National Infrastructure Commission                            CCS0038

SUPPLEMENTARY EVIDENCE FROM THE NATIONAL INFRASTRUCTURE COMMISSION FOR THE INQUIRY ON CLIMATE CHANGE AND SECURITY

Dear Mr Dunne

I am writing following the National Infrastructure Commission’s appearance at the Environmental Audit Committee evidence session on Tuesday 14 May. Following the hearing, a member of the Committee, Claudia Webbe MP, requested further information from the Commission regarding flood risk for both new and existing properties, which is detailed below.

Protecting new developments from flood risk

The Commission is clear that new development should not increase the number of properties at risk of flooding. It broadly supports the government’s approach which requires that flood risk is considered as part of land use planning considerations. Developers are expected to assess a site’s present and future flood risk and take steps to ensure that it will be protected from different sources of flood risk and not increase flood risk elsewhere. In relation to river and surface water flooding, the development should protect properties from a flood with a one per cent annual probability. For tidal flooding, properties should be protected from a 0.5 per cent annual probability.

The Commission recommends that the protection from river flooding should be increased to 0.5 per cent to be consistent with tidal flooding. This is also consistent with the Commission’s view of what is reasonable to expect for existing properties. For surface water flooding, the Commission agrees the standard should remain at one per cent. This reflects the challenge that comes with addressing this source of flood risk.

It remains important that mitigations put in place through planning conditions are enforced. Implementing Schedule 3 of the Floods and Water Management Act 2010 should help with enforcement.

Protecting existing properties from flood risk

In the second National Infrastructure Assessment the Commission recommended that the government deliver infrastructure to protect existing property and development between now and 2055. This should include allowing for the effects of climate change.

The level of protection to be achieved at a particular location should be developed in discussion with the community at risk. This will allow for local circumstances to be taken into consideration. It may be that the economic, social or environmental impacts of delivering a high level of protection are undesirable. In such circumstances the communities need to understand their residual risk and appropriate measures, such as advanced warnings and the ability of property to recover quickly from flood events, are put in place to manage this.

In order to make sure appropriate strategic plans are put in place and funded the Commission recommended that the government sets a target over the long term based on an assumption that it will deliver protection from flooding from rivers and the sea of at least a 0.5 per cent annual probability, with a higher level of 0.1 per cent annual probability in the most developed places. This will require annual investment to rise from the current £1 billion to around £1.4 billion by the mid 2030s.

In relation to the risk of surface water flooding, the Commission recognises the challenge of implementing measures to significantly reduce the risk, and that the starting point should be an ambition to reduce the number of properties at high risk (that is an annual probability of 3.3 per cent) by around 60 per cent by 2055. This reflects the particular challenge of addressing this risk of flooding through enhancements to drainage systems.

The Commission recognises that more work is required to fully understand the impact of climate change on flood risk. It chose not to undertake further work on this as part of the second Assessment because the Environment Agency is close to completing work on the second National Flood Risk Assessment. This should be completed later this year and is expected to significantly improve the understanding of existing and future flood risk from all sources. The Commission is clear that the government should use this as the basis for setting out long term measurable targets to reduce flood risk. This will enhance the control of flood risk in new development and will also mean that the government and Environment Agency should be well placed to start reviewing their existing flood and coastal erosion risk management policy statement and strategy. Once the flood risk assessment is in place, lead local flood risk management authorities will be able to further review and adapt their existing local flood risk management plans in light of its findings.

I hope this additional evidence is useful for the inquiry. If the Commission can support you further, please do not hesitate to contact my colleague Rita Beden, who can help to arrange a further discussion.

Yours sincerely,

Margaret Read

Director of Policy, National Infrastructure Commission