Environment Agency – Cabot Institute for the Environment blog

Flooding in the UK: Understanding the past and preparing for the future

Posted on October 25, 2019April 3, 2023 by janet.crompton

On the 16th of October 2019, Ivan Haigh Associate Professor in Coastal Oceanography at the University of Southampton – gave a presentation on the “characteristics and drivers of compound flooding events around the UK coast” at the BRIDGE research seminar in the School of Geographical Sciences. He began by outlining the seriousness of flood risk in the UK – it is the second highest civil emergency risk factor as defined by the Cabinet Office – before moving on to the first section of the talk on his work with the Environment Agency on its Thames Estuary 2100 plan (TE2100)[1].

Thames Estuary 2100 plan: 5-year review

The construction of a Thames barrier was proposed after severe flooding in London in 1953, and it eventually became operational 30 years later in 1983. Annually, the Thames barrier removes around £2bn of flood damage risk from London and is crucial to the future prosperity of the city in a changing environment.

The Thames Barrier in its closed formation. Image source: Thames Estuary 2100 Plan (2012)

Flood defences in the Thames estuary were assessed in the TE2100 plan, which takes an innovative “adaptive pathways management approach” to the future of these flood defences over the coming century. This approach means that a range of flood defence options are devised and the choice of which ones to implement is based upon the current environmental data and the latest models of future scenarios, in particular predictions of future sea level rise.

For this method to be effective, accurate observations of recent sea level changes must be made in order to determine which management pathway to implement and to see if these measurements fit with the predictions of future sea level rise used in the plan. This work is carried out in reviews of the plan at five-year intervals, and it was this work that Ivan and his colleagues were involved with.

There is significant monthly and annual variability in the local tide gauge records that measure changes in sea level, and this can make it difficult to assess whether there is any long-term trend in the record. Using statistical analysis of the tide gauge data, the team was able to filter 91% of the variability that was due to short term changes in atmospheric pressure and winds to reveal a trend of approximately 1.5 mm per year of sea level rise, in line with the predictions of the model that is incorporated into the TE2100 plan.

Compound flood events around the UK Coast

In the second half of his presentation, Ivan went on to discuss a recent paper he was involved with studying compound flood events around the UK (Hendry et al. 2019)[2]. A compound flood occurs when a storm surge, caused by low atmospheric pressure allowing the sea surface to rise locally, combines with river flooding caused by a large rainfall event. These can be the most damaging natural disasters in the UK, and from historical data sets stretching back 50 years at 33 tide gauges and 326 river stations, the team were able to determine the frequency of compound floods across the UK.

Along the west coast, there were between 3 and 6 compound flooding events per decade, whereas on the east coast, there were between 0 and 1 per decade. This difference between east and west is driven by the different weather patterns that lead to these events. On the west coast it is the same type of low-pressure system that causes coastal storm surges and high rainfall. However, on the east coast different weather patterns are responsible for high rainfall and storm surges, meaning it is very unlikely they could occur at the same time.

Number of compound flood events per decade at each of the 326 river stations in the study. Triangle symbols implies rover mouth on West coast, circles East coast and squares South coast. Image Source: Hendry et al. 2019 [2]

There is also significant variability along the west coast of the UK as well, and the team investigated whether the characteristics of the river catchments could impact the possibility of these compound flooding events occurring. They found that smaller river catchments, and steeper terrain within the catchments, increased the probability of these compound flooding events occurring as water from rainfall was delivered to the coast more quickly. From the improved understanding of the weather patterns behind compound flooding events that this work provides, the quality and timeliness of flood warnings could be improved.

From the question and answer session we heard that current flood risk assessments do not always include the potential for compound flood events, meaning flood risk could be underestimated along the west coast of the UK. We also heard that Ivan will be working with researchers in the hydrology group here at the University of Bristol to further the analysis of the impact of river catchment characteristics on the likelihood of compound flooding events, and then extending this analysis to Europe, North America and Asia.

