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Managing urban flooding sustainably

The Government's new strategy for flood and coastal erosion risk management (Making Space for Water) identified the need for an holistic, joined-up, and integrated approach to managing flood risk.  Such an integrated approach is particularly important in urban areas where there is an intricate array of drainage pathways and complex institutional arrangements.

One of the Making Space for Water projects is addressing integrated urban drainage management (IUDM) - how technical and institutional approaches to managing urban drainage systems can be improved to effectively deliver reduced flood risk in urban areas and at the same time contribute to delivering water quality protection and improvements, such as those required by the Water Framework Directive.

Map of pilot locations

Defra is funding 15 pilot projects to test new approaches to reduce the impact of urban drainage flooding.  The locations vary from established urban areas with combined sewers (e.g. North Brent), to greenfield locations where substantial new housing is planned (e.g. Marston Vale) and locations where river, costal and sewer flooding are all issues (e.g. Torbay).  Every pilot has established a partnership involving local representatives from the water company, Environment Agency and local authority.  The projects are managed individually by a lead stakeholder identified in each area, but coordinated by a team from Defra and Halcrow Group.

The pilot projects will focus on three main questions:

• Identifying causes of flooding in urban areas and considering the best ways of managing urban drainage to reduce flooding.
• Examining the effectiveness of current partnership working between the various drainage authorities (water companies, local authorities, Environment Agency, Internal Drainage Boards), and how it could be improved to find solutions to urban flooding problems.
• Testing new approaches to reduce the future impact of urban flooding on people and the environment, including: use of models to identify where the water is coming from, surface water management plans, and effective management of stormwater through sustainable drainage systems and above-ground flood routing.

The pilots finish in April 2008, after which Defra will develop new guidance on approaches to integrated urban drainage management, including issues around data-sharing, risk assessment (modelling and mapping), and cost-benefit analysis to influence investment strategies.  Defra will also produce an impact assessment of the institutional arrangements required to promote improvements to integrated urban drainage management. The findings from the pilot studies will provide evidence about whether any change can be justified in terms of cost effectiveness, sustainability, and equity considerations.

Further information is available from http://www.defra.gov.uk/environ/fcd/policy/strategy/ha2.htm.

Sebastian Catovsky, Defra
Elliot Gill, Halcrow Group

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