Eco-friendly dredging methods of changing fluvial landforms for enhancing hydraulic habitat quality and river corridor continuum

Hydraulic habitat connectivity, including the longitudinal continuum respect and lateral flood pulse, is critical for fish survival and organism dispersal. Inappropriate and excessive dredging for prevent flooding may harm river ecosystems. The main objective of this study is to evaluate whether eco-friendly dredging presented by changing local river landforms incorporating the concept of nature-based solutions could grow fish habitat quality for improving river continuity and achieving flood control effects. By combining various mathematical models and empirical formulas and verifying them with the data obtained through field surveys, we explore the interconnections of hydrology, river morphology, and the habitat dynamics of four endemic fishes in an alluvial river. The relationship between habitat structure, flood risk, and river topography, flow discharge was presented as the reference for developing the proper river dredging approaches. The results reveal that the primary habitat defects were lack of high-quality habitat, unsatisfied habitat diversity, deficiency in refugia, and disconnectivity. Longitudinal disconnectivity was induced due to shallow water depth, while lateral disconnectivity is primarily caused by fast flow velocity, suggesting different and specific dredging methods were instructed. We recommend that the corresponding eco-friendly dredging schemes for longitudinal and lateral suitable habitat linkages increase fish habitat quality and river corridor continuity. The win-win strategy for enhancing the connection between suitable habitats sustains a more beneficial aquatic corridor and simultaneously achieves alluvial flood disaster risk reduction. [Display omitted] •Environmental flow determined by endemic fish habitat quality was used to examine river corridor connectivity.•Pool-riffle-run structure is the central consideration in fluvial landform alternation for satisfying both flood prevention and ecological rehabilitation.•LonDred-30cm creates pool-run structure, while LatDred-60cm and LatFill30cm rehabilitate pool-riffle structure.•LonDred-30cm and LatDred-60cm successfully enhance longitudinal and lateral corridors for endemic fish species.•Mainstream and tributaries of a braided river play a critical role as refugia for aquatic organisms in dry and wet seasons