Learning from the flooding

Recently I have been privileged to serve on the UK government Scientific Advisory Group for Emergencies on flooding (SAGE).

SAGE, a multidisciplinary expert team, is providing evidence and opinion to Sir Mark Walport the government chief scientific advisor, who has been advising the prime minister and cabinet via Cobra.

One of many learning points I have noted is the need to improve management of flooding using a “systems” point of view.

The recommendations of the Pitt Review (2008) on the 2007 floods pointed to this approach.

Many domains intersect when considering flooding; hydrology, meteorology, geology, engineering and technology, ecology, economics, social sciences and politics.

As in most engineering interventions, economics has a vital part to play, and the Levels are no exception

For the Somerset Levels, the primary factors seized on by the media were not necessarily the most relevant or the key issues.

For example, the main drainage river, the Parrett, has a higher water flow due to tidal effects than run-off from the Levels, so dredging could have worsened the situation by increasing in-flow at high tide.

The desirability of controlling tidal in-flow is a key learning point, and control at the mouth of the Parrett could be of significant benefit. In order to ascertain the effectiveness of this, comprehensive hydrological modelling taking account of all the critical river sections is vital.

Engineering consultancies and universities will have an important role in contributing to this knowledge.

As in most engineering interventions, economics has a vital part to play, and the Levels are no exception.

The Environment Agency has to demonstrate a significant benefit/cost ratio for Treasury to sanction work. A systems view might focus on the absolute cost versus value of the total and permanent loss of arable land to farming, rather than the marginal effects of incremental improvement.

The last but not least factor is politics.

In a context more general than the Somerset Levels, this has promoted localism, reducing the influence of central government on local planning, increasingly making building on flood plains a decision of commercial actors.

In a national system of governance which relies on market forces rather than regulatory interventions, the insurance industry has a key role to play. Indeed, leading insurers are currently increasing their capability to create and interpret scientific and engineering evidence to better understand and control risk.

Professor Jeremy Watson is director of science and technology at Arup