New research investigates potential influences on UK’s recent winter floods

New modelling techniques disentangle natural fluctuations from effects of increased atmospheric CO2 concentrations

August 29th 2014

Scientists from the Centre of Ecology & Hydrology, the Met Office, and the Universities of Oxford, Exeter and Reading, have carried out a thorough review of the potential influences on the recent floods which devastated large parts of the UK in December 2013 and January 2014. Their investigation examines how factors such as the state of the global oceans may have interacted with wind patterns and subsequent high-level atmospheric features.

Lead author Dr Chris Huntingford from the Centre for Ecology & Hydrology said: “The challenge is to understand in full the subtle balances between the competing influences on UK winter weather, whether they are from the oceans, the amount of polar sea ice, or the atmospheric state itself. Highly refined modelling techniques are now emerging that can tease apart often large natural fluctuations in these drivers from any effects of increasing atmospheric carbon dioxide concentrations.”

The study does not provide a definitive answer as to whether human activity played a role in the magnitude of the UK’s winter floods. The scientists say that many of the possible influences exhibit large natural fluctuations. They believe, however, that the known decreases in Arctic sea-ice cover was not a factor in the particular characteristics of the winter rainfall. Their conclusion is rather that a complex chain of events involving the Pacific Ocean and an unusual jet stream brought about the exceptional nature of the winter flooding.

Co-author Dr Peter Stott of the Met Office said: “More work is needed to robustly detect any changes in storminess in the UK and quantify how the risk of such extreme winters varies with climate variability and change. However, climate models of sufficient resolution to capture storms and their associated rainfall are now becoming available and need to be deployed as soon as possible to provide a solid evidence base for future investments in flood and coastal defences.”

Dr Chris Huntingford added: “The continual advance in scientific understanding of how the climate system operates implies that we will soon be able to assess better if there is any likelihood of the rainfall patterns of last winter occurring with altered frequency. Capitalising also on the UK’s extensive datasets of meteorological and river measurements, in tandem with advanced hydrological models, this understanding can be translated to any expected future flood risk. This review provides a roadmap towards that aim.”

On coastal flooding, co-author Dr Jason Lowe of the Met Office said: “We saw a number of examples last winter that demonstrated the vulnerability of coastal regions to flooding from surge events. At present our best evidence points towards future increases in coastal flooding being driven by global sea-level rise. We still need to better understand if changes in atmospheric storminess can also play a part.”

The research was published on the 27th August in the journal Nature Climate Change. For further information, see the press release on the Centre for Ecology & Hydrology website.


Chris Huntingford, Terry Marsh, Adam A. Scaife, Elizabeth J. Kendon, Jamie Hannaford,Alison L. Kay, Mike Lockwood, Christel Prudhomme, Nick S. Reynard, Simon Parry, Jason A. Lowe, James A. Screen, Helen C. Ward, Malcolm Roberts, Peter A. Stott, Vicky A. Bell, Mark Bailey, Alan Jenkins, Tim Legg, Friederike E. L. Otto, Neil Massey, Nathalie Schaller, Julia Slingo and Myles R. Allen (2014) Potential influences on the United Kingdom’s floods of winter 2013/14. Nature Climate Change, DOI:10.1038/NCLIMATE2314.


Photo: Burrowbridge, Somerset © Copyright Mike Smith and licensed for reuse under this Creative Commons Licence. “Following prolonged rainfall in January 2014, the Somerset Levels were flooded, apart from small areas of higher land.”


Abandoned landfills are polluting UK rivers, say scientists

Untreated landfill sites are leaching chemicals into the environment

August 28th 2014

Scientists from the British Geological Survey have been carrying out research into river pollution from old landfill sites. The focus of their investigation was Port Meadow which lies on the banks of the River Thames, north-west of Oxford, and the location for 11 disused landfills. Landfills are now lined with a thick layer of clay to reduce the risk of chemicals leaking out into the environment. However, there are many historic landfill sites in the UK which were not treated with such a lining before being closed.