References

[1] Environment Agency (2012), “Thames Estuary 2100 Plan”.
[2] Alistair Hendry, Ivan D. Haigh, Robert J. Nicholls, Hugo Winter, Robert Neal, Thomas Wahl, Amélie Joly-Laugel, and Stephen E. Darby, (2019). “Assessing the characteristics and drivers of compound flooding events around the UK coast”, Hydrology and Earth System Science, 23, 3117-3139.

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This blog was written by Cabot Institute member Tom Mitcham. He is a PhD student in the School of Geographical Sciences at the University of Bristol and is studying the ice dynamics of Antarctic ice shelves and their tributary glaciers.

Tom Mitcham

Read Tom’s other blog:
1. Just the tip of the iceberg: Climate research at the Bristol Glaciology Centre

How accurate are the media on climate change and extreme weather events?

Posted on March 16, 2016April 12, 2023 by janet.crompton

I’ve always appreciated the environment, but had previously taken on the role of spectator. I credit this magnificent city of ours with inspiring me to change my passive respect of nature to taking an active role in trying to preserve it. The strong sense of community in Bristol and the green-mindedness of its residents is infectious, and is evident in the number of fantastic projects we have which are led by the people and by our local government.

I craved more information about our environment so started attending lectures and events that are regularly held by the Cabot Institute and various departments across the university. As my insight to the issues we face grew, I realised I needed to increase my understanding and hopefully align my career in a way in which I could have a positive impact. I decided to enrol in a masters in Climate Change Science and Policy so I could appreciate the scientific intricacies rather than relying on what I heard, and what I read in the media.

My course enabled me to learn about climate modelling and the difficulties of implementing environmental policies, not just logistically but in terms of ethics and opinion. It is one thing to be passionate about science and research, it is quite another to communicate that to a non-specialist in a way that the magnitude and seriousness of climate change is realised. A warming climate will affect the entire globe and all sectors within it. Bridging the gap in knowledge between climate scientists and policy makers/society is therefore paramount. People often rely on the media as their main source of information and indeed it can successfully act as an education broker between scientists and the public. The seemingly omnipotent power of the media to mould opinion can be beneficial, but do we really know if what we’re reading is the truth?

I was offered the opportunity to explore this question, and it was the Environment Agency (EA) that requested the answers. Specifically, I conducted my dissertation on the accuracy of the UK media in reporting of extreme weather events. It may seem a rather unusual project to be proposed by the EA, so I shall explain. Within the organisation is a climate change branch, a part of which is the ‘Climate Ready Support Service’. Their objective is to provide advice and support to businesses in order to prevent and mitigate the effects of extreme weather events and climate change. The Environment Agency uses recent extreme weather events to exemplify realistic scenarios that could befall a vulnerable business.

The speed, scope and accessibility of the media makes it a valuable tool, during and immediately after a weather event. The fast-paced nature of modern reporting and social media necessitates that to some extent the EA relies on information from news organisations. Additionally, there are vastly more journalists than there are staff in the ‘Climate Ready Support Service’ therefore media reliance is essential. When the EA republishes this information it must be relevant, accurate and consistent, and it was my mission to quantify the reliability of UK media and to assess the confidence that the EA can have in it.

I was not able to analyse all UK media so I studied a selected sample from the Guardian, the Telegraph and the Mirror. I chose them because they contain a mix of broadsheet/tabloid, political affiliations and demographics. I analysed sixty two articles across three extreme weather events: ex-Hurricane Bertha (2014), the spring floods (2012) and the Birmingham tornado (2005). This provided a range of recent short, high impact events and longer-lasting cumulative ones. I conducted content analysis on each article, breaking the text up into study units that could be verified by official sources such as government documentation, academic journals and weather data. Media accuracy is not as straightforward as being right or wrong, not just the objective facts. Subjective inaccuracies also play a part, and can fundamentally alter the final message or mislead the reader from the truth. I categorised these as omission of information, exaggeration/under-exaggeration, personalisation, sensationalism and general confusion.

