Policy, implementation and science. In that order.

I've just been to a conference all about flood risk management. Flooding's a big economic and social issue. The problem: lots of places flood, which destroys bridges, roads, crops, people's belongings. It's not nice, and it costs lots of money. It happens partly because we've built on floodplains and partly because we've speeded up the rate at which water flows through catchments, by straightening river channels, cutting down trees, draining fields, tarmacking the land, etc. And flooding will happen more often and in more places as changing climate means more rain falling in heavier rainstorms.

This is not my area of expertise, so I have an outsider's impressions. I might have got the wrong end of the stick. But I came away slightly cynically wondering about the right order of things when society needs to deal with a problem like flooding. This is how I saw it.

Traditionally we try to manage flooding by engineering - building levees and dams, and digging drains, and so on. There are various downsides to this, such as it being generally very expensive, and of course tending to cover the countryside in concrete. The new paradigm is Natural Flood Management (NFM for short. Bear with me). That's mimicking natural processes to try and slow down stormwater as it flows through the catchment, so that downstream towns aren't overwhelmed by all the water all at once. For example, by knocking down riverbank levees so that flood water can spread out slowly over the natural floodplain again, rather than flow straight down the river. Or by restoring meanders (remember GCSE Geography?) which were straightened decades ago, so that the river water has to travel further, which takes longer. Or by chucking lots of old tree branches and other woody debris into the river at various points, to form the kind of blockages which used to be there naturally, before we started clearing out river channels all the time.

This all sounds brilliant. As well as tackling flooding, it will make our rivers healthier and look nicer. So good, in fact, that it's already enshrined in law. New legislation says that NFM will now always be used in preference to traditional flood management techniques. Still sounds great, you say.

The problem is, NFM as an implementation approach is still pretty new. No-one really knows yet how effective NFM techniques are, or which are the best ones to use for any particular river. What we do know is that any one individual NFM technique tends to be less effective than equivalent traditional methods. So you need to use lots in tandem. Which often takes up lots of land (often useful land, like farmland) and gets more expensive. So people have started to set up demonstration sites to test different NFM measures in real life catchments, to collect data, measure how much they reduce flooding in different kinds of catchments, find out the practical problems about putting them in and managing them, and work out how much it really costs. Very sensible - but this is after it's become law. And we're talking about trying to work out how effective these measures are at mitigating a 1 in 100 year flood event. How long do you think you'll have to monitor for to be confident in an answer for that?

So for the next few years at least, it looks like the cart will be before the horse. I can see that we needed policy and legislative measures to drive this - almost certainly - sensible approach forward. But maybe some more time and money could have been put into finding out more about the details  first - the science bit, building up the evidence. Right now, the people charged with tackling flooding are working - not blind, but blinkered. And I worry that all the research and trials that go on now will be rushed to fit in with legislative timescales, and won't be as good as they could be.

Right, apologies, that was a bit in depth. I blame the twenty three presentations I've listened to in the last two days. A person can lose perspective. So I'll sign off now. It's time to go skiing. :-D