Until relatively recently, rivers in the UK were dredged regularly; a part of normal waterways maintenance. The dredgings were put on the riverbank.
Then the UK signed up to the EU Waterway Framework Directive.
The dredgings are now classed as 'hazardous waste'. Therefore they cannot be put on the riverbank. They have to be undergo chemical analysis, and if any of the substances in them exceed arbitrary EU limits, the dredgings have to be carted away and disposed of at a licensed site.
This is why a lot of dredging has ceased. Imagine the expense of going through this rigmarole in disposing of a substance which is essentially harmless.
My friend in Yorkshire adds (with my apologies for the intemperate language) ......
We have know-it-all idiots in charge of our rivers and drainage, plus Cameron's crew cutting the finance.
On top of that, new build is putting down hard landscape where once there would be natural seepage.
DEFRA and the Environment Agency have been messing around with computer models when they should have been out in the fields clearing ditches, dykes and dredging river beds. All common sense stuff which local folk have been telling the 'idiots' for years.
Another person I know in Yorkshire (JJ) sent the following:
Sad to see the flooding in various areas. Makes me wonder how much effort was put into maintaining the drainage ditches, culverts, watercourses and rivers over the last few years. 2007 saw severe impact on my village but research in the aftermath revealed that the drainage board had quietly stopped clearing the major drainage outlet from the village some years before.
....and finally a letter from the DT, edited slightly for clarity:
The floods in York remind us that flood defences do not remove water; they merely push it somewhere else.
The rivers Ure and Swale, which join to form the Ouse, are embankened across theVale of York, preventing flood water from spreading out over agricultural land. Ditches and streams are cleared by the Environment Agency, bringing land-water quickly into these rivers, but the huge volume of water reaching York is impeded in its progress by lack of dredging.
This is because the EU Water Framework Directive stops the Environment Agency from dredging the rivers.
HG, North Yorkshire
As for the cause of the heavy rainfall, Piers Corbyn, looking at sun cycles, says that currently they are affecting the Jet Stream, causing larger temperature differences between areas; these temperature gradients lead to heavier rain events.
1 Jan 2016