19
Examination of witnesses
Jamie Hannaford, Professor Jason Lowe and Professor Alan MacDonald.
Q1 The Chair: Good morning and welcome to the Lords Environment and Climate Change Committee. Today is the first session of our inquiry looking at drought preparedness. There will be two evidence sessions today to introduce us to drought and the issues it raises. Before we start, I should remind everyone that this session is webcast live and that a transcript will be taken and made public. Witnesses will be able to review the transcript and make minor amendments. I should also remind Members that any relevant interests should be declared the first time that they speak. I will take this opportunity to declare that I am a director of Peers for the Planet.
I now turn to our panellists for the first evidence session and welcome them very warmly. Thank you very much for taking the time to be with us today. Can I ask you, before we move on to the first question, to take a minute to introduce yourselves?
Jamie Hannaford: Good morning, everyone, and thank you for the invitation to come along today. I lead the water resources and drought group at the UK Centre for Ecology and Hydrology, a team of scientists looking at water resource variability past, present and future. In connection with today, in relation to drought, we also lead the national hydrological monitoring programme and the hydrological outlooks, providing monitoring and forecasting for drought in the UK.
Professor Alan MacDonald: Good morning, everyone. I am head of groundwater at the British Geological Survey. In the groundwater team we have hydrogeologists who look at groundwater and modelers who model current and future groundwater resources. In relation to this committee, we look after the national groundwater level archive.
Professor Jason Lowe: I work for both the Met Office and the University of Leeds. Today, I am representing the Met Office where I am a principal fellow and head of climate services for government. My background is in climate science and climate modelling, including producing the UK scenarios for climate change. The Met Office is the nation’s national meteorological service. It is an arm’s-length body of DSIT and operates as a trading fund.
The Chair: Thank you all for taking the time to be with us today. We are very pleased indeed to have you.
Q2 Lord Ashcombe: Good morning and thank you for coming, and two of you again. My question comes in two parts. I am going to keep the second bit for later. What are some of the challenges with how drought is currently defined and do you think that this is sufficient? As a second bit of the first question, who is responsible for monitoring and reporting drought risk?
Jamie Hannaford: Is it okay if we tackle the second question first on the responsibilities? That helps to then define the first part. One of the statutory actors in England, as I am sure you are aware, is the Environment Agency, which has the responsibility for monitoring and reporting on drought status, via its weekly and monthly situation reports describing the status of rainfall, river flows, reservoirs and so on. Water companies also have the statutory responsibility for monitoring, in accordance with their drought plans and in regular exchange with the Environment Agency.
To add to this, I also want to express the role that the organisations on this table have. We, in the UK Centre for Ecology and Hydrology, with colleagues in BGS and the Met Office, are responsible for running the national hydrological monitoring programme, which has been running since 1988. We also provide monthly situation reports, which include similar data, or the same data, as the Environment Agency, but the really key added value is in being able to add analysis and interpretation. It is that independent view of what the data is showing.
Another key aspect of that, and something that, again, all these organisations work on, is the hydrological outlook. So far we have been talking about monitoring and capturing the current situation, but the hydrological outlook adds significant value in providing seasonal forecasts. That is projections of where river flows and groundwater are going to go over the next one to three months, using the meteorological forecast provided by the Met Office that I am sure Jason will talk about. I do not know whether anyone wants to pick up from that.
Professor Alan MacDonald: I can speak to how groundwater drought is defined. I would certainly agree with what Mr Hannaford has said about who is responsible. There are challenges with defining groundwater drought as opposed to surface water and meteorological drought. There is no real, consistent measure of it. It is defined in three different ways: water levels passing a certain threshold or maybe a ranking percentile, or a new method that has been developed over the last 10 years of a standardised groundwater index for drought. That is how groundwater drought can be defined, but there is no accepted measure of it across the UK at the moment.
Professor Jason Lowe: The Met Office role is to provide information on rainfall. We provide observations and near-term weather forecasts. We also provide a seasonal outlook, which is a three-month look ahead. Additionally, we provide climate projections for long-term scenario planning. We work very closely with organisations such as UKCEH and BGS. We also work with a number of organisations through something called the Natural Hazards Partnership, which takes the information we have on the state of the weather and the forward look to a wide range of organisations.
Lord Ashcombe: Professor MacDonald, you mentioned that there is no real standard definition of drought. That seems fairly worrying if we seem likely to go into a drier climate.
Professor Alan MacDonald: This is for groundwater. Looking at drought propagating into groundwater is a relatively new science in the last 10 to 15 years that we have been developing and leading at BGS and with UKCEH. Groundwater levels respond in a slightly different way to drought than for rivers. It is a much longer period that they respond over and it all depends very much on the geology. However, I should say that the standardised method, so the standard groundwater index, shows an awful lot of promise. We have been rolling out that method of looking at groundwater drought and measuring that.
Lord Ashcombe: On the second part of my question, are the existing drought indicators and level of monitoring sufficient to accurately predict near-term and future droughts?
