Extensive removal of riparian vegetation and instream wood during the 19th and 20th centuries caused widespread geomorphic adjustment in rivers of southeastern Australia. With improvements in river management practice, signs of geomorphic and vegetative recovery have been detected since the 1980s. Using supervised classification of satellite imagery, we analysed decadal trends in riparian woody and non-woody vegetation across 20 coastal catchments of NSW and found an average 40% increase in riparian vegetation cover since the 1950s. In several catchments, present-day riparian cover reaches 60–80%.
Vegetation recovery has occurred alongside geomorphic recovery, detected as improvements in river physical structure and function. We use ergodic reasoning to quantitatively analyse changes in assemblages of geomorphic units (GU) across rivers at different stages of geomorphic recovery. GU assemblages were mapped and analysed for 78 river sections spanning eight River Styles. We find that geomorphic river recovery is not always linear and occurs in different patterns for different river types. The presence of benches and islands indicates recovery is underway across most river types. Statistically significant increases in abundance and area of benches, pools and decreases in abundance and area of floodplain steps can also signal recovery. In addition, bank-attached bars tend to become more compound in structure as recovery progresses.
Determining the indicator GUs and changes in assemblages to ‘look out for’ in the field or on remote sensing images can aid river practitioners in their detection and analysis of river recovery, providing invaluable insight for nature-based and recovery-enhancement approaches to river management.