From Defra

The Water Services Division at the Department for Environment, Food and Rural Affairs (DEFRA) has published a research report which concludes that the overall picture generated by the research is that it is “both rare and challenging” to achieve a strategic approach to surface water management through the planning system.

Introducing the research report, DEFRA said that climate change and development activity is making surface water management a growing challenge, commenting:

“Sustainable drainage systems (SuDS) that are incorporated into developments can provide effective drainage as well as mitigating against new flood risk and providing an opportunity to address existing flood risk. Strategic scale studies and strategies can be used to inform planning policy requirements for SuDS.”

The aim of the research, which was carried out by CAG Consultants on behalf of DEFRA, was to investigate the potential that strategic (catchment or sub-catchment) surface water management can contribute to inform the delivery of SuDS through the planning system.

The research, which was conducted in two phases, sought to:

• review the effectiveness of current strategic surface water management plans in defining requirements for SuDS
• describe advantages/disadvantages and barriers/opportunities for using strategic surface water management plans more effectively to define local planning authority SuDS requirements
• suggest how barriers might be overcome

The research identified a number of areas of improvement and presented 30 conclusions for the government to consider.

Numerous examples of strategic surface water management activity informing the planning system were identified in phase 1 of the research. However, the report says that the overall picture generated by the research was that it is “both rare and challenging” to achieve a strategic approach to surface water management through the planning system.

With regard to the question of how strategic surface water management approaches can support net reductions in surface water flood risk, the report concludes that in almost all cases, drainage objectives in new development were limited to site-specific considerations and to maintaining existing levels of risk.

The report says that while there were examples of net reductions in surface water flood risk being achieved as part of new development in areas with a history of significant flood events, these were “not typically as a result of planning policy being informed by strategic surface water management. Instead, such outcomes tend to be achieved through negotiation with developers as part of the development management process.”

Key findings in the report outline a number of ways in which strategic surface water management approaches could be improved, including providing access to a strong evidence base to inform planning policy, such as hydraulic modelling of surface water and drainage and/or other relevant studies or strategies. The report says “there is considerable variation across different councils in the evidence base” on surface water flood risks and that improving the quality and consistency of the evidence will “enable the development of more informed policy and more robust development management.”

The report goes on to suggest that the evidence base should be translated into a costed strategy for surface water interventions, with a particular need to ensure that surface water infrastructure needs are “fully factored into wider local infrastructure planning processes and the associated funding mechanisms” (planning obligations and the Community Infrastructure Levy).

Other recommendations contained in the report include:

• Leveraging complementary funding to support delivery of a costed strategy. Particularly in the case of strategic SuDS, identifying and securing funding from other sources is important to securing their delivery
• Ensuring strong and clear local plan policies which recognise the multiple benefits of SuDS. Even where policies on SuDS are not reflective of strategic issues in the area, simply having strongly worded policies on a requirement for SuDS, accompanied by clear guidance, is important in securing higher levels of on-site surface water attenuation.
• Ensuring that planners and developers have a strong awareness and understanding of SuDS.
• Ensuring that SuDS are integral to the design of development schemes – which could be further facilitated e.g. via provision of pre-application advice which is focused on sustainable drainage.
• Effective collaboration between the complex web of actors who play a role in the management of surface water. This includes Lead Local Flood Authorities (LLFA) who play a pivotal role by acting as an interface between strategic surface water management activity and the planning system – often through their statutory consultee role on major applications. However, the report says there is evidence that this role is being undermined by resource constraints, particularly in 2-tier areas where the LLFA must engage with multiple local planning authorities.
• Removing barriers to data sharing which currently exist. The research generated clear evidence of extensive data sharing by Water and Sewerage Companies (WaSCs) with other risk management authorities for the purposes of managing surface water risk and identifying SuDS schemes. However, this was not routine and a number of barriers to such including WaSCs having insufficient resources to make the data available and inconsistencies and incompatibilities between different datasets.
• Improving the alignment of responsibilities, particularly the alignment between WaSC responsibilities relating to surface water and those of other risk management authorities.
• Addressing resourcing issues which undermine the ability of some actors to engage with others.
• Building greater consistency into the metrics and methods which are used to design and model drainage.

“The gap between policy and practice is evident”

The researchers also say the gap between policy and practice is evident – which appears to be due in part to the priority that is attached to surface water risks in policy and guidance, relative to fluvial and coastal risks. The report states:

“An ongoing reliance in the National Planning Policy Framework (NNPPF) on designated Critical Drainage Areas was seen to be particularly unhelpful, given that these were not reported to be an accurate reflection of surface water risks. The equivocal nature of some of the policy and guidance was also seen to be undermining efforts to achieve more strategic approaches.

“Local planning authorities could justify strategic policies on SuDS on the basis of existing policy and guidance, but this is not ‘required’ of local planning authorities. There is scope to give local planning authorities considerably more leverage to demand delivery of net reductions in surface water where appropriate.”

Download the report “Assessment of How Strategic Surface Water Management Informs Sustainable Drainage Systems (Suds) Delivery in Developed Areas Through Spatial Planning and Development Management” here.