To carry out this investigation, the research team drilled a series of boreholes along a stretch of the Thames floodplain and took regular water samples for three years from 2010 to 2013. The samples were analysed for their ammonium content using isotopic analysis, which the researchers describe as “a kind of chemical fingerprinting technique.” This analysis was used to identify the different sources of the chemical and to estimate the total amount moving through the floodplain. As a result, the scientists were able to attribute 27.5 tonnes of the annual amount of ammonium to household waste. The researchers say that, over an 8km reach of the Thames at Port Meadow, this could increase concentrations of the chemical by up to 40%.

The problem with ammonium is that in water it breaks down into nitrogen, and this extra amount of nitrogen can damage water quality, reduce the amount of oxygen available to fish and other organisms, and trigger excessive growth in aquatic plants and algae. In particular, ‘blue-green algal blooms’ can produce toxins capable of killing animals and of causing illness in humans. The scientists say that around the UK there are potentially thousands of historic landfill sites which were not lined with clay and are currently leaching large amounts of nitrogen into major rivers. Their findings highlight yet another source of nutrient pollution which has been a growing concern for some years, and the causes of which include industrial waste and agricultural practice.

The research was published in the journal Science of the Total Environment and was reported recently on NERC’s Planet Earth website.


Photograph: Geese at Port Meadow in wintertime, 2011 © Copyright ceridwen and licensed for reuse under this Creative Commons Licence. “This expanse of common grazing land is subject to flooding when the River Thames overflows its banks as in the picture here.”

CIWEM – Urban Drainage Conference

Urban Drainage Modelling, Emerging Technologies and Future Visions

August 27th 2014

CIWEM’s Urban Drainage Group is holding its annual conference in Blackpool in November. This three-day event marks the Urban Drainage Group’s 30th anniversary and will feature representatives from utility companies, water boards, local authorities, government agencies and international organisations.

The conference opens with a research and development workshop on climate change and rainfall, whilst the second day sees a keynote presentation on the history of urban drainage modelling over the last 30 years with a look at what the future might hold for the next 30 years. This will be followed by three sessions of presentations on the themes of hydraulic modelling, intelligent catchment management, and developments in run-off modelling. The day will also include workshops on collaborative working and flood research. The third day begins with a keynote presentation on SuDS (Sustainable Drainage Systems), followed by sessions devoted to future visions for urban drainage, emerging technologies and their potential impact on future drainage, and water quality planning in the context of the Water Framework Directive.

The three-day event includes an exhibition, showcasing new technologies from manufacturers and suppliers to the urban drainage sector, and provides urban drainage professionals with a number of opportunities for learning, networking and discussion of the latest developments and research.

Further details of the conference are available from the CIWEM website at “UDG Autumn Conference”.


CIWEM is the The Chartered Institution of Water and Environmental Management, an independent professional body whose aim is to advance the science and practice of water and environmental management for the public benefit.

Flood Risk Management in Wales – Natural Resources Wales publishes report

£165 million has been invested in flood and coastal protection schemes in Wales since November 2011

31 Risk Management Authorities are implementing the Welsh Government’s National Flood and Coastal Erosion Risk Management Strategy for Wales

August 26th 2014

Natural Resources Wales has published a report on Flood and Coastal Erosion Risk Management in Wales, 2011-2014. The report, issued to Welsh Ministers, is the first to be produced under Section 18 of the Flood and Water Management Act 2010 and was compiled from information provided by the 31 risk management authorities in Wales. The risk management authorities include Natural Resources Wales, 22 local authorities, 3 internal drainage boards and 5 water and sewerage companies. The report looks at the work of all those authorities in managing flood risk and coastal erosion in Wales between November 2011 and March 2014.

In the reported period, there have been a number of major flood events in Wales, causing an estimated total of £71 million worth of damage to property and infrastructure and an average £40,000 worth of damage to people’s homes with over a thousand homes and businesses affected. Those major flood events include flooding in Ceredigion and North Wales in 2012, as well as the winter storms of December 2013 and January 2014.

