172 / 2024-02-26 15:15:42

Hydro-morphodynamic computation for physical habitat simulation

hydro-morphodynamic simulation,physical habitat simulation,river morphology,substrate,gravel-bed river

In general, the physical habitat simulation uses three habitat variables, namely flow depth, velocity, and substrate. The flow depth and velocity are obtained from the hydraulic simulation. However, the habitat suitability for the substrate is determined not from the hydraulic simulation but from the visual observation. This might provide one reason why the substrate has been treated less importantly compared to the other habitat variables. This study presents hydro-morphodynamic simulation, instead of hydraulic simulation, for physical habitat simulation. The hydro-morphodynamic simulation provides the change in river morphology and substrate as well as flow depth and velocity.



The study area is a 12.8 km long reach downstream of the Yongdam Dam, consisting of a series of bends, in the Geum-gang River, Korea. For the physical habitat simulation, the HEC-RAS 1D model and habitat suitability curves were used for hydro-morphodynamic and habitat simulations, respectively. Zacco koreanus, the most dominant and endemic fish species, was selected as the target fish. The hydro-morphodynamic model was validated for the flow and morphological change in the study area. The model was shown to predict not only the change in the flow and river morphology but also the change in the composition of the substrate. The physical habitat simulation was carried out for the target fish species, and the impact of the morphological change after the flood on the physical habitat for the target fish was assessed. Simulation results indicated that the composite suitability index fluctuates in the longitudinal direction, which is related to that erosion and deposition occur repeatedly along the river reach. This resulted in a decrease in the weighted usable area in the study reach. In the present study, the change in the substrate did not affect the habitat quality because the habitat suitability curve is not so sensitive to the change in the substrate