Hyporheic exchange in salmonid redds critically affects embryo development and biogeochemical cycling. Using coupled numerical models validated with high-resolution optical measurements from large-scale laboratory experiments, we examined how streambed permeability controls the transition from pressure- to inertia-driven hyporheic flows. Below hydraulic conductivities of 0.001 m/s, sequential surface-subsurface models adequately capture hyporheic fluxes and surface structures. At higher permeabilities, however, surface-subsurface feedback significantly alters flow patterns and exchange morphology. We propose a correction factor extending existing models to high-permeability regimes. These findings demonstrate the necessity of coupled modeling for permeable streambeds and inform habitat restoration and ecosystem engineering assessments.