant water runoff low lying - flood risk areas identified Wall - Zone 1. No Reawla significant - - - - flood risk identified Village of special character Gulval Zone 1. No Churchtown significant - - - - flood risk identified

Page 20 Settlement Flood Identified areas Source of Where new Allocated Zone & of flood risk: flood risk: windfall development Drainage Receptors Primary and development requiring a Strategy Secondary will add to Level 2 Catchment Hazards flood risk Assessment Ludgvan Zone 1. No Churchtown significant - - - - flood risk identified Sancreed Zone 1. No Churchtown significant - - - - flood risk identified Lamorna Zone 2 & 3 Oak Hill Bridge Lamorna Proposals in (fluvial) and Stream low lying area Lamorna Cove overtopping - (tidal) and Tidal and Storm Surge Treen Zone 1. No significant - - - - flood risk identified Gwinear Zone 1. No Churchtown significant - - - - flood risk identified Gwithian Zone 1. No 3 properties Pluvial Churchtown significant Surface - - flood risk Water Runoff identified Zennor Zone 2 & 3 Museum & car Overtopping Churchtown park of Zennor - - Stream Halsetown Zone 1. No significant - - - - flood risk identified Other villages Bojewyan Zone 2 & 3 Ponds Hill, St Overtopping Proposals in Ives Road of Portherras low lying area - Stream Tregeseal Zone 2 & 3 Village and Overtopping Proposals in Higher Bostraze of Tregeseal low lying area - Farm Stream

Page 21 Settlement Flood Identified areas Source of Where new Allocated Zone & of flood risk: flood risk: windfall development Drainage Receptors Primary and development requiring a Strategy Secondary will add to Level 2 Catchment Hazards flood risk Assessment Gwallon Zone 2 & 3 Gwallon Leat Overtopping Proposals in Cottage of Gwallon low lying area - Leat Cockwells Zone 1. No Various Field runoff & Proposals in significant properties and surface low lying area - flood risk A30 water runoff identified from road White Cross Zone 1. No Various Field runoff & Proposals in significant properties and surface low lying area - flood risk A30 water runoff identified from road Sand Sifter Zone 2 & 3 Access Road Overtopping Proposals in of Red River, low lying area tidally impeded Griggs Quay Zone 2 & 3 The Causeway Overtopping Proposals in of Hayle low lying area River and High Tide with Storm Surge Hayle Area Zone 2 & 3 Golden Sands Overtopping Proposals in Caravan Park of Angarrack low lying area and Trehayle Stream Parc Nancledra Zone 2 & 3 Ninnes Bridge Overtopping Proposals in Area of St Erth low lying area Stream Source: GIS desktop study and FRIS data supplied by the Environment Agency

Page 22 3 Process 2b: Stages of Risk Assessment

Process 2b1: Hazard Identification

3.1 The DEFRA/EA R & D Technical report FD2320/TR subdivides this process into five sub processes. For the purpose of this SFRA, Process 2b is assessed in two sections, process 2b1: Hazard Identification and Processes 2b2-2b5: Consequence and Significance of risk.

3.2 Process 2b1: Hazard Identification is broken down into four stages of risk assessment and comprises:

• Identification of sources • Identification of pathways • Identification of Receptors • Identification of Primary and Secondary Hazards

3.3 Each of these four stages are to be used to identify the source-pathway-receptor of hazards derived from all the types of flooding hazard outlined in paragraph 1.5 above, which describes the conceptual model for the SFRA. Table 6 outlines a summary of fluvial and tidal risk. Elements of the rest of the conceptual model are dealt with individually in the rest of the section.

Table 6 – Hazard Identification Source Zones 2 – Zones 3 – Developed Developed Settlement Pathway Pathway in zone 2 – in zone 3 – (m2) (m2) Receptors Receptors (m2) (m2) 1. Fluvial Flood Plains Roseworthy 1,433,034 18,814 Roseworthy Catchment Angarrack 1,255,007 486,445 124,992 59,342 Angarrack and Catchment Hayle Mellanear 82,752 72,634 20,404 Hayle Stream Lelant Stream 55,952 53,183 7,449 Lelant Nance Stream 184,415 167,497 13,091 7,648 Lelant Hayle River 1,448,251 1,353,043 47,275 St Erth, Catchment Relubbus and Canonstown Carbis Water 56,239 24,729 Carbis Bay Stream Stennack 163,262 106,143 115,943 58,823 St Ives Stream

Page 23 Source Zones 2 – Zones 3 – Developed Developed Settlement Pathway Pathway in zone 2 – in zone 3 – (m2) (m2) Receptors Receptors (m2) (m2) Zennor Stream 82,007 67,837 2,061 Zennor Porthmeor 11,708 10,784 - Stream Portherras 109,687 102,766 3,291 Bojewyan Stream Nancherrow 192,757 183,846 33,171 Tregeseal Stream Cot Valley 79,591 9,739 Stream Nanquidno 50,250 2,597 Stream Bosistow 13,114 Stream Porthcurno 40,644 8,449 Porthcurno Stream Penberth 296,140 291,463 8,165 Catchment Trevedran 8,449 - Stream Lamorna 445,115 432,235 5,974 Lamorna Cove Catchment Paul Catchment 92,307 20,949 Paul and Mousehole Newlyn Coombe 871,027 858,432 52,829 Newbridge, Catchment Drift, Buryas Bridge and Newlyn Lariggan 323,855 269,413 84,165 47,916 Penzance Catchment Chyandour 200,888 195,891 40,425 Heamoor and Brook Penzance Catchment Ponsandane 461,041 123,572 Gulval and Catchment Eastern Green Long Rock 44,756 8,963 Long Rock Stream Marazion 1,676,561 1,597,221 91,121 90,862 Lower Quarter Catchment (Ludgvan) and Crowlas

Page 24 Source Zones 2 – Zones 3 – Developed Developed Settlement Pathway Pathway in zone 2 – in zone 3 – (m2) (m2) Receptors Receptors (m2) (m2) 2. Tidal Floodplains Hayle Harbour 82,752 9,308 17,296 Hayle St Ives Sea 27,691 6,481 2,722 St Ives Front Mousehole 6,500 3,231 131 Mousehole Harbour Newlyn Sea 29,229 16,217 5,352 3,751 Newlyn Front Penzance Sea 71,884 24,306 6,071 3,478 Penzance Front Long Rock 42,115 4,284 Long Rock Rondabout (West) Marazion Sea 49,992 32,957 1,438 Front Source: GIS desktop survey

Fluvial Flood Risk

3.4 The primary causes of flood risk in the study area is from river and tidal flooding. River or fluvial flooding is often caused by the inadequate capacity to channel water flow through a flood plain. Also areas of the district are at risk from high tides because they are situated on relatively low lying land near the coast or an estuary. This is called tidal flooding. Coastal and surface water drainage are also causes of flooding and are key issues that need to be identified and addressed within the scope of this assessment.

3.5 The fluvial catchment areas in the SFRA area can be divided into three distinct drainage areas; the Lands End Streams, the Mounts Bay Streams, and the Hayle Estuary Streams. The major urban concentrations in the district are: St Ives (effected by the Lands End Streams); Penzance/Newlyn, and Long Rock/Crowlas (effected by the Mounts Bay Streams); and Hayle/Angarrack/Lelant (effected by the Hayle Estuary Streams). Table 7 outlines the main river catchments in the SFRA area.

Table 7 – River Catchment Areas in Penwith River Catchment Area Drained Upstream of; Area Drained km2 Lands End Streams Tidal Limits 128.5 Mounts Bay Streams Tidal Limits 153 Hayle Estuary Streams Tidal Limits 55.5 Source: Table 2: West Cornwall Consultation Report, June 1997.

Page 25 3.6 The management of the inland watercourse within the SFRA study fall within the remit of the Environment Agency and Penwith District Council. The Environment Agency currently manage the four designated 'main' rivers of the district. (Table 8)

Table 8 – 'Main' Rivers Flood Defences (m2) River Section Environment Local Authority Private Standard of Agency and County Protection Council Chyandour 135 78 60 1 in 150 Stream from Chyandour Square to outflow Hayle River from 5,382 38 654 2 in 100 Relubbus to outflow Angarrack 2,386 302 370 5 in 200 Stream from Angarrack village to Copperhouse Pool floodgate Mellinear Stream 41 105 59 2 in 100 from Mill Pond sluice gate to sewage syphon at outflow Source: West Cornwall Catchment Flood Management Plan, Scoping Report (January 2006).

3.7 In April 2005 the Environment Agency en-mained (upgraded the status to 'main') of fourteen Critical Ordinary Watercourses (COWs) in the district and transferred the management responsibility to the local authority by memorandum of Agreement. (See Table 9 below). Critical Ordinary Watercourses are ordinary watercourses identified as presenting potential flood risk to people and property. Management responsibilities for the en-mained watercourses include maintenance of channel and screens to prevent blockages and debris collection (twice a year) with screen attendance (weekly in the summer and fortnightly in the winter) and annual maintenance checks to culverts and associated flap valves (operational delivery). In addition to the en-mained watercourses, the local authority has to maintain stretches of inland watercourse within their 'riparian ownership), Under the Land Drainage Act 1991 all landowners whose property adjoins an inland watercourse are required to manage the said watercourse as being the responsible riparian owners.

Page 26 Table 9: En-mained Watercourses Managed by Penwith District Council River Name Length of Condition 0f Improvement Actions watercourse channel & (m) culvert Lengths Lelant Stream Culverted: 40m Condition 3 1.Enforcement by Old School Open: 520 (1 Screen) studio, Abbey Hill. COW: 560 2.Improvement to screens. Nance Stream Culverted: 20m Condition 3 1. Review upon CCTV survey Open: 2140m (0 Screens) results. COW: 400m Carbis Bay Culverted: 140m Condition 3 1. De-silt reach U/S of screen in Stream Open: 1520m (3 Screens) Carbis Valley. COW: 1660 2. Improvement to screens. Stennack Stream Culverted: 600m Condition 3 1. Refer to Capital Scheme. Open: 1900m (4 Screens) 2. If no scheme screen COW: 2500m improvements. Relubbus Brook Culverted: 10m Condition 3 1. Improvement and clearance to Open: 490m (0 Screens) highway culvert. COW: 500m Red River Culverted: 55m Condition 3 1. Dredging of channel. (Crowlas) Open: 6265m (0 Screens) 2. Improving raised bank. COW: 670m Long Rock Brook Culverted: 50m Condition 3 1. Improvement to screen. Open: 465m (1 Screen) 2. Improvement to culvert. COW: 515m Ponsandane Culverted: 30m Condition 3 1. Improvement to screen. Brook Open: 1420m (1 Screen) COW: 1450m Chyandour Culverted: 50m Condition 3 1. Improvement to screens. Stream Open: 2566m (1 Screen) 2.De-silt watercourse adjacent to COW: 2000m screen d/s from Polmere Road.

Larrigan River Culverted: 340m Condition 3 1. Improvement to screen on Open: 2100m (1 Screen) foreshore. COW: 2440m

Page 27 River Name Length of Condition 0f Improvement Actions watercourse channel & (m) culvert Lengths Newlyn Coombe Culverted: 15m Condition 3 None. River Open: 1435m (1 screen) COW: 1450m Paul Stream Culverted: 300m Condition 3 1. Improvement to screen. Open: 930m (1 screen) 2. Possible re-sewering of Tumble COW: 1230m Tyn Drain. Tumble Tyn Culverted: 220m Condition 3 1. Review upon CCTV survey Brook Open: 510m (2 Screens) results. COW: 730m 2. improvement to screens. Tregeseal Culverted: 20m Condition 3 None Stream Open: 2680m (0 Screens) COW: 1040m Note: All of the above en-mained watercourses are subject to the Environment Agency requirement for Public Safety Risk Assessment at extant screens, Generic and Dynamic Risk Assessments with an annual inspection and report.

Fluvial Flood Defences

3.8 Development proposals situated in proximity to flood defences must be assessed to ensure that the development does not have an adverse effect on the standard of protection afforded by the flood defence structure(s). It is essential that Flood Risk Assessments investigate the standard of protection of relevant flood defences, as the standard may have decreased since its construction. This may occur due to development since its construction or due to the potential impact of climate change to the flood risk. This will ensure that the proposed and adjacent developments and will have the appropriate standard of protection from the flood defence.

Table 10 - Fluvial Flood Defences River Fluvial Flood Defence Newlyn Coombe Stream Newlyn Coombe Chyandour Stream Chyandour Ponsandane Brooke Eastern Green (Ponsandane Bridge) Long Rock Stream Long Rock Hayle River Relubbus to St Erth Mellanear Stream Foundry (Hayle) and upstream of Mill Pond Angarrack Stream Angarrack to Ventonleague (Hayle) River Stennack Trenwith to Higher Stennack (St Ives) Source: Environment Agency Floodmap

Page 28 3.9 The Environment Agency is responsible for building and maintaining coastal and designated 'main' river flood defences and has overall supervisory role over all flood defences in England. Local authorities also have the power to undertake flood defence works on watercourses not designated as 'main' rivers (under the 1991 Land Drainage Act) and flood defences to prevent coastal erosion if a designated maritime district authority (under the Coast Protection Act 1949). In the West Cornwall Catchment there is approximately 58.1 km of defended river length along designated 'main' rivers. Table 10 above outlines the current fluvial river defences maintained by the Environment Agency, the Local Authority and privately. The lengths are given in metres.

Coastal Flooding and Sea Defences

3.10 Coastal flooding occurs when high tides combined with extreme weather conditions create wave energy strong enough to overtop sea defences, causing flooding to adjacent low lying land. Flood damage can also be caused by wave energy directly where sea defences prove inadequate or are nonexistent.

