The hydraulic erosion of the rock mass within dam spillways must be considered when assessing the stability of dam infrastructures. As this erosion results from the interaction between water and the rock mass, commonly applied methods to evaluate this phenomenon use the notion of a threshold line, a correlation between the water’s erosive force and the resistance of the rock mass against erosion. These methods are empirical or semi-empirical, and they have limitations regarding the characterization of this phenomenon. These methods are based on specific hydraulic and rock mass parameters, including a number of parameters that are irrelevant to the erosion process; thus, there is a need to upgrade the existing methods or to seek new solutions to characterize hydraulic erosion. We present a laboratory-scale physical model to determine the effects of rock mass parameters on erosion. This model is designed to determine individual and interactive effects of several hydraulic and rock mass parameters on erosion, including joint opening, block size, joint shear strength, and the nature of potentially erodible surfaces, as well as water pressure (static and dynamic), variations of flow rate and velocity, and channel roughness.