Article by Mark Topping, Director of Design, Lanpro
Around 325,000 UK homes are currently at a high risk of flooding following heavy rainfall, according to a National Infrastructure Commission report. Without action, the report says, climate change and urbanisation could put an additional 230,000 properties at high risk by 2055.
In November the UK Green Building Council, in response to the announcement of Defra’s Flood Resilience Taskforce, said that the government must do more to mitigate the effects of climate change and flooding risks.
Schedule 3 of the Flood and Water Management Act
Following the historic case of flooding in 2007, the SuDS (Sustainable Drainage Systems) Manual was first published to provide guidance on planning, design, construction and maintenance of sustainable drainage systems.
2007 also saw the publication of the Pitt Review, which highlighted necessary lessons to be learnt and ultimately led to the framework for the Flood and Water Management Act 2010.
The proposed changes in Schedule 3 of the Flood and Water Management Act 2010 included making sustainable drainage systems a legal requirement for most new developments and amending the right to connect to public sewers.
However, in 2014 the then government decided not to implement Schedule 3 in England, in favour of strengthening planning policy. In 2022, the government sought to determine whether to implement Schedule 3 and The review for implementation of Schedule 3 to The Flood and Water Management Act 2010 was published in January 2023 but no decision was taken.
The current government is committed to reviewing how policy changes could slow the spread of impermeable surfaces, publishing this review by the end of 2024 and publishing standards for SuDS design, construction, operation, and maintenance. Although the 2024 deadline has been missed, I am still hopeful that the (relatively minor) legislative change will be made, and that the impact will have considerable benefits.
The change would mandate that new developments incorporate SuDS (nature-based approaches to reduce flooding, improve water quality and protect the environment) to manage runoff water.
It is also likely that the government will establish a Sustainable Drainage Approving Body (SAB) as a local authority service which ensures new developments have drainage systems that are fit for purpose. SABs will be responsible for evaluating and approving drainage applications, adopting and maintaining surface water drainage systems, providing pre-application advice, and inspecting and enforcing.
The benefits of change
In the last year, we’ve seen how the recent Biodiversity Gain Requirements (Exemptions) Regulations 2024 has reshaped the planning system to ensure that biodiversity gain is mandatory in development across England and Wales.
Schedule 3 of the Flood and Water Management Act could introduce similar requirements relating to water catchment on site or in the vicinity of a new development, to ensure that the development both accommodates the existing baseline capacity and also provides a defined improvement facilitated by the development.
For example, if the development provided a 10 per cent gain in water catchment, this would not only mitigate any additional flooding brought about by development, but considerably reduce the local flood risk. This approach would enable developments to facilitate improvements to local flooding and water management either onsite or offsite in a similar way to biodiversity net gain (BNG). This would reduce local flooding issues at source but would also contribute to wider downstream improvements.
Such systems would align to the principles of BNG and could indeed contribute to BNG in a holistic and fully integrated way, creating high value flood management systems which, when integrated with BNG requirements, can be sustainably managed in perpetuity.
Offsite requirements could also be used to implement much needed flood alleviation systems in areas most at risk or hardest hit by flooding. An example of this is already being used successfully at Hardcastle Crags near Hebden Bridge in Yorkshire. Here, upstream natural flood management is being implemented into along existing water courses and catchments through native woodland planting upstream and even incorporating art. The Art as Natural Flood Management (NFM) project enables renowned artists to create a series of artworks that respond to the climate emergency by delivering NFM measures. These artworks reduce flood risk, using NFM principles to help slow the flow of rainwater.
Although this is a private initiative funded by the National Trust, it could be implemented across England and Wales and part-funded by offsite contributions where necessary, making such solutions less reliant on private individuals, charities and Defra funding.
The impact of the delay
The impact of the delay in reviewing Schedule 3 is a cause for concern. Not only is there no clear guidance or a timeline for rollout of new requirements, but plans for a consultation did not occur as was initially anticipated. Furthermore, the change of government has left local authorities unsure as to what changes will occur.
Effective management
Management is an important consideration for such systems, as poor management of water systems can exacerbate flooding issues. Legislation should also enable the careful management of existing watercourses adjacent to development sites, meaning that such sites could benefit from a holistic approach with funding from development offsets.
Because the impacts of flooding are not limited to a specific development site, it is important to commence a project such as this with a comprehensive understanding of the local context.
Other important considerations are deliverability and commerciality. While there are clear commercial benefits in taking a landscape-led approach and investing in ‘blue’ infrastructure, any new requirements will meet with dissent if they are not implementable and affordable from a developer’s point of view.
From a government and local authority point of view, it will be important to avoid a repeat of the restrictions relating to nutrient neutrality, for instance – these restrictions, whilst well-meaning had the effect of neutering development sites – as we saw in Norfolk and elsewhere.
Lanpro has long advocated a landscape-led approach to development: ensuring that development works in harmony with the natural environment, retains a strong connection with nature and provides attractive open spaces which feature mature trees and hedgerows. To incorporate requirements brought about by changes to Section 3 into such an approach would have little impact on the viability or desirably of new housing developments and would bring about many benefits.
Legislation that is deliverable, understands commercial, social and environmental balances and benefits would stimulate further growth, would align to current BNG requirements and alleviate flooding and water quality whilst at the same time delivering high quality and affordable new communities.