The results suggest that overall the UK media is 77.9% accurate. The Guardian achieved the highest overall accuracy (83.8%), followed by the Telegraph (76.2%) and the Mirror obtained the lowest accuracy rate (72.5%). Of more consequence to the EA is objective (factual) accuracy as opposed to subjective accuracy, and, the Guardian is the most reliable of the three publications in this respect (94.3%). Even though it is a broadsheet, the Telegraph was less objectively accurate than the Mirror with 85.8% and 87.3% accuracy respectively. Across all three publications, factual inaccuracies such as measurements, geolocations, timings, names etc. were most prevalent with 30%. This was followed by omission/addition as the next most common error (27%). Exaggeration was also significantly evident in the press accounting for 17% of the total inaccuracies.

What does this mean for the EA? This research hopefully clarifies which publications are worth relying on most heavily when obtaining their information. I would still recommend the agency continue to conduct their own internal fact checks because evidently there are still errors. Additionally, it was a one person study, with only one perspective and a limited sample size. As with any research, there’s always more that can be done to validate the findings and as this was the first study to investigate media accuracy of extreme weather events, more is warranted before sweeping conclusions can be made.

What I found interesting was that of the sixty two articles analysed only four of them mentioned climate change within the content. It is the EAs aim to embed climate change messages within all aspects of their organisation, and with the projected increase of such events I would have expected more linkage in the media. After interviewing some journalists a lot of them agreed that climate change should be associated with not just extreme weather stories, but all topics such as education, health and finance. There are practical limitations in achieving this but perhaps in the future, climate change will always be considered in all aspects of our global society. For now we should remain hopeful that we make some significant steps forward after the United Nations Climate Summit in December, and that Bristol continues its European Green Capital ethos into 2016 and beyond.

It was a great experience knowing that my work might have a real world impact and my contacts in the Environment Agency were really helpful throughout the process. I am now working within the Sustainability Department here at the University of Bristol with the aim of reducing our environmental impact by implementing the S-Labs Initiative (Safe, Secure, Sustainable Labs).

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This blog is written by Anna Lewis who recently graduated from the Climate Change Science and Policy MSc at the University of Bristol. As part of her course she undertook a Cabot Institute pilot project called Community Based Learning which connects postgraduate students with organisations in order to help them solve a real-world problem. If your organisation would like to get involved in Community Based Learning with the University, please contact cabot-cbl@bristol.ac.uk.

Anna Lewis

Anna now works at the University implementing sustainable laboratories throughout the institution.

Is benchmarking the best route to water efficiency in the UK’s irrigated agriculture?

Posted on March 7, 2016April 12, 2023 by janet.crompton

Irrigation pump. Image credit Wikimedia Commons.

From August 2015 to January 2016, I was lucky enough to enjoy an ESRC-funded placement at the Environment Agency. Located within the Water Resources Team, my time here was spent writing a number of independent reports on behalf of the agency. This blog is a short personal reflection of one of these reports, which you can find here. All views within this work are my own and do not represent any views, plans or policies of the Environment Agency.

Approximately 71% of UK land (17.4 million hectares) is used for agriculture – with 9.3 million hectares (70%) of land in England used for such operations. The benefits of this land use are well-known – providing close to 50% of the UK’s food consumption. Irrigated agriculture forms an important fulcrum within this sector, as well as contributing extensively to the rural economy. In eastern England alone, it is estimated that 50,000 jobs depend upon irrigated agriculture – with the sector reported to contribute close to £3 billion annually to the region’s economy.

It is estimated that only 1-2% of the water abstracted from rivers and groundwater in England is consumed by irrigation. When compared to the figures from other nations, this use of water by agriculture is relatively low. In the USA, agricultural operations account for approximately 80-90% of national consumptive water use. In Australia, water usage by irrigation over 2013/14 totalled 10,730 gigalitres (Gl) – 92% of the total agricultural water usage in that period (11,561 Gl).

However, the median prediction of nine forecasts of future demand in the UK’s agricultural sector has projected a 101% increase in demand between today and 2050. In this country, irrigation’s water usage is often concentrated during the driest periods and in the catchments where resources are at their most constrained. Agriculture uses the most water in the regions where water stress is most obvious: such as East Anglia. The result is that, in some dry summers, agricultural irrigation may become the largest abstractor of water in these vulnerable catchments.