Professor Jason Lowe: There are two parts to the question. There is monitoring what is happening now and understanding what has happened in the past, which is important for looking for trends. If we are going to understand what happens in the future, it is incredibly important to also have models alongside the observational data. One could also ask, for instance, whether the models are adequate. We know that weather forecasts have a high degree of accuracy in the near term, and the accuracy of those has increased. A four-day forecast now is as accurate as a one-day forecast 30 years ago.
When it comes to climate modelling, looking further into the future, we have probably the best set of national climate scenarios in the world in the UK. Climate modelling moves on, and we are probably at a point where there are a number of improvements we might want to make, including running more model variants so we can better sample the relative uncertainty, providing more simulations of the present day and adding in more focus on reasonable worst-case scenarios.
Jamie Hannaford: On the same question around the sufficiency, but returning to the observational data itself, the first thing, before we talk about gaps or where monitoring might not be sufficient, is to talk about how fortunate we are to have such a very rich data resource. The UK has a very dense network of observations, in terms of rainfall, river flows and groundwater, by any global standards. It is very high-quality data with very rigorous quality control. The UK stands out in international terms with that. Also, there are some very long records. There are many stream flow records going back to the 1960s and some going back into the 19th century.
It is important that we say, before we look at some of the gaps, that we have very dense observational datasets. It is really important to ensure that resources continue to be prioritised, because you can only manage what you measure.
Lord Ashcombe: Do you think that the datasets are in the right place? I suspect that there is concentration in some areas and it is a little bit lacking in others, maybe.
Jamie Hannaford: That is absolutely a good question and something I was going to raise as one of the gaps. Where monitoring happens is a key question and we cannot monitor every single point on the river network or in terms of aquifers, so there are gaps in space. There has been lots of promise in recent decades over the use of ways to fill in those gaps. We use hydrological models. We have already talked about using those to predict into the future, both on the seasonal timescale and for climate change, but they are also useful for looking at where you have unsampled spots. We use those models a lot to measure current status as well.
There is also a big role for satellite observations. There has been some really good progress in using those observations and bringing them alongside our in-situ streamflow and other measurements. There have been some big efforts to fill gaps, although it remains a key challenge.
Another key challenge is where you have things that are less easy to monitor, such as soil moisture, which is a really critical variable for agriculture, wildfires and so on. That is more difficult to measure and you typically, in the past, have had very point measurements. Over the last decade, UKCEH has been leading on the COSMOS-UK soil moisture network. These are in-situ observations of soil moisture at a large field scale, providing real-time information. That is a really good way of picking up new information on something that has historically been hard to monitor.
The final thing I will say on gaps is that there has been a big effort to fill gaps in monitoring through trying to provide more local-scale information. As well as all the static reports we put out every month with our summaries and the ones that the EA does, the UK Water Resources Portal we launched in 2020 enables people and individuals to see far more rich data at a local scale and to actually interact with, plot and visualise that data.
The Chair: We have a question coming up on gaps later, so we can explore that in more detail.
Q3 Lord Duncan of Springbank: I should declare that I am a fellow of the Geological Society. I am trying to understand the definition of drought. When I was studying—and it is a long time ago now—there were several definitions that could apply and it would affect how they were legislated for. You could go from what would be a meteorological drought to an agricultural drought to a groundwater drought to a socioeconomic drought. Then you could theoretically have a political drought, where, at a certain point, politicians have to act because something is going on.
These are defined by the consequence, not, ultimately, by the amount of water, either in the groundwater or in precipitation. Does that affect the way that you determine policy? The committee is going to be looking at the impact of various socioeconomic developments. How do these different definitions intersect with the work that you do and what does it mean for planning?
Jamie Hannaford: On the question of definitions, you very rightly point out that there are many definitions and types of drought. It is a very vexed question in the scientific literature. An interesting question for me is that there is a distinction. In the scientific world, we recognise all those very complex, different definitions. Drought means very different things to different people in different sectors. It is all about the different impacts, ultimately.
On the policy side, or at least in terms of drought declarations, the Environment Agency has a much higher-level way of declaring drought or going through various stages, so prolonged dry weather and into drought, recovering drought and so on. There is sometimes a bit of a disjunction between those things. You need that high-level traffic-light style assessment of the overall status, but that sometimes does not correspond to what is actually happening on the ground because of those different definitions and complexities.
A good example would be what we have seen this summer, where drought might be declared relatively late on in the summer because it is based more on the overall picture, whereas farmers may have been dealing with the impacts of drought very early on. We had a soil moisture drought and an agricultural drought very early on. We had environmental impacts. There are lots of impacts that occur on the ground way before you have this high-level declaration of drought. That tension between those sides is interesting.