SMPs and the Planning Framework

3.11 The planning system exercises an important influence over the way the coastline is conserved or developed through strategic development plans and development control. Planning policy in the new Local development Framework (LDF) must be determined against both statutory documents such as Planning Policy Statements and certain non-statutory documents where relevant. Shoreline Management Plans (SMPs) are high level documents which although not statutory, are informed by policies in statutory development plans. The role of SMPs in the planning framework is twofold: to inform the statutory planning process; and to plan for future coastal defence management. The two principle issues addressed by the SMPs relate to: coastal defence, planning for the protection of property situated along the present shoreline; and coastal planning, in regards to possible setback due to coastal erosion or sea advance and long term suitability of certain developments along the coast. The SMPs inform the statutory planning process on issues relating to:

• areas at risk of erosion; • areas at risk of flooding; • sea level rise and its implications; • the protection of vulnerable coastal habitats; • offshore dredging and the disposal of spoil; • deterioration of natural and man made sea defences.

3.12 It is important that SMPs feed into the new LDF process ensuring that inappropriate development does not occur in areas at risk from flooding or erosion, both now and in the future. The Planning Policy Statement 25 in effect makes SMPs a material consideration for planning guidance when assessing future coastal development proposals. The peninsular coastline of Penwith is divided between two SMP catchment areas.

Page 29 Flood and Erosion Risk on the South Coast

3.13 The south coast of the district from Cudden Point to Lands End is covered by Lizard Point to Lands End SMP. The south coast of the SFRA area can be divided into three distinct erosion zones, east, central and west:

• The eastern zone covers the area from Cudden Point to Marazion and suffers from the most significant erosion rate in the district. Along this stretch of coast unprotected cliffs are eroding at a rate of up to 0.5m per year; • The central zone covers the area of Mounts Bay which includes the most significant developed area in the district (Penzance/Newlyn, Eastern Green, Long Rock and Marazion) and the low lying area of Marazion Marsh. The SMP anticipates that the erosion rate in this zone is unlikely to exceed 2m over the next century; • The western zone incorporates the rest of the southern coast to Lands End, which is a predominantly granite coastline which (like the rest of the granite headland of West Penwith) contributes little to the sediment budget. Therefore coastal erosion is not of concern in this zone.

3.14 SMPs divide the coastline into manageable stretches called Management Units, which are further subdivided into Implementation Lengths. Table 11 lists all of the Management Units along the south coast of the district, highlighting where action against erosion and flood risk have been identified by the SMP.

Table 11 – Flood Risk Summary of the South Coast Management Unit and Threat/Defence Strategic Option and Implementation Length Preferred Strategy 8 Cudden Point to Greeb Length 2 Porthpean Beach Defended length backing Retreat or do nothing several properties at risk unacceptable as it will lead to from cliff (6-7m high head) loss of built assets. erosion. Local authority rock armoured defence around slipway. Perran sands eroding at average rate of 0.51m/year with a peak rate of 0.66m/year. Also threat to rear access road. 9. Greeb to St Michael's Mount Length 2 Defended length Privately defences owned by Hold the line along defended east of Venton Cove St Aubyn's Estate. Two frontage. Do nothing along Length 4 Marazion Frontage threats identified: 1. Retreat undefended lengths, monitor of low water mark effecting foreshore levels and cliff Length 5 Harbour Area of St access and habitat at St erosion rate to justify future Michael's Mount Michael's Mount. 2. defence works. Continued erosion of cliffs to east of Marazion is likely to cause damage to property.

Page 30 Management Unit and Threat/Defence Strategic Option and Implementation Length Preferred Strategy 10. Chapel Rock to Penzance Harbour Length 1 west Marazion Defence owned by St Hold the line policy along defended frontage (Chapel Aubyn's Estate but defended length to protect Rock to end of defence. maintained by PDC & CCC transport link (railway, A30 Length 3 Defended frontage Defence owned by St Aubyn corridor and heliport) and from Marazion Marsh to Estate from Marazion dunes development backing Penzance to railway pedestrian defences. Need to monitor crossing. From the crossing foreshore to prevent potential to before Penzance Station undercutting of defences. defences owned by PDC. The final 400 yard section is owned by Railtrack. Length 2 Marazion Marsh Undefended shore line with Hold the line through dune remnant dune system of management fronting botanical interest. Marazion Marsh.

11. Penzance Harbour to Newlyn Harbour One Length Defended PDC maintained defence. Do nothing or retreat the line frontage between and Weakest line in defence policy unacceptable. Hold incorporating the two identified at west Promenade the line strategy and monitor harbours. section. foreshore to prevent undercutting. 12. Newlyn Harbour to Carn Du Length 1 Newlyn Harbour to Privately owned defences at Hold the line of defended Penlee Point Mousehole. 300M long frontage to protect built Length 2 Defended frontage revetment wall south of assets and roads. Do of Mousehole Newlyn c.1920, anticipated nothing along undefended life span of 5-10 years. frontage Erosion of foreshore to south of Newlyn Harbour threaten undermining of defence. 13.Carn Du to Gwennap Head Length 2 Lamorna Quay and Privately owned defences. Hold the line, any retreat the defended frontage line or do nothing unacceptable. 14. Gwennap Head to Lands End One Length No defences, one developed For this area the only viable site at Lands End tourist policy is of non intervention. attraction site. Only threat Do nothing to maintain located at Carn Les Boel environmental and geological earthworks (SAM) erosion of interest in the area. the inlet threatens to cutoff the site. Source: Lizard Point to Lands End Shoreline Management Plan.

Page 31 Flood and Erosion Risk on the North Coast

3.15 The north coast of the district from Lands End to Fish Cove is covered in the Lands End to Hartland Point SMP. Table 12 below is a summary of the management units covered in this SMP relating to the northern coast of the SFRA study area. The northern coast can be divided into two main areas relating to coastal processes. The western zone consists of the rest of the coastline following the granite headland of West Penwith from Lands End to Clodgy Point just before St Ives. There are no problems relating to erosion along this section. The rest of the coastline is incorporated into St Ives Bay and represents the eastern zone, characterised by large stretches of sandy beaches and sand dune systems. Although there are isolated problems relating to coastal erosion in this zone, on the whole sediment accretion is the defining problem.

Table 12 – Flood Risk Summary of the North Coast Management Unit and Threat/Defence Strategic Option and Implementation Length Preferred Strategy 7A-1 Western Zone: Lands Little coastal development along this stretch of coast with End To Clodgy Point the exception of Sennen Cove. Lands End to Sennen One Length Sheer cliffs with no Do nothing as no assets at development exposed below risk and important natural the coastal shelf. habitats need to be maintained. Sennen Cove to Whitesand Bay Length 1 Sennen Cove Defended frontage to Hold existing defence line. development. Some risk Do nothing or retreat from overtopping to adjacent unacceptable. Need to built assets. maintain defences from degradation which would threaten the road. Length 2 Whitesand Bay Dune system over relic valley Do nothing. slope. No immediate threat. Aire Point to Clodgy Point One Length Sporadic assets along the Do nothing to maintain coast the old wheal houses biological, geological and at Botallack Head. Defences archaeological importance. present at Priests Cove and Cape Cornwall 7A-2 Western Zone: St Ives Deep concave bay with sand dominated shoreline Bay encompassing the main settlement areas of St Ives, Carbis Bay, Lelant & Hayle. Clodgy Point to Carrick Du One Length No built assets at risk. Do nothing

Page 32 Porthmeor One Length Porthmeor Defence present. Contains Hold existing line and prevent Beach commercial and residential degradation of defence assets behind defence. St Ives Head One Length St Ives Head Low erosion rate, no threat to Do nothing built assets.

St Ives Length 1 Porth Gwidden Defences current along all Maintain and hold line of Length 2 Bamaluz Cove three lengths including low existing defences to protect walls behind pocket beaches, developed assets along the Length 3 Harbour Beach coastal wall to pier, a frontage. breakwater fronting the harbour and a large sea wall backing the harbour. Carbis Bay Length 2 defended section of Defended stretches back Hold the line strategy. Do Porthminster Beach built assets. Threat of nothing or retreat the line is Length 4 defended frontage increased erosion around unacceptable. of Carbis Bay river mouth in Carbis Bay with sea level rise predictions, threatening cafe, hotel and railway line. Length 1 Pedn Olva to Undefended vegetated Do nothing in the short term, Porthminster beach huts coastal slopes. Not monitor cliff stability to Length 3 End of Porthminster considered to be at short assess justification for future defences to Carbis Bay term risk of erosion. In the defence works defences long term however it is recognised that assets Length 5 Carbis Bay including the backing railway defences to Porth Kidney line could become at risk Sands from rising sea levels Hayle Estuary Length 2 Lelant Towans to Defence structure along the Hold the line policy. Do Carnsew Pool partially interior of the estuary are nothing or retreat the line is defended frontage privately owned on the unacceptable due to risk to Length 3 Carnsew Pool to western side. The Harbour built assets and transport North Quay defended Company maintaining all the links. frontage defences on the eastern side. There is considered no immediate risk to built assets along both the undefended and defended stretches.

Page 33 Length 1Porth Kidney Sands Undefended frontage Hold the line in the short term Length 4 Harvey's Towans comprising of sand dunes to while monitoring dune the west and the east of the erosion. Undertake sand estuary mouth. Threat of dune management. May erosion to both sand dune need to relocate some systems. chalets on the east side to allow dunes to re-establish (i.e. Retreat the line in the long term may be acceptable). Hayle and Gwithian Towans Length 1 Hayle Towans Dunes form part of a natural Do nothing Length 2 Common, Phillack, defence backed by tourist and Upton Towans and residential assets. No risk identified Length 3 Gwithian Towans Length 4 Sand Extraction Defended by large man made Do nothing or retreat the line Site sand bund. is unacceptable. Length 5 Godrevy Undefended but considered Do nothing. A hold the line as low risk from erosion. policy would be unacceptable Back by National trust given the environmental and property. Possible long term historic value of the National threat to Godrevy access trust property which it fronts. road. 7A-3 Godrevy Point to Trevose Head Godrevy Point to Portreath Part of one Length Godrevy No risk to built assets in the Do nothing on environmental Cove to Fish Cove long term. grounds Source: Lands End to Hartland Point Shoreline Management Plan.

Coastal Retreat

3.16 Managed coastal retreat may be the only practical alternative to accommodating the future risk of flooding due to rising sea levels due to the effect of climate change along certain stretches of coastal flood plain. Managed coastal retreat is one option available to protecting the coastline other then where a hold or advance the line policies cease to be viable options. PPG25 notes that development on flood zone 3 adjacent to the coast should be avoided where the risk of future coastal flooding is identified.

3.17 Managed coastal retreat may require the removal or setting back of sea defences to allow for more natural forms of sea defence mechanisms to develop, such as the increase of beach material derived from eroding cliffs and the creation of dune systems and salt marshes. In this way managed coastal retreat could afford sustainable methods of flood protection while creating new biodiversity habitats at the same time.

Page 34 3.18 Only one area has been identified in the SMPs covering the district where a retreat the line strategy has been suggested as a possible long term strategy; where erosion to the dunes at Harvey's Towans to the east of the mouth of the Hayle Estuary threaten built assets. The retreat would afford the dune system to re-establish naturally. The area involved is localised to about 100m and would require the relocation of half a dozen holiday chalets.

Surface Water Run-off Flooding

3.19 This type of flooding is caused by heavy downpours of rain, when the volume of water falling or flowing onto metalled surfaces or fields is unable to soak into the ground and overwhelms the existing drainage system. This type of flooding is usually short lived but causes particular problems in urban areas where metalled surfaces (pavements, car parks, roofs and roads) force the volume of water into the drainage system in a short space of time. Drainage systems are designed to deal with specific volumes of water intake. The intensity of a heavy rainfall could easily overspill the capacity of a drainage system and cause localised flooding in low lying urban areas.

3.20 Flood risk from surface water run-off is recognised as an issue in the SFRA. Flood history records a number of surface run-off flood events associated with fluvial flooding affecting specific areas of the district. It is to be noted that the Environment Agency flood maps do not record flood risk from surface run-off flooding but PPG25 emphasises that development resulting in change of land use will effect the surface run-off dynamics of an area. Consequently Flood Risk Assessments are required to take into account the potential affect a proposed development has on surface run-off both on site and the adjacent area so that the flow rate of surface run-off from the site should remain the same as before the development. If it is found that the development will increase the surface run-off, then the installation of Sustainable Drainage Systems (SUDSs) will be required.

3.21 Penwith engineers indicate that there are no records concerning Surface Water Run- off flooding prior to the heavy storm event of 2002/03 (New Years Eve) which highlighted the problem in Crowlas and Long Rock. During the winter of 2002-2003 Crowlas suffered from eight separate flood events all attributed to field run-off from neighbouring agricultural land. Since this event however, mitigation measures for surface run-off at Crowlas and field run-off at Long Rock resolved many of the problems recognised as contributing to the flooding. The Environmental Stewardship targeting Statement for the West Penwith Joint Character Area (JCA) recognises the need to promote flood conscious forms of agricultural practice in the area of Crowlas and Marazion Marsh by making grants available for Catchment Sensitive Farming (CSF). This is also intended to address problems of diffuse pollution caused by field run-off flooding. Following the floods of autumn 2000, the Flood Hazard Research Centre (FHRC) review found that 25% of flood cases affected individual properties namely that they were not attributed to a watercourse. Based on these findings FHRC determined an economic impact model for non-fluvial flooding as being one third of that of fluvial and tidal sources. The Environment Agency FRIS incident database found that 48% of flood incidents relate to non-fluvial events in the west Cornwall Catchment Area.

