Hydrodynamic modeling to evaluate the influence of inland navigation channel training works on fish habitats in the Upper Yellow River

The need to balance inland waterway engineering with river ecological integrity has attracted increasing attention from waterway engineers. Quantitative tools for evaluating the effects of waterway engineering on fish habitat serve as an effective basis for engineering design assessment and improvement. A tourism waterway construction project along the Upper Yellow River (UYR) is located within a core area of the National Aquatic Germplasm Resources Conservation Area. The evaluation of the habitat design performance of waterway training works (which is similar to the term of Inland navigation channel training works, it involves structures and measures that reshape a river channel to create reliable depths and widths for safe and dependable vessel transit.), however, are rare in China. To evaluate the effects of waterway engineering on fish habitats and improve engineering design, we evaluated the influence of waterway training works on habitats for endangered adult Platypharodon extremus (Han et al., 2016) by applying a 2D hydrodynamic model to three scenarios: with and without training works and with improved training works. The simulations reproduced changes in flow velocity and water depth within the navigation discharges range. The size and distribution of suitability indexes of water depth and flow velocity and their combined habitat suitability index were employed to assess available habitats for adult Platypharodon extremus to evaluate the influence of engineering actions. The simulations show that the habitat losses due to waterway training works in the study reach can be restored by introducing eco-friendly concepts into training structures and dredging design. Habitat availability for adult Platypharodon extremus has been reduced after waterway training works, especially at low and moderate discharges (the percentage of available area decreased from 13.48% to 11.69% at designed lowest navigation discharge). Habitat availability is much less sensitive to training works at high discharge than at moderate levels. The available habitat can be restored to at least 97% of its original level through the introduction of eco-friendly conceptual designs (the percentage of available area at designed lowest navigation discharge can be recovered to 13.41%).