Professor Alan MacDonald: To relate that to groundwater as well, I would echo a little bit what Jamie has said there. There is this kind of widespread drought that we would look at as scientists. That is where I was talking about how we are still working on the definitions for drought, but there is a standardised way of looking at it. However, the water companies and the Environment Agency are looking at these localised impacts for drought. For example, if groundwater levels fall below a certain level it will impact water supply in that area or impact a receptor, such as a chalk stream. They then manage that and have trigger levels and definitions for it around that localised level, which differentiates from the regional level of widespread drought.
Lord Duncan of Springbank: The notion of consumption is also important, so how much water you take out, and defining a more widespread level of drought elsewhere.
Professor Alan MacDonald: That is a very interesting question. Trying to detangle the drought from general water overuse or high levels of abstraction is something we spend a lot of time looking at and detangling.
Lord Duncan of Springbank: That is helpful. Thank you.
Q4 Lord Jay of Ewelme: Does the concept of a national definition of drought have much meaning, or should we be looking at regional definitions? It often rains in Yorkshire but not in Sussex.
Professor Jason Lowe: If we think about the drivers of drought, so the temperature and the rainfall, that varies across and even within the nations of the UK. When it comes to a planned response, there are also local measures that take place. In the case of the Met Office, we work with local resilience forums, for instance, using civil contingency advisers. We think that the idea of having a local metric is very useful for response.
Also, though, we need to be able to aggregate that up to a national level. I am currently working on a project that forms part of the fourth climate change risk assessment. There, being able to aggregate up and form a UK picture of where critical investigation or action is needed becomes really important. We need both.
Lord Trees: Professor Lowe, you have hinted about the accuracy of forecasting the weather and we know that you have that buttoned down. I realise that the drought situation is much more complex and there is likely to be a considerable lag between cause and effect. To what extent can you forecast drought and how accurately ahead could you advise appropriate authorities and policymakers?
The Chair: I am going to park that question for question 3, because forecasting will feature within that quite comprehensively, I think. I will move to Lord Krebs for your question, which will address variability, so I hope that we can pick up some of the issues there.
Q5 Lord Krebs: Thank you to the panel members for coming to give evidence to us. I wanted to understand from you what the causes of drought are and what factors influence the severity and propagation of drought. Perhaps one way of framing it is in terms of the hydrological cycle. In equilibrium, what goes up must come down. Water is not being created or destroyed, so there ought to be the same amount of water all the time, except if you resolve it into temporal or spatial scales. Within that framing, can you give us an insight into what goes wrong with the hydrological cycle to create a drought?
Professor Jason Lowe: As we put more energy into the system, we perturb the hydrological cycle. We expect a warmer atmosphere to be able to hold more moisture. We can, of course, track how water moves through that cycle, both with observations and in models.
If we focus in on the UK, we also need to take into account local atmospheric changes and atmospheric circulation, so how much water is transported over the UK. When it comes to rainfall, there is a lot of variability in the past record in rainfall, but we already see a signal that shows that the nature of rainfall is changing. More of the rainfall—a greater fraction—is falling in heavier events. We have also seen increases in rainfall in the UK. There has been approximately a 10% increase since the 1970s, and that has happened in the winter half of the year. That is a clear, measurable signal.
The other part of the hydrological cycle that we need to consider is evaporation. When we are thinking of a drought, we have to consider not only a reduction in rainfall, but also an increase in evaporation. Temperature records are very comprehensive in the UK. We have the longest temperature record in the world. If we look at recent decades, we have seen an increase of around 1.25 degrees since 1970, so we have that condition of increasing temperature.
We have increases in water in the winter. We are not yet seeing a strong signal in the summer. If we look forward in our climate models—they capture the physical understanding we have of how the system works and they are built on equations such as the Navier-Stokes equation—we see a very clear signal. It is a movement towards warmer, wetter winters and hotter, drier summers. In effect, with rainfall we are seeing a stretching out of the annual cycle, so the winter becoming wetter, but the summer becoming drier. Alongside that, there is the increase in temperature.
When we put that together and ask, “What can we learn about changes in drought?”, our climate models show we can expect an increase in drought in the UK. One study that I personally was involved in looked at 2 degrees of global warming and found roughly an 86% increase in droughts like that in 2010. It also looked at a higher scenario of 4 degrees of warming and found an approximately 150% increase.
Lord Krebs: I should actually have declared an interest that I am the former chair of the Adaptation Committee, so you are aware of that.
Professor Jason Lowe: I know.
Lord Krebs: Does anybody want to add to the causes of drought? Jason has given us a clear account of the impact of climate modelling. Is there anything else you would like to say about, for example, levels of abstraction and use?
Professor Alan MacDonald: I can talk to groundwater. Groundwater is the water stored in our aquifers under the ground and they respond to changes in precipitation. They are slightly different, in that what drives groundwater level variation is winter recharge. It is rainfall that happens when there is no evapotranspiration. That is what drives groundwater drought. It takes several months, maybe six months, for that drought to develop. By the end of the winter or beginning of the spring, you have a fairly good idea of what is going to be happening over the next six months. You talked about maybe forecasting. That allows us a bit of time to see what we think might happen to the groundwater levels.
