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Several journalists have asked the SMC about the prolonged period of dry weather and anticipated drought this summer. Below are some comments from scientists on these topics in case useful.
Comments sent out Friday 12th August 2022
Dr Paola Sakai, a research economist at the University of Leeds, said:
“We need to recognise that clean water is a resource that we need to use wisely. There are plenty of measures we can implement at all scales.
“In Leeds, having a tighter water efficiency policy is helping to decrease water demand in new homes. It was a good step contributing to save 15 litres of water per person per day in new developments. In the first 7 months or so, the policy managed to save around 102,000 litres of water. This is how Leeds has counteracted the lack of National guidance.
“Climate projections point at hotter summers in Yorkshire. We need local action and working together to adapt our infrastructure and behaviours to manage this precious resource.”
Andrew McKenzie, Principal Scientist, Hydrogeology, British Geological Survey, said:
“2021 was an average year for rainfall in the UK, and at the start of 2022 groundwater levels in the UK’s largest aquifers were at average levels. The dry spring of 2022 meant that aquifers stopped filling from winter recharge earlier than they normally would, and they have fallen during the summer slightly faster than normal. But though levels are now below normal to notably low in parts of the UK, they aren’t yet exceptionally low. An exception is along the coast in the southeast of England and in South Wales, where aquifers have relatively low storage and respond rapidly to rainfall, or a lack of rainfall.
“The impact of low groundwater levels is first felt in two ways:
“The larger supplies used by Water Companies for public supply are usually sited in the parts of the aquifers where groundwater supplies are most resilient and reliable so aren’t as affected in the early part of a drought as smaller supplies for isolated communities, individual households and farming, that are often in less productive parts of aquifers and where yield can reduce or ultimately dry up. These large public supplies tend to be affected in the later stages of a drought. Groundwater is managed in the UK under a system of abstraction licences and the total amount of water that can be extracted from an aquifer is controlled to ensure supplies are shared between users, and to minimise the impact of pumping on rivers and wetlands. It is common for licences to specify that pumping groundwater should reduce, or cease, when water levels drop below specified limits, or when flow in rivers that depend on groundwater drops too low.
“So, what is the current outlook for groundwater resources? Our models allow us to be confident that levels in aquifers will remain low to notably low, but only in a few places exceptionally low (defined as below the level expected once every 20 years) for the next 1 to 3 months. Beyond October it becomes harder to predict how quickly groundwater levels in aquifers will recover. We will certainly require above average winter rainfall to recover levels back to where we started in early spring 2022, and another dry winter that fails to replenish aquifers back to normal levels could leave groundwater much more vulnerable to drought in 2023.”
Prof Hannah Cloke, Professor of Hydrology, University of Reading, said:
“The decision by the National Drought Group, convened by the Environment Agency, to announce an official drought is perhaps overdue. While for technical, procedural and legal reasons there needs to be a point at which we all step up efforts to preserve supplies, it is just weird that one day the government and Environment Agency says “nowhere in England is considered to be in drought” and the next day, we are in drought. The reality is of course much less binary than that.
“As our response requires individuals and businesses to change their behaviour, more thought needs to be applied to how people respond to mixed messages like that.
“Of course water companies need to do what they can to keep supplies to people flowing. But having to extract more water from rivers, or pump more groundwater than we would usually like, puts more pressure on nature. We need to plan longer term to cope with drought and water stress, in the same way that we need to plan to deal with heavy rainfall without homes being flooded or overflowing sewage being allowed to run into our rivers. We need to see our rivers and wider environment as our own life support system, as well as that of wildlife and nature.
“Some rain is forecast in the weeks ahead, but this is unlikely to be long-lasting or widespread enough to make a big difference to some exceptionally low levels in reservoirs and rivers.”
Dr Mike Rivington, senior scientist at the James Hutton Institute, said:
“This situation is a warning signal that the issue of water needs to be taken a lot more seriously as droughts have consequences on the ability of nature to function and provide society with the essentials for life. Biodiversity, particularly soil micro-organisms that maintain soil fertility, may struggle to recover impacting next year’s farming productivity. Climate change makes droughts more likely meaning agricultural productivity will be further reduced leading to even higher food prices”.
Comments originally sent out Thursday 11th August 2022
Mr Rob Lawson, Director at Artesia Consulting Ltd, and Chair of CIWEM’s Water Resources Specialist Panel, said:
“Is the potential upcoming hosepipe ban by Thames water expected?
