I met with Minster Emma Hardy on a Yorkshire chalk stream earlier in June to discuss what this government might do to help chalk streams. The meeting was mentioned in parliament as excerpted below and I have also received a letter from the Minister setting out the government’s ambition for chalk streams, also below.
I’m obviously as disappointed as anyone that government has dropped the Defra chalk stream recovery pack. I’m still not sure why it has chosen to when the fate of our fragile and unique chalk streams is so obviously important to such a broad range of people and to so many people … including Sir David Attenborough.
Encouragingly, however, Minister Hardy has written “chalk streams will continue to be fundamental to our mission to reform the water system”.
The proof of the pudding, as they say …
I have heard good things about what may in the pipeline (following the Cunliffe and Corry reviews) in terms of revitalised and empowered catchment management, and the easing of the treacle-wading bureaucracy that is a sheet anchor to river restoration efforts. Both much needed. So, it may well be – fingers very crossed – that the progress we make through this term will move things forward for chalk streams.
Nevertheless, the CaBA chalk group continues to feel that the gist of its recommendations – greater protection for chalk streams, prioritised abstraction reduction and phosphate reduction targeted to where it will most benefit ecology (not some obtuse economic algorithm) are all very much in the gift of Defra and Ofwat, and are total no-brainers if we want to restore our chalk streams and deliver on the collegiate, universally supported work of the past 5-years.
The Parliamentary Under-Secretary of State for Environment, Food and Rural Affairs (Emma Hardy): Chalk streams are not only a beautiful and iconic part of our precious natural landscape; they are symbols of our national heritage. The protection and restoration of our cherished chalk streams is a core ambition in our overall programme of reform to the water sector.
Luke Murphy: I am grateful to the Minister for her response. In Hampshire, we are blessed with several rare and irreplaceable chalk streams, including the River Loddon, the River Itchen and the River Test. The Minister will be aware of the campaigns to secure greater protection for these irreplaceable habitats, including during the passage of the Planning and Infrastructure Bill, and I pay tribute to the Hampshire & Isle of Wight Wildlife Trust, Greener Basingstoke, and Natural Basingstoke for all their work. Can the Minister confirm that this Government are committed to the protection of chalk streams, and set out what further steps they will take to restore these precious habitats?
Emma Hardy: My hon. Friend is quite right: chalk streams are a source of beauty and national pride. Just a few weeks ago, I had the privilege of visiting a chalk stream restoration project with Charles Rangeley-Wilson, who is a passionate campaigner for chalk streams. Under this Labour Government, water companies will spend more than £2 billion to deliver over 1,000 actions for chalk stream restoration, and will reduce their abstraction from chalk streams by 126 million litres per day.
Mr Gagan Mohindra (South West Hertfordshire) (Con): The River Chess in Rickmansworth is one of the chalk streams that goes through my constituency. The volunteers at the Rickmansworth Waterways Trust are keeping our canal heritage alive, despite funding for the Canal & River Trust being cut. I believe the cut is short-sighted, because these waterways tackle water shortages, boost biodiversity and protect 2,500 miles of national assets for a modest cost. Will the Minister rethink the funding cuts and back the Fund Britain’s Waterways campaign, so that local champions like David Montague and his team at Batchworth lock are not left to sink or swim on their own?
Emma Hardy: The hon. Gentleman is quite right to say how important volunteers are in supporting our natural environment up and down the country. He will be aware that the decision to reduce the funding for the Canal & River Trust was taken by the previous Government, and that was extended under this Government. There will be a tapering off of some of the funding, but we continue to support water projects up and down the country. As I have already mentioned, the changes that we are introducing for water companies will help to protect not only our beautiful chalk streams, but all our rivers, lakes and seas.
I enjoy Simon Cooper’s chalk stream focussed newsletters, for a variety of reasons, not least that they are well written, sardonic and interesting. No matter what he writes – unarguable truth or arrant nonsense – there’s never a dull moment.