Therefore, feeding into what Professor Lowe was talking about, climate change is a mixed picture for groundwater. If we have wetter winters, the groundwater levels might not decline so much. However, the increase in temperature means that you might get an earlier start to spring, so there is a little bit of a trade-off here. In the modelling that we have done on response in groundwater resources, it is much more mixed, rather than a long-term decline in groundwater levels.
The Chair: I wonder whether I can ask a very basic question. Could you say what the difference is between groundwater and an aquifer?
Professor Alan MacDonald: The aquifer is the rock that contains the groundwater. For example, sandstone has pore spaces within it. The sandstone is the aquifer and the groundwater is what is stored within it. Our other major aquifer is a chalk aquifer, which you see in the south-east of England. The groundwater there is stored mainly in fractures within the chalk.
Lord Krebs: Jamie, before you answer, could I ask you to address the question of feedback loops? Is it the case that, as the ground gets drier, the albedo changes, which in turn affects evapotranspiration, which could exacerbate drought? Is that important or not?
Jamie Hannaford: There are certainly land-surface feedbacks. Especially in continental Europe, this has been shown very extensively, but also in the parts of the UK on the edge of the continent as well, where you have this feedback. As you are getting drier, you are getting more losses. The soil is getting drier and that is feeding back to the atmosphere and resulting in further impacts.
Professor Jason Lowe: One very strong feedbacks is that, when you get to the point that you have evaporated the majority of moisture away from the surface, you no longer have latent heat cooling to the same extent, so the surface warms up. That can feed back into the atmosphere, leading to even higher temperatures. We saw some of this in summer 2022, for instance, in the UK.
Q6 Baroness Whitaker: Thank you for coming in. I am impressed by your knowledge of what has happened and is happening about drought. You partly answered my question, which was about whether you have enough knowledge of the precursors of the variables. I know that you said something about that. There may be more to add. Also, what about the communication systems for informing the people whose work lives are going to be affected by what happens next year or next month?
Jamie Hannaford: Earlier I mentioned gaps, spatial gaps and so on. I have referred to the UK Water Resources Portal. I would like to highlight that the idea behind this portal, which we co-developed with a whole range of stakeholders from the water sector, agriculture and all sorts of uses, is to be able to provide that crucial local-scale information. This was a demand from the community to have more information than was available in the static reports that go out from the Environment Agency each month.
It has been able to take advantage of really big innovations in not just monitoring but also the informatics tools that enable that information to be put out, so real-time feeds from the Environment Agency providing daily updates of its river flows. That has only really happened in the last half a decade or so, but it has been really important in enabling us to build these systems that enable people to get that information very quickly, rather than every month, and on a much more localised scale than was possible in the past. That is one area. It is opening up the data and making it available.
When we designed that portal, we made sure that the visualisations that were used spoke to the needs of the community. Water managers are often managing drought by looking at how it compares to historical analogues. On these tools, you can look at how the current drought compares to a given drought of choice in the past. Also, we made sure that the colour schemes and bandings represent the schemes that are used by the Environment Agency and water companies, so that it speaks the language that is used in day-to-day drought management.
Q7 Earl Russell: Good morning, gentlemen. Thank you for your evidence. I begin by making a declaration of interest that I am a non-exec director and board member of the Water Retail Company. Obviously we all want to improve drought resilience. In relation to doing that, my question is about the gaps in our knowledge and the data for doing that.
Jamie Hannaford: We have very good datasets and we talked about some of the gaps around soil moisture and so on. Some of the time there is a real gap in having a full process understanding of what goes on in catchments. It is a really exciting time at the moment with the Flood and Droughts Research Infrastructure and this £38 million investment in monitoring in catchments around the country. What is great about that is this very high-intensity measurement of all these different variables of the hydrological cycle, as well as some of the impacts on water quality, in very high density so we can unlock some of that process understanding. That is one key gap.
Another is something that we have found in our engagement with many stakeholders over the last decade. This is in the whole international community as well and recognised by the UN agencies, such as the World Meteorological Organization, as a real global priority. It is trying to get better at monitoring impacts. While we are good at measuring rainfall, river flow and so on, it is the impacts on society and the environment that we really care about in drought. Tracking those impacts helps us to identify the best mitigation actions and plan better for the future.
There have been some real improvements in gathering impact information. A lot of this data is gathered by the Environment Agency, such as impacts on quality, drying catchments, fish kills and so on. One big gap is getting that information into a format where it is readily available and can be brought into the wider monitoring that we have been doing. There has been some good progress on that in recent years, but there is a long way to go in unlocking the sets of impacts that are recorded, by not just these agencies, but all the other agencies involved in water management, community groups and farmers around the country. This is done a lot in other countries, for example in the US, and there is a really big opportunity for us to get better at tracking impacts and then being able to forecast impacts too.
