dredging a stream or a river is an example of what

The notion is that by removing the amount of sediment within the channel you are able to increase its capacity. In the UK the principal reason for river dredging is flood defence. With all of these potential changes, why do we bother? Greater streampower leading to the transport of coarser sediment downstream of the dredging activity, combined with a greater fine sediment load to cause bed armouringĪ number of studies have considered environmental/ water quality/ biodiversity issues, but there hasn’t been much focus on lowland systems.Vertical incision leading to river bank instability and potential channel widenning.Reduced sediment availability leading to a simplified channel planform in inherently braided systems.An increase in channel slope upstream of the dredging activity, potentially creating a knickpoint.A reduction in bedload supply and therefore channel slope downstream of the dredging activity.

A few key papers have highlighted the following morphological effects of dredging in high-energy rivers: I’d invite you to highlight examples where what I suggest should happen, hasn’t happened.Īnother point to make is that the academic literature has relatively little information on the geomorphic effects of river dredging in low-energy rivers. The exact ramifications of river dredging upon geomorphology will be a function of the river typology, sediment characteristics, the dredging technique employed, existing floodplain connectivity and antecedent environmental conditions – the points made within this post are theoretical and generic, just like my post on the geomorphic impact of weir removal. It seems the community has been crying out for a post of this nature and so here I am gallantly riding into the maelstrom of a politically sensitive issue, on the back of my watery steed, wielding my lance of science and wearing my armour of academic integrity.įor starters, this is a complex topic.

Dredging a stream or a river is an example of what