Manage surface water and flood risk

The potential impacts of extreme weather are inherently uncertain. Experience has taught us to avoid the most obvious high-risk locations.

Elaine Johnson / Alamy

For example the settlements along the upper and middle Thames and similar major rivers are generally set back from the flood zone which floods extensively and often. However, very extreme events rarely happen repeatedly in the same place, and so there is no way of knowing whether the major flood events in recent years such as at Hull, Carlisle, Sheffield will be repeated again soon in those places.

Learning the lessons identified in the Pitt Review into these events is crucial.

The one certainty is that they will happen somewhere in the UK, every few years, and climate change will mean they are likely to happen with increasing frequency and severity. UKCIP provides information on the projected scenarios for rainfall.

There are three different modes of flooding in urban areas: pluvial (surface water flooding); fluvial (river flooding); and tidal (coastal and estuarial flooding). Flood risk is a combination of the probability of flooding and the consequences. Both of these aspects of risk can be managed.

Surface water run-off is one of the prime causes of inland flooding in the UK and is directly influenced by the design and management of our cities and towns. An example of an effective approach to surface water management is green infrastructure-based landscape planning and design. This involves the evaluation of the functionality and benefits of a complex network, with the capacity to ameliorate the impacts of extreme events, but also with the potential to be adapted to mitigate and compensate for future climate change.

Evaluation of this type of green infrastructure network (such as that contained within a river catchment or sub-catchment of rivers like the Severn or Trent) will lead to recognition of the existing features, systems and their benefits and the diversity and scale of the different organisations involved in managing them.

At site level, it is important that the principle of landowner/developer responsibility applies. Every site should be planned and designed to avoid increasing risks for others. Ideally, the knowledge we have now will lead to sustainable and creative water management within the site footprint, rather than reliance on solving water management problems off-site at the expense of others.