Professor Jason Lowe: You talked a lot about the monitoring aspect. I would also like to highlight that, as earlier, there are some approaches we can do to further improve the modelling, including building in more of those feedbacks that were referred to in the previous question. There is scope to improve our seasonal forecasts, so looking perhaps three months ahead. In our climate forecasts, we can better sample the uncertainty in the next generation of scenarios.
There are some improvements to be made around communication aspects and, in particular, making sure more of the data that we produce is available to others to incorporate into their decision-making systems. When it comes to drought, so far we have focused on it as a hazard, but ultimately we want to understand the risk. That involves bringing the hazard together with asset locations and knowledge of the vulnerability. There are limitations in the asset knowledge that is available and the datasets. There are also limitations in the vulnerability datasets and, in particular, getting up-to-date information, for instance, on improvements and defences into those datasets. This was evidenced this year by a report published by the Climate Financial Risk Forum, which is available online.
The Chair: May I ask whether the £38 million invested by UKRI is sufficient to meet the gaps that you have highlighted so far?
Professor Alan MacDonald: It is never enough. The FDRI £38 million investment is in infrastructure for three catchments across the UK: one in England, one in Wales and one in Scotland. The investment there is to put the kit in the ground to monitor the whole water cycle together, so from rainfall and evapotranspiration through surface water flow to groundwater.
The money is good for putting the infrastructure in. However, with the way that funding happens within UKRI, there is not the funding alongside that for the research. It is capital money to put that infrastructure in. What needs to go alongside that is the funding to do the research using that capital infrastructure.
Earl Russell: What are the plans for the other catchment areas? Are there any plans for the other catchments? You said that there are three.
Jamie Hannaford: I agree with everything that Alan has said. It is great, but it is three catchments. It is also putting a lot of effort into developing digital infrastructure. That is tools to enable the new and novel datasets from those three catchments to be embedded with all the flows of information coming from existing networks around the country. That is a really big part of it.
There is a huge part of it around trying to develop the community and stakeholder side of things as well. Even though the monitoring is focused on three catchments, it is very much national scale in trying to improve the digital side and the actual capacity of the community. In terms of instrumentation, even though it is focused on these three catchments, there is also an investment in mobile infrastructure, so UAVs and other tools that can be used and deployed in other areas that are not sampled. That is going to be really good from the point of view of, when there are extreme events, being able to go out and use that kit to take additional measurements. When we see further droughts, we will be able to go out and target the areas and hotspots that are most in need.
The Chair: Earl Russell, I know that you have further questions. This is a very important issue. I would very much appreciate it if each of you could write in to the committee with your thoughts about gaps that need to be addressed from your perspectives.
Earl Russell: Maybe you could add the best way for that programme, and the advantages you have from the three catchment areas, to be rolled out into more of a national programme.
The only bit I wanted to pick up going forward is what more could be done on targeted interventions and pre-planning. Is there more, in terms of data and stuff, that we could do?
The Chair: Can we leave that to question 5? That would be much appreciated.
Q8 Lord Lennie: There is never enough money. Following up from Lord Trees’s question and reframing it, how will climate change affect the frequency, data and severity of future droughts? How certain—you touched on this—are these projections?
Professor Jason Lowe: Coming back to how it will affect droughts, and building on the earlier answer, we have very high confidence in the fact that the temperature will increase and in the spatial pattern of that increase. It will not be the same everywhere over the UK. The increase will likely be greater in the south‑eastern parts of the UK.
We have reasonably high confidence in the change in rainfall because it is built on the basic physics of the hydrological cycle. We expect the hydrological cycle to become more intense, but it is more of a complex problem because we need to understand the changes in atmospheric circulation. However, we can compare multiple lines of evidence. This, for instance, involves looking at different types of model, looking at observations of the past and going back and thinking about the basic physics. That gives us confidence towards that idea of a drying in the summer and a wetting in the winter.
When it comes to the droughts themselves, we see, from different types of study with different modelling approaches, the same broad type of result that, typically, over the UK, the number of droughts tends to increase, so they are more frequent. Also, the intensity of those droughts tends to increase. For instance, if you look at metrics that focus on the hydrological drought, or you go further and focus also on the meteorological drought, you will see that signal. It is the so-called SPI. You will also see it in indices that take account of evaporation.
Having said that, there are uncertainties that we need to be aware of. The first one is natural variability. We know, if we look at the historic record, that the weather varies from hour to hour, week to week and year to year. That obscures the change signal for some variables in the present day.
As we go into the future, that still contributes to uncertainty. There is uncertainty from which emissions pathway the world will follow. The way we deal with that uncertainty is to look across a range of alternative pathways. We see an increase in the drought frequency even in the lowest scenarios, so the 2-degree world.
The third uncertainty we would focus on is around the modelling approach and the response along a particular scenario. We are able to quantify that in our scientific studies by running multiple model variants and comparing those model variants in terms of their behaviour, but also asking whether those models validate well in the past period, so we know which models are more credible than others. Overall, that builds a picture of the degree of certainty.
