Time and Tide
With a glorious spring estuary weather to guide us along the way, Tuesday morning was spent having a sneaky upstream view of Wivenhoe from within the epicentre of the Colne Flood Barrier.
The event was part of the annual Open Day organised by our friends (steady) from the Environment Agency. Three sessions were advertised, each with a maximum capacity of twenty flood barrier nosey parkers.
Arriving fashionably late as ever, it was great to see around one hundred Wivenhoe locals being allowed within the control room of the EA operations for a brief talk, Q & A’s and then a stroll out along the Wivenhoe arm of the barrier itself.
The presentation was part historical, part technical. We learnt that tidal patterns are monitored down at the Colne each day from as far up as North Scotland. This gives a thirty-six hour advance warning for any abnormal high tides ahead.
Thursday 10th already has the thick red marker pen treatment on the EA calendar. Sleep well though lower Wivenhoe – the barrier protects us (and a large area of Colchester) from five up to five metres of above average sea level.
To put this into perspective, if the barrier was around during the last great floods of 1953, Wivenhoe wouldn’t have noticed any difference down by the Quay.
Computer generated predictor models are constantly in place to help the protection. It’s not just the tidal surge that can cause problems – fresh water travelling downstream from the Colne is also taken into account. Those nice insurance companies are constantly asking questions about possible Wivenhoe tidal woes…
And now for the science:
Two hydraulically operated cylinders close the Colne Flood Barrier. These weigh seven tonnes each, and cost £94,000 when they were first manufactured back in 1992. If one of them fails, then the single cylinder can still shut and open the barrier.
The barrier is powered with a stand-alone oil bio-degradable generator. If Wivenhoe experiences a power cut and this coincides with a flood, rest assured – we won’t be getting wet in the dark. It takes fifteen minutes for the barrier to close, with an estimated 3,000 homes falling under the protection footprint.
The barrier is being refurbished in two years time on the twentieth anniversary after first being built. Half a million pounds of central government funding is paying for this. This has been ring-fenced free of any cuts, costed out as a safety analysis requirement. The work will take place over the summer of 2013, when the tide is traditionally at a seasonal low.
And then it was time to walk it like the man from the EA was talking it, and take a spring stroll out across the Colne Flood Barrier.
This was without a doubt the highlight of the morning. With a stunning early spring lighting up all the way down from the Hythe out towards Brightlingsea, the view was a crystal clear combination of blue (ish…) water and blue sky.
It gave you a fresh perspective of Wivenhoe and the surrounds from a commanding mid-steam position. I hadn’t realised the extremity of the bend that the Colne follows around the Roman River. Likewise I hadn’t counted on the sheer length of stretch that is West Quay, when compared to the old Quay itself.
A quick stroll back through the control room, and blimey – I found myself all alone at the master desk, key in the switchboard and a big red button flashing in front of me.
Now would not be a good time to make my mark in Wivenhoe by closing the barrier and creating a temporary bridge across to Rowhedge.
For all the knocking of the EA of late (um, by me) and the vandalism of the Colne sea wall, this really was a wonderful morning. It also *wasn’t* the most appropriate time to take the engineers of the barrier to task about the wider programme of destruction carried out by their unevironmentally sound sea wall colleagues.
The message that I took away from the morning is that the Colne Flood Barrier is all about systems, protocol and back-ups. Every eventuality has been taken into account to help keep Wivenhoe safe from future floods.
It may not be the most beautiful piece of architecture out in the estuary wilds, but the future may look a lot bleaker if it wasn’t there to keep an eye on the Colne for us.