All water companies in England and Wales will be monitoring the emerging drought situation very closely and will be planning how to respond as part of their predetermined drought plan. Given that areas of southern and eastern England saw less than 10% of the average July rainfall (link) and that the lack of rainfall in the Thames catchment over the last six months is only surpassed by recent droughts in 2010-12, 1995/96 and 1976. The rainfall deficit is similar to when Thames Water last imposed a hosepipe ban, in 2012 (based on visual analysis of SPI data from https://eip.ceh.ac.uk/hydrology/water-resources/).
“Is the potential upcoming hosepipe ban by Thames water necessary?
Yes. Hosepipe Bans will only be enforced as part of the pre-planned response to drought conditions by water companies. They are implemented to reduce demand on water resources and therefore extend the time that water supplies during drought periods, when there is a lack of rainfall or groundwater recharge to replenish these resources.
“What are the areas that would be affected by a Thames water hosepipe ban?
It’s uncertain at the moment whether the Thames Water HPB will apply to all of the Thames Water supply region or to specific water resource zones.”
Dr Oliver Gibson, Senior Lecturer in Exercise Physiology, at Brunel University, said:
“We see greater heat related morbidity and mortality when heat waves are more intense (hotter), or prolonged (longer). This is then further amplified when the two combine.”
Comments originally sent out Tuesday 9th August 2022
Prof Hannah Cloke, Professor of Hydrology, University of Reading, said:
“Most people won’t even have a hosepipe anyway. But a hosepipe ban is a useful shorthand way to ask people to curb unnecessary water use, and comes with a range of restrictions on the use of mains water to wash a car or fill a pool, for example.
“The Thames Water area is huge and is generally well supplied with fresh water via storage in reservoirs and aquifers. But current reservoir levels are very low in some locations, and dropping fast. With almost no rain forecast in the coming days and weeks across the south of England, and a new heatwave likely to make people spend time outside and think about their gardens this weekend, a hosepipe ban is a sensible way to preserve dwindling water supplies.
“However, this is an exercise in demand management that requires the willing cooperation of consumers. People are less likely to comply with rules if they think the authorities are not doing their bit too. The appalling recent water wastage that we’ve seen in the Thames Water area, and its inability to fix leaking pipes faster across its network, will lead many people to cut their water use only grudgingly.
“Water companies need to get their act together in fixing leaks faster, and showing that they are making progress, or they will face issues similar to those of the UK government in enforcing lockdown rules during the pandemic. It is hard to ask people to make sacrifices when the authorities look profligate.”
Professor Jeremy Biggs, CEO, Freshwater Habitats Trust, said:
“People often worry that drought is damaging to life in freshwater – after all, how can aquatic species survive without water? But in practice many freshwater plants and animals can readily survive, or even need, periods of drought. While some aquatic species – like fish – need water all the time, many freshwater plants and animals have lifecycles that are well-adapted to, periods of drying out.
“Most of the globe’s freshwater network is made up of temporary water bodies and around 50% of the world river network is believed to be seasonal, drying out for part of the year. In hot and dry parts of the world, people are far more used to seeing temporary waters and recognise them as ‘typical’ freshwater habitats. These are less familiar to us in Britain because so many of our temporary waters have been drained and because we assume, incorrectly, that in a wet country like ours temporary water is rare.
“In the UK, an estimated 30% of ponds are semi-permanent or seasonal and, while some may only dry out once in 10 or 15 years, others will dry every year. These small waters are a vital part of the resilience of the freshwater environment and, because they are biodiversity rich, form a vital part of the post-drought recovery network.
“At our Cutteslowe Meadow demonstration site, near Oxford, for example, experimental populations of four of Britain’s most endangered water and wetland plants are currently doing well – despite their ponds on the floodplain of the River Cherwell being almost completely dry. Indeed, in a drought, networks of small, seasonal, waterbodies remain important to wildlife and livestock as this is where, even though the water may have disappeared, vegetation generally remains lush for longest.
“However, it is important to say that, although our research has shown that many freshwater species readily bounce back from occasional periods of drought, we also know that excessively hot, dry weather year after year caused by global heating can bring more profound long-term changes to both standing and running waters. These changes can be due to simple shifts in temperature and availability of permanent water, but more usually involve complex community relationships – for example the presence of algae smothering other plant species or knock-on effects such as water evaporation in high temperatures concentrating the damaging cocktails of pollutants that water animals and plants have to live in.
