ABSTRACT
This chapter looks at the evidence for ‘contemporary’ erosion and sedimentation by rivers in Britain, broadly that which is apparent over a matter of decades or perhaps a century or two. A simple framework for looking at such activity is provided by Figure 2.1. This emphasises that erosion, transport and sedimentation are components of the same fluvial system, and that the overall transfer of material from hillslope to ocean is accomplished through a number of steps, some of them effectively repeated time and again. For example, soil material may be weathered on site for millennia, and then rapidly eroded from a hillside – only to be stored as slope-foot colluvium for further centuries before being picked up again at an eroding river bank. From then on material may be moved short distances (and be mechanically broken down on the way) from cut bank to sedimenting channel margin where again it may be stored as part of the floodplain for centuries before being picked up once more by the migrating river channel. These processes are also not all physical and inorganic: soil leaching may lead to preferential removal of mobile elements, while organic processes may lead to selective solute uptake.
