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Flood risk considerations with planned development

The Government's National Planning Policy Framework (NPPF) requires local authorities to demonstrate the issue of flood risk has been considered as part of the planning process. It also requires that flood risk is managed in an effective and sustainable manner and where, as an exception, new development is necessary in flood risk areas.

The aim of the policy is to make developments safe, without increasing flood risk elsewhere and wherever possible, reduce flood risk. This process is referred to as the Flood Risk Management Hierarchy.

Flood Risk Management Hierarchy
Step 1 Assess Appropriate flood risk assessment
Step 2 Avoid Apply the sequential approach
Step 3 Substitute Apply the Sequential test at site level
Step 4 Control For example, SUDs, design, flood defences
Step 5 Mitigate For example, Flood resilient construction

Flood risk sequential test

The Sequential Test is a decision making tool designed to ensure that areas at little or no risk of flooding are developed in preference to areas of higher risk. The NPPF advises that 'the aim of the sequential test is to steer new development to areas with the lowest probability of flooding. Development should not be allocated or permitted if there are reasonably available sites appropriate for the proposed development in areas with a lower probability of flooding'.

A Strategic Flood Risk Assessment (SFRA) should provide the basis for applying the sequential test.

Flood risk exception test

The NPPF allows the application of the Exception Test where following application of the sequential test it is not possible, consistent with wider sustainability objectives, for development to be located in zones with a lower risk of flooding. The exception test therefore provides a method of managing flood risk while still allowing development to occur.

Further guidance on how planning applications will be considered in relation to flood risk issues and in particular the sequential test, exception test and Flood Risk Assessments (FRA).

Strategic Flood Risk Assessment (SFRA)

A SFRA provides an overview of all sources of flood risk. This includes rivers, surface water, groundwater, large reservoirs, lakes and sewers.

Further advice on flood risk management is available from:

Surface Water Management Plan

Surface water is water collecting on the ground after heavy rain causing flooding to people, their properties and other infrastructure. A Surface Water Management Plan (SWMP) is a tool to identify areas more vulnerable to surface water flooding, and to identify measures to reduce the flooding, recognising that it is not possible to eliminate flooding altogether.

The Greater Manchester SWMP was completed in January 2013 and comprises two stages. Stage One considered Greater Manchester as a whole and Stage Two developed area specific SWMPs, one of which relates to Water Street in Radcliffe. Stage one and two provide:

  • a strategic overview of surface water flood risk in Greater Manchester and the interrelationships between districts
  • a more detailed assessment of surface water risk in Water Street
  • evidence to inform Bury's Local Flood Risk Management Strategy
  • good practice guidance to inform future strategic, area or site based surface water management planning activities within the Borough.

Emergency planning considerations

The Greater Manchester Civil Contingencies and Resilience Unit has prepared a guide on flood risk and emergency planning considerations when assessing relevant planning applications.