Reconstructing Single Side of Riverbanks Minimizes Adverse Effects on Sailfin Suckers’ Habitat

ABSTRACT

River reconstructions, encompassing flood and erosion control along with the restoration of fish habitat, can alter hydrodynamics within the constructed channel, thereby impacting fish habitat. This study aimed to assess the influence of specific river reconstruction practices, particularly spur dikes, on both hydrodynamics and fish habitat, to optimize the design of spur dike constructions for fish habitat restoration. The study utilized ecohydraulic modeling to examine the design of river reconstruction strategies and provide valuable insights on their efficacy, with a focus on refining these practices to enhance the suitability of habitat for Myxocyprinus asiaticus (Chinese Sailfin Sucker) in the Yangtze River. We used various flow rates and time periods to test hydrodynamic and habitat responses and long-term stability of the restoration schemes. The results suggested that the habitat quality of all the tested cases increased with flow rates and then decreased. Modelling results indicated a ranking of the habitat status from high to low in the following scenarios: baseline channel without riverbank constructions, with straight or T-shaped spur dikes installed on a single riverbank, and with straight or T-shaped spur dikes installed on both riverbanks. For post-effects of the restoration strategies, each approach would scour the riverbed. Installing spur dikes on both riverbanks would severely degrade the fish habitat suitability level, with the overall suitability index decreasing over time. In summary, installation of spur dikes along a single riverbank minimized the impact on the suitability of fish habitats and was the preferred scenarios to optimize habitat suitability for Chinese Sailfin Sucker.