On the 6th June Simon asked “where do all the water company fines go?”. Good question! The Conservative gov’t introduced the idea that these fines ought to go to improving the environment damaged by water company malpractice. But the sums aren’t ring-fenced. So, of the £242-million levied on the industry in 2022/23, only £11-million found its way into the Water Restoration Fund. We need to ask this question repeatedly: “who is trousering the fines?”
This week Simon is on the water company case again, lampooning Southern Water’s Tim McMahon. McMahon had claimed that the south-east of England was “drier than Istanbul”. Simon called this “Southern Water Fantasy Maths”.
“McMaths,” he wrote “who probably hones his calculating skills watching endless repeats of the numbers game on quiz show Countdown had to perform two feats of contorted logic to arrive at this implausible claim. Firstly, he had to include the population of London in his calculations. The last time I looked our capital was most definitely not in the south-eastern portion of England but hey-ho Tim perhaps you are lining yourself up for a Nobel Prize double to include geography. Secondly, Tim has used the historic average for Istanbul rainfall but compares it to one of the driest periods on record for South-East England.”
In fact Tim had said to the BBC: “If you look at the south-east of England, it’s drier than Sydney, Istanbul, Dallas, Marrakesh. We have got a very densely populated area and we need to start investing to cater for that. We need to reduce customer usage. Otherwise we will have to put other investments in place, which will not be good for customers and might not be the best thing for our environment.”
If I were to pick that statement apart, it would not be to make a petty objection to the “drier than …” statement.
The point is kind of obviously rhetorical, not literal. Tim is also clearly referring to the geographical reality, not the regional concept. London is undeniably in south-east England. It is a region in itself, however, so it is not technically in the region described as “the South-East”.
To match the pedantry I looked up the “centre of England” and found it – deemed so by Ordnance Survey – to be a village in Leicestershire called Fenny Drayton, definitely above and to the left of London.
As for the rainfall, across the south-east of England it is generally a bit less than 650mm a year. Sydney’s average rainfall is 1150mm, Istanbul’s 820mm, Dallas’ 880mm, and Marrakesh’s average is 250mm.
So, McMahon was wrong about Marrakesh.
To his wider point, however: south-east England is undeniably dry. Why object to someone saying that blindingly obvious truth?
And I’m glad Tim has pulled London into his justification, because it is around London that our chalk streams are most damaged by abstraction. That’s because there are too many tea-pots, basins, showers, loos, baths and gardens relative to how much rain falls in the Thames basin.
The Misbourne is regularly dry. As are the upper Beane and Darent. Abstraction in the upper Lea is 90% of average recharge. The poor-old Lea doesn’t really become a river until the Luton sewage works discharge.
That’s why we do need investment, a national grid for water, pipelines, reservoirs and de-salination. The lot.
The part of Tim’s statement that is of concern is the idea that if we don’t trim usage we may have to put other investments in place, which might be bad for customers.
That’s the bit to focus on.
Demand reduction per head of itself solves only one problem: demand increase through development. On it’s own trimming customer usage just allows the government to build more houses.
To see chalk streams flowing naturally again, we need to reduce the amount of water we take out of chalk aquifers. And we can’t do that without investment.
It took me a while to get my head around the concepts in this post, so bear with me. This is aimed especially at eNGOs and other campaigners for chalk streams, because the more people there are who understand this counter-intuitve idea, the better.
Here it is: you can save many chalk streams from unsustainable abstraction by conceivably using the aquifer in times of low flows and drought.
That is a head-muddler. But this idea could unlock real abstraction reduction, making the bad much better in the foreseeable future. This is far, far preferable in my view than holding out for a perfection (natural aquifers) that will never come.
It starts with my best attempt at explaining what I understand of the complexities of the interactions between groundwater, river flow and groundwater abstraction. Given that I vainly spent a long night in a hut in Iceland trying to explain the very same ideas to two angling friends of mine (they were belligerently uncomprehending in a (successful) effort to annoy me), this will be no easy task.