Jamie Hannaford: I agree with everything that Jason has said on the meteorological side. To add to that, in terms of the hydrological response there is another layer of uncertainty. To know about the impacts of droughts on rivers in the future, we need to use hydrological models, so simulation models of catchments. We have different models that give different responses. Iin fact, in some of the recent studies that have been done, so our eFLaG projections, where we have made nationally consistent river flow and groundwater projections through the 21st century, the uncertainty due to the hydrological modelling side is bigger than the uncertainty due to the different regional climate model simulations that have applied. So there is an added layer of uncertainty in terms of the hydrology as well.
I would add another complication that goes back to everything we have said previously about how, when it comes to the hydrological side, the same meteorological deficits can have very different impacts depending on where you are in the country and the type of catchment. On the more groundwater-dominated catchments, winter deficits are so important. Because winters are getting wetter, as has already been elaborated, that brings a whole range of uncertainty to the types of droughts we might see.
We are very confident that we are going to see these drier summers, so these arid summer spells like we have had in 2022 and 2025. On the very long droughts, so the multiannual droughts that have caused big impacts in the English lowlands, the groundwater-dominated areas, such as 2004 to 2006 or 2010 to 2012, there is much more uncertainty because of the role of the intervening winters. We know that, because we are going to see more variability in the future, even if winters on average are getting wetter, the combination of some dry winters with those arid summers will result in more severe impacts.
Q9 Lord Duncan of Springbank: We cannot control the weather, setting aside our ambitions within a climate change world. What we can control, therefore, is the consumption of the water. I am thinking again of the wider range of consumptions, from agriculture through to human consumption and so on. Presumably these are the test grounds where we will need to be focused in the future, not really upon the weather itself, but rather upon what we do with water, how we manage water, how we stop the leakage of water and, ultimately, how we stop people using it in ways that are destructive to the overall hydrological cycle. Would that be a fair analysis?
The Chair: That is an important question. Can I take Lord Krebs’s and Lord Layard’s as well?
Lord Krebs: Jason, you explained to us very clearly how, in climate projections, rainfall will become lumpier. Drought is partly not that there is less rain, but the rain comes in bigger lumps and there are gaps in between. I wanted to go back to the question of spatial scale, because presumably the rain will be not only lumpier but also more concentrated in certain parts of the country. If we talk about drought risk, we are not talking about the UK as a whole, but particularly the south-east as opposed to the north-west. Is that right, yes or no?
Lord Layard: I do not have a clear feeling for how big this problem is. Things may begin to change, but, in your world, are you feeling frustrated that people are not recognising the size of the problem or not doing things that they ought to be doing?
The Chair: I was hoping to address that in the final question, but your early thoughts would be appreciated, with succinct answers, please.
Jamie Hannaford: Certainly there have been enormous improvements in resilience over the years. There is a recognition of the problem of drought, increasingly, as well as flooding, and there have been big improvements in resilience. We are far more resilient now than we were in 1976. That drought would not have the same impacts now. We saw this summer that, in many areas, it was worse than 1995, but the impact is actually far lower because of the amount of connectivity and the way systems have been joined together in the wake of previous droughts. There has been a lot of progress and there is an increasing recognition of the importance of planning, not just at the small scale, but at the regional and, indeed, national scale through the national framework.
The Chair: Who would like to address uncertainty of rainfall and the impact of human activities?
Professor Alan MacDonald: You will have to do the rainfall, but I can give an answer about abstraction and groundwater, which I think was Lord Duncan’s question. Trying to untangle the meteorological effects from abstraction is key. In our research, we have found that very high abstraction of catchments affects or amplifies droughts. However, lower abstraction is a much more mixed picture. It is managed locally at the moment, so seeing whether some boreholes, for example in the Chess catchment, affect a river.
It is done at that much more local level, so there is not a very strict one-to-one relationship with abstraction and amplification of drought effects on groundwater. It very much depends—and this goes to Lord Krebs’s question—on the spatial variability. Our aquifers are very variable across the country. If you are in a big sandstone aquifer, there might not be as much of a problem, unlike if you are in a small aquifer without much storage. For example, the north-east of Scotland experiences a lot of drought impacts with its private water supplies because they are based on very small aquifers. Understanding the geology and resilience of the system in that way is key to understanding impacts and how much abstraction is safe to use in these drought periods.
Lord Duncan of Springbank: We do not regulate in that fashion at all when it comes to extraction, do we? We do not say, “This particular aquifer in this particular region can allow this amount to be extracted”. We do not tend to do that.
The Chair: Shall we move on to question 4? It is that question.
Lord Duncan of Springbank: That would follow on. If we have the answer to that question we can move on.
Professor Alan MacDonald: I am sure you are going to have the Environment Agency in to discuss this, so it will be able to answer that fully. There are localised drought management plans put in place that are negotiated between the Environment Agency and the water companies about how much water they can abstract during drought periods.
Q10 Lord Mancroft: How long does it take for aquifers, reservoirs and, indeed, the ground to replenish following a drought? What interventions could we, government or anybody do that might improve the speed of that process, or is it not possible to speed it up?
