Opinion: Dredging up trouble

AS Britain recovers from the wettest January since 1766, with parts of the country experiencing more than 200 per cent of average rainfall for six weeks in a row, communities are coming to terms with the aftermath of the floods that devastated large tracts of Southern England.

Inevitably there has been a big debate as to why the damage was so severe this time and, incredibly, whether or not someone or something was to blame other than the weather. Listening to some of these characters you would think that there was absolutely no link between what falls out of the sky and why our rivers might overtop onto their floodplains – like they are supposed to do and like they have always done.

I know I wasn’t the only angler this winter raging at some of the stupid comments made by politicians and the media about the “magic dredging cure-all” that could prevent flooding and restore order to our troubled land. Of course someone had to be blamed so they picked on the Government’s Environment Agency for not dredging the hell out of enough rivers, never mind that all the evidence showed that in many cases dredging either has no impact on reducing flood risk or can make matters worse by moving water more quickly down the catchment and causing problems for areas downstream.

As anglers we know that rivers are supposed to flood their floodplains – the clue is in the name. If politicians want something other than the weather to blame for the floods perhaps they should look at their own policies which have allowed ever more building on the floodplains and taxpayer subsidies for intensive farming practices that channel more and more water down the catchment at a faster rate?

The good news is there are some encouraging signs that sanity is beginning to reassert itself. A lot of hard work by the Angling Trust, working in partnership with other environmental groups and supportive MPs, has seen a growing realisation that Britain can’t dredge its way out of trouble but that we can do something about the way we manage the land.

The self scouring power of our rivers was illustrated by a dramatic aerial photograph of the UK, taken on February 16, which shows a massive plume of sediment pumping out into the Irish Sea beyond the Welsh coastline. More than anything else, this loss of millions of tonnes of valuable topsoil demonstrated the need to adopt far more sustainable farming practices including “no plough zones” and the planting of upland trees and buffer strips to stabilise the land and encourage greater water penetration, rather than the flash flooding that has become the norm in many river valleys.


An aerial map of Britain taken on February 16 showing the huge plumes of silt pouring into the Bristol Channel and Irish Sea. Much of this is a result of poor agricultural practices upstream but it graphically demonstrates the self-scouring power of the Severn and Wye catchments.

Thames Troubles

Now I was brought up in and around the same Lower Thames communities, to the west of London, that were so badly flooded this winter and have taken an interest in the history of England’s largest river. The River Thames flows for 354 km from its source at Thames Head Bridge in the Cotswolds to confluence with the North Sea at Shoeburyness in Essex. The Thames is unquestionably the most heavily modified water body in Britain with 44 locks and weirs and its catchment is home to a human population of over 12 million.

There have been many recorded flood events, including those of 1894 and 1947, which prompted various studies and attempts to manage this great watercourse. Schemes proposed in 1914 included impoundment of floodwaters in storage reservoirs. These were dismissed by all engineers on the basis of the calculations carried out by Mr. Leach (Engineer to the Thames Conservators at the time), which indicated that six reservoirs, each nearly four square miles and 15 feet deep, and costing £1.5 million, would hold less than an inch of water flowing off the whole drainage area.

Dredging the river became a huge activity after the 1947 floods – costing £millions when £millions was a significant amount of money. All the key engineers even then always thought it was a complete waste of time and money, because the hard bed of the Thames hasn’t change over centuries – as exemplified by the fact that they were pulling out Bronze Age remains when they dug into the riverbed.

Dredging even did some damage in places by leading to erosion and bank collapse and they had to stop some distance either side of bridges anyway for structural reasons, which negated a lot of the point of dredging in the first place. Eventually, the engineers’ concerns were heeded and hard bed dredging stopped in the early 1980s and they moved to very localised shoal dredging – for navigation purposes – mainly at the entrance to locks and on bends where gravel bars had developed.

It took the best part of a century to recognise the futility of dredging a dynamic river system as flood prevention strategy but we got there in the end. Nowadays, we spend our money more effectively on engineering solutions like the mighty Thames Barrier to control tidal incursions and flood relief channels to bypass vulnerable communities. However, the fact remains that much more needs to be done to store water in the uplands and to work with the grain of nature rather than against it.

After the record droughts and record floods of the last three years, even some of the madder Climate Change sceptics are now conceding that perhaps something is happening to the weather on our planet. I guess we Brits can take some comfort from the fact that, unlike Tony Abbott, our Prime Minister does at least recognise this simple truth. What we do about it, however, is another matter.

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