§ 23. Mr. LuffTo ask the Minister of Agriculture, Fisheries and Food what recent advice he has received from the Environment Agency about the contribution that dredging can make to the alleviation of local flood risk; and if he will make a statement. [142360]
§ Mr. MorleyWhile for many rivers dredging is an important part of the maintenance regime, there can be a limit to the amount of dredging that may sensibly be performed. On some rivers, for example, too much dredging could cause the river banks or walls to collapse; larger watercourses often do not need dredging as they tend to be self cleaning; while deepening a tidal river will not create any additional capacity in the river as the level will be governed by the tide.
On some rivers with a very large catchment, such as the Severn, the volume of water is such that any increase in channel capacity would have to be extremely large to have even a noticeable effect on flood levels. This would go far beyond simple dredging and would create a channel which would be unsustainable during normal flows. The Environment Agency consider that they cannot justify carrying out dredging work for flood defence purposes on such rivers because benefits are so limited.