Benefits of Targeted Dredging

dredge09:22 Monday 31st March 2014
BBC Radio Cambridgeshire

[A]NDIE HARPER: A major report by the UN into the impact of climate change on humans has been released today, and it comes as dredging begins on the Somerset levels, following severe floods this winter. Many have blamed a lack of dredging for the floods crisis, but the Environment Agency has maintained it would not have prevented it. Only last week the Met Office said we will see more wet and warm winters, thanks to climate change. So is it time that we all sat up and took notice? David Thomas is the Chief Engineer of the Middle Level Commissioners. David, good morning to you.
DAVID THOMAS: Good morning Andie.
ANDIE HARPER: And of course the lack of dredging, or the cutting back of dredging over the years was roundly blamed for the flooding in the Levels this time round. Is just dredging therefore the answer?

DAVID THOMAS: No. No of course just dredging is not the answer. And I think you always have to be careful. I think in this instance the pundits who are saying that if the rivers had been dredged flooding would still have occurred, but I think there’s good consensus now that suggests that the amount .. the extent of flooding and the duration of flooding wouldn’t have been so severe if dredging had taken place.
ANDIE HARPER: Why was dredging cut back? And I can remember when I was younger and lived in East Anglia, and rivers were regularly dredged. Not always the nicest thing to see, because you always felt it was disrupting all the plant life and the water life in general. But it was done more regularly. Why were there cutbacks? Purely economic?
DAVID THOMAS: I think mainly economic. I think that also as you suggest, there were issues with the environment. And I think we have as an industry been a little bit more aware of the impact of things like dredging on the environment. So we do need to be careful. But of course with all of these things it’s a question of the pendulum swinging one way or another. And possibly at the moment the pendulum’s gone too far in the direction against dredging, and needs to return a bit. Dredging is appropriate in certain instances, particularly in pinch points, where if you can remove the pinch point you can release the water.
HARPER: Thankfully we didn’t have the issues in this part of the world, and you would have thought if Somerset flooded, there is no reason on earth why the Fens shouldn’t flood. And the fact that the Fens didn’t flood is not purely down to dredging here, is it? It’s so much more that has happened over the years, and is that what they need to do in Somerset?
DAVID THOMAS: Yes. I think it’s all about pre-planning, all about being prepared. So we need to invest our time and energy in looking at systems, identifying where maintenance works are required, and then doing it in advance of a flood. because of course once a flood’s occurred, it brings everything into sharp focus. But of course it’s too late then. What we really need to do is be investing our time and money in advance.
ANDIE HARPER: I was talking earlier to a professor about this meeting in Japan, and about global warming and climate change. There are still many many people who don’t subscribe to it. But do you have to take note of changing climates, given your occupation as it were?
DAVID THOMAS: Yes. I’ve always seen the debate as being in two halves, climate change itself, and the causes. And there does seem to be quite a big debate over whether or not man’s had an impact on changing climate. But I think myself the question is partly whether or not man is having an impact, but also the acceptance that actually over time climate does change. We’ve had a number of ice ages, over millions of years, and it’s a natural process for climate change. So I think we need to be aware of what’s going on with the climate, and again be ready for those changes to occur. So yes, we have been looking forward, and the works we’re doing over the last few years and the few years to come are all in preparation for expected climate change.
ANDIE HARPER: What is the biggest threat to us here in Fenland, in East Anglia? Is it just more and more rainfall, or rising sea levels?
DAVID THOMAS: I think the answer is both.
DAVID THOMAS: Rising sea levels of course (UNCLEAR) an impact, and with the surge tide that we had only a few months ago, we saw how uncomfortably close that came to overtopping some of our flood defences. But also with more intense storms obviously we have to deal with a potential for flooding. But then dryer summers, we need to be investing in storing water over those winter months, so that it’s available during the summer. I think we’ve a head start in East Anglia, because we’ve centuries of experience in actually managing the environment. And this being one of the driest regions, although this winter you wouldn’t have known it, we have been looking at things like this, and we have been working towards dealing with them. There’s always room for further investment and more inventive thinking, but we are active.
ANDIE HARPER: Just returning to dredging finally, it is a slow painstaking operation, isn’t it? It’s not going to be, oh all the rivers in the levels are going to be dredged in the next few months, and then next winter it will be fine. My memories of dredging, it’s very slow slow progress along a river.
DAVID THOMAS: It is. It is. But I think that’s the industry we’re in. It’s a long term continual rotational process, where it isn’t about short wins, it’s about investing for the long term. We as an industry, we need more money. And we need Government to recognise that they need to be investing year on year to make sure that the money’s available that we can do these works. And I think the other thing with dredging is actually it can have environmental benefits. Over-silted watercourses do lead to a reduction in bio-diversity. So it’s not just about the negative impacts. There can be positive impacts. And I think targeted dredging actually can create something a little bit more interesting.
ANDIE HARPER: On that positive note, we’ll leave it. David it’s been really good to talk to you this morning. Thanks for joining us.
DAVID THOMAS: Thank you.
ANDIE HARPER: Cheers. That’s David Thomas, Chief Engineer for the Middle Level Commissioners.