4.2 Floods

Policies such as these facilitate adaptation to climate change but may not be strictly adaptive themselves. One organisation with a key role in England and Wales is the EA with its remit including flooding and coastal defence. Increased frequency and severity of storms and wetter winters increase the risk of flooding through higher peak river flows, sea levels and tidal surges. Flood risk management aims to reduce the probability of flooding from rivers and the sea through the management of land, river systems, and flood and coastal defences. Flood damage can also be reduced through effective land use planning, flood warning and emergency responses.

The 2004 ‘Foresight future flooding report’

This report evaluated a range of possible scenarios for climate change in the UK over the next century. It estimated that the risk of flooding from rivers and the sea will at least double by the 2080s, and could increase by up to 20 times. The number of people at a high risk of flooding could rise from 1.5 million to between 2.3 and 3.5 million over the same period, with the cost of flooding rising from the current £1 billion a year to between £1.5 billion and £21 billion. The cost of damage through coastal erosion will increase three to nine times by the 2080s, although the worst case (£126 million per year) is still well below current flood losses. Foresight was updated as part of the Pitt Review covering the 2007 floods, but the original report raises some key points that remain relevant:

  • Should we accept increasing levels of flooding, maintain existing risk levels, or try to reduce the risks of flooding?

  • Reducing the severity of climate change could make the task of managing flood risk substantially easier.

  • Changes in risk and the costs of flood management are uncertain, particularly for urban flooding. Investment in better modelling and flood prediction is needed for us to plan ahead more effectively.

  • How should we use land, balancing the wider economic, environmental and social needs against creating a legacy of flood risk?

  • How should we manage the balance between state and market forces in decisions on land use?

  • How should we use market mechanisms and incentives to manage future risks, while recognising the central role of government?

The EA sees Foresight as promoting its messages that we must take all reasonable steps to help reduce climate change along with a tougher line against actions such as floodplain development that can increase the problems associated with flood risk.

Some key EA strategies are:

  • Catchment flood management plans, which seek to understand the factors that contribute to flood risk within a catchment and recommend the best ways of managing that risk over the next 50 to 100 years. Within the EU Water Framework Directive (which includes a requirement to restore water bodies to good ecological status by 2015), there are also related river basin management plans.

  • The provision of standing advice on flooding to the planning sector, both developers and local authorities.

  • The Water Resources Strategy launched in March 2009. This notes key pressures (including climate change) on water resources and covers the actions required to ensure there is enough water for people and wildlife. There is an associated report, ‘Water resources in England and Wales – current state and future pressures’, which includes how the availability of water varies from place to place and how water is abstracted for various uses.

Typical flood defences include embankments, walls, weirs, sluices and pumping stations, with some, such as the Thames Barrier, only used when there is a high tide or flood. Such ‘hard defences’ were generally put in place for long-term flood protection, although the increased flood risk associated with climate change means that reassessment of their effectiveness is required – including the Thames Barrier, which protects 125 km2 of central London from tidal surges. However, the EA increasingly uses more natural methods, known as ‘soft defences’ or ‘managed realignment’. These use mudflats and saltmarshes to provide space for floodwater and prevent flooding elsewhere, a method which also creates wildlife habitat. Managed realignment generally uses a larger area of land than a hard defence, but is cheaper and lower maintenance. In coastal and estuary areas, saltmarshes help break the power of incoming tides, reducing the impact of a wave by up to 95%. One example is the Cuckmere estuary in East Sussex which is being allowed to return to being a tidal estuary.

Activity 12

  • Visit the Environment Agency's website to find the predicted flood risk for your area.

  • Read through the Cuckmere fact sheet. Consider how managed realignment might be applied to a river or coastal area you are familiar with. Looking at ‘Managed Realignment Electronic Platform’ by the Environment Agency, what might drive or constrain this in your chosen area?

4 Climate change: national adaptation

4.3 Sustainable urban drainage systems (SUDS)