However, the report finds that major investment in flood and coastal protection schemes has directly reduced the risk of flooding for more than 6,500 homes and businesses, whilst investment in flood defences along the Welsh coastline during the recent winter storms helped to protect 75,000 properties from flooding.

Since November 2011, £165 million has been invested in flood and coastal protection schemes in Wales, the majority coming from the Welsh Government as well as European funding. The Welsh Government has also adopted a National Flood and Coastal Erosion Risk Management Strategy for Wales which has been implemented by all risk management authorities. The report finds that the strategy, and substantial advances towards greater collaborative working within Wales, has helped significantly during those major flood events.

John Griffiths, Minister for Natural Resources, Culture and Sport, welcomed the report, citing it as evidence that the Welsh Government’s sustained investment in flood risk management, together with its National Strategy and proactive approach to flood and coastal risk management, were making a difference to those communities at risk. “Managing flood risk remains a priority area for the Welsh Government,” he said, “but it is not a problem we can tackle alone. Natural Resources Wales and our local authorities play a significant role in preparing our communities and protecting them from flooding and I thank them for all their ongoing contribution to this important work.”

The report highlights a number of schemes and projects that have contributed to the overall work of reducing flood risk in Wales, including:

  • 624 community and business flood plans are now in place across Wales
  • 600 properties now benefit from individual property protection, supplied by Natural Resources Wales, if a flood scheme is not viable in the area
  • Improved modelling and mapping as well as new flood schemes have reduced the number of homes at risk of flooding from 220,000 in 2009 to 208,000 in 2014
  • The work of water companies, such as the Dŵr Cymru (Welsh Water) Rainscape project in Llanelli, is helping to reduce flood risk by diverting water from the drainage system

The report has been published as a PDF document and is available from the Natural Resources Wales website at “Natural Resources Wales | Flood and Coastal Erosion Risk Management in Wales, 2011-2014”.

Coastal defences combined with rising sea levels could increase flood risk, say scientists

Scientists show for the first time that local coastal defences such as sea walls could cause tides to change dramatically with rising sea levels

August 21st 2014

Researchers at Bangor University have made a surprising discovery. Working on a research project funded by the Natural Environment Research Council (NERC), they set out to discover what effect rising sea levels over the next century would have on tides. Computer models were used to simulate how the tides would change if sea levels were one metre higher than at present. They looked at the effect on tidal range – i.e. the difference between high water and low water – to find out if this rise in sea levels would cause any potential changes in the time of high water and tidal velocities. The result of the simulation showed that a rise in sea level by up to a metre had little effect on tides.

However, the surprise came when they decided to factor coastal defences into the computer model. Three different states of coastal defences were simulated: the first, no coastal defences; the second, coastal defences similar to the levels in place at present; and the third simulated a situation where the entire coast was protected by a wall. Whilst the first had little effect, the third caused a small change. But the largest effect was caused by the second, i.e. with flood defences that allow only part of the coastline to flood. The researchers conclude that a combination of localised coastal defences and rising sea levels could change typical tidal ranges and increase the risk of flooding.

Explaining these results, lead researcher Dr Holly Pelling of Bangor University thinks that the walls in place around the coast could cause the tides to reflect and amplify, which could lead to flooding. She explains: “The tide is basically a wave with a certain amount of energy and it dissipates energy as it travels… But if it builds up behind coastal defences you get this honeycomb effect with narrow channels which funnel the water. The walls could cause the tidal energy to be reflected and this could change where the energy is dissipated. So some areas will find the tidal amplitude is higher while others will find they are lower.”

Coastal flood defences are localised and protect only a small section of land, but the researchers argue that a more unified approach is needed to the building of coastal defences. Holly Pelling says that the implementation of coastal defences needs to be viewed from a basin-wide perspective and reassessed on an international scale. She was not making predictions but said that the mechanism could be important and more detailed research needed to be done.

For further information, see the Planet Earth website at “Coastal defences could contribute to flooding with sea-level rise”. The research was published in the journal Continental Shelf Research.


