Housing development and sustainable water supply in the Cambridge area

denversluice08:08 Tuesday 5th January 2016
BBC Radio Cambridgeshire

DOTTY MCLEOD: The headlines have been dominated by the devastation that flood waters have brought to the North of England over the last few weeks. Cambridgeshire has been spared the heavy rainfall this year, but one Cambridge academic has warned that instead of floods, the greatest challenge facing this county could be chronic water shortages in the coming years. Of course Cambridgeshire hasn’t always escaped flooding. In 1947 much of Fenland was inundated as rivers and drains broke their banks. These people remember what happened.
ONE: The Sunday night was very bad. Wind, the men had to rope themselves together on the banks to stop from falling into the river. Yes I were out on them banks and breaching them up with sandbags.
TWO: I went up to Earith because I’d heard rumours the bank had blown. When I got there it was really frightening. The bank was really shaking.
THREE: The one journey that I really recollect is the night that I was called out to go to Hilgay. The water in the river was so high that it was coming over.
DOTTY MCLEOD: There were also of course the terrible East Coast floods of 1953, when 300 people died, and as a result of that, a large scale flood protection scheme was introduced. Since then the flooding we’ve experienced in Cambridgeshire, although it’s always awful for anyone whose home is affected, it has normally been fairly localised. Dr Bob Evans is a Visiting Fellow at the Global Sustainability Unit at Anglia Ruskin University. Morning Bob.
BOB EVANS: Good morning.
DOTTY MCLEOD: Are we prepared then for the kind of deluge that we’ve seen in the North of England here in Cambridgeshire?
BOB EVANS: Well the North of England has had about three times its average rainfall in December. That is fairly rare.
DOTTY MCLEOD: Its average annual rainfall?
BOB EVANS: No no. Average for December.
DOTTY MCLEOD: OK.
BOB EVANS: So it’s an enormous amount of rainfall. We’ve had just over the average. So one of the reasons is we’ve had a lot less rainfall, and at the moment we’re coping. The river levels, I cross Jesus Green nearly every day and they’re not very up at all. And that’s been so for quite a long time.
DOTTY MCLEOD: Suppose we did have that kind of level of rain that they’ve seen in places like Cumbria, three times the average. Would we just be inundated here?
BOB EVANS: We would I think be more like what you’ve just been saying on the radio, that it would be local. Because it would be a question of how quickly you could shift the water through the system. And generally when we’ve had big floods it’s because the water can’t get out quickly, because the sluice at Denver is not allowing the water to go out to sea, because the tidal levels are very high. So you’d usually need two things to get really massive flooding. So I think you’ll just get local flooding, which as you say is fairly horrendous for the people who are affected. It won’t be massively around the Fens.
DOTTY MCLEOD: Now you say that actually water shortages are something that we’re more at risk of in the long term.
BOB EVANS: I think certainly more than flooding, because we’re busy developing Cambridge like nobody’s business. It’s absolutely fantastic. And a few years ago I did a quick and very crude calculation as to whether there would be enough water in the system that Cambridge Water Company supplies. And I thought it would be very tight by the 2030’s. And in fact the latest Local Draft Plan suggests there’s going to be .. is it about another nine and a half thousand houses extra in the Cambridge area? So I think it’s more than likely that we’ll be short of water. Because there was a sustainable appraisal done, that sounds grand doesn’t it .. ?
DOTTY MCLEOD: (LAUGHS)
BOB EVANS: .. of the Local Draft Plan about two or three years ago. And they said they thought that Cambridge would have a water deficit by 2031.
DOTTY MCLEOD: OK. And where does our water come from?
BOB EVANS: It comes from the chalk which underlies the land just to the South of Cambridge, so Royston and that area. And it’s pumped up from boreholes in the chalk. And about 95% of Cambridge Water Company’s water comes from the chalk. So they know how much water there is stored in the chalk. And they put in a safety factor. And they also put in leakage and stuff like that. And we’ll be very very close to the safety margin.
DOTTY MCLEOD: So what can you do about it? How do you get more water? Do you have to pipe it in?
BOB EVANS: Well you’d probably have to do something like that. Yes. So it would be very expensive. There was at one point a reservoir put forward to be built, a couple actually, one just to the South of Newmarket, and one somewhere on the Fens near Feltwell. Those were proposed after the great drought of ’75/76. But nothing really has come about, though part of the system for moving water about, that is there. So you can move the water down to just South of Newmarket, up over the chalk escarpment, and then into the rivers that go down into Essex. So Essex gets a lot of its water from in fact Norfolk.
DOTTY MCLEOD: OK. So it sounds like this is something that the authorities are aware of. They had their sustainable water appraisal. They know about this situation, that we could be facing a water shortage a couple of decades down the line. Is action actually being taken?
BOB EVANS: Well I would like somebody to make a decent appraisal and say yes or no, there is enough water in the system. Because at the moment we just seem to be flogging along developing Cambridge. And though we do need housing, there’s no problem about that, we do, is there enough water in the system without actually having to ship it in from Anglian Water or whatever? So I would guess there’s going to have to be some moving of water around the system.
DOTTY MCLEOD: The more common concern that people raise when it comes to water and development is that the more you build, the less space there is for water to absorb into the natural landscape.
BOB EVANS: That’s right.
DOTTY MCLEOD: Is that something as well that concerns you?
BOB EVANS: It is. Yes. Because you get a lot more runoff very quickly. But Cambridge city itself I think is reasonably well known for its work on what’s called sustainable urban drainage schemes. So that’s putting in ponds and slowing the water down so it hits the concrete. In fact University west side, Cambridge side, has lots of ponds to contain the water when it runs off all of the buildings and the roadways that are being built. So there are schemes afoot, and Cambridge I think is quite well aware of those, and doing things about it. But there’s going to be a lot more development, so there’ll have to be quite a lot of land taken out to build those ponds and slow the water down, so it doesn’t all hit the Fens at the same time.
DOTTY MCLEOD: This is the thing. If you’re looking at building 30,000 odd houses in South Cambridgeshire and Cambridge city alone over the next few decades, are you ever going to have good enough sustainable urban drainage solutions to mitigate the effect of all of that work?
BOB EVANS: I’m hoping they’re putting that into the system.
DOTTY MCLEOD: But do you think they are?
BOB EVANS: I don’t get the impression that they’re trying hard enough probably. Shall we put it that way?
DOTTY MCLEOD: OK Bob. Really good to talk to you this morning. It’s fascinating stuff. Thank you for coming in.
BOB EVANS: Thank you very much.
DOTTY MCLEOD: Bob Evans there, Dr Bob Evans who is a Visiting Fellow at the Global Sustainability Unit at Anglia Ruskin University

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