“It is not all gloom and doom however. There are important things that can work to help our freshwater wildlife cope with recurrent drought and increasing temperatures. Freshwater Habitats Trust’s long term Water Friendly Farming project shows that simply doubling the number of clean water ponds in an area can provide resilience against drought and other stresses across the whole region: reducing landscape scale species losses from all waterbodies. Adding new clean water habitats to landscapes in this way is a very positive way we can support freshwater biodiversity in a rapidly heating world.”
Comments originally sent out Monday 8th August 2022
Catherine Sefton, hydrologist at the UK Centre for Ecology & Hydrology, said:
Is this weather quite normal for England or unusual?
“Whilst it is not unusual to have periods of low rainfall, we have seen an extended period of below average rainfall, particularly in the south-east of England where it was the third driest November to July on record (from 1836). Far from being relieved, the dry conditions intensified in July, with less than 10% of the usual July rainfall recorded across much of the south east of England (Anglian, Thames and Southern regions each saw their driest July on record, from 1836). The situation has continued into August, with South East England receiving no rainfall so far this month.
Is the water situation as simple as that it hasn’t rained for a while, or is it more complex than that – where does our water come from?
“In areas where river flows respond rapidly to rainfall, such as western Scotland and the north-west of England, river flows have recovered from the dry spring and are about normal for the time of year. In the south-east of England, by contrast, the continued dry weather means that many river flows remain notably or exceptionally low, and hydrological forecasts suggest this situation will persist over the next few months. Where river flows are supported by groundwater that recharges during the winter months, the impact of dry weather is reduced. But a continuation of below average rainfall into a second winter would likely result in serious hydrological and environmental drought, with further intensification of the water supply restrictions and fish rescues that we are starting to see in the south east.”
Prof Hannah Cloke, Professor of Hydrology, University of Reading, said:
“While there are different definitions of drought, we are clearly facing drought conditions in many parts of England. Water levels in several major river systems are very low. Some upper parts of rivers, including the Thames, have dried up almost completely.
“Our water supplies come via different routes, with some areas supplied from aquifers and others from rivers or reservoirs, but ultimately our freshwater is dependent on having enough rain. At the moment, we are facing an acute lack of rain in the short-term, as many parts of the South haven’t had any rain for weeks. Rainfall over the longer term has been lower than average, but we are just about clinging on to the water supplied from rain that fell months or even years ago, stored in rocks and soils. But this won’t last forever.
“The response to this requires everyone to help. I’ve stopped watering the garden, and we are having fewer baths and showers. But it is understandable why people feel less inclined to cut their water use when they see leaks seeping out of the ground, like the one I ran past this morning, pumping fresh drinking water straight down the drain.
“Our fairly complex system of water ownership and regulation means that everyone seems to be pointing the finger at everyone else to find a solution. Water companies ask consumers to use less. Consumers say, what’s the point when water companies aren’t fixing leaks fast enough. Regulators can impose fines and name and shame, but they can only do so much in a privatised system in which profits are guaranteed and costs ultimately come back to bill payers.
“Ultimately we need to spend more on improving our water infrastructure, but this will require major investment, and politicians won’t do anything that looks like it could increase people’s bills while other bills are soaring.
“We need to move past this impasse, or we will still all just be blaming each other as the car goes over the cliff.
“There are lots of examples worldwide of what happens when inequality, poor planning and corruption combine to create drought. The example of Cape Town, where some people enjoyed swimming in their pools during a major drought while others had to fill up containers from standpipes, is a good example of what can happen when the system breaks down.
“Unless the UK collectively gets its act together, and builds greater resilience into its water system at every point, we face a more uncertain future in which the tap could run dry. There is a better future, where we use water better where it falls and don’t waste as much. But we need a fundamental shift in understanding from almost everyone to get there.”
Prof Paul Jeffrey, Professor of Water Management, and Director of the Water Theme, Cranfield University, said:
Are we technically in a drought or not; if not why not and what makes something a drought?