With climate change creating a degree of uncertainty surrounding future water availability across the country, it has become a necessity for policy and research to explore which routes can provide the greatest efficiency gains for agricultural resilience. A 2015 survey by the National Farmers Union found that many farmers lack confidence in securing long term access to water for production – with only a third of those surveyed feeling confident about water availability in five years’ time. In light of this decreasing availability, the need to reduce water demand within this sector has never been more apparent.

Evidence from research and the agricultural practice across the globe provides us with a number of possible routes. Improved on-farm management practice, the use of trickle irrigation, the use of treated wastewater for irrigation and the building of reservoirs point to a potential reduction in water usage.

Yet, something stands in the way of the implementation of these schemes and policies that support them: People. The adoption of new practices tends to be determined by a number of social factors – depending on the farm and the farmer. As farmers are the agents within this change, it is important to understand the characteristics that often guide their decision-making process and actions in a socio-ecological context.

Let’s remember, there is no such thing as your ‘average farmer’. Homogeneity is not a word that British agriculture is particularly aware of. As a result, efforts to increase water use efficiency need to understand how certain characteristics influence the potential for action. Wheeler et al. have found a number of characteristics that can influence adaptation strategies. For example, a farmer with a greater belief in the presence of climate change is more likely to adopt mitigating or adaptive measures. Importantly, this can also be linked to more-demographic factors. As Islam et al. have argued, risk scepticism can be the result of a number of factors (such as: age, economic status, education, environmental and economic values) and that these can be linked to the birth cohort effect.

This is not to say that all farmers of a certain age are climate-sceptics but it does point to an important understanding of demography as a factor in the adoption of innovative measures. Wheeler et al. went on to cite variables of environment values, commercial orientation, perceptions of risk and the presence of an identified farm successor as potentially directing change in practice . Research by Stephenson has shown that farmers who adopt new technologies tend to be younger and more educated, have higher incomes, larger farm operations and are more engaged with primary sources of information.

Yet, there is one social pressure that future policy must take into account – friendly, neighbourly competition. Keeping up with the Joneses. Not wanting Farmer Giles down the lane knowing that you overuse water in an increasingly water-scarce future. This can be harnessed within a system of benchmarking. Benchmarking involves the publication of individual farm’s water use, irrigation characteristics and efficiency and farming practice. Although data is supplied anonymously, individual farmers will be able to see how they measure up against their neighbours, competitors and others elsewhere.

Benchmarking is used in other agricultural sub-sectors. A 2010 survey found that 24% of farmers from different sectors used benchmarking in their management processes. This is particularly evident in the dairy sector, where both commercial and public organisations use the methods as a way to understand individual farm performance – an important example of this would be DairyCo’s Milkbench+ initiative. In 2004, over 950,000 hectares of irrigated land in Australia, 385,000 hectares in China and 330, 000 hectares in Mexico were subjected to benchmarking processes as a mean to gauge their environmental, operational and financial characteristics.

The result is that irrigators would have the means to compare how they are performing relative to other growers – allowing the answering of important questions of ‘How well am I doing?’ ‘How much better could I do?’ and ‘How do I do it?’ Furthermore, this route can be perceived as limiting the potential for ‘free-riding’ behaviour within a catchment as well emphasise the communal nature of these vulnerable resources. We’ve all seen ‘Keeping up with the Joneses’ result in increased consumption – benchmarking provides us with an important route to use this socialised nudging for good.

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This blog is written by Cabot Institute member Ed Atkins, a PhD student at the University of Bristol who studies water scarcity and environmental conflict.

Ed Atkins

Read part 1 of this blog series Why is there a difficult absence of water demand forecasting in the UK?

Why is there a difficult absence of water demand forecasting in the UK?

Posted on February 25, 2016April 12, 2023 by janet.crompton

Image credit: Ralf Roletschek, permission from – Marcela auf Commons.