Pelling, H.E., Mattias Green, J.A. ‘Impact of flood defences and sea-level rise on the European Shelf tidal regime.’ Continental Shelf Research (2014). DOI reference:


Creative Commons Licence
St Ives, Cornwall © Copyright Anthony Bloor and licensed for reuse under a Creative Commons Attribution-ShareAlike 4.0 International License.

Managing Drought – NERC funds new research

Five research councils are funding a five-year research programme on ‘UK Droughts and Water Scarcity’

August 20th 2014

The Natural Environment Research Council (NERC), in collaboration with the other four leading research councils, is funding a five-year interdisciplinary research programme on UK Droughts and Water Scarcity. NERC says that “droughts and water scarcity jointly pose a substantial threat to the environment, agriculture, infrastructure, society and culture in the UK, yet our ability to characterise and predict their occurrence, duration and intensity, as well as minimise their impacts, is often inadequate.” The aim of the £12 million programme is to support improved decision-making in relation to droughts and water scarcity “by providing research that identifies, predicts and responds to the interrelationships between their multiple drivers and impacts.”

The project, led by the Centre for Ecology and Hydrology, will aim to identify interactions between natural and social systems in the production and management of droughts since the late nineteenth century, taking into account hydro-meteorological, environmental, and agricultural factors, as well as the social and cultural impacts of water scarcity together with government policy and resource management. A team from Oxford University will analyse the history of regulating water scarcity and its economic impacts in the UK, drawing on case studies of key historic droughts.

NERC says that “pressures on freshwater availability and security in the UK are increasing rapidly and pose mounting challenges for sustainable water management, particularly in southern England.” Over-abstraction to meet the demands of agriculture, industry, and a growing population, together with the effects of climate change, are causing multiple challenges in many water-stressed regions. The impact of water scarcity is becoming increasingly critical for food production, industrial efficiency, households and the environment. Understanding the interrelationships between natural and social factors will be a key objective of this interdisciplinary research: “At present, the drivers of drought and water scarcity, both meteorological (e.g. through anticyclonic blocking) and societal (e.g. supply and demand balance, water storage, transfer and utility trends), are considered in isolation.”

A major research outcome will be the first “droughts inventory” for the UK. The droughts inventory will provide a common reference for policy makers, regulators, water supply companies and UK business. For further information, see the NERC website at “UK Droughts and Water Scarcity”.


Photograph: Dry field of wheat, Bilsington, Kent © Copyright Christine Johnstone and licensed for reuse under this Creative Commons Licence.

Contaminated Land – Brownfield Briefing hosts conference

‘Risk Assessment and Remediation 2014’ will be held in October

August 19th 2014

Brownfield Briefing is hosting its annual Risk Assessment and Remediation conference in October. The conference will be held in London and takes place over two days, with one day focused on risk assessment and a second on remediation. The theme of the conference is Robust and Demonstrable Risk Assessment to achieve Cost-effective, Sustainable and Justifiable Remediation.

The conference will include sessions on regulatory guidance, remediation technologies and case studies, and hear perspectives from the Government, developers and financiers. The two-day event provides interested parties with the opportunity to hear about the latest developments in remediation technologies, to hear about the latest changes in regulatory guidance, to exchange views on brownfield development from different perspectives, and to discuss best practice.

Key speakers include Maggie Charnley, Defra’s Head of Soils and Contaminated Land, who will give the Government’s perspective on contaminated land policy in practice. This will include an assessment of the impact that revisions to statutory risk assessment guidance and the National Planning Policy Framework are having on brownfield development and contaminated land remediation.

As well as hearing a developer’s perspective on the challenges of brownfield development, the conference will also hear a financier’s perspective on brownfield sites. A leading financier will explain the investor’s attitudes to risk and brownfield development and will outline the types of projects receiving investment. Paul Nathanail of Land Quality Management Ltd will outline the development of S4ULs (suitable for use levels) and how they have been derived, and will also explain their role in effective risk assessment.

There will be a discussion on strategies for the identification, remediation and re-use of asbestos-contaminated materials, and a number of case studies will illustrate the costs, benefits and practicalities of existing and emerging remediation technologies.

The full programme is available from the Brownfield Briefing website.