Professor Alan MacDonald: Groundwater is our largest natural reservoir in the UK. Ten times the amount of freshwater elsewhere in the system is in groundwater. The length of time to recover depends on the type of aquifer. If it is a very small storage aquifer, it might recover in several months’ worth of rainfall, because there is not so much space to fill up.
For the largest sandstone aquifers, for example the Sherwood sandstone aquifers that provide the water supply for the Midlands, it might take two years of winter recharge for them to become fully recovered again. However, the corollary to that is that they take a lot longer to go into drought.
For chalk, which is very important for the south-east of England, a good winter’s recharge could generally allow that aquifer to recover from a drought period. That is why, as Mr Hannaford has said, with multiyear droughts, if there was a period lacking winter rainfall for several years, that becomes a problem for the chalk.
Those are the timescales, from several months to a couple of years, for recovery for groundwater.
Lord Mancroft: We have had a drought this summer and, in the last few weeks, for the first time, quite a lot of rain in short periods, rather as you were describing earlier. Yet you can go out on the ground 24 or 48 hours later and it is rock hard again. It is obviously absorbing a vast amount. We are two months after a drought, but it does not show yet, does it?
Professor Alan MacDonald: From the groundwater perspective, we need much longer than that. One heavy rainfall period will not replenish the aquifers. It needs sustained rainfall when there is not anything growing to allow the groundwater to recharge and to fill up. As I have said, for some aquifers, it might take two years’ worth of heavy winter rainfall to recover fully.
Lord Mancroft: If we are doing what Lord Duncan was just talking about, which is abstracting too much, it naturally is not going to catch up, is it? It might eventually, but it is going to slow the process up.
Professor Alan MacDonald: The recharge, so the way it fills up, is different from the amount of water that you are taking out of it. They are slightly different processes. We are looking at the amount of water that will go into the aquifer system across the piece, as opposed to the abstraction, which generally can be quite a localised effect. Where the boreholes are, you might have a localised effect around there, while the rainfall and recharge of the whole aquifer system is happening more regionally over a larger area.
It is a good question and one that we are still trying to do a lot more research into. It also depends on the 3D geometry of the aquifers. The rock types are not particularly even as you go under the ground. There is a lot of 3D geometry, which means that, as water levels fall, they behave in a slightly different way.
Professor Jason Lowe: I do not think that I can comment on the time of filling the aquifers, but there is a missing part of the argument that was implied by the earlier question. That was that we cannot influence the rainfall. That is incorrect, because the change in rainfall and evaporation varies very strongly with the emission scenario and whether we are on a 2-degree path or a 4-degree path, which implies a strong human intervention possibility through mitigation.
Q11 The Chair: Bringing it back to the present, we have had a drought this summer. Maybe you can bring us up to date with the forecast for this winter’s rainfall, Professor Lowe. This is probably the right time to address this before we move on to the very important last question on collaborative working.
Professor Jason Lowe: Throughout the period from March to the end of August, we have seen very big rainfall deficits, so typically less than half the rainfall we would expect. There was above-average rainfall in September. October has been very dry. When we look forward to the next three months in our three-month outlook, our seasonal forecast, there is a signal of a greater chance of being in the dry category. We would typically expect that to give a 20% chance. The signal we are seeing is that there is a 30% chance of being in the very dry category.
The Chair: Going back to Lord Mancroft’s question, given this scenario and the low levels of groundwater in aquifers that we already have, would it make sense to have some planning in place to address what could happen?
Jamie Hannaford: The hydrological outlook that came out yesterday, taking the meteorological forecast and looking at river flows and groundwater, is suggesting over the next three months a continuation of below-normal river flows in the south and east parts of the country and a continuation of normal to below-normal groundwater levels. There is lots of action already. There are the water companies. The Environment Agency, I think this Friday, is releasing its prospects report, where it has done a whole load of scenario modelling and looking at what will happen, based on various trajectories of how the winter might unfold, and what that would mean for the hydrological situation as we go into the spring and summer. There is a lot of effort from the statutory actors. We are providing a lot of the science to help underpin that through the modelling that we are doing.
Q12 Lord Layard: What is the level of engagement between the scientific community and the water companies, government and Environment Agency? Is it enough to ensure that the latest understanding of drought is shared and understood?
I would like to add to that, going back to my previous question, perhaps to the other two witnesses. Are we facing a very large problem that the people who are going to have to handle it have not faced up to?
Professor Jason Lowe: In terms of how we, as the Met Office and the wider scientific community, work with government, the water companies and the EA, the Met Office works very closely with EA. We have EA colleagues onsite in our flood forecasting centre. We have routes that are well established for sharing weather and climate data. EA has a very strong role in thinking about how we design our next set of climate projections. Our seasonal forecast—our three-month outlook—is shared with a number of organisations, including being distributed across government, but also goes to the water companies.
