Advertisement

  1. ITV Report

Major lessons are emerging from the UK's floods

A house surrounded by floodwater in Egham, Surrey. Photo: Frantzesco Kangaris/PA Wire

Paul Sayers is a flood consultant and visiting fellow at the University of Oxford, Environmental Change Institute.

His views do not necessarily reflect those of ITV News.

Although the focus is rightly on helping those that have been affected by the ongoing flooding there are some major lessons emerging. Over the last 20 years policy and practice has moved from flood defence to flood risk management.

This is not just a change in name but recognises that we can not ‘defend’ ourselves from all storms; and could not afford to try.

Policy documents such as ‘making space for water’ and the idea of ‘flood resilience’ rightfully require an acceptance of the need to make space for flood water and to provide homes and services (communications, electricity, etc) that continue to function when flooded.

A flooded field next to a River Thames tributary in Oxford. Credit: Steve Parsons/PA Archive

Scientists and engineers accept this approach but do the public? Are we prepared to say success is when we allow our floodplains to flood more frequently but damage and disruption is less? It is clear that in many cases this big conversation simply hasn’t started.

There are also clear lessons for the way flood schemes are planned. Today the design and planning of flood infrastructure is largely based on ‘single’ design storm – a single coastal storm or rainfall event.

The 2007 floods highlighted that a single spatially coherent event could affect large parts of the country simultaneously with severe knock impacts for supply chains and critical service provision.

The recent floods further expose this simple view as inadequate, highlighting the fundamental difference between a ‘single event’ and a ‘prolonged sequence of storm events’; with one storm after another arriving on an increasingly saturated land and attacking weakened structures (such as the rail line in Dawlish).

Workmen assess a huge hole after the sea wall collapsed in Dawlish. Credit: Ben Birchall/PA Wire

The importance of both the spatial coherence and temporal sequencing of storms events is something we have known about for some time but is not a standard consideration in our design and management approach.

It is to be expected that those affected by floods recall days past when things were better – this local experience is invaluable in shaping a strategy to manage flooding.

But flood risk can only be managed successfully through a portfolio of actions and the focus on dredging is misguided.

The removal of blockages and the debris that could cause blockage are important activities but dredging of the river bed is rarely useful.

More often the flood levels are not controlled by the local depth of the river bed but by downstream water levels (that in turn may be constrained by local structures or sea levels).

Worcester Cathedral is pictured in flood-hit Worcester. Credit: Joe Giddens/PA Wire

In only a few cases will dredging help – mostly it will waste money and succeed only in damaging the river ecosystem, and with it the reasons why we enjoy the river 90% of the time.

The recent floods demonstrate that we can do better and must do better – but lets learn the real lessons and act upon those.

More on this story