Page 35 Table 13 – Flooding from Field and Surface Water Runoff Settlement Receptor Source Type of Flooding Gwithian 3 properties Heavy Rainfall Surface Runoff Hayle R/O Beatrice Terrace Inadequate Drainage Surface Runoff Love Lane Heavy Rainfall Surface Runoff Penmare Hotel Site Heavy Rainfall Surface Runoff Commercial Road Intense Rainfall Surface Runoff War Memorial Unspecified Surface Runoff St Ives Tregenna Place Heavy Rainfall Surface Runoff Stennack Inadequate Drainage Surface Runoff Windsor Hill Heavy Rainfall Surface Runoff Carbis Bay Longstone Hill Heavy Rainfall Surface Ponding Madron Frogmoor Unspecified Surface Runoff Heamoor Old Black Smith's Inadequate Drainage Surface Runoff Penzance The Ropewalk Choked Drains Surface Runoff Clarence Street Choked Drains Surface Runoff Mennaye Sewer System Surcharge Surface Runoff Lidden Road Sewer System Surcharge Surface Runoff Alexander Road Sewer System Surcharge Surface Runoff Morrab Road Sewer System Surcharge Surface Runoff Cornwall Terrace Sewer System Surcharge Surface Runoff Polweath Road Sewer System Surcharge Surface Runoff Market Jew Street Sewer System Surcharge Surface Runoff Coombe Road Sewer System Surcharge Surface Runoff Heavy Rainfall Field Runoff Tolver Road Inadequate Drainage Surface Runoff Tolver Place Drain Surcharge Surface Runoff Empress Drive Drain Surcharge Surface Runoff Rotary Boating Club Drain Surcharge Surface Runoff Liberal Club Drain Surcharge Surface Runoff Medrose Terrace Sewer System Surcharge Surface Runoff Alverton Road Sewer System Surcharge Surface Runoff Road Drainage Surface Runoff Lansdown Place Road Drainage Surface Runoff Chyandour Square Choked Drains Surface Runoff Chyandour Coombe Sewer System Surcharge Surface Runoff Heavy Rainfall Field Runoff

Page 36 Settlement Receptor Source Type of Flooding St Just Bosorne Road Sewer System Surcharge Surface Runoff Drain Surcharge Surface Runoff Inadequate Drainage Surface Runoff Church Street Sewer System Surcharge Surface Runoff Fore Street Inadequate Drainage Surface Runoff Higher Bostraze Heavy Rainfall Surface Runoff Sennen Cove Old Success Inn Road Drainage Surface Runoff Paul Road by Bryher Barn Sewer System Surcharge Surface Runoff Trevithal Farm Heavy Rainfall Field Runoff Mousehole Higher Mountain Inadequate Drainage Surface Runoff Lobster Pot Sewer System Surcharge Surface Runoff School and Lynwood Road Drainage Surface Runoff Newlyn Penpons Close Sewer System Surcharge Surface Runoff Drain Surcharge Surface Runoff Newlyn Art Gallery Sewer System Surcharge Surface Runoff Newlyn Strand Storm Drains Burst Surface Runoff Church Street Sewer System Surcharge Surface Runoff Chywoone Hill Road Sewer System Surcharge Surface Runoff Chyvellas Close Heavy Rainfall Field Runoff Tredavoe Sewer System Surcharge Surface Runoff Gulval Posses Lane Culvert Surcharge Surface Runoff Branwell Lane Heavy Rainfall Surface Runoff Sewer System Surcharge Surface Runoff Eastern Green Roundabout Heavy Rainfall Surface Runoff Long Rock Safeway Unspecified Surface Runoff Mini Roundabout Heavy Rainfall Surface Runoff Main Roundabout Strong Winds Surface Runoff St Erth Little Mill Lane Blocked Drains Surface Runoff Chenhals Lane Blocked Drains Surface Runoff Marazion Property flooded Collapsed Sewer Surface Runoff Peranuthnoe Intense Rainfall Field Runoff Goldsithney Primrose Hill Intense Rainfall Field Runoff Relubbus B3280 Road Drainage Surface Runoff Carnhell Green Unspecified Surface Runoff Cockwells A30 and Properties Heavy Rainfall Surface Runoff

Page 37 Settlement Receptor Source Type of Flooding White Cross A30 and properties Heavy Rainfall Field Runoff 2 cottages Road Drainage Surface Runoff Crowlas Church Square Heavy Rainfall Surface Runoff Village Drainage Failure Surface Runoff A30 and Village Heavy Rainfall Field Runoff Star Inn Unknown Source Surface Runoff Penlee Cottage Unspecified Surface Runoff Source: Environment Agency FRIS and Flood History data

Rapid Inundation Zones

3.22 PPS25 requires that Rapid Inundation Zones are identified in the SFRA. For the purposes of this study a rapid inundation zone is defined as an area of land which can become inundated by flood water to a depth of 30 cm within 30 minutes of the over topping or breach of a flood defence structure. Rapid inundation zones have been identified as areas behind raised defences having a standard of protection of greater than 1 in 100 years (above 1%). The area designated within Environment Agency flood zone 3 is to be regarded as a potential rapid inundation zone. Water levels could build up to a level higher than the surrounding land protected by the raised defence. If the water overtops the defence or the defence was to collapse the lower level land would become rapidly inundated by flood water causing serious risk to life. The width of such an area is determined by the potential head of water contained by the defence and structural and topographical barriers which will impede the spread of flood water.

3.23 Penwith engineers have highlighted that the greatest risk of rapid inundation in the district is situated in the low lying areas of St Ives due to surface run-off along Wharf Road.

River Erosion

3.24 River erosion occurs when the rock or soil which form the banks and bed of a river are gradually worn away. This can occur through a number of natural processes:

• Abrasion: when sediment carried in the river abrades against the river's banks and the bed causing the channel to widen and deepen over time; • Attrition: where the sediment within the river is broken down into silt due to constant collision of the material particles; • Solution: when the water of the river chemically reacts with soluble minerals in the sediment causing it to dissolve; • Hydraulic: The velocity of the river current removes sediment from the bed and banks of the channel.

Page 38 3.25 River erosion could naturally change the course of a river over a period of time. The identification of possible sites at risk from rivers changing their course is possible by studying old O.S. maps to locate areas of river which have changed their course in the intervening time.

3.26 On a strategic level this SFRA has not identified any areas at high risk from river erosion. Penwith District Council Engineers have indicated that there are no concerns relating to river erosion in the area and that there is only one instance where gabions (mesh river bank defences) are in place (Ponsandane Bridge). However, at a site specific level, developers are required to investigate the potential risk of river erosion on a proposed site in a Flood Risk Assessment. Where identified, mitigation measures must be undertaken, usually in the form of soft flood defences (such as vegetation planting) as hard defences usually create problems further downstream.

Groundwater Flooding

3.27 Groundwater flooding results from the over spilling of aquifers (underground water reservoirs). This usually occurs in areas of porous ground such as chalk, limestone, gravels and sands after periods of heavy rainfall, which fill the aquifers to overflowing. The natural cycle of groundwater spillage occurs in the winter when the aquifers fill up from winter rains activating springs and winterbournes which discharge into streams and rivers, providing regular river flow throughout the year. Exceptional periods of rain can cause groundwater to overflow from the aquifers prematurely causing inundation of the surrounding area. Groundwater flooding does not necessarily occur near rivers but does usually occur following heavy rainfall. An early indication of possible groundwater flooding is often when property cellars start to fill with water.

3.28 The Environment Agency monitor aquifer levels throughout the year, so the possible occurrence of groundwater flooding can usually be predicted well in advance of the flood event. This type of flooding is difficult to mitigate against due to the large volumes of water involved and because it is not contained or channelled. For this reason engineered flood defences cannot offer a solution. Mapping of groundwater emergence areas has potential value in monitoring the overall flood risk of this type of event at a strategic level. There are no major aquifers in the SFRA area, but the geological characteristics of the district (granite plateau and Cornish Killas), present rock forms which constitute a network of numerous minor aquifers. Most of the aquifers on the granite plateau feed into watercourses. It is recognised that some of the minor aquifers situated on the low lying land on the Cornish Killas could present risk of localised flooding on a small scale. Penwith District Engineers have no record of major incidents of groundwater flooding in the SFRA area, although two flood events of this nature are recorded in Relubbus (The Old Post Office) and Mousehole (The Ship Inn). A requirement of PPS25 is that the potential threat of groundwater flooding must be assessed in site specific Flood Risk Assessments. At a strategic level the risk of groundwater flooding is not a major problem in the district.

Page 39 Local Sewage System Deficiencies

3.29 The Environment Agency has highlighted the potential flood risk associated between new development and the increase in discharge from sewage treatment works. The limited capacities of watercourses which would receive the increased rates of discharge could be potentially overloaded, the surplus volume of polluted water will then over top the river channel and flood the surrounding flood plain.

3.30 PPS25 recognises the potential impact that development has on the existing capacity of sewage treatment outflows. Consequently Flood Risk Assessments must take into consideration the flood risk impact a development will have on existing sewage outflows. Advise must be sought from the relevant water authority to ensure that sewage treatment works maintain consented discharge volumes. It is identified in this SFRA that any significant further development in the village of St Buryan will raise issues concerning the current capacity of sewage treatment outflow.

Table 14 – Sewage Treatment Works and Consented Discharge Rates Sewage Treatment Works Consented Peak Flow Discharge Population Discharge Location Equivalent (DWF) Served Nancledra, Cripplesease 10.4 62.4 SW 3717 169 (TR20 8NB) 2170 Treen, St Buryan 11.86 71.14 SW 3930 76 (TR19 6HH) 2335 Porthgwarra, St Levan 10.4 62.4 SW 3717 9 (TR19 6JR) 2170 Tredavoe Lane, Newlyn 10.45 62.71 SW 4537 67 (TR20 8TW) 2876 Tregeseal, St Just 300 1800 SW 3675 852 (TR19 7PH) 3195 Tregeseal No 2 1,042 6,252 SW 3717 3,671 (TR19 7PH) 3490 Bosweddan, St Just 7.18 43.06 SW 4420 46 (TR19 7RG) 3100 Little Trethewey, Polgigga 8.11 48.67 SW 3820 52 St Levan (TR19 6LL) 2389 Sancreed, Newbridge 9.67 58.03 SW 4190 62 (TR29 8QD) 2980 Trevithal, Paul 11.54 69.26 SW 4620 74 (TR19 6UQ) 2670

Page 40 Sewage Treatment Works Consented Peak Flow Discharge Population Discharge Location Equivalent (DWF) Served Newbridge, Newbridge 33.54 201.24 SW 4255 215 (TR20 8QD) 3150 St Buryan, St Buryan 100 600 SW 4080 682 (TR19 6BB) 2520 Drift, Sancreed 13.57 81.43 SW 4401 87 (TR20 8QD) 2872 Treloweth Lane, St Erth 10,182.9 172,800 SW 5593 65,275 (Hayle) 4326 TR27 6EY) Churchtown Road, Gwithian 9.05 54.29 SW 5898 58 (TR27 5BX) 4169 Source: South West Water requested information

3.31 Rivers have a natural ability to render the main constituents of effluence harmless providing the discharge is regulated. Four of the largest sewage treatment works (in bold) operate with discharge consent from the Environment Agency. Dry Weather Flow (DWF) is used as a measure of gauging the consented outflow allowance for these sites. DWF makes allowance for the approximate dry weather flow of rivers in the catchment based on an average weekly rainfall of less than 2mm. Maximum peak flow rates are based on anticipated river flow in wet weather which is usually estimated at six times the level of DWF. All the other sites listed in table 12 have descriptive consents as they serve below 250 population or equivalent. For these smaller sites the estimated peak flow allowance had been estimated by multiplying the DWF flow rate by a factor of six. River flow rates for both the DWF and Peak Maximum Flow are counted in metres cubed per day. (Source of information from South West Water).

3.32 The risk to settlements from sewage discharge overflow in the district is considered to be low. All of the Sewage Treatment Works are currently operating under their consented or descriptive discharge rates. During peak river flows, Sewage Treatment Works are protected by storm flows to mitigate the risk of flooding.

Page 41 4 Processes 2b2 – 2b5: Consequence and Significance of Risk

4.1 The remainder of Process 2b: Stages of Risk Assessment, refer to processes analysing the consequences and significance of flood risk in the district in term of vulnerability, spatial scale, probability of occurrence and the comparison of current baseline data with future scenarios, namely the impact of climate change. The following processes outlined in the Defra/EA guidance FD2320/TR2 will be addressed in Table 14 below and comprises of:

• Process 2b2: Consequence Identification (AOD asset vulnerability) • Process 2b3: Magnitude of Consequences (spatial scales of consequence) • Process 2b4: Probability of Consequences (100 year flood event) • Process 2b5: Significance of Risk (current risk and impact of climate change)

4.2 The rest of this section is presented as an assessment of flood risk on the Infrastructure of the district in terms of: Community Facilities; Abstracted Water Supply; Critical Transport Links; the Critical Sewage Asset; and the Environmental Asset.

