Preferred Options

(1) 18. Flooding and Water

Introduction

18.1 Flooding from rivers is a natural process that plays an important role in shaping the natural environment. However, flooding threatens life and causes substantial damage to property. Although flooding cannot be wholly prevented, its impacts can be avoided and reduced through good planning and management. However, climate change over the next few decades is likely to mean milder wetter winters and hotter, drier summers in the UK. These factors will lead to increased and new risks of flooding.

18.2 Warwick District has a history of flooding due to the many rivers and watercourses through the area, including the rivers Avon, Sowe, Leam, Itchen and Canley Brook and Finham Brook. In the last thirty years there has been flooding on many occasions due to heavy rainfall increasing watercourse and river levels and, more recently in 2007, being largely attributable to drainage problems. The anticipated implications of climate change will only increase the District’s vulnerability to such events and it is important therefore to appraise, manage and reduce the risk of flooding within the District.

18.3 The provision of a safe and efficient supply of water to meet the needs of new development is essential and the Council acknowledges the role of water conservation and efficiency measures in achieving this.

18.4 Standards for water consumption are set out in The Code for Sustainable Homes, (BREEAM) with accompanying technical guidance on how these can be achieved. Severn Trent’s Water Resources Management Plan outlines the ways in which continuous supplies can be maintained and expanded to meet the additional demands made by new developments in the area.

Relevant Issue & Strategic Objectives

Relevant Issues:

• To manage the risk of flooding to people and property within the district
• To ensure that new development does not increase surface water flooding
• To ensure that an adequate supply of water is available to meet increasing demands
• To ensure that waste water treatment is adequately met and does not result in a deterioration of the quality of receiving water courses or undermine the ability to meet ‘good status’
• To increase the proportion of water bodies meeting ‘good status’

18.6 Strategic Objectives: See in particular objectives 5, 6 and 12 as set out in paragraphs 4.13 to 4.15 above. Objectives 9 and 14 also apply to this topic

18.7 Related SCS aim: The built and natural environment has been protected and enhanced. People feel safe.

Justification for Preferred Option

18.8 The latest national planning policy on flooding and water issues is set out in the National Planning Policy Framework (NPPF) which states that: “Development will be directed away from areas of high flood risk and inappropriate development in areas at risk of flooding will be avoided. A strategic approach will appraise, manage and reduce flood risk by:

• Identifying and assessing land at risk from all forms of flooding by preparing a Strategic Flood Risk Assessment;
• Planning new development to avoid increased vulnerability to flooding and reduce surface water run-off.
• When new development is brought forward in areas which are vulnerable, care should be taken to ensure that risks can be managed through suitable adaptation measures
• Applying a sequential, risk-based approach to the location of development to avoid where possible flood risk to people and property and manage any residual risk, taking account of the impacts of climate change.”
• Steering new development to areas with the lowest probability of flooding. Development should not be allocated or permitted if there are reasonably available sites appropriate for the proposed development in areas with a lower probability of flooding.
• If, following application of the Sequential Test, it is not possible, for the development to be located in zones with a lower probability of flooding, the Exception Test can be applied
• Ensure that flood risk is not increased elsewhere and only consider development appropriate in areas at risk of flooding where, informed by a site-specific flood risk assessment following the Sequential Test
• within the site, the most vulnerable development is located in areas of lowest flood risk unless there are overriding reasons to prefer a different location
• development is appropriately flood resilient and resistant, including safe access and escape routes and that any residual risk can be safely managed and gives priority to the use of sustainable drainage systems (SUDS)”

18.9 Future Water, the Government’s Water Strategy for England, Defra, February 2008: The government’s vision for water policy and management is to have:

• improved the quality of the water environment and the ecology which it supports
• provided high levels of quality drinking water
• sustainably managed risks from flooding and coastal erosion
• ensured the sustainable use of water resources
• >implemented fair, affordable and cost reflective water charges
• cut greenhouse gas emissions
• embedded continuous adaptation to climate change and other pressures across the water industry and water users, by 2030

18.10 At the County level, Warwickshire County Council is the ‘lead local flood authority’ with responsibility for developing, maintaining and monitoring a local flood risk management strategy in partnership with other relevant bodies in the area. They are required as the Sustainable Urban Drainage Approving Body (SAB), to be responsible for the approval of drainage systems within Warwick District, and also for adopting and maintaining SUDs serving more than one property.

18.11 The Environment Agency is responsible for preparing Catchment Flood Management Plans (CFMPs) covering the whole of England and Wales. They provide an overview of the flood risk across each river catchment and recommend ways of managing those risks by promoting sustainable flood risk management.

Water Quality

18.12 In terms of water quality, the European Water Framework Directive (WFD) has the following objectives:

• To prevent deterioration in the status of aquatic ecosystems;
• That all water bodies should meet ‘good’ ecological status by 2015;
• To promote the sustainable use of water;
• To reduce or phase out pollutants that pose a significant risk to the aquatic environment;
• Reduce the pollution of ground water; and,
• Contribute towards mitigating the effects of floods and droughts

18.13 As the ‘competent body’ responsible for delivering these objectives the Environment Agency (EA) has prepared a series of River Basin Management Plans which set out the current status of the water body and an action plan for meeting ‘good ecological status’ in line with the WFD. In addition, the EA also strives to manage and protect groundwater sources and plans activities that might affect groundwater. Water quality has improved significantly over the last 20 years. The chemistry and biology of rivers has improved together with a reduction in nutrient (phosphates and nitrates) levels.