It is complex … kind of. It’s also quite simple really. Rather as the moon affects the tides, a simple idea leads to a complex set of manifestations.
Idea 1. Chalk streams flow from underground.
If you’re reading this blog you’ll already know that chalk streams derive most of their flow from groundwater. Rain sinks into the ground filling fractures in the underlying chalk and then lower down the slope it seeps out again as springs to create a chalk stream.
Idea 2. The level of the groundwater drives the flow in the river.
This is pretty simple. I used the bucket analogy before. Drill a single hole in the base of a bucket. Fill the bucket with water. As the bucket fills gravity drives water at an increasing velocity out of the hole. Now stop filling and let it empty. The flow diminishes to a trickle. EVERYONE gets this because it’s the same when you pee!
The rate of flow from springs in a chalk valley is driven by the hydraulic head of the groundwater above the springs. The higher the level, the greater the flow …… In more or less the same way as the water level in the bucket determines the force at which the water is driven through holes in the side of the bucket.
Idea 3. Groundwater rises in winter and falls in summer.
If you pour water into the bucket faster than water can leave it through the hole(s), the level in the bucket rises. If you stop pouring water in, the level falls as the bucket drains. This is exactly the same with a chalk aquifer. In winter, when it rains a lot, and it’s cold and the ground is wet and nothing is growing, more rain flows into the aquifer than can leave it and so the groundwater level rises. In summer, much less rain – if any – reaches the aquifer and so the groundwater level falls.
Groundwater rising. This chalk valley is dry most of the time but in February 2021 when recharge vastly exceeded discharge, it had filled to overflowing.
Idea 4. The higher the groundwater rises up the valley, the more the water pours out of it.
As groundwater level rises, stream flow increases. But not in a linear way as it would with a single hole at the base of a columnar bucket. In fact for every unit of rise in groundwater level, flow will increase by approximately X2 to 2.5 . Kind of like having twice as many holes at each level in the bucket as the level below.
There are a number of reasons for this which were debated at a recent groundwater conference. There is a summary of these ideas in Section 2 of John Lawson’s report Flow Recovery Following Abstraction Reduction which we updated following the conference and contributions from the likes of Rob Soley and Alessandro Marsili.
In short, this non-linear response is probably caused by a combination of:
• the shape of the valley – if you imagine the groundwater filling the valley bottom and hillsides, assuming a perfect V- shape valley, for every unit increase the groundwater rises the area of saturated zone exposing springs rises two-and-a-half fold. Chalk valleys are not quite V-shaped but that’s the general idea.
• the fracture density in the chalk – which increases in the valley bottoms and with altitude. At depth chalk is very solid, but in the valley bottoms and higher up the slope and where water has flowed for thousands of years, the fracture density is much greater and the flow pathways are bigger.
• layering within the chalk – chalk accreted in layers under varying climatic / geological conditions and these layers are in turn interrupted by bands of clay and flint. These layers and the varying permeability and transmissivity can influence the way groundwater reaches with the surface.
• as the surface flow pathways lengthen (winterbournes rising higher and higher up the valley) the groundwater pathways shorten.
The fracture density and layering in the chalk, the shape of the valley and the length of flow pathways, all conspire to mean that when chalk valleys fill, flows will rise exponentially.
Idea 5. The impact of a constant groundwater abstraction has a varying impact on varying flows through the year
This is where things gets a bit more discombobulating. All of the above essentially means that as groundwater rises, flows increase exponentially. If that is true, then the reverse is true. For every unit of decrease in groundwater level, flows decrease exponentially.
This means …. drum roll … groundwater abstraction (which lowers groundwater levels) has a greater impact on high flows than low flows! This is a totally skull-tightening idea. Everyone thinks the reverse must be true. But it isn’t.
Groundwater levels and groundwater abstraction
Let’s start with the impact of groundwater abstraction on groundwater levels. In a natural aquifer system, the discharge from the valley must equal the recharge over time. Natural recharge = natural discharge / Time. This stands to reason: if it didn’t the valley would either fill to overflowing or empty (because over time one would exceed the other).
