James Heath, Chief Executive Officer at the National Infrastructure Commission, has set out the approach the Commission is taking to its ongoing study on surface water flooding, together with potential areas the NIC is likely to make recommendations on, including governance, performance standards and investment levels.

In a speech at Westminster Energy, Environment and Transport Forum on 19 April this week, James Heath said that the study is intended to help inform the upcoming Price Review in 2024 - the NIC will publish its report in November.

The recommendations will also form a key part of the second National Infrastructure Assessment (NIA) which will be published in autumn 2023 - the first assessment was published in July 2018.

He told delegates the Commission is conducting the study to examine the best approaches to the management of surface water flooding at the request of HM Treasury.

The focus of the work is on drainage systems – both above and below ground, water company controlled and non water company controlled – and the protection they provide to property and to infrastructure services.

Explaining that surface water flooding was an area that the Commission has not previously looked at in great depth, he pointed out that at the time of the first NIA – published in summer 2018 – the data needed to assess the costs and benefits of different resilience standards for surface water flooding had not been available.

He commented:

“Since starting the study, I’ve learnt three things about surface water flooding, which will be familiar to this audience but may not be widely known outside it.”

i. surface water flooding is the single biggest source of flooding with over 3 million properties in England at risk

ii. surface water flooding is the flood risk we know least about - partly because it’s a highly localised and complex risk to model. The science of surface water flood mapping is also not as mature as that for rivers and the sea.

iii. surface water flooding risk, if left unchecked, is only going to get worse due to a combination of more regular extreme rainfall and storms, drainage infrastructure that is ageing and in need of maintenance or replacement, and urban development which reduces the capacity of the ground to provide natural drainage, with the potential to increase surface water run-off.

Addressing the surface water flooding problem

He went on to say that ‘the policy space does look crowded’ – referring to the fact that Defra is examining whether to implement Schedule 3 of the Flood and Water Management Act, which would introduce more sustainable drainage systems within new construction developments.

He also flagged up the Government’s “clear ambition to reduce storm overflow discharges”, and the upcoming draft Drainage and Wastewater Management Plans which are due to be published shortly.

“All this activity presents challenges – for example, dealing with combined sewer overflows could eat up a lot of industry investment over the next few cycle. But there are also opportunities, if we can manage rainwater in ways that reduce both sewer overflows and surface water flooding risks” he said.

He told his audience that the NIC “absolutely agree” that the overriding policy aim should be to deliver flood risk management that better plans for, protects, responds to and helps people recover from surface water flooding. The study is mainly looking at the ‘plan’ and ‘protect’ elements of resilience as this is where infrastructure, whether nature-based or engineered, has the biggest role to play.

However, the Commission “certainly don’t think that an effective flood management strategy equals ‘protection’, full stop” and it was “not possible or indeed desirable to try and stop all surface flooding from happening.”

Instead, surface water flooding should be treated as a tolerable risk problem, with the key policy questions being:

• First, what is the scale and frequency of surface flooding incidents that we as a society deem acceptable?
• Once we agree what these outcomes are, what are the appropriate solutions based on cost-benefit analysis?

Emerging thinking

Heath said that the study is exploring the drainage performance and standards we should be aiming for – but that there was “no absolute way of determining the right standards, of course.”

“What is affordable and achievable will vary over time. It will require expert judgement. But without knowing what good looks like, it is hard to make intentional progress,” he added.

In terms of scope, the Commission is looking at measures to minimise the impact of new development: everything built from now on should be climate resilient, or there is a risk of making the existing problem worse.

According to the NIC Chief:

“We must also consider how best to upgrade and retrofit existing assets to reduce current risks – which, we know, will be the biggest challenge.”

The Commission is examining the potential of nature-based solutions and other ways of holding back water, particularly where they offer wider benefits than just addressing flooding. Delegates heard that the NIC would look at whether the current regulatory model sufficiently supports these approaches.

However, James Heath acknowledged that the reality is that “sometimes rainfall will beat the capacity of even upgraded drainage systems”, saying that the NIC would also look at ‘designing for exceedance’ and how to minimise the impact on property and vital infrastructure services of that excess.

As part of the study, the Government’s official infrastructure adviser is also considering the specific issues and solutions for different terrains – urban, suburban, and rural.

The NIC CEO concluded by offering what he described as “a sense of the areas where we are likely to make recommendations to government, although it’s too early to say what our actual recommendations will be.”

The Commission’s recommendations to government will look at both short term and longer term measures in the infrastructure space, he said, outlining these as follows:

“In the shorter term, we will try and ensure our findings help inform the process of finalising the Drainage and Wastewater Management Plans and PR24, but the timing here is clearly challenging as we are running in parallel with those processes – and we are only likely to learn more on what government intends to do about Schedule 3 in the autumn.

“For the longer term, looking out to 2050, you can expect us to say things about the importance of achievable resilience standards for surface water flooding, and recommend timelines for implementation. We will also set out what we think is the appropriate level of investment and how costs might fall between bill payers and taxpayers, in order to achieve these standards.

“And, finally, we will hope to make recommendations on the best mix of above and below ground solutions to provide greater resilience.”

Ownership and responsibility to construct and maintain drainage systems "quite fragmented”

In addition, the governance of surface water flooding is another area where the NIC is likely to make recommendations, including on how the range of different organisations working to address flood risks can best work together. At present, Heath said the ownership and responsibility for constructing and maintaining drainage systems “does look to be quite fragmented”, which leads to various challenges, including:

“The extent to which we have a shared understanding of the problem – how can we share data and knowledge more effectively between different bodies, and agree who needs to act to effect change where it is needed?

“…the lack of consistency in drainage standards across different assets and realms of responsibility is another challenge.”

The study will therefore offer a view on whether the current governance system is fit for purpose and, if not, how should it be reformed. As part of this, the Commission will also consider whether “the different parties have the right incentives to work effectively together.”

The Commission’s final report and recommendations to Government will be published in November.