Dredging

If you are a riparian owner you may be tempted to make the river deeper by dredging it, thinking that it will reduce the risk of flooding. 

Dredging a river without an Environment Agency consent or exemption is illegal. Your local council can't give you consent to dredge a main river. Most winterbournes in the Kennet Catchment are classed as main river, even though they don't flow all year round. 
 
There is good strong evidence that dredging does not work. This is particularly true on chalk streams, where flooding is most usually due to high groundwater. 

As a riparian owner you have responsibility to let water pass unimpeded through the stretch of river you own. So you must not block the channel, or put things next to the river that could be washed into the watercourse and cause a blockage further down stream.  You do not have to remove watercress, silt, or even tree branches that can be secured to the bank - as long as water can get past them and there is not a risk of them being washed downstream.

Dredging rivers may temporarily increase the river capacity by a tiny percentage, but it will always silt up again and in a flood event which threatens homes it will not have enough impact to make a difference. Dredging removes the naural river bed material, which destroys fish spawning habitat, leaves banks unstable and vulnerable to erosion and can make downsteam flooding worse.  A literature review is available
here. 

Taking action upstream to slow the flow of water, restoring channels to their natural state or creating safe spaces like water meadows for water to overflow into are all more effective way to reduce flood risk. Rain gardens, sustainable drainage systems and wetlands can all help to reduce flood risk.

If your home or community is at risk of flooding and you would like to explore what action you can take please get in touch.


More information about your responsibilities as a riparian owner.