## 4 Discussion
### Considerations around the Instrumented Particle's Design  
The instrumented particle presented herein is a novel sensing equipment for the study of bedload transport of particles. The results of this study and derived distribution models are accurate and can be used directly for parameterizing the transport of solid particles that are lighter than sediment. This can find a host of modern direct eco-hydraulic and engineering applications, including habitat assessment and monitoring [68] as well as transport of plastics through the fluvial vector, which are emerging research fields. These results are also directly applicable in helping further identify, also for the first time, trends in the dynamics of particle transport and their interaction with the bed surface, for a range of assessed parameters, including (a) solid particle density, (b) bed surface roughness, and (c) flow conditions, above threshold. These are of great importance for computational fluid dynamics and discrete element modelers (CFD-DEM, e.g., [21]), which can use such stochastic models to match any coefficients behind their constitutive or particle micromechanical models and validate them.  
The size and shape of the instrumented particle are selected so that for the range of flow conditions trialed herein, a range of solid transport rates above threshold can be achieved. A fully spherical particle allows for a relatively higher transport rate for the same flow conditions. The particle size is miniaturized to scales comparable to natural sediment particles (of diameter \(<\)80 mm, e.g., large, rounded pebbles). Future research may focus on particle shapes to study the dependence of particle transport dynamics on different shapes, following the same design of experiments and framework of analysis as shown here. Typically, the instrumented particle's casing size is limited by the IMU sensor's size, but this can be further miniaturized with custom designed electronics and sensor calibration routines, as shown recently [48], enabling assessing trends for a wider range of transported particle properties. Despite these differences to natural sediment particles, the mode of transport by saltation as well as the modeling of distributions of a range of metrics used to assess it are found to be comparable to what other researchers have found for natural sediment particles.  
The instrumented particle used in this study addresses limitations of active or passive tracer methods [69; 70; 71; 72] such as inaccessibility, high initial purchase and deployment costs, low recovery rates (due to different deployment methods), as well as requirements for professional labor to apply the technique. It is a robust, stepper-like device that can offer advanced insights for the dynamics of bedload transport. An improved understanding of sediment transport dynamics can be obtained by analyzing the flow forces acting on individual sediment particles near the channel bed surface, under certain hydraulic and hydrodynamic conditions towards enabling more robust assessment of the geomorphic processes and allowing for adopting improved sediment management strategies and water resources planning [38; 73].