The river runs through it

ON 8 November 2001 - a cold and unsurprisingly rainy day - the UK Minister for Flood Management, Elliot Morley, was presented with an independent report on flooding at the London offices of the Department for the Environment, Food and the Rural Affairs (DEFRA). The Learning to Live with Rivers report, undertaken by the Institution of Civil Engineers (ICE), was developed in light of the Autumn 2000 floods where some 10,000 houses were flooded in the UK, causing US$1.4B worth of damage. Coupled with the prospect of further flooding in the country, this event prompted Morley to invite the ICE to establish a commission to advise the government on how to alleviate flooding in the future, and to examine the existing flood defence infrastructure in the UK.

'The floods of 2000 provided a severe test to arrangements and flood defence infrastructure,' said Morley. 'It is essential we examine potential weaknesses in our technical understanding and ability to respond and ensure our policies are robust and effective.'

Flooding is a natural phenomenon, and, try as you might, it cannot be prevented. However, its impacts can be minimised through flood protection and forecasting. With experts predicting that extreme rainfall events are likely to become more frequent, a comprehensive and effective system is needed to manage the risk of flooding.

Speaking at the launch, the recently appointed president of the ICE, Mark Whitby, said he hoped that the report - which gathered evidence from a range of interested parties, including the Environment Agency (EA), Water UK and the Met Office - will provide guidelines for flood risk assessment and management in the 21st century. It is also expected to promote a continual appraisal of the techniques used, rather than just reassess techniques currently put in place following major flooding events.

Raising awareness

The recent periods of widespread and sustained flooding have no doubt raised awareness of the damage and distress that can occur. The report points out that it is crucial to take advantage of this raised state of awareness to communicate the realities of flood risk and how to manage the risk, and suggests that a long-term education initiative is required to stress that flood risks cannot be removed and to explain the uncertainties inherent in flood forecasting.

Involving people in preparing emergency plans is suggested as one way of raising flood awareness among householders and businesses at risk. This should also include planning and resources for recovery from flooding.

Greater awareness of flooding could also be achieved through the publication of data by transport authorities, says the report. It emphasises that these authorities should commission and publish flood risk surveys of flood prone routes or locations, especially where heavily trafficked routes are capable of being severely affected. It also recommends the country's archive of daily rainfalls be fully computerised and the resulting files be made freely available in the public domain to encourage more local analysis, as is the case in the US.

Flood risk maps are considered a valuable source of information for both the public and those involved in development control and flood risk management. However, the present maps are highlighted in the report as being 'not accurate or detailed enough to give confidence in the guidance that they provide'.To help remedy this situation, it is suggested that the EA should give high priority to this area to ensure that the maps give up-to-date and reliable information.

Health damage

A further point emphasised by the report is that the human distress and health damage caused by flooding has been overlooked in the strictly economic approach to assessing the benefits of flood mitigation interventions. It argues that the human cost should be built into future benefit-cost assessments.

The flooding of houses with sewage as a result of overloaded sewers is often however even more distressing than surface water flooding and poses a considerable health risk. In the year 1999-2000, around 3800 properties were flooded due to over loaded sewers. The report recommends the development of national standards for the infrastructure of sustainable urban drainage systems.

The responsibility for such flood risk management issues should be consolidated around one executive agency with enhanced supervisory powers over the various operating authorities, the report suggests. This agency should have resources allocated directly from the government and have responsibility for spending prioritisation, preparation and implementation of catchment flood management plans.

Under-investment

At the launch of the report, it was indicated that while compiling Learning to Live with Rivers, the ICE Commission received evidence of under-investment in maintenance of flood defences over recent years and a lack of planning and programming of maintenance in accordance with need. This trend, it says, needs to be reversed, so that existing flood alleviation schemes perform as designed. The use of risk-based analytical techniques and regular condition surveys, and the establishment of a national database of flood defence assets should facilitate this process.

From the evidence presented to the Commission, the report claims there is a strong case for significant increases in real terms in public spending on all aspects of flood risk management, from maintenance of existing flood defence assets, to the provision of new flood defences to flood warning and emergency planning procedures.

With regards to flood defence schemes, it is no longer considered acceptable by the ICE Commission to design flood defence schemes on the basis of a single event. Scheme design should extend the analysis to look at sensitivity to flows higher than the present design flow to take into account climatic and land use changes. The report urges that design engineers take advantage of the power of the Flood Estimation Handbook (CEHW, 1999) techniques to explore the sensitivity of the flood regime to climate change and land use.

Further research

The need for further research is a highly emphasised point in the report. The present structures of the research councils (Natural Environment Research Council, Engineering and Physical Sciences Research Council, Social Research Council, Medical Research Council, Biological and Biomedical Sciences and Office of Science and Technology) has failed to nurture cross-boundary projects in the area of flood risk management, especially with respect to technical, health, social and environmental impacts, says the report. It recommends the structure of the research councils should be reviewed.

It is also suggested that consideration should be given to a long term strategy for developing research skills within the UK for flood analysis. The report has identified there are considerable gaps in knowledge and a move to a solution-orientated culture by all concerned with flood risk management will enable these gaps to be filled.

Further research should be carried out into all the available options for improving the flood resistance of both existing and new buildings. The report suggests the aim should be to identify innovative and cost-effective solutions that will be readily adopted by the building industry.

An important tool mentioned to help meet this aim is computer modelling. Modelling has been developed not only to allow the testing of flood scenarios based on current catchment conditions, but also a dynamic perspective through investigation of future scenarios with various climate change and development assumptions.

The report identifies a need to develop and further integrate hydro-dynamic modelling, examining channel change and sedimentation, with hydrological sensitivity analyses to improve the accuracy of flood level estimates.

After fully reading the report, it becomes clear that the general conclusion is that the appropriate technical skills are lacking within the industry, from drainage engineers in local authorities to river engineers in the EA and skilled hydraulic specialists in universities. This lack of skills resources requires urgent attention. Through the report, the ICE hopes that such situations will be addressed.

As Elliot Morley concludes: 'We all recognise that we cannot stop natural disasters such as flooding, but I am sure that by using the most up-to-date knowledge and working together we can minimise the economic and social impact to this nation and its population.'