Dr Julian Lewis: To ask the Secretary of State for Environment, Food and Rural Affairs, what recent comparative assessment he has made of the effect of (a) increases in the volume of rainfall and (b) decreases in the volume of river dredging on the (i) quantity and (ii) extent of flooding in each of the last 10 years; if he will make it his policy to increase river dredging; and if he will make a statement. 
[Due for Answer on 4 March.]
The Parliamentary Under-Secretary of State for the Environment and Rural Opportunities (Rebecca Pow): Dredging is one of the interventions used by the Environment Agency (EA) to manage rivers. The EA prioritises those interventions which achieve the greatest benefit in terms of better protecting people and property from flooding. Dredging and clearing channels are important parts of the EA’s maintenance regime. Dredging is used where it is technically effective, good value for money, does not significantly increase flood risk for others downstream, and is environmentally acceptable. Dredging is unlikely to be effective in isolation but it can be part of a solution involving multiple interventions. A useful reference on the effectiveness of dredging was published by CIWEM in 2014, entitled, ‘Floods and dredging, A reality check’.
Other activities the EA uses to manage rivers include clearing aquatic weed within rivers, removing blockages such as shoals of silt, clearing debris from screens and gates and removing obstructions such as trees, so that water can flow freely along the channel. Over each of the past three years, in real terms, the EA has spent between £45 million and £55 million per year on channel maintenance compared with between £39 million and £55 million per year in each of the three years to April 2013. Without these interventions more flooding would have occurred over the last decade, although it is difficult to quantity this benefit.