Consequence and Significance of Fluvial/Tidal Flood Risk

Table 15: Consequence and Significance of Fluvial/Tidal Flood Risk Settlement Process 2b2 Process 2b3 Process 2b4 Process 2b5 Annual Average Number of 100year flood Variance Damage (£) Properties event -1% between Affected Annual current and Probability (£) future risk Penzance 2,645,035 623 50,187,862 +43.07% St Ives 1,874,308 232 35,572,327 +49.3% Newlyn 2,651,275 200 50,302,212 0 Marazion 1,664,333 143 31,565,132 +8.53% Angarrack 1,614,001 129 30,612,681 +52.53% Crowlas 2,089,346 103 39,623,415 0 Mousehole 582,515 94 11,050,120 0 Carbis Bay 703,746 55 13,356,038 0 Source: Table 3.2 West Cornwall Catchment Flood Management Plan – Scoping Report – January 2006.

4.3 Variance between current flood risk and future flood risk has been estimated taking zone 2 boundary to be future zone 3 and comparing the developed area within zone 3 and that within zone 2 as a percentage increase of flood risk on the developed asset. Annual Average Damage (AAD) is determined on a range of frequency flood events, and is intended to give an indicative average level of damage expected in any given year.

Page 42 Consequence and Significance of Runoff and Groundwater Flooding

4.4 Unlike flooding attributed to watercourse or tidal sources, surface water source flooding is difficult to quantify in terms of the economic value of the problem. This is primarily due to the lack of information on the overall extent and frequency of occurrences. Table 16 below outlines the extent of non-fluvial flooding in the district.

Table 16 – Economic Impact of Surface Water Runoff and Groundwater Flooding No. Field Run- Highway Drainage Ground AAD Incidents off run-off water Penwith 95 6 68 19 2 5,414,690 Includes 17 2 0 15 0 968,945 Penzance & St Ives 5 0 4 1 0 284,984 Catchment 397 37 237 119 4 22,627,704 Total Source Environment Agency: West Cornwall Catchment Flood Management Plan Scoping Report (January 2006) . AAD estimated at annual average of 22 million and based on 100 year flood event damage (1% annual probability). Total damage of non-fluvial estimated at £429 million.

4.5 The consequence and significance table indicates the following:

• The principle form of flood risk in the district is derived from fluvial/tidal flooding; • That this takes the form of 1% annual probability (or 1 in 100 year flood event); • That the main settlements proposed for future development in the Core Strategy; Penzance, Hayle (Copperhouse) and St Ives are affected by flood risk; • That the net percentage increase of developed area at risk will rise by 48.3% (the average for the estimates for Penzance, Hayle and St Ives) by 2080 to 2110.

Flood Risk and Community Facilities

4.6 No community facilities within the district were found to be within the 1 in 100 year flood zone. One location was identified as being located within approximately 10 metres of the the Stennack River flood extent, namely the Stennack Surgery in St Ives (within the flood plain of the Stennack River).

Flood Risk and Abstracted Water Supplies

4.7 Fluvial flooding and surface water runoff has the potential of contaminating public serviced water supplies when overtopping their natural watercourse and inundating the surrounding floodplain. This applies to public serviced water which is abstracted from surface water and groundwater in the district. In the SFRA area South West Water have three sites where water is abstracted for public service requirements (drinking water). Table 17 below outlines the three sources.

Page 43 Table 17 – South West Water Public Service Abstraction Sites. Source Abstraction Type Daily Licensed Annual Licensed Quantity (Ml) Quantity (Ml) Drift Reservoir Surface 12.274 3,982.36 River Hayle Surface 3.64 454.6 Polteggen Well Groundwater 1.963 227.3 Note: (Ml) equals Megalitres (1 million litres). Source: West Cornwall Consultation Report 1997 (Local Environment Agency Plan).

4.8 There is little determined risk of flood contamination on the two surface abstraction sites at the Drift Reservoir and at the River Hayle. Groundwater abstraction sites in general are however prone to contamination by flooding. The underlying granite geology of Penwith does not contain any major aquifers. Granite is classed as a minor aquifer, whereby water is stored in joints and faults in the rock thus producing a limited supply of groundwater. Granites have a low permeability which allows for the rapid movement of water to refill aquifers quickly. Because of the nature of granite geology, a majority of aquifers and consequently bore holes, are situated close to rivers and streams making them vulnerable to surface water pollution, particularly during periods of flooding. The 1992 Groundwater Protection Policy Criteria (National Rivers Authority) classified granite aquifers as 'highly vulnerable' to surface water pollution. Polteggan Well is the only public groundwater abstraction site in the district, located at an aquifer which issues as a tributary of the Lariggan Stream. As the floodplain of the Lariggan Stream terminates at the sinks above where the Polteggan spring issues (outside of flood zone 2), it is considered unlikely that the aquifer itself is at risk from surface water contamination.

Flood Risk and Critical Transport Links

4.9 The risk of flooding from both the sea and rivers is a very real threat to the critical transport infrastructure of the district. During severe weather conditions overtopping from the sea and fluvial flooding have often combined to cause disruption to a number of areas in the district. The areas where the critical transport infrastructure is at highest risk is summarised in table 18 below:

Table 18 – Critical Transport Links and Potential Flood Risk Location Watersource Threat Hayle, Ventonleague Angarrack Stream B Road Hayle, Loggans Moor Angarrack Stream Primary Road Dual St Erth Hayle River C Road Crowlas Red River Primary Road Single Relubbus Hayle River C Road St Ives River Stennack B Road

Page 44 Eastern Green Ponsandane Brook Primary Road Single and Primary Road Dual Chyandour Square Chyandour Stream, the sea Primary Road Single Penzance, Promenade Overtopping A Road Sennen, Sennen Cove Overtopping C Road Source: Environment Agency Flood Zone Map

Flood Risk and Critical Sewage Assets

4.10 Consideration into the effect of potential risk from fluvial, tidal and coastal flooding will have on the critical sewage assets of the district must be taken into account to enable an assessment of the possible environmental impact this may have on the surrounding areas. The critical sewage assets include both Wastewater Treatment Works (WWTWs) and Sewage Pumping Stations (SPSs). Table 19 below summarises the critical sewage assets of the district against potential flood risk. The Historic Flood Map indicates that the WWTW in Angarrack was in close proximity to the flood extent of the Angarrack Stream in 1985.

Table 19 – Flood Risk and the Critical Sewage Asset Location Grid Reference Flood Risk St Buryan, St Buryan SW 4080 2520 None (WWTW) Sancreed, Newbridge SW 4190 2980 Little to none (WWTW) Newbridge, Newbridge SW 4255 3150 Little to none (WWTW) Drift, Sancreed (WWTW) SW 4401 2872 Little to none Little Trethewey, Polgigga SW 3820 2389 None St Levan (WWTW) Treen, St Buryan (WWTW) SW 3930 2335 None Porthgwarra, St Levan SW 3717 2170 None (WWTW) North Cliff, Mousehole (SPS) SW 4690 2640 None Trevithal, Paul (WWTW) SW 4620 2670 Little to none Roskilly, Northcliff, Newlyn SW 4690 2760 Little to none (SPS) Penlee Beach, Newlyn (SPS) SW 4660 2840 None Tredavoe Lane, Newlyn SW 4537 2876 None (WWTW) Wherrytown, Penzance SW 4660 2840 Little to none (SPS) South Pier, Battery Road, SW 4760 2990 None Penzance (SPS)

Page 45 Cyandour Beach, Penzance SW 4780 3080 Little to none (SPS) Posses Lane, Eastern Green, SW 4840 3130 Little to none Penzance (SPS) Long Rock Beach (SPS) SW 4990 3120 Little to none Green Lane, Marazion Bridge SW 5130 3120 Little to none (SPS) Car Park off Kings Road, SW 5160 3060 Little to none Marazion (SPS) Adj. Cage, St Michaels SW 5140 2980 None Mount (SPS) Chymorvah, Marazion (SPS) SW 5260 3050 None Car Park, Perranuthnoe SW 5390 2930 None (SPS) Nancledra, Cripplesease SW 3717 2170 Little to none (WWTW) Rospeath Road, Crowlas SW 5150 3280 Little to none (SPS) Gwallon Lane, Trenewjack, SW 5370 3090 None St Hilary (SPS) Relistian, Gwinear (SPS) SW 6030 3650 None Porthgwidden, St Ives (SPS) SW 5200 4090 Little to none Bussow, St Ives (SPS) SW 5012 3921 Little to none Carbis Bay (SPS) SW 5280 3870 Little to none Lelant Saltings (SPS) SW 5430 3630 Little to none Treloweth Lane, St Erth SW 5593 4326 Little to none (WWTW) Treloweth Lane, St Erth SW 5470 3580 Little to none (SPS) North Quay, Hayle (SPS) SW 5570 3770 None East Quay, Hayle (SPS) SW 5570 3760 None Hayle Towans SW 5540 3890 Little to none Churchtown Road, Gwithian SW 5898 4169 Little to none (WWTW) Tregeseal, St Just (WWTW) SW 3675 3195 Little to none Tregeseal No 2, Geevor SW 3717 3490 Little to none Mne (WWTW) Bosweddan, St Just SW 4420 3100 None (WWTW) Botallack, St Just (SPS) SW 3650 3280 None Sources: South West Water, Environment Agency various, PDC Planning records.

Page 46 Flood Risk and the Environmental Asset

4.11 PPS25 (paragraph 3) states that: All forms of flooding and their impact on the natural and built environment are material planning considerations. There are a large number of environmental conservation area constraints within the study area. Many of these areas are designated due to their wetland habitat value and so are not necessarily at risk of flooding as, by their very nature, are dependent upon regular flooding to sustain their associated fauna.

4.12 Of the environmentally protected sites 1 of the 19 SSSIs are under threat from coastal flooding. 11 of the County Wildlife Sites (areas designated of county significance for their habitat importance by the Cornwall Wildlife Trust) are at risk from coastal erosion or fluvial flooding. It is to be noted that those sites at threat from fluvial flooding are directly associated with habitats surrounding particular watercourse, being predominantly wooded stream valleys (See Table 20 below).

4.13 Flood risk mitigation also affords an opportunity to create, enhance or restore natural wetland habitats. Wetland habitats depend on regular flooding and are beneficial to coastal and fluvial floodplains for their ability to absorb rapid changes in water volume. It is therefore important that the planning mechanism recognises that the creation of new wetland habitats mitigates against flood risk and has the potential to increase the biodiversity value of the district through planning gain.

Table 20 – Flood Risk and the Environmental Asset Designation Location Risk Site of Special Cudden Point to Prussia Cove Coastal Erosion Scientific Interest Loggans Moor Fluvial Flooding (SSSI) County Wildlife Sites Lelant Sand Hills Coastal Erosion (CWS) Hayle Dune System Coastal Erosion Prussia Cove to Stackhouse Cove Coastal Erosion Stackhouse Cove to Perran Sands Coastal Erosion Trevaylor Stream Woods Fluvial Flooding Truthwall Valley Fluvial Flooding St Leven Valley Fluvial Flooding Rosemorran Stream Valley Fluvial Flooding Moorcroft, Trewoofe & Upper Lamorna Fluvial Flooding Boscawen-noon/Bejowans Valley Fluvial Flooding Rospannel, Alsia & Trevorgans Moor Fluvial Flooding Source: Penwith Local Plan Proposals Maps 2004 and Environment Agency Flood Zone Map.

Page 47 5 Process 2a2: Prioritisation of Risk

Distribution of Development in the Core Strategy

5.1 The Core Strategy identifies that development will be focused on the main towns of Penzance/Newlyn, Hayle and St Ives/Carbis Bay. The two smaller towns of St Just and Marazion and the larger villages are also assessed as being able to accommodate further development in scale with the level of facilities, services and accessibility. Development in the smaller villages, hamlets and other dispersed rural farmsteads will be limited to local affordable and employment need.

5.2 Table 13 summarizes the prioritisation of flood risk in the district, identifying where investigation will be necessary for future proposed development. As the LDF progresses, new sites will be identified for allocated housing development during the preparation of the Area Action Plans (DPDs). As these sites are identified, the Level 1 Coarse Assessment Part 1will be updated when necessary to include an analysis of flood risk on newly proposed sites.

Flood Risk and Defined Urban Areas

5.3 Table 21 presents a summary of flood risk and those urban areas identified in the Core Strategy for future development from both allocated and windfall proposals. The list comprises of the settlement hierarchy outlined in the Penwith Local Plan policies H-3, H-4, H-5 and H-6.