“As of the first week of August most of England has been characterised by the Environment Agency (who are responsible for strategic drought planning in England) as being in a ‘period of prolonged dry weather’. The EA, through the National Drought Group, operate a four point warning system and prolonged dry weather is one stage before formally declaring a drought. Similar groups meet for Wales and Scotland. There is no single definition of drought. The Environment Agency talk about three types of drought: Environmental (where very low rainfall has a detrimental impact on the environment leading to reduced river flows, low groundwater levels, and low soil moisture levels), Agricultural (not enough moisture in soils to support crop production), and Water supply (when a shortage of rainfall causes potential shortfalls in the ability of the water companies to meet customer demand). It’s easy to become fixated by the definition of and official declaration of a drought when the reality is that, unlike a flood, drought is a slow onset phenomenon, the impacts of which play out at varying intensity and pace over the landscape.
Are temporary localised measures such as the hosepipe bans we’ve seen sensible and evidence-based?
“Water companies affected by water shortages are required to manage the impacts by following their drought plans. These plans set out a range of short-term actions to monitor and manage the impact of drought on customers and the environment. The localised measures we have seen implemented to date have been proportional and will have been triggered by supply-demand balance considerations and modelling. However, there are many forms of connection between water systems and demand patterns in different regions. The longer we go with no or low rainfall then the more geographically far-reaching the impacts are likely to be.
Is the water situation as simple as that it hasn’t rained for a while, or is it more complex than that – where does our water come from?
“Climate change, increasing demand, and an ageing asset base are all playing a role here. The lack of rainfall will reduce the availability of water in both surface (e.g. rivers) and subsurface (e.g. aquifers) sources but changing weather patterns more broadly are introducing volatility into the spatial availability of water which, in turn, presents challenges for managing the supply-demand balance. Average water demand per person in England and Wales has been creeping up in recent years which, with an increase in population, has resulted in increased volumes of water being needed to meet household requirements. Lastly, whilst important progress is being made on reducing leakage, significant investment is still needed to bring leakage levels down to what the regulator considers reasonable.
Any other comments specific to the current situation with weather and rainfall this week?
“Universal metering is long overdue in the UK and would go some way towards dampening demand as customers would be able to see how much water they use. Meters also provide useful intelligence for managing supply and discovering leaks. We’re all going to have to learn how to use water more efficiently – both at home and at work. The behaviours that will underpin a sustainable water future for us all are likely to be very different in five years’ time than they are today. We will also see growth in innovative ways of providing water services. These might include water recycling for non-potable uses, smaller scale water services provision for new neighbourhoods in particular, or integrated stormwater management and water supply systems. Examples of these can already be found around the country.”
Prof Liz Bentley, Chief Executive, Royal Meteorological Society, said:
“Droughts are not very easy to define and not every drought is the same . There are a whole range of types of drought including; agricultural (farming), meteorological (weather), hydrological (surface water) and socio-economic (ones which affect humans).
“A meteorological drought is usually defined as a period of significantly below-average rainfall. Although it may take consecutive seasons of below-average rainfall to experience a hydrological drought.
“Since May 2021 every month, except October 2021 and February 2022, has experience below-average rainfall for most parts of the UK. Higher temperatures and increased amounts of sunshine also lead to an increase in evaporation of moisture from the ground, and from rivers and reservoirs.
“Southern England and East Anglia reported their driest July (2022) on record. Rainfall distribution is not equal across the UK, with a stark contrast between the wetter northwest and the drier southeast in 2022. Met Office statistics reveal that Scotland got 81% (83.6 mm) of its average July rainfall, whereas Wales had 53% (52 mm), Northern Ireland 51% (45.2 mm) and England received just 35% (23.1 mm). The Met Office also announced that the period between January and June 2022 has been the driest in England since 1976.
“The current situation has been compared to the 1976 drought. There are some similarities, for example if you compare the potential soil moisture deficit (PSMD) which is the balance between rainfall and moisture loss due to evaporation, for example. However, just looking at the amount of rainfall on its own, England has had 30% more rain over the first six months of 2022 compared to the same period in 1976.
“Climate projections show that the UK’s summers are likely to become hotter and drier, with the driest areas being in the south and east, while its winters become warmer and wetter. They also show that by 2050, some rivers could have between 50 and 80% less water during the summer months, according to the Environment Agency. A changing climate is likely to bring greater variability in rainfall and higher temperatures, meaning that water management may become more of a challenge.”