From August 2015 to January 2016, I was lucky enough to enjoy an ESRC-funded placement at the Environment Agency. Located within the Water Resources Team, my time here was spent writing a number of independent reports on the behalf of the agency. This blog is a short personal reflection of one of these reports, which you can find here. All views within this work are my own and do not represent any views, plans or policies of the Environment Agency.

In a world away from Melanie Phillips and David Bellamy, it is widely accepted that the twinned-spectres of climate change and population growth will likely affect levels of water availability in England and Wales, whilst also exposing the geographic imbalance of water supply-demand dynamics within the country. The Environment Agency has utilised a number of socioeconomic scenarios to predict total demand to change at some point between 15% decrease (if the nation undergoes a transition towards sustainability) to a 35% increase (in a scenario of continued and uncontrolled demand for the resource).

It is within this context that the need to understand future patterns of water demand has become essential for the future resilience of the nation’s water. The Labour government’s Future Water strategy (signed-off by Hilary Benn) 2008 set a national target of reducing household water consumption by 13%. This plan was further incentivised by Ofwat’s scheme to reward companies that reduce annual household demand by one litre of water per property, per day in the period 2010/11-2014/15.

What does our future household water use look like? Whilst per capita consumption will decrease, the number of people using the water grid will increase: resulting in a growth of overall demand. 22 predictions related to public water supply projected a median change of +0.89%. However there are additional complexities: as certain uses of water will decrease, others will increase; as appliances become more water efficient, they will be more likely to be used; and as one business closes, another may join the grid. It is this complexity that creates a great deal of uncertainty in gauging the future water demand of the sector.

Image credit: Nicole-Koehler

But, there exists a problem. Whilst the legally-mandated water management plans of the public water suppliers provide us with a wealth of forecasts of the future water usage within our homes, there exists a lack of available information on the current use of water within many other sectors and how such usage may shift and transform in the years between today and 2050.

This report lays out an extensive review of available literature on the current and future demand of a number of sectors within the UK. It found nine studies of the agricultural sector – with a median projection of 101% increase in water usage. Three studies of the energy sector projected a median decrease of 2% on a 2015 baseline. But, it also found some gaps that restrict our understandings of future water demand.

Want to find out how much water is used in the construction sector? Tough, no chance. The mining and quarrying sector – ready your Freedom of Information request. Want to calculate the future water footprints of our food and drink – prepare to meet that brick wall. If such information is available, it is not in the public domain. Without having a publicly-available baseline, how can we even dream of predicting what our future demand may be?

Crop irrigation. Image credit: Rennett Stowe.

Water is not just turning on the shower in the morning or boiling the kettle at the commercial break. It is present in our food, our energy and our infrastructure. As a result, it is of the utmost importance that we look to gauge the water use of sectors. Yet, in this regard, we are blind. Although there do exist academic studies and research into the future water demand of the agricultural and energy sectors, this has proved limited and relatively inconclusive, due to the nature of the studies. Furthermore, there is an absence of any such work conducted across the manufacturing and industrial sectors (with the exception of the food and drink industry). This limitation of information makes providing a confident summary of what the water demands of many of these sectors will look like in 2050 highly difficult.

Yes, the key areas of missing research identified in this document do not necessarily equal a lack of information within these sectors – just that such information is either not publicly available or is very difficult to find. It would be unwise to believe that the sectors in question have no understanding of what the future may hold, regarding their water demand. But, in a world of the interdependencies of the food, energy and manufacturing sectors with water usage – it is important for research to know how this nation’s water is used, where it is used and how this demand can be met and/or decreased in an increasingly uncertain future. The food and drink sector is heavily linked to the agricultural sector; the power industry is linked to decisions made within the extractive industries (such as those surrounding fracking); and all are linked to mains water supply and direct abstraction.

These interdependencies and lack of information provide future water demand with even greater uncertainty. Whilst carbon emissions are monitored and water quality is policed, there continues to be a lack of transparency of how certain sectors are using this nation’s water. If this continues in a world that will increasingly be formed of policy and environmental trade-offs, there is a realistic danger that any potential water crisis may be much worse than we expect.