Natural recharge derives from rain and natural discharge from river flow (and some evapotranspiration and flow through the ground). If I add another form of discharge in the form of abstraction, then the former natural discharge MUST go down. If it didn’t, the aquifer would progressively empty until there was no water left (an aside … hydrogeological literature generally describes anything less than draining the aquifer “sustainable”, because the aquifer is being lowered to a new dynamic balance, not mined. This is not the same as ecologically sustainable, however).
Now, as I showed with the bucket, the ONLY way in which the former natural discharge can go down is through a reduction in groundwater levels. If groundwater levels didn’t go down, then because the discharge is driven by the groundwater level the natural discharge would remain the same. As shown above, that is impossible.
Theis, the Isaac Newton of groundwater theory, wrote all this in 1940. The only way that the former natural discharge can go down (and balance the equation) he wrote, is by a reduction in the “thickness of the aquifer”.
Okay, so pause and get your head round all that.
• a single unit of rise or fall in groundwater level has a (very roughly) two-and-a-half fold impact on flows.
• ipso facto a single unit of reduction in groundwater level at high groundwater levels has a much greater impact on flows than a single unit of reduction in groundwater level at low groundwater levels.
It still hurts the head, but the discombobulating stuff above means that at high groundwater levels groundwater abstraction reduces flows by quite a lot more than 100% of the amount abstracted. And conversely, at low groundwater levels groundwater abstraction reduces flows by quite a lot less than 100% of the amount abstracted. Albeit over time groundwater abstraction must reduce flows by (essentially) 100% of the amount abstracted (it’s generally less than that for reasons that aren’t that important to the general concept, but basically because not all discharge occurs in the form of flow).
See the chart below to see what the Chalk Streams First modelling indicates % flow recovery would be if abstraction was reduced to zero in the River Ver. It varies through the flow cycle.
The above chart from Page 52 of John Lawson’s report shows that the % flow recovery (green line) at high flows (l/h end of X axis) is well over 100% and at very low flows (r/h end of X axis) is about 30% – 20%.
Idea 6. Groundwater abstraction at low flows is like a credit card.
The obvious question is … if groundwater abstraction at low flows reduces those flows by a lot less than 100% of the amount being abstracted, where the bloody hell is the rest of the water coming from? The answer: if it’s not a direct reduction from flows at the time, it is coming from aquifer storage.
This is easy to understand if you think of a large abstraction next to a small and diminishing stream. In the winter when the stream is gushing, there is more than enough water to satisfy the pumping. In the summer the stream reduces to a trickle or perhaps even dries up. But the pumping continues. At this point the abstraction is clearly not taking water from stream flow because there isn’t any. Another aside … I’ve read hydrogeologists describe this state as abstraction having “no further effect on flows”. This might be literally correct at the time. But it is misleading. The abstraction is effecting future flows.
When a chalk stream dries but abstraction continues it is clear that the abstraction is no longer subtracting water from the river’s flow, but from aquifer storage: this is basically a debt to future flows.
At times of low flow and into droughts, groundwater abstraction increasingly draws on storage, upon which future flows are built. If you unnaturally drain the aquifer, it will clearly take longer to fill when it starts raining again, all before the flows in the river can respond to the rise in groundwater levels.
Therefore groundwater abstraction at low flows is like a credit card: much more a debt against future flows than an impact on present flows. This is a key idea behind the confusing concept of using groundwater abstraction to unlock abstraction reduction .
Idea 7. If you turn off the pumps you get greater flow recovery at high flows than low flows.
Essentially what all this means is that when you cease or lower abstraction you get well over 100% of the amount no longer abstracted at high flows and much less than 100% at low flows. That is what the chart above shows on the River Ver.
Water resources needs a constant supply of water. Groundwater abstraction gives that. Chalk Streams First says “turn off (or down) the pumps and take the water from river flows much lower down the catchment”. And while you get loads of water back in winter, you get less back in summer. Generally, you must have a storage reservoir to make it work and balance out the varying recovery rates into a constant and reliable supply.