Dr Robert Thompson, Postdoctoral Research Scientist and Teaching Fellow, Department of Meteorology, University of Reading, said:
“While at the University of Reading, as with much of the South July broke the record as the driest, we have had drier Junes and Augusts in the past, so this is not particularly unexpected. Nor are the longer-term dry conditions we’ve seen this year. However, the current dry spell is unusual because it has combined with the extraordinarily high temperatures we saw in the UK in July. The July heatwave led to more water usage and when paired with a deficit in rainfall is leading to water shortages. Unusually hot weather occurring simultaneously with unusually dry weather really amplifies the impacts of both on society. With no sign of rain in the South and another heatwave, this situation is only likely to worsen in the next week.
“This demonstrates that we should not be looking at climate hazards in isolation, but instead considering their impacts in combination with others.”
Andrew McKenzie, Principal Scientist, Hydrogeology, British Geological Survey, said:
Groundwater’s role in the current drought
“During this summer concern for water resources has focussed on the lack of rainfall, low flows in rivers, low stocks in reservoirs and increased demand. Groundwater which plays an important role in water supply in the UK, both for public supply (in the South East of England about 50% of public supply is from groundwater) and for agriculture and industry, and in sustaining flows to groundwater fed-rivers such as Chalk streams, and to wetlands, hasn’t received much attention.
“Aquifers act as reservoirs that fill in the wet winter months and can be drawn upon in dry summer months. At the start of 2022 groundwater levels in the UK’s largest aquifers were at average levels, and although the dry spring meant that levels began to fall earlier than normal, and levels are now low, they aren’t generally exceptionally low yet. Water company supplies are usually sited in the parts of the aquifers where supplies are most resilient and reliable, but that doesn’t mean the resource is unaffected by drought. As river and reservoir supply drops groundwater becomes increasingly important to the water companies. Smaller boreholes and wells, often used by remote households or for agriculture, in less productive parts of aquifers can dry up, and as levels fall in aquifers the outflow of groundwater to rivers reduces, further stressing the environment.
“Recharge of groundwater over the winter of 2022/23 will be watched intensely, as a dry winter that fails to replenish aquifers back to normal levels could leave groundwater in a precarious state in 2023.”
Dr Leslie Mabon, Lecturer in Environmental Systems, The Open University, said:
“The science is very clear: as global temperatures increase and carbon dioxide concentrations in the atmosphere increase, the likelihood of weather extremes like droughts occurring becomes higher and higher. Above all else, the drought risk we are seeing in the UK is a reminder that we urgently need to tackle the problem at source: this means reducing emissions from fossil fuels to limit the extent of harmful climate change we will face. Moreover, countries like the UK, which have traditionally had more a more temperate climate and have less experience of managing the prolonged effects of hot dry spells, need to plan now to adapt to hotter weather. More than encouraging individuals to save water, this also means looking at our water infrastructure and considering where investments are made to ensure we are better prepared for managing water in hot spells.”
Prof Tim Palmer, Royal Society Research Professor, University of Oxford, said:
“Q: Are we technically in a drought?
A: In the sense of an extended period of several weeks of dry weather, yes.
Q: Is this normal?
A: Historically, we can expect one every 10 years or so.
Q: Will these droughts become more commonplace under climate change?
A: Summer conditions are predicted to be drier as well as hotter, so yes.
Q: But winters are predicted to get warmer and wetter, isn’t that right?
A: Indeed so.
Q: So we can expect the drought to break later in the year and for the reservoirs to be filled up by the warmer wetter winter that follows.
A: Probably, but not necessarily.
Q: What do you mean “not necessarily”?
A: Well the anticyclonic conditions that led to the summer drought could continue into the autumn or winter.
Q: But it would be a disaster if the drought continued through into next year. Industry would have to be rationed, as well as individual households.
A: Quite so.
Q: What’s the likelihood of such a multi-season drought?
A: Actually it’s not something we can give any reliable estimates of. Historically, droughts that span several seasons are really very unlikely indeed. However, the big question is whether climate change will increase the likelihood of multi-season droughts. But we currently can’t answer such a question.
Q: Really? Why don’t we know this sort of thing?
A: Because the climate models that are used to estimate likelihoods of long-term drought do not do a good job in simulating the anticyclonic conditions associated with such long-lived climate anomalies.
Q: Why’s that?
A: Because the spatial resolution of climate models is relative poor. Much poorer, say, than weather forecast models.
Q: And how do we solve that problem?
A: We need to run the climate models on larger computers. This will allow us to increase their spatial resolution.
