Loss of morphological diversity (rivers)

A reduction in the amount of natural variation in channel width and depth observed in a water body, as a result of physcial modifications to the channel bed and banks. A natural river channel generally exhibits a degree of width and depth variability, supporting deep, narrow reaches and wider, shallower reaches depending on localised geomorphological controls. The width-depth variability of a river is dependent upon factors such as the substrate type, flow regime and underlying geology. As natural width-depth variation decreases, conditions within the channel become more uniform and dominated by a single type of geomorphological process (e.g. sedimentation in a uniform, slow flowing channel). This limits the morphological diversity of the channel and the types of habitats that can be supported.

A modified (1) and less modified (2) reach of the River Darent in Kent, with very little, and more natural, width and depth variability (respectively)

Mitigation measures