Nice (short) article from the Guardian on why doing nothing is often better for flood risk than overengineering

For many of us across the UK it has felt like another wet winter; yet again homes have flooded and politicians are under pressure to improve flood protection. Engineering our rivers and building defences might bring reassurance, but recent research shows that doing nothing is often more effective at reducing flooding.

George Heritage and Neil Entwistle from the University of Salford studied the River Caldew in Cumbria; responsible for three major floods in Carlisle since 2010. Their results, published in the journal Water, show that the straightening, deepening and widening of the river has increased the rate at which sediment whooshes downstream, dumping its load in Carlisle and increasing the chances of overflow there. But where this upstream river maintenance has been relaxed they found the river has reverted to wandering, depositing more sediment upstream and reducing the clogging up in Carlisle.

And the River Caldew is no exception. The same debate is being played out in New Zealand, where scientists are arguing for the rewilding of rivers, giving them space to move. Confining rivers has created valuable agricultural land like that seen on the Canterbury Plains, but has come at a cost of increased flood risk downstream. It’s time to release our rivers.