Spur dikes are widely used for bank protection and flow training in alluvial rivers, yet their stability is frequently compromised by local scour driven by coherent turbulence structures such as the horseshoe vortex system (HSV) and wake instabilities. This study experimentally evaluates a novel modular spur dike featuring regular, connected three-dimensional volumetric porosity, namely a fully porous spur dike (hereafter referred to as “Chine”), against a conventional impermeable spur dike and a hybrid three-row porous shell configuration. Experiments were conducted in a recirculating rectangular flume (B=0.60 m) under near-threshold clear-water conditions (U/Uc=0.96, Fr≈0.23, h=0.15 m) over uniform sand (d50=1.2 mm). Instantaneous three-component velocities were measured using a down-looking Nortek Vectrino II ADV at 50 Hz, while post-test bed topography was surveyed using a laser profiler (vertical accuracy ±0.5 mm). Results show that regular volumetric porosity enables a controlled bleed flow through the structure, which relieves upstream stagnation pressure, weakens near-bed downflow, and reduces the strength and near-bed influence of high-vorticity cores. Relative to the impermeable spur dike, the fully porous Chine reduced the maximum equilibrium scour depth by 23.7% (submerged) and 22.8% (non-submerged) and promoted a more stable, spatially organized downstream deposition pattern (submerged deposition-bar onset was observed 35.6% closer to the structure). The findings indicate that geometrically regular 3D porosity can function as a distributed energy dissipator that mitigates local scour risk in river-training applications.