Resilience measure: Dredging of watercourse

definition

The term dredging is used to refer to the systematic removal of accumulated material from river or other watercourse channels. In its most extreme form dredging may be used to re-align river channels creating linear, canalised watercourses. While implementing such a measure the cross section of channels and waterways is enlarged i.e. their carrying capacity is increased assisting in carrying flood flows. (CIWEM, 2014).

Co-benefits and impacts

Dredging of watercourse or i.e. channel enlargement has some drawbacks too: environmental degradation as of the result of the loss of natural channel features and vegetation during the enlargement process (recovery may take a long time); channel instability due to the removal of vegetation that helps to prevent erosion and maintains the integrity of the riverbanks; sedimentation in the engineered channel leading to the formation of shoals and bars, and eventually to the reversion to a smaller, more natural channel (frequent intervention may be required in the form of desilting to keep the desired channel size, again with adverse environmental impacts); a stark and unnatural appearance, particularly in the usual low-flow conditions (which are much more common than flood flows).
(Environment Agency, Channel enlargment, accessed on Sept. 2016 )

conditions

Dredging of watercourse works require careful consideration and the involvement of an experienced geomorphologist to ensure they are stable in the long term and do not result in adverse impacts.
(Environment Agency, Channel enlargment, accessed on Sept. 2016 )

Related Links





Time scales (Show all)

Long term

Synonym of Resilience Measures (Show all)

Channel enlargement

Measure types (Show all)

Engineering

Problem types (Show all)

Fluvial



Last modified: Sept. 16, 2016, 11:21 a.m.