Table 21: Settlement Hierarchy and Flood Risk Settlement Flood River type Flood FRIS Other Flood Risk Zone Defence /Culvert Main Towns Penzance 2 and 3 En-mained and Yes Yes High Tide/Storm Surge main Pluvial Surface Runoff Newlyn 2 and 3 En-mained Yes Yes High Tide/Storm Surge Pluvial Surface Runoff St Ives 2 and 3 En-mained Yes Yes High Tide/Storm Surge Pluvial Surface Runoff Carbis Bay 2 and 3 En-mained Yes Yes Pluvial Surface Runoff Hayle 2 and 3 En-mained and Yes Yes High Tide/Storm Surge main Pluvial Surface Runoff Small Towns St Just 1 None No Yes Pluvial Surface Runoff Marazion 2 and 3 En-mained No Yes Tidal/Storm Surge Larger Villages

Page 48 Settlement Flood River type Flood FRIS Other Flood Risk Zone Defence /Culvert Madron 1 - - Yes Undetermined probably sewage surcharge Heamoor 2 and 3 En-mained No Yes - Gulval 2 and 3 En-mained Yes Yes Tidal/Storm Surge (Trevarrack) Ludgvan 2 and 3 Ordinary No Yes - (Lower Watercourse Quarter) Crowlas 2 and 3 En-mained No Yes Pluvial Field and Surface Water Runoff Long Rock 2 and 3 En-mained Yes Yes Tidal/Storm Surge St Buryan 1 - - - - Pendeen 1 - - - - Goldsithney 1 - - Yes Field Runoff St Erth 2 and 3 Main Yes Yes Pluvial Field and Surface Water Runoff Lelant 2 and 3 En-mained Yes Yes - Connor 1 - - Yes Field Runoff Downs Mousehole 2 and 3 En-mained Yes Yes High Tide/Storm Surge Pluvial Surface Runoff Groundwater Paul 2 and 3 En-mained No Yes Field Runoff Newbridge 2 and 3 Ordinary No Yes - Watercourse Nancledra 2 and 3 En-mained No Yes - Trewellard 1 - - - - Sennen Cove 2 and 3 - No Yes High Tide/Storm Surge Pluvial Surface Runoff Sennen 1 - - - - Churchtown Porthcurno 2 and 3 Ordinary No Yes - Watercourse Relubbus 2 and 3 Main Yes Yes Pluvial Surface Runoff Groundwater Perranuthnoe 1 - - Yes Field Runoff Rosudgeon – 1 - - - - Perran Downs

Page 49 Settlement Flood River type Flood FRIS Other Flood Risk Zone Defence /Culvert Canonstown 2 and 3 Ordinary No Yes - Watercourse Phillack 1 - - - - Angarrack 2 and 3 Main Yes Yes - Carnhell 1 - - Yes Pluvial Surface Runoff Green Wall - Reawla 1 - - - - Source: GIS desktop study, FRIS data supplied by Environment Agency

5.4 It is identified from tables 13 and 20 that the highest risk of flooding to development is located in the low lying areas of the main towns of Penzance, St Ives, Newlyn, Hayle (Foundry and Copperhouse) and Carbis Bay. The smaller town of Marazion and the larger villages of Angarrack, Crowlas/Lower Ludgvan, Heamoor, St Erth, Lelant and Mousehole are also recognised as locations presenting risk to current and future development.

5.5 The most significant risk of flooding is located in the low lying areas of existing settlements exposed to fluvial and tidal flooding. PPS25 advises that the effects of climate change for the South West currently suggest a predicted increase in fluvial flows (20% by 2050 and 30% by 2110) and sea level rise (250mm by 2050 and 400mm by 2080) will have a significant impact on a number of specific locations. It is recognised by this SFRA that urban expansion and infill development will necessitate the prioritization of low risk flood zone 1 sites following the procedures laid out in the Sequential Test of PPS25.

5.6 Table 5 shows that the flood risk indicators reasonably reflect the current and future situation regarding development and flood risk in the district. In addition to the indicators listed, the table is able to inform us that 8.13% of all development (0.7km2 out of a total developed area of 12.5km2) in the district is currently in flood zone 3. The overall affects of climate change will increase this percentage to 12.8% (adding current 1 in 1,000 year zone 2 development of 0.9km2 into the equation) by 2080 - 2110. These figures serve as a stark reminder that even if all future development is sited in low risk zone 1, the affects of climate change will have an immense impact on the current distribution of development in the district. This will inevitably lead to the issue of having to seriously consider the relocation of existing development and established communities to lower risk areas in the future.

5.7 Although the preferred option for development should be in zone 1, it is recognised that the strategic focus for developmentt will be in the main towns of Penzance / Newlyn, St Ives / Carbis Bay and Hayle. Development pressure in these settlements will inevitable lead to the selection of proposed sites in low lying areas at risk in zones 2 and 3 and therefore bring conflict with the sequential test of PPS25.

Page 50 Allocated Sites and Flood Risk

5.8 Penzance, Hayle and St Ives are areas identified where flood risk from fluvial and tidal storm surge is an issue with the current allocated development proposals in the Penwith Local Plan. These sites include: Alexandra Road-Western Promenade, Penzance (0.61ha); North, East and South Quays and Foundry Square, Hayle (14.9ha); and the Old Stennack, St Ives (0.26ha). All of these locations are protected by existing flood defences and flood alleviation schemes, although their defence standards will have to be reassessed against an allowance for climate change impact in the light of PPS25. Future development proposals of these sites will require a Level 2 assessment.

Page 51 6 Process 2a3: Level 2 Intermediate Assessment

Identified Need for Level 2 Intermediate Assessment

6.1 The principle purpose of a Level 2 Intermediate Assessment is to facilitate the application of the Exception Test. The Level 2 assessment will be undertaken for proposed allocation sites identified in the Core Strategy which fall within flood zones 2 or 3, as recognised in the Level 1 Assessment. The Level 2 Intermediate Assessment will identify where development in a higher risk zone may be appropriate if the overall affect of the development is deemed to have a negligible impact on the flood extent of the surrounding area of the flood cell, taking into account future affects of climate change.

6.2 The Level 2 Intermediate Assessment is an expansion of the Level 1 Coarse Assessment where the results of the latter assessment indicate that a further detailed analysis of the nature of flood hazard within a flood cell is necessary due to either:

• a high degree of uncertainty in the information available to clearly mark areas within the flood cell as being of less flood risk to enable development; or • it is apparent that development will have to take place in an area of high flood risk

6.3 The Level 2 Assessment collects more detailed information on the spatial distribution of flood risk in the flood cell where the proposal is to be located with the aim of collecting and analysing further flood risk indicators to clarify the ambiguities surrounding flood risk, as identified in the Level 1 Coarse Assessment. This level of assessment would require additional data to that used in the Level 1 Assessment, taking into account the existing flood risk management measures, such as flood defences and alleviation schemes, the use of existing models (primarily available from the EA) and undertaking hydraulic modelling to improve accuracy with the aim of:

• reducing the degree of uncertainty surrounding the clear demarcation of areas of greater and lesser flood risk within the flood cell; and • identify which aspects of flood risk will have to be addressed to allow for development to take place in higher risk areas of the flood cell.

6.4 The principle output of the Level 2 Assessment is therefore to provide guidance on what type of risk management measures are appropriate for adoption on allocated sites situated in flood zones 2 and 3, which are protected from flooding by existing defences. The assessment must take account of the current condition and defence standard of existing flood defences and alleviation schemes protecting the flood cell. The assessment would appraise the probability and consequences of overtopping or a breach to the flood defence, identifying the extent of potential inundation zones. A design event of an appropriate design standard will be taken as the basis for the assessment (1% for fluvial and 0.5% for tidal) including an allowance for climate change and free board. The level of detail required of the flood hazard includes: flood probability, flood depth, flood velocity and the rate of onset of flooding.

Page 52 Clarification of Uncertainty

6.5 DERA/EA R & D Report FD2320 TR/2 section S3.2 sets out guidance on how to address risk to people behind flood defences. The report outlines three approaches in increasing complexity: Simple, Intermediate and Complex. The level of detail to be taken is dependent on the nature of the flood hazard, the complexity of their identified pathways behind the defence and the vulnerability of the proposed development. The Level 2 assessment should seek to reduce the element of uncertainty by;

• identifying the areas of uncertainty; • dividing the areas of uncertainty into areas of low or high uncertainty; • where there is an identified uncertainty relating to degree of flood risk the worst case scenario should be assumed;

Development Proposed in High Risk Zones

6.6 The Level 2 Assessment needs to be sufficiently detailed to allow for the application of the Sequential Test to be applied giving a comparison between 'actual' flood risk in flood zones behind defences with EA estimates of flood risk which do not take account of flood defence protection. The Assessment is identify to identify what policies, practices and other mitigation steps are necessary to allow the proposed development to proceed in higher risk areas while satisfying the requirements of the Exception Test. This is achieved by:

• the subdivision of zone 3 areas into the two planning response areas described in PPS25 (table D.1): zone 3a – High Probability; and zone 3b – the Functional Floodplain; • subdividing zone 3 into defended and undefended areas, identifying existing standards of protection; • re-categorising the flood hazard in the flood cell by probability of inundation taking into account the existing defence standard, analysing history of breaches, overtopping and flood extent; • within urban areas, assess levels of service of the artificial drainage system (known as the minor system) in relation to current flood management strategies for the natural drainage system alongside the urban surface (known as the major system). Although the modelling systems for this type of assessment are still in their infancy, reasonable assumptions can be made using local knowledge and best practice guidance. • Defra has recently suggested in a consultation exercise, that Integrated Drainage Plans could be undertaken to constitute a strategic approach to urban flood risk planning, incorporating combined and surface water sewage systems and ordinary water courses.

Identified Areas for Level 2 Assessment

6.6 A future Level 2 Intermediate Assessment will be undertaken (if required) to expand on this Level 1 Coarse Assessment when site specific allocations are proposed during the preparation and consultation stages of the Area Action Plans DPDs. This will occur where proposed sites emerge within higher risk zones 2 and 3 or where

Page 53 they are located in areas of uncertainty.

6.7 Until site specific allocation proposals are brought forward, it is evident from the Level 1 Coarse Assessment that a Level 2 Intermediate Assessment (if required) would cover proposals in low lying areas of:

• the main towns of Penzance/Newlyn, St Ives/Carbis Bay and Hayle (Foundry and Copperhouse); • the smaller town of Marazion; • the main villages of Crowlas/Lower Ludgvan, Heamoor, Lelant, and St Erth; and • the larger villages of Angarrack, Paul, Mousehole, Relubbus and Canonstown.

Page 54 7 Processes 2a4: Level 3 Detailed Assessment

Identified Need for Level 3 Detailed Assessment

7.1 A Level 3 Detailed Assessment Part 2 has to be undertaken for proposed site specific allocations (at the development brief or master plan stage) which emerge during the preparation of Area Action Plans, identified by the Level 2 Detailed Assessment as having a limited ability to develop outside of the higher risk zones. The Level 3 detailed assessment will, where appropriate, assess what level of mitigation against flood risk must be undertaken. The level 3 assessment is similar to a FRA in setting broad guidance for such mitigation prior to the detailed application stage of the proposal.

7.2 A Level 3 Assessment should also be considered where the size and location of the proposal indicates the potential increase to flood risk to the surrounding area. For proposals on smaller sites the assessment can also be used to assess the sustainability of including SUDs to mitigate against flood risk when determining policy constraints.

7.3 The Defra/EA R & D Report FD2320/TR2 lists the requirements for undertaking a Level 3 Assessment with the advice that if data is limited in which to inform the LDF, an allowance should be made by making policies appropriately precautionary.

7.4 Plans of the proposed development area are to include:

• geographic features, street names and all water bodies; • flood defences and other flood alleviation measures stating standard and condition; • identified structures that influence hydraulic conditions both within the proposal area and surrounding areas, their maintenance and operation; • historic flood information (levels, extent and dates of flooding) and the identification of changes to the area since last recorded flood (if possible); • identification of safe access and exit routes to the development area (but not within the area).

7.5 The results of the Level 3 Assessment should include broad assessments of:

• potential sources of flooding; • the hydraulic performance of the existing artificial drainage system (both storm and foul); • the existing frequency of flooding • the behaviour of flooding across the area in terms of sequence, rate of water level rise, flow velocities, depth and duration; • the likely change of conditions progressively away from the development boundary (upstream and down stream), estimating the volume of runoff likely to be generated by the development (with or without SUDs); • the potential impact on fluvial or coastal morphology and issues of long term stability and sustainability; • the residual risks after inclusion of necessary mitigation measures.

Page 55 7.6 A Level 3 Detailed Assessment may be required for any future development briefs or master plans for the Local Plan Proposals: H-C Wherrytown, Penzance; the Old Stennack, St Ives; and North, East and South Harbour Quays (Hayle). However, the appropriateness of a Level 3 Assessment or deferment until a site specific FRA will be determined in consideration to the type of development proposed and the type of flood hazard identified.

Page 56 8 Processes 3: Options Appraisal

Options Appraisal – The Sequential Test

8.1 This stage constitutes the appraisal of the development proposal taking into account all planning issues (other than flood risk) including objectives derived from sustainability appraisal. Carrying out the Sequential Test of PPS 25 is the first part of this process. The Defra/EA R & D report FD2320/TR2 divides process 3 into six stages of analysis:

• 3.1: Have options been identified ('do nothing', maintain existing levels etc.) • 3.2: Have the options been evaluated (considering the social, environmental and economic objectives of sustainable development and technical feasibility) • 3.3: Has an assessment of flood risk been carried out for the options (if required) • 3.4: Have options been revised (if required) • 3.5: Have options been re-evaluated (if required) • 3.6: Has the preferred option been identified

8.2 The LDF is to identify sufficient land supply for future development to meet the needs identified by the RSS. The purpose of a Level 1 Coarse Assessment is to inform the local spatial planning process of flood risk during the preparation of the Core Strategy. The assessment will inform the Core Strategy on the comparative levels of flood risk across the district. in order that the risk based approach of PPS25 can be undertaken.

8.3 If at any stage of a proposal it becomes clear that the development can be accommodated within a more favourable lower risk zone 1 area, it would than be appropriate to move to the next stage of Options Appraisal and the application of the Sequential Test.

8.4 If a Level 2 Intermediate Assessment has not been carried out it is recommended that new development should only be allocated to sites within areas of low risk zone 1. If it proves acceptable to place all development outside of the higher risk zones the Option Appraisal does not need to be very extensive, outlining any planning constraints considered appropriate which will need to be applied to the proposal to mitigate against the possibility of increasing flood risk to existing development. This would mostly apply to the affect of the development on surface water runoff.