John Lawson – who came up with the Chalk Streams First idea – has long known this. We argue (with empirical evidence) that the flow recovery at low flows is actually much higher than the most pessimistic predictions claim, but nevertheless this variation in response is an issue we have to address. The answer is a reservoir.
BUT … then you get to the prolonged droughts when water companies are under real pressure. In these times, the flow recovery could conceivably drop even lower. What to do? The public must have water. This low flow recovery at very low flows in long droughts threatens the whole idea of reducing abstraction through schemes like Chalk Streams First. Especially now that we have to plan according to 1:500 year contingencies.
Idea 7. In droughts use groundwater abstraction to guarantee public water supply … so long as you’ve turned the abstraction right down to ecologically sustainable levels 95% of the time.
The insurance against the Achilles Heel of low flow recovery in a drought is a groundwater-fed public water supply scheme. There is one in existence already called the West Berkshire Groundwater Scheme (WBGWS). It is a series of wells in the Berkshire chalk that can, in extremis, be turned on and deliver a large amount of aquifer water into the Berkshire chalk streams, from where it flows to the Thames to be captured into the London reservoirs. The scheme is used very, very rarely: no more than once every 25 years. But it’s there. And it guarantees water in a drought.
The West Berkshire Groundwater Scheme wellfield: this scheme is rarely used but guarantees water in extreme droughts. It is a counter-intuitive idea that could unlock abstraction reduction in the Colne, Lea and Ouse chalk streams.
The impacts on the chalk streams are a) one of flow relief in the drought, because the flows get boosted. Albeit – and I have to emphasise this – flow augmentation in not the aim of the scheme, it is a bi-product. And b) at the end of the drought, when the pumps are turned off, the aquifer must recover before flows return to natural levels, so you get lower flows the following year.
But this is crucial: in modelled scenarios, the flows in the year of recovery are still better than they would be if abstraction ran all the time as happens at the moment in streams like the Ver, Misbourne and Beane.
So WBGWS type schemes could unlock Chalk Streams First type abstraction reduction in other settings, such as on the chalk streams of the Colne, Lea and Ouse (even the Darent). As such a scheme would insure against the public supply deficit in droughts created by replacing upper catchment groundwater abstraction with lower catchment surface water abstraction (the Chalk Streams First concept).
BUT …the Environment Agency is very cautious of such schemes
This is understandable because there have been some bad schemes in the past. But flow augmentation to compensate for the collateral damage of abstraction is a different thing altogether.
Some schemes were developed in the past whereby to compensate for abstraction (which had dried the stream) water was pumped from the aquifer into a losing reach of stream and the whole thing was a highway to nowhere.
Other times the concept of augmentation is used to justify continuing, unsustainable abstraction. These schemes have given the whole idea of flow augmentation a bad rap, and one that has stuck like glue.
RevIvel claim that a flow augmentation scheme putting 0.5 ml/d into a dry river bed is not a good type of augmentation scheme, especially if it delays a proper solution to the unsustainable abstraction. This is the kind of scheme is very different from the idea promoted in this blog post.
BUT, I would argue that we need to be more pragmatic and open minded than a presumption against these schemes if we are to achieve the heretofore irreconcilable goals of reliable public water supply and restored chalk streams. Aquifers in the south east are managed one way or another. We need to make sure they are managed mindfully to achieve the specific outcomes we want and in this regard holding out for “natural” when a more flexible approach would unstick hopeful schemes such as Chalk Streams First would surely be counter-productive?
I understand the Environment Agency may be consulting on this topic later in the year. I know from many discussions I have had with chalk stream advocates that the ideas I have outlined above will be surprising and counter-intuitive to most of us, as indeed they are to me.
But it is vital we give the EA the encouragement to take a flexible, if ultra cautious approach, because the gains of doing so could be massive.
Chalk-Streams 