Q: And how do we do that?
A: Pool resources internationally to allow new-generation exascale computers to be dedicated to climate change research.
Q: So what you are saying is that we need to pool computer resources to assess whether multi-season droughts will become more or less likely under climate change. Is that right?
A: Exactly right.
Q: So why isn’t this happening?
A: Beats me. Must be some politics involved somewhere along the line.”
Prof Martin Siegert, Co-Director of the Grantham Institute for Climate Change and the Environment, Imperial College London, said:
“Climate heating is understandably on everyone’s minds when the UK is scorching, its water becomes scarce and crop yields reduce. While such things are consequence of greenhouse gas emissions, and because global temperatures will rise further, we must renew our efforts to reduce our emissions to ‘net zero’ as soon as we can. The Grantham Institute’s “9 Things you can do about climate change” (https://www.imperial.ac.uk/Stories/healthy-planet/) is a handy guide to get you started on the journey – a journey that we must all be on. If we all took action, our lives would be improved, our cost of living would be reduced and the planet we hand to our children and those who come after them will be more habitable.”
Dr Rachel Helliwell, Director of Scotland’s Centre of Expertise for Waters, said:
“An evidence report by Scotland’s Centre of Expertise for Water provides a review of studies that have assessed historical and future river flow and water availability changes in Scotland, and how they may influence water resource availability in the future. Some of the key findings of the review include that river outflows have increased significantly over the 1961-2010 period in Scotland. While total annual outflows in the UK may not change significantly, future seasonal projections in the UK generally show seasonal reductions in spring and summer flows, a mixed pattern in autumn flows, and small increases in winter flows.
“The review highlights that there is uncertainty regarding future frequency, duration and magnitude of droughts, including their timing and spatial extent. However, there is a consensus that Scotland-wide, the climate is warming. Droughts and floods are projected to occur across eastern Scotland and the Highlands and Islands, including the Loch Ness and River Tay catchments in the far future. In the 2050s, irrigation demand, especially in summer, may rise due to an increase in temperatures alongside an increase in potential evaporation and transpiration.”
Prof Richard Allan, Professor of Climate Science, Department of Meteorology, University of Reading, said:
“There are many scientific reasons why drought events become worse in a climate heated up by emissions of greenhouse gases from human activities. A warmer atmosphere is thirstier and can more effectively dry out the ground, and heatwaves further exacerbate the development of drought conditions. Also, because the continents are warming so rapidly, dry conditions can worsen because ocean winds cannot blow enough moisture over the land to satisfy the atmosphere’s thirst for water.
“The uneven distribution of global warming can also disrupt our weather patterns and where it is very dry or very wet: the rapidly warming Arctic and slower warming North Atlantic are altering the jet stream that steers wet weather over or away from the UK with some evidence suggesting periods of more persistent wet or dry conditions may become more common.
“Human caused warming of climate is intensifying the global water cycle and disrupting weather patterns leading to more severe droughts but also more serious flooding events across the globe.”
Comments originally sent out Friday 5th August 2022
Mr Alastair Chisholm, Director of Policy, at CIWEM said:
Is this drought unusual or is it expected?
“Not especially. Droughts are part of the British climate. The last time we had use restrictions and drought conditions was 2018, prior to 2012 and before that 2006. The key to droughts is winter rainfall which normally recharges reservoirs, aquifers and rivers. We had a quite dry winter (particularly in the south-east), a dry spring and then a record dry July exacerbated by record heat. So the weather has been particularly extreme – the Met Office released some maps recently here https://www.metoffice.gov.uk/about-us/press-office/news/weather-and-climate/2022/driest-july-in-england-since-1935 – this has probably come on quicker than some dry periods (and it should be noted we are still officially in “prolonged dry weather status” rather than drought status).
What is the current situation with the level of rainfall?
“It’s very dry in the south and east, some other parts (SW) have had little rainfall. The issue is significantly less acute further north and west.
Is it just rainfall that influences the reservoir levels?
“No, it’s how much water we use too. That’s why water efficiency is important, as well as reducing wastage such as mains leakage. Experts consider that in combination reducing leakage from its current level, by 50% being demanded by Ofwat over coming decades, alongside significant improvements in efficiency (with average consumption reducing from 140 litres per person per day to more like 100) will make the biggest difference. But new resources will be needed in coming decades as well as increased ability to move water around geographically.
