Historical channel-floodplain dynamics along the River Trent: Implications for river rehabilitation

The geomorphological history of the River Trent, UK, is documented from historical (documentary and cartographic) information to establish the character of the river along a 60-km reach in the seventeenth and eighteenth centuries, prior to intensive regulation. Using aerial photography, 28 former channels, as well as a number of growth bends characterized by scroll meandering, could be identified. However, many of these features date from the early medieval period and some reaches are shown to have had an extremely stable history, with the river experiencing little or no planform change since at least enclosure times. Along the 60-km reach examined, 21 per cent of the length could be classed as being stable over the 400-year period. Unstable reaches were associated with tributary confluences of the Dove, Derwent and Soar. While 79 per cent of the reach showed some evidence of channel mobility and reworking of floodplain sediments, in most reaches lateral mobility was restricted to a narrow (< 200 m) corridor. It is recommended that: 1. (1) channel dynamics and natural vegetation successions should be restored in habitat ‘islands’ at tributary confluences; 2. (2) the geomorphologically active reaches of the upper sector, together with adjacent floodlands, should be protected; 3. (3) along the lower sector, floodlands should be expanded, and 4. (4) throughout the river corridor, specific floodplain features, such as backwaters and woodlands, should be maintained and enhanced, including works to restore connectivity with the main channel and between patches.