We additionally work with water companies through a range of research projects. For instance, the one that led to part of eFLaG being produced, the UK Climate Resilience Programme, involved three water companies getting actively involved in the research around flooding and drought. With government centrally, the Met Office works very closely with Defra on issues of adaptation and providing evidence. We also provide evidence into, for instance, the climate change risk assessment.
Q13 Lord Ashcombe: You just described the meshing of what you do with water companies, the Government and everything else. Do you think that there is a case for some more education of the general public, without scaremongering at this stage, I suggest? I do not think that they have a clue that everything is quite as tight as it maybe is.
Jamie Hannaford: We did a review for Defra and the Environment Agency of some of the drought communication in the UK, which reported last year. A key tenet of that review was recognising that there is lots of good monitoring and engagement, and trying to underscore the importance of the education side as well. It is recognising that it is not just about drought management when you are in a drought in the here and now. The long-term resilience comes through trying to connect the drought to future changes. Crucially, it is about not just how the public get monitoring information, but the “so what?” What can they do about it? What are the actions that can be taken?
Q14 Earl Russell: Would you generally agree that there is more in this space that the Government could do, working with other bodies, to promote and support citizen science to help collect data?
Professor Jason Lowe: There is massive potential in citizen science. We are running a project at the moment that looks to improve the temperature part of the datasets that we have available using citizen science. When you combine that with the internet of things and the novel observations that come with that, there is a fantastic potential.
Q15 The Chair: In last week’s private briefing, we heard that greater data sharing between the scientific community and water companies would be beneficial, as there is currently a limited understanding of the role of anthropogenic water use—something Lord Duncan was concerned about—from households, industry and the commercial sector. Professor Lowe, you mentioned earlier that there seems to be a lack of understanding of the impact of climate change on assets and infrastructure. I was wondering whether there is a big knowledge gap within that and how we address it.
Professor Jason Lowe: The gap that I was highlighting is that, if we want to understand risk, there are gaps in the datasets, for instance, around asset locations, asset types, the levels of protection and the vulnerability of particular assets.
The Chair: Could you give us a quick example?
Professor Jason Lowe: For instance, consider that you have a business with a datacentre or factory in a particular region. Where is that precisely located? What are the defences? What levels of rainfall or surface water flooding would overwhelm that datacentre?
The Chair: Is there an example of datasets held by the NHS that were compromised during one of the recent droughts?
Professor Jason Lowe: I do not know enough to comment on that particular dataset.
Jamie Hannaford: On the benefits of greater sharing of abstractions and discharges, there is a really good example in the last couple of years of a DESNZ-funded project: CS-N0W. We have talked a lot about the eFLaG projections of future river flows based on climate change. We are also able to make future projections of how anthropogenic changes will occur, so how demands will occur, in future.
That was all made possible by the Environment Agency opening up some of the abstractions and discharge data. It has enabled that to be made into a publicly available dataset, so that the whole scientific community now has a better handle on abstractions and discharges, which can be used to help with current management and projections for the future.
Professor Alan MacDonald: There is a lot of good data sharing between the researchers in the groundwater community and the EA, and with the water companies. For example, today there is a workshop between the two of them. A key issue here is about balancing the abstraction versus the environmental impact. If you are abstracting groundwater, what is the environmental impact? That is what we, as scientists, are trying to work out to balance that, to give the evidence to both the regulator and the water companies.
The Chair: Before I let you go, I wonder whether you can each answer this question. Where does responsibility for drought preparedness stop? With whom does the buck stop? Who is responsible, ultimately, for preparing for future scenarios?
Jamie Hannaford: Fundamentally, the Environment Agency and water companies have that responsibility. The water companies have the responsibility for ensuring security of supply through their water resource management plans. It is not necessarily a single organisation. The national framework has this responsibility for making the projections of future water resources.
The Chair: Who heads up the national framework?
Jamie Hannaford: That is an Environment Agency-led initiative, but it embraces all the water companies. A great thing about it is that there is an increasing recognition of the role of multistakeholder planning. Some of the regional groups, for example, bring in agriculture, energy and other abstractors. That is a really positive thing.
The Chair: You agree that the framework is working well. I will ask each of you that question.
Jamie Hannaford: It is a really positive thing, for sure.
Professor Alan MacDonald: Defra, through the Environment Agency, and water companies, through their drought management plans, are the ones that have the responsibility for drought preparedness, but it is, as we have said, much wider than that. As a scientific community, we are trying to provide that evidence that helps each of them to make these really difficult decisions about how to manage our water supplies and environment during drought and look into the future. The responsibility on who we are, as the scientific community, is in providing that good evidence to those who have the regulatory responsibilities.
Professor Jason Lowe: I would see this very much as a multiagency problem. The Met Office has a very clear role, and that role is to provide information on weather variables and climate change. We work very closely with the other agencies and try to respond to their needs in doing so.
The Chair: That is excellent. Thank you all very much again for your time. I am sorry to have taken up more of it than we had anticipated.