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This blog is written by Cabot Institute member Ed Atkins, a PhD student at the University of Bristol who studies water scarcity and environmental conflict.

Ed Atkins

Read part two of this blog series Is benchmarking the best route to water efficiency in the UK’s irrigated agriculture?

Why do flood defences fail?

Posted on December 9, 2015April 12, 2023 by janet.crompton

More than 40,000 people were forced to leave their homes after Storm Desmond caused devastating floods and wreaked havoc in north-west England. Initial indications were that the storm may have caused the heaviest local daily rainfall on record in the UK. As much as £45m has been spent on flood defences in the region in the previous ten years and yet the rainfall still proved overwhelming. So what should we actually expect from flood defence measures in this kind of situation? And why do they sometimes fail?

We know that floods can and will happen. Yet we live and work and put our crucial societal infrastructure in places that could get flooded. Instead of keeping our entire society away from rivers and their floodplains, we accept flood risks because living in lowlands has benefits for society that outweigh the costs of flood damage. But knowing how much risk to take is a tricky business. And even when there is an overall benefit for society, the consequences for individuals can be devastating.

We also need to calculate risks when we build flood defences. We usually protect ourselves from some flood damage by building structures like flood walls and river or tidal barriers to keep rising waters away from populated areas, and storage reservoirs and canals to capture excess water and channel it away. But these structures are only designed to keep out waters from typical-sized floods. Bigger defences that could protect us from the largest possible floods, which may only happen once every 100 years, would be much more expensive to build and so we choose to accept this risk as less than the costs.

Balancing the costs and benefits

In the UK, the Environment Agency works with local communities to assess the trade off between the costs of flood protection measures, and the benefits of avoiding flood damage. We can estimate the lifetime benefits of different proposed flood protection structures in the face of typical-sized floods, as well as the results of doing nothing. On the other side of the ledger, we can also estimate the structures’ construction and maintenance costs.

In some cases, flood protection measures can be designed so that if they fail, they do the least damage possible, or at least avoid catastrophic damage. For example, a flood protection wall can be built so that if flood waters run over it they run into a park rather than residential streets or commercial premises. And secondary flood walls outside the main wall can redirect some of the overflow back towards the river channel.

Thames Barrier: big costs but bigger benefits.
Ross Angus/Flickr, CC BY-SA

The Environment Agency puts the highest priority on the projects with the largest benefits for the smallest costs. Deciding where that threshold should be set is a very important social decision, because it provides protection to some but not all parts of our communities. Communities and businesses need to be well-informed about the reasons for those thresholds, and their likely consequences.

We also protect ourselves from flood damage in other ways. Zoning rules prevent valuable assets such as houses and businesses being built where there is an exceptionally high flood risk. Through land management, we can choose to increase the amount of wooded land, which can reduce the impact of smaller floods. And flood forecasting alerts emergency services and helps communities rapidly move people and their portable valuables out of the way.

Always some risk

It’s important to realise that since flood protection measures never eliminate all the risks, there are always extra costs on some in society from exceptional events such as Storm Desmond, which produce very large floods that overwhelm protection measures. The costs of damage from these exceptional floods are difficult to estimate. Since these large floods have been rare in the past, our records of them are very limited, and we are not sure how often they will occur in the future or how much damage will they cause. We also know that the climate is changing, as are the risks of severe floods, and we are still quite uncertain about how this will affect extreme rainfall.

At the same time we know that it’s very hard to judge the risk from catastrophic events. For example, we are more likely to be afraid of catastrophic events such as nuclear radiation accidents or terrorist attacks, but do not worry so much about much larger total losses from smaller events that occur more often, such as floods.

Although the process of balancing costs against benefits seems clear and rational, choosing the best flood protection structure is not straightforward. Social attitudes to risk are complicated, and it’s difficult not to be emotionally involved if your home or livelihood are at risk.

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This blog is written by Cabot Institute member Dr Ross Woods, a Senior Lecturer in Water and Environmental Engineering, University of Bristol. This article was originally published on The Conversation. Read the original article.

Ross Woods