How common are hosepipe bans and other drought measures? Are they sensible/necessary?
“Hosepipe bans are common, early measures and for good reason. They tackle profligate use first, before more essential use needs to be constrained. A lawn sprinkler can typically use 1000 litres in an hour. That’s more than one person on average uses at the moment a week! Arguments that have been put forward in recent days that we need more things like desalination plants so that people don’t need to restrict their water use in the summer months are non-sensical. These are expensive and energy intensive. In a climate crisis building more of these so people can continue watering their lawns is completely counter-productive. The public have also shown recently (in response to things like the sewage crisis) that they value a healthy environment. Hosepipe bans will help reduce pressure on the water environment too again by reducing non-essential use.
“As we face climate change we are going to need to adapt our own behaviours (and become more efficient) as well as building greater resilience. This involves a range of actions, from water efficiency (with smart metering and water efficiency labelling on water-using devices and fittings being particularly effective enablers of this) all the way through to major new infrastructure. The latter in particular will be expensive. In a cost of living crisis, getting a meter and using a bit less water in everything you do is an ideal way to save on bills when all the others are increasing.
How localised are these drought measures?
“For the time being quite localised but they are likely to spread more widely in the parts of the country which are shown as particularly dry in those met office graphs if the dry weather continues through August.
How do authorities decide when/whether a hosepipe ban is warranted?
“Each water company is required to prepare a drought plan, setting out the pressures in their area and how they will respond to manage them under conditions such as these. These pressures will include the size of population, and water demand and factors like the number of sensitive rivers from which they abstract their water. This will determine how quickly they feel they will need to commence communication campaigns, temporary use (hosepipe) bans, as well as more critical, drought permits (to abstract extra water) or emergency drought restrictions.”
Prof Chris Binnie, Honorary Professor at the University of Exeter, and water resources consultant said:
Is this drought unusual or is it expected?
“Weather varies and thus dry spells come and go. Thus occasional droughts are to be expected. Climate change does imply that summer dry spells, particularly in the South of England are likely to become more frequent.
What is the current situation with the level of rainfall?
“Exceptionally dry in parts of the South of England. My July rainfall is generally over 30mm (I have a rain gauge in my garden). Last month we had 5mm.
Is it just rainfall that influences the reservoir levels?
“No, The demand for water, and the temperature, a higher temperature leading to greater evapotranspiration.
How common are hosepipe bans and other drought measures? Are they sensible/necessary?
“Hosepipes are a normal use of water that is factored into water company plans. However banning their use is a way of conserving water in an unusually dry year. The forward met prognosis is that rain may not come to the South for a period. Thus expect more hosepipe bans in areas served by smaller reservoirs. Groundwater levels were normal but this dry and hot spell means that there is a greater soil moisture deficit thus groundwater recharge will not occur until there has been a greater rainfall. Thus groundwater supplied areas may also institute a hosepipe ban.
How localised are these drought measures?
“Currently, hosepipe bans only apply to part of the south of the country. They are likely to extend across the areas that have not had rain, other parts of the south of England.
How do authorities decide when/whether a hosepipe ban is warranted?
Water companies decide after assessing the situation compared with their drought plan and after consultation with the Environment Agency.”
Dr Mike Rivington, senior scientist at the James Hutton Institute, said:
“The scale of heatwaves and droughts we’re currently experiencing has been projected by climate research for many years now. What we are seeing is a clear signal of what the future is going to be like. Warmer temperatures mean increased evaporation from soils and plants, so when there is also reduced rainfall, there is less water entering soils and into rivers and reservoirs to replenish water stocks. In the future, there is a substantial risk that the recharge of water tables by winter rainfall may not be sufficient to make up for the increased summer water deficit, so if there are two successive years of drought, water shortages will be even more severe”.
Dr Barnaby Dobson, Research Associate, Department of Civil and Environmental Engineering, at Imperial College London said:
“Water companies are required to publish drought plans every 5 years. In this they set out what they will do under a set of different drought scenarios to ensure reliability of water supply. These drought plans are then iterated with the Environment Agency to ensure they are defensible, cost effective and sufficiently protective of the environment. This whole process is explained in quite a friendly way here: MaRIUS_Drought_Primer_2017.pdf (aboutdrought.info)
“In the drought plans, there are defined ‘trigger levels’ that say how severe the current water supply situation is. These are usually based on reservoir levels or groundwater levels. The level that the water supply situation is in determines what emergency actions the water company may take.