18.14 The district lies predominately within the Warwickshire Avon area of the Severn River Basin Management Plan of which, in relation to the requirements of the Water Framework Directive, 11% of water bodies are currently at good ecological status and are expected to remain the same at 2015. A small area of the district lies within the Tame, Anker and Mease area of the Humber RBMP area of which only 3% of water bodies are at good ecological status however this is expected to remain the same.

(1) Water Provision

18.15 In terms of water provision, the national strategic vision for managing water resources in England up until 20305 includes the following measures:

• Reduced per capita consumption of water to an average of 130 litres per person per day or potentially 120 litres per person a day;
• Amend building regulations to include a minimum standard of water efficiency in new homes; and,
• In areas of severe water stress it is believed that near universal metering will be needed.

18.16 Severn Trent Water is the appointed water company for the district with the responsibility of providing sufficient quantity and quality of water to meet demand whilst minimising the impact on the environment. They are responsible for the operation and maintenance of the existing public foul drainage network and for providing waste water treatment capacity for future domestic development. They are also responsible for the public surface water drainage networks. From 2011, all private sewers and lateral drains draining to public sewers were transferred into the ownership of the appointed water company removing the burden on householders and allowing for a more integrated sewerage system.

18.17 Severn Trent published their water resources management plan to demonstrate how they intend to meet future water demand over the next 25 years. The plan sets out the strategy for ensuring the security of customers’ water supplies between 2010 and 2035 by reducing demand and ensuring the sustainable use of water resources. The overall aim is to maintain and achieve target levels of service whilst minimising impact on the environment by reducing leakage, managing the demand for water and developing new resources.

18.18 Severn Trent AMP5 Delivery Programme 2010 – 2015 (Longbridge): Severn Trent Water's AMP5 investment programme is essential to delivering higher standards in the quality of water supplied, treatment of sewage and ensuring that the company's asset base and infrastructure are maintained. Work currently underway will help improve efficiency of the treatment plant for both clean and waste water. More details relating to all water infrastructure can be found in the Draft Infrastructure Plan.

What is the situation now?

18.19 A Stage One Strategic Flood Risk Assessment has been undertaken which assesses and maps all forms of flood risk from groundwater surface water, sewers and river sources, taking into account future climate change predictions. It identifies the areas currently under threat and the potential for further flood risk due to climate change based on a 20% increase in flow down the watercourse. The initial assessment showed areas at highest risk followed routes adjacent to rivers and canals. A number of locations within the district are also known to suffer from surface water flooding. This evidence is used to locate future development primarily in low flood risk areas.

18.20 River Severn Catchment Flood Management Plan, EA, 2009: In the next 50 to 100 years, it is estimated that as a direct result of climate change and urbanisation the number of properties at risk from flooding in a 1% flood event will rise to approximately 210. The aim of the plan is to establish flood risk management policies which will deliver sustainable flood risk management for the long term, so preparing for the impact of climate change and planning investment.

18.21 Water Cycle Study, March 2010: The Water Cycle Study advised that for:

• Sustainable water management

  • Across large parts of the district, infiltration type SUDS will be suitable and should be promoted
  • To ensure that run-off from the developed sites is equivalent to greenfield run-off, the drainage assessment shows that less than 10% of development sites would be taken up by storage requirements.

• Water quality

  • Waste water treatment works which discharge to watercourses with a higher dilutive capacity are preferable
  • Growth must not cause deterioration in water quality
  • New consents to accommodate growth should be discussed early with EA and STW
  • Water quality assessments should be carried out where new development is proposed upstream of combined sewer overflows

18.22 There is no reason to believe that this advice would change in relation to the current Preferred Option development sites, many of which are unchanged from those promoted through the now superseded Core Strategy preferred option.

18.23 River Basin Management Plan Severn River Basin District, Dec 2009: the plan focuses on the protection, improvement and sustainable use of the water environment. The key issues to address include:

• diffuse pollution from agriculture and other rural activities;
• point source pollution from water industry sewage works;
• physical modification of water bodies; and
• diffuse pollution from urban sources

18.24 The plan identifies actions to reduce the impacts of transport and the built environment on the natural environment, including improving management of surface water drainage by use of sustainable urban drainage systems (SUDS) and setting aside land during development for surface water storage providing a resource for reuse on industrial and residential development).

18.25 The Environment Agency introduced a new classification system in 2011 enabled by The European Water Framework Directive (WFD). This system allows for more rigorous and accurate assessment of water quality. Some water bodies will never achieve good ecological status however, because they have been physically altered for a specific use, such as navigation, recreation, water storage or flood protection

18.26 Warwick District Council Climate Change Adaptation Study, 2011 assists the understanding of the impacts on its own buildings and estates and planning for new development in the face of climate change. The flood performance of new buildings can be improved by the use of flood resilient construction methods and existing buildings can be made more flood resilient during restoration works.

Other Options

18.27 If inappropriate development were to be allowed in the functional flood plain or other areas at risk from flooding, it could put property and lives at risk.

18.28 A lack of planning for infrastructure and water supply would result in low water pressure or lack of supply for new developments and for existing residential and commercial uses. It could also affect water quality at the river basins or in supply or in the drying out of streams and other water sources. It could also have a severe effect on the capacity of sewage treatment works and again result in poor water quality.

18.29 To meet the Government’s requirements for the future protection of people and buildings from flood and to provide quality water supplies and treatment facilities, the Council’s preferred option is the only option which will support growth and new development.