Can the regulation of Golden Inland Waterways meet the needs of navigation, flood control, and ecology? A model-based case study

In recent years, the ecological functions of inland waterways have received much attention. Roughness elements have been used in waterway regulations (WRs) to guard the riverbed and improve physical habitat. However, the response of aquatic organisms to regulations varies widely. It is controversial whether inland waterway regulations can achieve the sustainable function of navigation, flood control and ecological needs.This paper evaluated the influence of WRs on aquatic habitat by using the physical habitat simulation models combining a 2D hydrodynamic model and habitat models. Compared with a reference model with no-engineering, the habitat suitability of zoobenthos, four major species of Chinese carp's spawning ground and the Yangtze finless porpoise at different flow discharges were simulated under different densities of river training structures and types of roughness elements. Results showed that the implementation of the WRs can adjust the distribution of the suitability of aquatic habitats, but does not change the pattern of suitability with discharge. The response of biological habitats to regulation projects varied by species. Regulation can maintain the stable habitat during dry and flood periods, reducing the effect of extreme weather on aquatic organisms. Roughness elements are not suitable for large-scale use in WRs. The “win-win” agreement between economic and ecological issues can be obtained through pre-optimization.