8.5 Where areas of high flood risk are included into a proposed allocation following appropriate Level 2 Intermediate and Level 3 Detailed Assessments, a more detailed Options Appraisal will be required, taking into consideration the appropriate planning constraints required to control identified residual flood risk. In setting out planning policies and constraints the following criteria will need to be assessed:

• flood warning systems; • emergency planning; • flood resilient building design; • defence assessment to determine if improvement of existing or new required; • drainage requirements (including SUDs);

Page 57 • Appropriate use of other flood mitigation measures; • Adaptation options of flood risk analysis, such as the inherent uncertainties in climate change projections and its impact.

8.6 The Level 1 Coarse Assessment has identified that any proposed allocations situated in the low lying higher flood risk zones situated in the following settlements will be subject to the criteria of the sequential test:

• the main towns of Penzance/Newlyn, St Ives/Carbis Bay and Hayle (Foundry and Copperhouse); • the smaller town of Marazion; • the main villages of Crowlas/Lower Ludgvan, Heamoor, Lelant, and St Erth; and • the larger villages of Angarrack, Paul, Mousehole, Relubbus and Canonstown.

Application of the Sequential Test

8.7 As potential allocation sites are brought forward during the preparation of the Area Action Plans, the Sequential Test will be undertaken to determine how appropriate the development is in regards to flood risk by answering the following questions:

Level 1 Assessment: Undertake Sequential Test Where All Hazards identified 1. Are all planned development areas at low risk? • If No a Level 2 Intermediate Assessment is required • If Yes go to question 2 2. Does the development increase flood risk elsewhere? • If Yes or not sure a Level 2 Intermediate Assessment is required • If No go to question 3 3. Is the level of uncertainty sufficiently low? • If No a Level 2 Intermediate Assessment is required • If Yes the proposal can proceed in the preparation of the DPD Level 2 Assessment: Undertake Sequential Test 4. Are all planned development areas at high risk? • If Yes a Level 3 Detailed Assessment is required • If No go to question 5 5. Does the development increase flood risk elsewhere? • If Yes a Level 3 Detailed Assessment is required • If No go to Process 4 (Monitoring and Review) Level 3 Assessment 6. Carry out Detailed Assessment 7. Prepare SPDs 8. Go to Process 4 (Monitoring and Review)

Page 58 PART 3

APPENDICES

Page 59 APPENDIX A

Compensatory Flood Storage/Conveyance

What are Floodplains

A.1 A floodplain is an area of land in which river or sea water flows are stored during periods of flooding caused by meteorological or tidal processes. Floodplains extend beyond the immediate vicinity of the normal constraint feature, that is the shoreline or the banks of the watercourse. There are two types of floodplain:

• River Floodplains : Fluvial (river) water channels have a limited capacity. When this capacity is exceeded due to heavy rains, the surplus water rises and overspills the banks into the adjoining low lying area of the floodplain.

• Coastal Floodplains: These are areas of low lying land adjacent to the coastline which are prone to flooding by the sea during periods of extreme tidal events or extreme weather conditions. Coastal floodplains act as a buffer zone protecting the hinterland from sea water intrusion. Tidal flood plains in estuaries (such as Hayle) are liable to flooding from both the sea and the rivers which feed into them.

Development and Floodplains

A.2 Flood plains serve an essential environmental role in conveying or storing flood water. This function can be seriously impeded by inappropriate development. Any development on a flood plain reduces its natural storage capacity, by which flood waters can be contained before conveyance of the water flow is undertaken downstream. Consequently the speed and height of the flood water will increase as it progresses downstream. Conversely, development can block the natural channel of the water flow through the flood plain which increases the flood levels upstream. Other forms of development also have a significant impact on the performance of floodplains. Drainage systems and hard surfaces such as roads and car parks will raise flood water levels by rapidly dispersing heavy rainfall into adjacent rivers, increasing the probability of overflow in the watercourses.

Compensatory Flood Storage/Conveyance

A.3 Ground raising operations for developments on undefended floodplains (outside of the functional floodplain) present major implications of increasing residual flood risk elsewhere in the flood cell. Although individual developments may only present a minimal impact, the cumulative affect of several developments could be more significant. For this reason it is important that provision is made for compensatory flood storage and or conveyance to be allowed for in all developments on fluvial floodplains. The raising of ground levels on undefended tidal floodplains is not considered likely to have an impact on tidal levels

Page 60 A.4 An assessment of the impact of new development on floodplains behind defences should be undertaken to understand how the ground raising works relate to the potential loss of storage capacity for the flood cell and how the flow path (conveyance) of flood water may be impeded if the defence is overtopped or breached.

A.5 A Level 2 Assessment assesses the potential impact new development proposals will have on the storage and conveyance of flood water behind defended flood cells and the potential affect of increasing residual flooding to other properties. An assessment of how a development may affect conveyance can be calculated by evaluating the contour profile of the area. To calculate the impact a new development will have on the storage capacity of a flood cell the following equation can be used to estimate the significance: (a) x (b/c) = (d) where;

• (a) = estimated depth of flooding if defence is breached or overtopped • (b) = total area of land allocation • (c) = total area of flood cell defended against flooding to a standard of 1% (fluvial) or 0.5% (tidal) • (d) = impact of loss of storage

Page 61 APPENDIX B

Surface Water Runoff Rates

What is Surface Water Runoff

B.1 Surface water runoff is the runoff or drainage of surface water, from rainfall or a flood event, which flows from higher to lower ground. On undeveloped sites a natural system of drainage absorbs water into the ground or conveys the water flow to low lying watercourses. The amount of runoff is determined by a number of variables including; rainfall intensity, rainfall duration, and the permeability of the ground cover.

Development and Surface Water Runoff

B.2 The general effect of development on undeveloped sites is to disrupt this natural process of drainage by replacing natural permeable ground cover with impermeable hard surfaces and altering the natural flow paths to nearby watercourses. These changes to a site's natural drainage response to surface water disposal affects both the volume and peak runoff rate of surface runoff, increasing the risk of flooding not only to the proposed development site but also properties in the surrounding area.

PPS25 and Surface Water Runoff Rates

B.3 PPS25 emphasises that the disposal of surface water runoff is a material planning consideration in determining proposals and states; that the volumes and peak flow rates of surface water leaving a developed site are no greater than the rates prior to the proposed development, unless specific off-site arrangements are made and result in the same net effect.

Sustainable Drainage Systems (SUDs)

B.3 A managed flood risk development can counter the potential affect of increasing surface water runoff by adopting Sustainable Drainage Systems (SUDS). SUDS mimic natural drainage processes through a system of infiltration, collection, storage and evaporation. The key objective of applying SUDs to new development is to limit the peak rate of discharge and the total volume discharged from the proposals.

B.4 Local planning authorities are to ensure that policies in the LDF encourage the use of SUDs. Priority is to be given to filtration techniques. Where this is not viable, preference should be given to discharging surface water runoff to watercourse rather than through the use of sewers.

B.5 It is emphasised that developers must take into account the issue of surface water management and the potential use of SUDs at the earliest possible stage of the site assessment for the proposed development, factoring in the potential need for mitigation, layout, the most practical type of SUD to use and overall costs.

Page 62 Table 22 – SUD Types and Environmental Benefits Feature Environmental Benefits Green roofs Attenuated runoff, improved ascetics, climate change adaptation. Water butts Attenuated runoff, water conservation. Porous and pervious Infiltration to promote attenuation and groundwater recharge, paving treatment by detention, treatment by filtration. Rainwater harvesting Attenuated runoff, water conservation. Filter strips Green links/corridors through a development, runoff attenuation, filtering of contaminants. Swales Can be planted with trees and shrubs, provides green links/corridors improved visual amenity, conveyance of storm water. Infiltration basins Potentially compatible with dual-use eg sports pitches, play areas, wildlife habitat. Can be any shape – curving or irregular - with scope for improved visual amenity. Treatment by detention and filtration. Detention basins Can be designed as an amenity or wildlife habitat. Treatment by detention. Retention ponds Open water bodies which can significantly enhance the visual amenity of a development. Treatment by detention. Wildlife habitat. Fishing, boating and other water sports. Can abstract water for re- use – eg irregation. Wetlands Provide a range of habitats for plants and wiildlife. Biological treatment linear wetlands can also provide green corridors. Source: Table 4.2, Development and Flood Risk: A Practice Guide to PPS25, Living Draft (February 2007).

Surface Water Management Plans (SWMPs)

B.6 The idea of developing Surface Water Management Plans is currently being explored by the Government for local planning authorities to develop more general water management plans focusing on managing flood risk and optimising the provision sustainable surface water drainage systems . These plans are likely to take the form of an SPD to be incorporated into the LDF portfolio. These plans are anticipated to act as a vehicle for integrating the requirements of River Basin Management Plans (RBMPs).

B.7 The SWMPs will be structured in two parts: Policy Statements section referring to, flood risk management, avoidance of combined drainage, managing surface water on the surface and the use of SUDs; and the Local Surface Waters Management Plan, which will map watercourse corridors, other water features, areas of known surface water flooding, floodplain and other flood risk areas, flood routes, aquifers, soil types (permeability), drainage areas etc. The objectives of the SWMP is to safeguard the the state and quality of the water environment while improving flood risk management by identifying and protecting areas suitable for SUDs.

Page 63 APPENDIX C

Flood Warning and Evacuation Planning

C.1 The responsibility for flood warning within England and Wales rests with the Environment Agency. The Environment Agency provide flood warnings for designated Flood Warning Areas. There are currently 29 Fluvial Flood Warning Areas and 2 Tidal Flood Warning Areas within the Environment Agency Cornwall Area. Currently 1 Fluvial Flood Warning Area and parts of both the Tidal Warning Areas are contained within the SFRA study area.

C.2 The Environment Agency provides a Flood Warning Dissemination System known as Floodline Warning Direct (FWD). Messages are sent to recipients via telephone, fax, SMS Text Messages, Alpha Pager and email. Currently FWD sends messages to both residents within flood zone 3 , as well as Professional Partners and the Media. This service requires residents of at risk properties to register their telephone number or email address with the Environment Agency. The Environment Agency also supply an indirect phone-inwarning service known as Floodline, accessable by telephone on 0845 988 1188 or on the website address www.environment-agency.gov.uk/subjects/flood/floodwarning/.

C.3 The District Authority has no formal responsibility or system for providing flood warning. This role is undertaken by Cornwall County Council Emergency Planning section, who work alongside the emergency services, the Environment Agency and district councils during severe flood events. Together these bodies facilitate activities such as distributing sandbags to at risk properties and if necessary organising evacuation procedures and emergency accommodation.

Table 23 – Flood Warning Areas in Penwith Primary Settlement at Risk Coastal/River Name Warning Stations St Ives and Hayle North Cornwall Coast from Ilfracombe Lands End to Hartland Point Penzance and Newlyn South Cornwall Coast from Newlyn, Plymouth and Lands End to Plymouth Devonport Mousehole, Marazion, River Hayle from Relubbus to Relubbus, St Erth Relubbus and St Erth St Erth Source: Environment Agency (October 2006).

C.4 A number of projects have been facilitated by the Environment Agency to develop flood prediction model systems which link flow monitoring of watercourses with rainfall measurements to develop a new warning systems related to rainfall forecasts. Additional research into rapid response catchments has been prompted since the Boscastle disaster in August 2004. A number of trial catchments have been selected throughout Cornwall due to commence during 2006. In the SFRA area these include the following proposed projects: Stennack River – St Ives; Red River – Crowlas; and Lamorna Stream - Lamorna

Page 64 APPENDIX D

Organisational Responsibilities for Flood and Flood Risk

DEFRA

D.1 The Department for Environment Food and Rural Affairs oversees flood and coastal defence, determining strategy and policy and helps fund capital schemes to fund flood defence. DEFRA funds most of the Environment Agency's flood management activities in England and provides grant aided funding to other operating authorities (local authorities and internal drainage boards).

Environment Agency

D.2 The Environment Agency (EA) replaced the National Rivers Authority in April 1996 taking on the water related issues of the former department. These responsibilities include: flood risk management; waste regulation; pollution control; water quality management; water resource management; navigation; and fisheries. The Environment Agency is required to arrange all of its flood defence functions to be carried out by Regional Flood Defence Committees (RFDCs). The SFRA area falls under the jurisdiction of the South West Regional Flood Defence Committee. In relation to flood defence management the Environment Agency is responsible for building and maintaining coastal and designated 'main' river flood defences. The EA also monitors water levels and flows and issues flood watches and flood warnings to alert the public of potential flood risk. The EA is the principle 'operating authority' in England relating to flood risk management. Other operating authorities include local authorities and internal drainage boards. The EA has overall supervisory role over all flood defences in England.

County Councils

D.3 County councils through their respective emergency planning committees, share the role with the EA in co-ordinating emergency responses to major flood events alongside local authorities and the emergency services. Strategically flood response procedures are to be set out in County Flood Plans with annexes for local authority flood plans. The emergency planning committees are also responsible for helping the EA to disseminate flood warnings and facilitate flood plan training.

Local Authorities

D.4 After the EA, local authorities have a responsibility to build and maintain flood defences. Under the Land Drainage Act 1991 local authorities have the power to undertake flood defence works on watercourses not designated as 'main' rivers which lie outside of internal drainage board areas. As one of the 88 maritime district authorities Penwith has powers to build coastal defences to prevent coastal erosion

Page 65 under the Coast Protection Act 1949. Following guidance from local authority flood plans, district councils are to develop and implement Major Incident Plans for areas recognised as being of high flood risk. In the event of flooding local authorities assist emergency responses and help to provide sandbags, supporting police with arranging for evacuation and providing temporary rest centres and emergency accommodation.

Internal Drainage Boards

D.5 Internal drainage boards are independent operating authorities who manage drainage systems in areas recognised for their special drainage need, such as in the Fens in East Anglia and the Somerset Levels. There are no internal drainage boards in Cornwall.