“Here is a screenshot from the South East Water (SEW) drought plan. We can see that the different groundwater level triggers are changing cyclically. We can also show a black line with the historic groundwater level over time, starting off in the green area (increased communication around water use), at some point entering the orange area (hosepipe bans) and even at one point close to the red area (non essential use bans). From a water company perspective, this is what a drought looks like, and they will be monitoring these levels carefully to see what state their supplies are in.
“Here is another example from the SEW that shows what actions they may take depending on the drought level. We see that when we are in level 1/2/3 the water company can do things like hosepipe bans (temporary use bans) and activate some of their water supplies that might have some environmental impacts (e.g., drawing down a river more than they usually would).
“Exactly what are the actions associated with the different levels, and what are the triggers depend on the water company. But all water companies will associate the different levels with different expected return periods (i.e., over a long period of time, how frequently would we expect these things to happen). For example, Thames Water for example expect Level 1 with a return period of 5 years, Level 2 with 10 years, Level 3 with 20 years and Level 4 never.
“There isn’t anything particularly controversial about the implementation of a hosepipe ban or droughts in general provided a few things are true:
“(I should note that I have no data and have done no research on the current drought so cannot say anything about whether these are true or not. Reaching out to water companies is probably the best bet!)
“An interesting point is that SEW says in their drought plan that the expected return period of a hosepipe ban is 10 years. This of course depends on our hugely variable rainfall patterns, however it is to note that their last hosepipe ban was in fact 10 years ago.
“Whether this drought planning is the most effective way to plan for droughts is a very complicated question, but I would say that in the middle of a drought is not the best time to decide! Whether climate change is impacting a specific drought is also very difficult to answer, although we can say with some confidence that if carbon emissions continue to follow their business as usual trend that they have been following since we started doing carbon emission projections (RCP8.5 tracks cumulative CO2 emissions | PNAS) then the probability of a hosepipe ban occurring is likely to increase. My research shows that, averaged across the UK, a business as usual carbon emissions scenario would likely double the probability of a hosepipe ban by 2050 (The Spatial Dynamics of Droughts and Water Scarcity in England and Wales – Dobson – 2020 – Water Resources Research – Wiley Online Library).”
Declared interests
Mr Rob Lawson I’m a Director and co-owner of Artesia Consulting Ltd, a company that provides data science and consultancy services to water companies to help them understand and manage their water resources and in particular how to reduce household and non-household demand and to reduce leakage
Prof Paul Jeffrey: “No conflicts of interest.”
Andrew McKenzie: “No conflicts of interest.”
Professor Jeremy Biggs: “Freshwater Habitats Trust receives funding from Thames Water, Anglian Water and Yorkshire Water.”
Catherine Sefton: “No interests.”
Prof Hannah Cloke is a natural hazards researcher & climate expert. Her research is funded by UKRI NERC, UKRI EPSRC, FCDO & the European Commission. She is a member of UKRI NERC council and a fellow of ECMWF. She advises the Environment Agency and DEFRA on environmental hazards.
Dr Robert Thompson: “No conflict of interests I’m aware of.”
Dr Leslie Mabon: “Dr Leslie Mabon has no Conflicts of Interest to declare in respect to this comment, and is commenting as an independent expert who does not stand to gain financially or otherwise from the nature of his comment.”
Prof Tim Palmer: “No conflicts of interest.”
Dr Rachel Helliwell: “The Centre of Expertise for Waters receives funding from the Scottish Government.”
Mr Alastair Chisholm is a Royal Chartered professional institution for water and environmental management professionals, aiming to advance the highest levels of professional practice. We have more than 10,000 members who work across water resources, water quality, flood risk management, pollution and wider environmental management / conservation. Those members work for water companies, regulators, government, local government, engineering and other specialist environmental consultancies, and academia. We are bound by our royal charter to be impartial and advance the use of science and evidence.
Dr Barnaby Dobson: “Dr Dobson collaborates closely with water companies on research projects, however the relationship exists to understand the physical behaviour of their water systems and apply research techniques to model and optimise these systems. He has performed paid consulting work for the company Mott MacDonalds, however this work is not focussed on droughts. Neither can influence what he can say or publish.”
For all other experts, no reply to our request for DOIs was received.