Flood Risk - Managing Flood Risks
Flooding has been a frequent event across the South East in recent years. Challenges for flood risk management are posed by our changing climate and development proposals. Investment in flood defences and flood warning systems will reduce the risk to
Flooding of land adjacent to rivers and the coast is a natural process that can have far reaching effects on people and property due to land use. Costs
associated with flooding are not only financial and economic, such as damage to property and disruption to business, but also personal in terms of distress, injury and loss of life. During such events, considerable demands are placed on the emergency services and upon public services generally. Flooding of developed areas can result in a loss of public confidence in the planning services. However, flooding can also have many benefits to the environment including a contribution to the maintenance of certain important habitats. Capital investment in flood defence has doubled since the early nineties, and represents between 40 and 45 per cent of total flood defence expenditure. Continued significant growth in investment is needed if the existing flood defence infrastructure is to be both sustained and improved. In certain situations it may not be economically or environmentally appropriate to undertake capital works to reduce flood risk and other floodplain and catchment management options may be considered.
The Government’s Planning Policy Guidance Note 25: Development And Flood Risk (PPG25) provides the context for managing future development to minimise distress and damage. PPG25 points out that inappropriately drained development can contribute to flooding elsewhere. Excessive rainfall can overwhelm the drainage capacity of land, particularly when the Planning Policy Guidance Note 25: Development And Flood Risk ground is already saturated or when channels become blocked and this issue should be assessed as part of a planning application. There are also established areas of development exposed to flood risk without adequate defences currently in place. Because of the high profile of recent flooding events a major challenge for the Environment Agency will be to manage the expectations of the public as to what the Environment Agency can, and cannot, do. The planning pressures in the South East are likely to increase regulatory activity by the Environment Agency on flood risk matters and planning authorities will need to focus on flood risk. Climate change scenarios will also need to be taken into account when planning in the medium and long term.
Defra has set three key objectives for flood andcoastal defence:
- To encourage the provision of adequate and cost effective flood warning system.
- To encourage the provision of technically, environmentally and economically sound and sustainable flood and coastal defence measures.
- To discourage inappropriate development in areas at risk from flooding and coastal erosion.
In November 1999 Defra issued a set of ‘High Level Targets’ for authorities who have flood defence responsibilities including the Environment Agency, local authorities and Internal Drainage Boards. The High Level Targets are a comprehensive set of fourteen targets that provide the framework by which performance is being measured and monitored.
The coastline of the South East is subject to huge dynamic forces and is largely the product of ongoing management for both flood defence and coastal protection reasons. Climate change is placing further pressures on this heavily managed coastline. Inundation by the sea is largely due to combinations of high tide, storm surge and wave activity but may also be associated with structural failure of defences. Significant stretches of our coastline and rivers are monitored each year by the Environment Agency to assist with coastal and river management decision making. There is considerable development pressure in the South East for new housing both on greenfield sites, and also on previously developed brownfield sites that are often located in floodplains. The Environment Agency seeks to discourage inappropriate development in the floodplain and to enforce compliance with Bye Laws. It will be vital to focus more strongly on Sustainable Drainage Systems (SuDS), which use
techniques to control surface water run-off as close to its origin as possible before it enters a watercourse.
Four indicators have been used to monitor flood risk:
Indicator 18 Change in beach volume
The coastline of the South East is subject to huge dynamic forces. Significant stretches of our coastline have been monitored by the Environment Agency by surveying beach profiles each year to assist with coastal management decision making. Some of these data sets extend over 25 years and enable coastal trends to be determined and they are increasingly invaluable for investment planning purposes. This indicator is based on the Environment Agency’s Beach Monitoring Programme and is used to highlight areas suffering coastal erosion and indicates where future investment in flood defence schemes is required. The data is analysed to assist in the design of these defences or development of management strategies. For example, the beach management strategy for Seaford is currently being reviewed and will utilise this data.
Indicator 19 Number of properties ‘at risk’ from flooding
A property is currently identified as having the potential to be at significant risk of flooding if it falls within an Indicative Flood Plain. This represents a one per cent chance of flooding in any one year from a river (fluvial) or a 0.5 per cent chance of flooding in any one year from the sea (tidal) under present conditions, or the highest known flood. Indicative Flood Plains, which are areas that would flood without the presence of defences, make up some 11 per cent of the total land area in the South East, which is slightly higher than the figure of 10 per cent for England as a whole.
Indicator 20 Number of flood warningsIndicator
The Environment Agency operates a staged system for issuing warnings to the public. warn of imminent river and coastal flooding. Several factors can affect the number of flood warnings and flood events in the future, including the adequacy of current flood defences, the amount of inappropriate development in ‘at risk’ areas and weather conditions. Climate change scenarios predict more intense summer thunderstorms and an increase in winter rainfall, which could result in more frequent river flooding in the future. It is also predicted that climate change will increase the frequency of storm surge conditions and flooding from the sea. Many developed floodplains benefit from flood alleviation schemes, the design of which are based upon analysis of historic records that may not reflect future risk. Furthermore the presence of defences can encourage development in potential flood risk areas.
Indicator 21 Future development and flood risk
A key objective of the Environment Agency is to contribute to the Government’s policy of reducing the risks to people and the natural and built environment due to flooding. Inappropriate development should be discouraged in areas at risk of flooding and the provision of sustainable drainage encouraged to ensure that new development does not increase flood risk elsewhere. The contribution to the reduction in flood risk that can be achieved by discouraging inappropriate development is significant. The 8.1 million people who live in the South East represent 13.5 per cent of the UK’s population and occupy 3 million households. The South East faces development pressures greater than anywhere outside London and this is reflected in development plans. Local planning authorities allocate development land and define policies that influence development in their Local Plans and determine planning applications. The Environment Agency is a statutory consultee in the plan making process and has a lead role in providing advice on flood issues.