Water Companies

D.6 Water companies are responsible for maintaining water supply and sewage management. During periods of heavy flooding the water companies must ensure that the public are warned if water from the main supply becomes contaminated by floodwater. Also, if untreated wastewater spills out of the sewage drainage system, they are responsible for reducing the spillage as much as possible and for cleaning contaminated areas once the flooding has subsided.

Page 66 APPENDIX E

FLOOD RISK GUIDANCE FOR PLANNING OFFICERS

E.1 Guiding Principals

It is important to note that flood risk is recognised as a material planning consideration. Therefore all applications for land use change and development are to be assessed by planning officers in terms of potential flood risk. The advice presented in this SFRA is aimed at helping to identify the level of flood risk and whether further information is required. When assessing potential flood risk the following points should be taken into consideration:

• Is the proposed development at risk of flooding • The extent of the area liable to flooding. • Need to identify the potential source of flooding (coastal, tidal, fluvial, surface water run-off or groundwater); • If the location of the proposal is within a flood zone the suitability of the development type must be assessed against the category of flood zone. This will indicate whether a site specific Flood Risk Assessment will be required. Table 16 below summarises the role of the EA and initial planning response for flood zones by development type:

Table 24 – Initial Planning response Matrix Development Within Main Within Flood Within Flood Within Flood Type River bye-law Zone 3 Zone 2 Zone 1 distance Domestic Consult EA Standard Standard No Planning extensions Response Response Comment Industrial /Comm Consult EA Standard Standard No Planning ercial extensions Response Response Comment less than 250m2 Change of use to Consult EA Consult EA Standard No Comment a more 'flood risk Response sensitive' use Camping and Consult EA Consult EA Standard General surface Caravan Sites Response water drainage information Operational Consult EA Consult EA Standard General surface development Response water drainage less than 1 ha information Operational Consult EA Consult EA Consult EA Standard development Response between 1-5 ha

Page 67 Civil emergency Consult EA Consult EA Consult EA Standard infrastructure Response less than 5 ha All operational Consult EA Consult EA Consult EA Consult EA development greater than 5 ha Source: Environment Agency Standing Advice Development and Flood Risk – Initial Planning Response Matrix 2004 (updated October 2005)

• The possible impact of the proposal on a flood plain. A proposed development or land use change could affect the natural function of a flood plain and so increase the likelihood of flooding either upstream or downstream of the location; • The defence standard of existing defences should always be reviewed in light of new development by using flood estimation techniques. • The impact of climate change must also be considered alongside the expected life span of the development, as flood extents are likely to increase over the next few decades. The Environment Agency's suggested model of extending the zone 3 boundary to a mid point between it and the zone 2 boundary is the accepted standard; • If a proposal requires a site specific Flood Risk Assessment, it must be submitted to the local planning authority along with the planning application; It is the developers responsibility to provide a Flood Risk Assessment in accordance with the requirements of PPG25; • The Environment Agency must respond to all proposals requiring a Flood Risk Assessments. The comments of the Agency must be applied to each proposal where possible unless an exception status has been identified and appropriate flood mitigation measures approved; • Planning officers should use the strategic guidance in this SFRA and its GIS package in the initial stages of assessing a proposal; • The SFRA provides strategic guidance in helping to identify areas of growth for allocated sites proposed in the new Local development Framework; • The SFRA will inform the Local Development Framework on issues of flood risk associated with allocated sites for development and regeneration in main town locations situated in areas of high flood risk, particularly where rapid inundation is a concern, recommending adequate alleviation measures where appropriate.

Page 68 APPENDIX F

ALLOCATED SITES AND FLOOD RISK

Background to Housing Provision Requirements

F.1 Cornwall Structure Plan 1997 Policy H3 proposed a housing provision for Penwith based on an average development rate of 240 dwellings per year from 1991 to 2011 (a total provision of 4,800 dwellings over 20 years). The 1997 Cornwall Structure Plan was superceded in 2004 by the 2004 Cornwall Structure Plan and remains the current development plan document until the Regional Spatial Strategy is adopted. The 2004 Structure plan revised the housing requirement for Penwith to 220 dwelling per year between 2001 and 2016 or a total of 3,300 dwellings over 15 years. At present the draft Regional Spatial Strategy (RSS) has adopted a similar housing provision target for Penwith at 240 dwellings per year between 2006 and 2026 or a total of 4,800 over 20 years.

Strategic Housing Land Availability Assessment

F.2 Reflecting Government policy of concentrating development on previously developed land, Planning Policy Guidance3: Housing, advised local authorities to undertake an Urban Capacity Study to determine areas of potential allocated growth to be carried forward in preparing Local Plans. A joint UCS was undertaken in 2001 with Cornwall County Council and the Cornwall district authorities. The results of the study were included in the Penwith Local Plan (adopted 2004) as housing allocations. Planning Policy Statement 3: Housing (December 2006) supercedes PPG3 in April 2007, requiring local authorities to undertake a Strategic Housing Land Availability Assessment (SHLAA) to identify potential development sites in urban areas, rural communities and urban extensions. When complete this assessment will provide up to date information to feed into the preparation process for the Area Action Plans DPDs (as a part of the new Local Development Framework). Until the results of the SHLAA become known, this SFRA will look at those allocated sites saved from the Local Plan which are affected by flood risk. The SFRA will be continuously updated as new sites emerge in the assessment which have flood risk implications. Only two allocated sites identified within the SFRA area which lie within areas of high flood risk, these comprise of the allocation proposals H-C, H-J and TV-D of the Penwith Local Plan and are situated at:; the Old Stennack (St Ives), Alexandra Road/Western Promenade (Penzance), Hayle Harbour Regeneration (Hayle).

Page 69 APPENDIX G

The Sequential and Exception Test

A Risk Based Approach

G.1 Planning Policy Statement 25 (PPS25) - Development and Flood Risk, outlines Government guidance to local planning authorities on how to address issues relating to development on sites susceptible to flooding. The Statement requires LPAs to give priority to allocating and permitting applications to sites within the lower flood risk zones. This is the Sequential Test, which assesses development by location in relation to four flood zones as defined by the Environment Agency (See Table 25) and by type of development based on vulnerability to flooding (See Table 26).

G.2 PPS25 states: The aims of planning policy on development and flood risk are to ensure that flood risk is taken into account at all stages in the planning process to avoid inappropriate development in areas at risk of flooding, and to direct development away from areas at highest risk. Where new development is, exceptionally, necessary in such areas, policy aims to make it safe without increasing flood risk elsewhere and where possible, reducing flood risk overall.

Table 25 - Flood Zones and PPS25 Flood Zone / Annual Probability Appropriate Use FRA Requirements Risk Rating of Flooding (with flood defences where they exist) Zone 1 River, Tidal and All use of land appropriate FRA only required Low Coastal less than 0.1 in this zone. where scale may affect Probability (1 in 1,000 annual Surface run-off probability) Zone 2 River: 0.1 – 1.0% Subject to Sequential Test All development Medium (between 1 in 100 highly vulnerable uses proposals in this zone Probability and 1 in 1,000 annual appropriate only if they should be accompanied probability) pass the Exception Test by a FRA. Tidal & Coastal: 0.1 – 0.5% (between 1 in 200 and 1 in 1,000 annual probability) Zone 3a River: 1.0 or greater Water compatible and less All development should High (1 in 100 or greater vulnerable uses are be accompanied by a Probability annual probability) appropriate. more FRA. Tidal & Coastal: 0.5 vulnerable and essential or greater (1 in 200 or infrastructure only greater annual permitted if they pass the probability) Exception Test. Highly vulnerable should not be permitted.

Page 70 Flood Zone / Annual Probability Appropriate Use FRA Requirements Risk Rating of Flooding (with flood defences where they exist) Zone 3b River, Tidal and Appropriate for water All development should Functional Coastal: 5% or compatible uses . Essential be accompanied by a Floodplain greater (1 in 20 or infrastructure also subject FRA. greater annual to passing the Exception probability) Test Source: PPS25 Table D1

Table 26: Flood Risk Vulnerability Classification Essential ● Essential transport infrastructure (which cross areas at risk) Infrastructur Stratigic utility infrastructure (electricity stations and substations) e ●

Highly ● Emergency services and telecommunications Vulnerable ● Basement dwellings

● permanent residential caravans, mobile homes and park homes

● Installations requiring hazardous substances consent

More ● Hospitals Vulnerable ● Residential institutions (residential care homes, prisons and hostels)

● Dwellings, student residencies, pubs, nightclubs and hotels

● Non-residential health services, nurseries and education

● Landfill and waste management sites for hazardous waste.

● Holiday/short-let caravans and camping, subject to specific warning and evacuation plan

Less ● Shops, financial, professional, offices, restaurants, cafes, hot food Vulnerable takeaways, general industry, storage and distribution, non residential (not included above), assembly and leisure

● Agricultural and forestry

● Waste treatment (except landfill and hazardous waste)

● Minerals workings (except sand and gravel)

● Water treatment plants

● Sewage treatment plants (with adequate pollution control measures) Source: PPS25, Annex D, Table D.2

The Sequential Test

G.3 Development in higher risk flood zones may be permitted whereby such development is required to avoid social and economic stagnation. This would usually occur where extensive areas of land are available on the periphery of main urban settlements.

Page 71 Such developments would have to undergo a criteria based assessment in the planning process involving a Sequential Test and if required, an Exception Test.

G.4 During the selection process of potential allocated sites in the LDF, local planning authorities must demonstrate that the flood zone information presented in the SFRA has been used in applying the Sequential Test and, if required, the Exception Test.

G.5 The objective of the Sequential Test is to ensure that the 'more vulnerable' category of development is not located in areas of high risk. The test therefore assesses the compatibility of type of land use proposed by the development with the level of flood risk posed at the location. If the proposal is to be located in a high flood risk zone, the applicant is to demonstrate during all stages of the Test that no alternative suitable development sites are available in lower risk zones. The Sequential Test comprises of a sequence of criteria based tests which must be satisfied before the Exception Test can be undertaken. These include a series of evidence based demonstrations in ascending order flood risk:

• that no alternative site is available in flood zone 1; • that there is no other site in flood zone 2 of less flood risk available; • that no alternative site is available in flood zone 2; • that there is no other site in flood zone 3 of less flood risk available;

G.6 Where the proposal cannot be diverted to a lower risk zone or a less risk area within a high risk zone, there is a need for the applicant to demonstrate that there is no reasonable alternative option available – providing that:

• All requirements relating to a Flood Risk Assessment (FRA) are met. • Residual risks of flooding are assessed and managed. • Where appropriate the Exception Test is passed • can be seen as a positive contribution to sustainable development.

The Exception Test

G.7 The Exception Test is applied where development on flood zones 2 and 3 is deemed necessary for broader sustainability reasons. The following stringent conditions must be met for a proposal to pass the Exception Test:

• the sustainability benefits provided by the development to the community outweigh the potential hazard of flood risk; • the location must be developable previously developed land; • that a site specific FRA must be undertaken to demonstrate that the proposal is safe and does not cause an increase in residual flood risk elsewhere, aiming to reduce flood risk overall.

G.8 The decision making principles that regional and local planning authorities have to adhere to in PPS25 are clearer and more explicit than in PPG25, especially in regards to the issues of the Sequential Test and the new Exception Test. Furthermore PPS25 recognises that flood risk is not the only issue concerned with spatial planning and the new Exception Test redresses the balance required to achieve the wider aims of sustainable development.

Page 72 G.8 Flooding Direction

A standing Flood Direction is proposed for major developments for which a local planning authority proposes to grant permission despite a sustained objection from the Environment Agency (i.e. after being consulted after an initial objection) on flood risk grounds. This will enable such applications to be called in for decision by the Secretary of State.

Page 73 APPENDIX H

FLOOD RISK ASSESSMENTS (FRAS)

H.1 The Environment Agency is now consulted on a statutory basis over all planning applications where the threat of flood risk is identified as a potential issue. Where the Environment Agency consider there is a threat of flood risk to a proposed development, they will normally require the developer to have a Flood Risk Assessment undertaken to accompany any planning application. Applications which require particular consideration to potential flood risk include not only coastal and fluvial floodplains but also areas of low lying land where ground water levels are close to the surface and flooding is prone to occur after periods of heavy rainfall. Locations of applications considered to be of flood risk outlined in PPG25 (paragraph 62) include those which are:

• within a river floodplain or washland shown on the indicative floodplain map prepared by the Environment Agency; • Within a coastal flood plain, including that adjacent to the tidal length of a river, shown on the indicative flood plain map prepared by the Environment Agency; • Within or adjacent to any watercourse, particularly where there might be potential for flash flooding; • Adjacent to or including any flood bank or other flood control structure; • Situated in an area where the Agency have indicated that there may be drainage problems; • Likely to involve the culverting or diverting of any watercourse; or • of such size or nature relative to the receiving watercourse/drainage system that there could be a significant increase in surface water run-off from the area.

H.2 The Flood Risk Assessment addresses the affect a flood will have on a development and the affect a development could have on flooding elsewhere in a flood plain. As the FRA ultimately determines whether a planning application is granted or refused, it will need to be completed at an early stage of the proposal. The initial stages of an FRA involves preliminary discussions with the Environment Agency to identify and address particular issues of flood risk associated with the specific site. Once this scoping exercise has been completed information can be collated relating to the proposed development. The information required for a FRA will include the following:

• The proposed development site level in relation to potential flood levels (AOD); • The source and flow of flood water during a flood event; • Calculating the possible severity of a flood event in terms of annual probability; • Historical data search on past flood events; • An assessment of existing flood defences; • The need for warning systems and emergency evacuation procedures; • Recommendations for required flood mitigation measures to be undertaken to achieve the minimum level of flood risk impact of the development.

Page 74 APPENDIX I

PENWITH AREA PROFILE

Physical Topography

I.1 The scope of this SAFRA covers the Penwith District Local Authority area. Penwith is 304 km2 in area and forms a peninsular, surrounded on three sides by approximately 80.5km of coastline. Penwith lies at the far western extremity of the county and is the smallest mainland district in Cornwall. Penwith adjoins Kerrier local authority to the east.

The topography of the district is distinctly divided into two geological areas.

The Granite Uplands

I.2 The landform to the west of the district is an elevated granite plateau variously known as the Lands End or the West Penwith Peninsular. This headland forms one of a series of granite intrusions which run the length of the south west of England. Theses consist of; Dartmoor in Devon, Bodmin Moor, then on to Carmenellis in the adjacent authority area. The uplands of Penwith form an arc of gently rounded hills with occasional weather exposed rocky outcrops (carns) encompassing an area from Trencrom Hill (165m AOD) in the east, to the high points of Trendrine Hill (247m AOD) , Watch Croft (252m AOD), where it descends to the south west , terminating at Chapel Carn Brea (196m AOD) above Sennen Cove. This spinal ridge forms the main watershed of the district, feeding streams in all directions. This watershed slopes more steeply to the north, west and south forming deep watercourses called zawns. To the north and west the inland hills fall from about 120m AOD to 100m AOD to the coastal shelf where sheer cliff slopes of granite with intrusions of Dolerite and Devonian slate descend rapidly to the sea. The plateau is marked by significant expanses of rough grassland broken by intermittent areas of upland and lowland heath and is partially enclosed by margins of low coastal heath known as morrop (slightly inland of the coastal shelf). Pockets of wet woodland occur to the south, in sheltered narrow river valleys.

I.3 The watercourses to the south east and east of the watershed feed mainly into Mounts Bay, following the longer but gentler slopes which descend into the shallow valley depression which links Mounts Bay with the Hayle Estuary to the north.The centre of the granite mass is an irregular plateau. The average annual rainfall on the moors is high, and, as the underlying rock is granite (with a thin layer of impoverished humic soil) rain water has little chance to soak into the ground. Surface drainage is therefore poor and impeded leading to partial collection in level basins forming areas of fen, bog, mire and wet heathland. The streams that drain from the granite core (particularly to the north and west of the watershed) often follow steeply sloping watercourses (zawns) which efficiently drain rapid rainfall,.

Page 75 The predominant settlement pattern takes the form of dispersed farmsteads and small hamlets with the occasional fishing village along the south coast between Sennen in the west and Mousehole in the east. The densest population centre is situated at St Ives on the slope descending to the east into St Ives Bay. The next most populated area is spread along the nineteenth century mining area on the west of the headland and comprises of the settlements of St Just, Trewellard and Pendeen. These settlements follow a linear pattern of development along the coastal road.

The Lowland Cornwall Killas

I.4 The remainder of the district incorporates lowland country killas. Killas are soft rocks almost entirely comprised of slate which, throughout Cornwall, occupy the low lying land below the granite intrusions. Above the killas the soil is richer and deeper enabling productive agricultural activity. The most fertile area of market garden cultivation occurs on the slopes that run down to Mounts Bay and in the St Erth Valley where the only grade 1 agricultural land in Cornwall is situated, This area is known locally as 'the golden mile'. The lowland area of Penwith comprises of the low shallow valley which runs north east to south west along the St Erth Valley connecting Mounts Bay with the Hayle Estuary. This generally follows the course of the Hayle River and demarcates a former isthmus which once separated the Penwith Peninsular from the rest of the mainland. This valley is bounded to the west by the lower slopes of the granite plateau (100m AOD) and the gentler slopes that rise up to St Hilary and Goldsithney to the east (50m AOD). The eastern lowland zone of the district can be divided into two areas, Mounts Bay and Hayle

I.5 Mounts Bay is a wide south west facing bay fronting a gently sloping hinterland which supports the principle settlement in the district, Penzance/Newlyn. From Newlyn in the west, the coast forms a low flat arc eastwards to Marazion where the ground rises to the hills that run east of the River Hayle. Several rivers run down from the granite uplands that issue into Mounts Bay presenting potential flood risk to proposed developments within their respective floodplains.. The hinterland of Mounts Bay is predominantly given over to agricultural cultivation, beef and dairy farming. Semi- natural habitats occur along the slopes of river valleys supporting areas of mixed woodlands of ash, willow and sycamore and pockets of wild meadow.

I.6 The principle population density of the area is focused upon the settlements of Penzance/Newlyn, Long Rock, Crowlas and Lower Ludgvan, with Marazion to the east of the bay. These settlements follow the main A30 corridor. In the interior the settlement pattern takes the form of scattered farmstead and clustered nucleated villages based around the historic churchtowns of Madron,Gulval and Ludgvan. Because of the low lying terrain around Mounts Bay both the settlement and transport infrastructure of the area is under threat from coastal flooding. The remote location of Penwith in general, and Penzance in particular, emphasises the importance of maintaining transport links with the rest of Cornwall. The two major links for Penzance are the A30 and the rail link to St Erth, both of which run alongside the coast and are prone to occasional flooding during extreme weather conditions. Flood defences are extant between Newlyn and Penzance harbours and an engineered sea defence currently protects the transport corridor to the east of Penzance.

Page 76 I.7 The Hayle area covers the hinterland of St Ives Bay, with broad sand beaches, dunes and the tidal estuary of Hayle. Some of the sand beaches are backed by sand dunes (towans) both to the west and the east of the estuary, reaching up to 72m AOD. These dunes cover previously hard land. The estuary and its associated water, Copperhouse Pool, separate the town from the bay proper and the dune system to the north.

I.8 The River Hayle is the largest river in the district., and along with the headwaters of the Roseworthy Stream, drain the greater part of the area. This river crosses the narrowest part of the peninsular north west from Mounts Bay to its outlet into Hayle Estuary where there are extensive tidal mud flats and sandbanks. The river rises in Godolphin Downs and follows a continuous irregular woodland banked watercourse which follows the natural depression of the former isthmus to the peninsular. Several other streams run down from the upland killas hills which flank the river, the estuary and the town of Hayle affording possible flood risk along their respective floodplains.

I.9 Dunes and marras grass take up a marginal zone behind the broad sand beaches on the north coast. Inland, this gives way to a landform of gently undulating hills and shallow valleys with interlocking areas of mixed woodland. Most of the land is utilised by pastoral farming with a low proportion of arable cultivation.

I.10 The largest settlement in this area is Hayle situated to the east of the estuary. The settlement pattern inland takes the form of an even scattering of hamlets and village interconnected by a network of minor lanes. The larger settlements, such as Connor Downs and St Erth are focused on crossroads. Unlike the area to the south surrounding Mounts Bay, the infrastructure of the transport corridor is not immediately threatened by coastal flooding. However, there remains a potential flood risk for low lying areas around the estuary which have been alleviated by the development of the the Hayle tidal barrier.

Climate

I.11 The climate in Penwith is predominantly influenced by the prevailing weather systems of the Atlantic Ocean. This takes the form of moist air carried inshore on westerly winds. The location of Penwith at the south west extremity of the United Kingdom affords it a milder temperate climate than the rest of the mainland, the influence of the warmer waters of the gulf stream influencing an almost subtropical climate to the district.

I.12 Exposure to salty sprays along the coastline and the stronger westerly winds on the higher moorland impacts on stunted growth forms, while in the sheltered deep river valleys and the lowland zone to the east of the moors, fertile soils alongside a warm climate affords a congenial environment for woodland and agricultural production. In West Cornwall it has been estimated that there are 1700 day degrees centigrade with more than 250 frost free days per year on average. The rainfall on the higher moors is above average, the warm moist air from the Atlantic rises to the top of the headland plateau causing precipitation. Consequently the lower parts of the district receive less rainfall.

Page 77 I.13 Across the County of Cornwall the pattern of rainfall is varied. The highest average rainfall is recorded in the centre of the district around Bodmin at 126mm. The west of the county averages at 110mm and the east at 85mm. Rainfall in the county follows a strongly cyclical pattern with the heaviest average falling from October to January. Similarly the intensity and length of rainfall varies from year to year. The autumn of 2000 was one of the wettest on record for over 270 years. In the wake of this, the following winter the west country was hit by ten days of continuous storms and torrential rain from 29th October. Up to 270mm of rain fell in this period (100mm recorded at Lands End), a third of which fell in just 30 hours. Eight times the regional average of rainfall for the same ten day period.

I.14 There are nine rain gauges distributed throughout the West Cornwall Catchment area (three within the district area) which provide good coverage of the annual rainfall average. Results from the gauges show that the total average annual rainfall varied between 935mm to 1266mm between 1961 -1990). The Cornwall Association of Rainfall Recorders (CARR) have been accurately measuring rainfall across Cornwall since 1940, producing monthly tallies to Meteorological Office Standards. Analogies drawn from CARR data shows that currently average rainfall levels in Cornwall have increased by 25% since 1940. Most of the increase occurs in the winter, although summers have become marginally wetter as well.

Page 78 Glossary of Flooding Terms

Catchment An area of land drained by a river and its related network of tributaries .

Coastal Cell Distinct coastal zones defined by sediment transportation from source to deposition.

Critical Ordinary A watercourse that is not a main river but which the EA and other Watercourse operating authorities agree are critical because they have the potential to put at risk from flooding large numbers of people and property.

Flood Defence A man made structure (or system of structures) designed to alleviate against flood risk. Defences are built to a Standard of protection, that is to a level of flooding before the defence is breached.

Flood Zones The Environment Agency Flood Map describes potential flood risk areas in terms of Flood Zones 2 (low to medium risk) and 3 (high risk). The return periods 1 in 1000 years and 1 in 100 years (equivalent to 1 in 200 years tidal) are used by the Agency to distinguish the flood zones by probability.

Flood Risk The possible effects of flooding measured in terms of frequency or probability and impact or consequential damage to assets.

Floodplain An area of land over which river or sea water flows are stored during periods of flooding caused by meteorological or tidal processes. Flood plains extend beyond the immediate vicinity of the normal constraint feature, that is the shoreline or the banks of the watercourse.

Fluvial Floodplain The area at risk from an overspill when a river or watercourse rises above its banks.

Main River A certain watercourse designated on a statutory map by DEFRA.

Ordinary A watercourse that does not form part of a main river. Watercourse

Probability The likelihood of a flood event occurring of a specific magnitude in the space of a year. This is calculated by by dividing 1 by the return period of the potential flood event. For instance the probability for a 1 in 100 year flood occurring in a given year is described as 0.01 or 1%.

Tidal Floodplain The area at risk from an overspill from the sea or high tide.

Return Period The return period of a specific flood magnitude describes the probable average recurrence of the event within a given time span. For instance a 1 in 100 year flood denotes that a peak flood flow could occur at any time during a 100 year period and may even occur more than once.

Page 79 Sea Level The elevation for development in terms of flood mitigation is often described in terms of AOD and ACD. AOD (Above Ordnance Datum) is the datum point taken from the mean average sea level as recorded at the Newlyn Tidal Observatory. ACD (Above Chart Datum) is the level below which the tide will not often fall below. In the UK this is usually equivalent to the level of the Lowest Astronomical Tide (LAT) which equals -2.90m AOD. This is the plane to which all tidal heights are gauged. The variance between the two measurements is compensated by shifting the bench mark of the datum to correct to ACD. For the Newlyn datum the gauge variance is 3.05m (+ or -). (Newlyn tidal statistics are published by the British Oceanographic Data Centre).

Watercourse All rivers and streams and all ditch drains, cuts, culverts, dikes, sluices and sewers, other than public sewers, and passages that carry water.

Page 80 References

Adapting to climate change impacts on water management: A Guide for Planners, AEA Technology

Cornwall Structure Plan 1997, Cornwall County Council

Cornwall Structure Plan 2004, Cornwall County Council

Guidance for Flood Risk Management (2005), Strategic Flood Risk Assessments, Environment Agency

Hayle Estuary Hydrodynamic Modelling Report 2003, Babtie Group Ltd

Local Environment Agency Plan, West Cornwall Consultation Report (1997), Environment Agency

Newly En-mained Watercourses; Penwith District Council Area (2005), Environment Agency

Penzance Promenade Condition Survey (2004), Hyder Consultancy Ltd

Penzance Promenade Options Review (2004), Hyder Consultancy Ltd

Penzance Promenade Sea Defence Option Study (2005), Hyder Consultancy Ltd

Penwith Local Plan 2004, Penwith District Council

Planning Policy Guidance 25 (2004); Development and Flood Risk, Office of the Deputy Prime Minister

Proposed Planning Policy Statement 25 (2006): Development and Flood Risk, Office of the Deputy Prime Minister

The Regeneration of Hayle Harbour, ING Real Estate (www.hayleharbour.com/exhibition)

Regional Spatial Strategy South West 2006, South West Regional Agency

Sea Defence Works In Penzance (1967), Peter Tressider

Shoreline Management Plan, Lands End to Hartland Point, Halcrow Maritime

Shoreline Management Plan, Lizard Point to Lands End, Halcrow Maritime

UKCIP02 Scientific Report: Climate Change Scenarios for the United Kingdom,

UK Climate Impact Programme (2005), Updates to regional net sea-level change estimates for Great Britain (www.ukcip.org.uk/resources/publications/documents/124.pdf)1

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