<p>Rock mass erosion has been prevalent in many hydraulic structures which endangers their stability. Rock block orientation plays an important role in the rock mass erosion process in dam spillways. Determining the effect of individual parameters on the erosion process at dam sites is very complicated, and hence, laboratory scale model testing becomes a powerful tool in this scenario. In this study, model tests are performed on modelled blocks of size 15 cm x 15 cm x 30 cm to understand the effect of joint orientation. Three different joint orientations are tested under three different joint aperture and four different flow rate conditions to obtain the pressure distribution around the central instrumented block. This block is designed to capture the static and dynamic pressures together with high accuracy. The coefficient of uplift values obtained from the test results are found to be positive ranging from 0.2 to 0.6 and 0.1 to 0.6 for blocks arranged against and towards the flow respectively which exhibited the possibility of uplift occurrence. Stability analysis carried out using the pressure results revealed that the blocks arranged against the flow direction tend to topple (FS ranging from 0.5 to 0.8) and align towards the flow before being uplifted, whereas the blocks arranged towards the flow direction presents exhibited uplift occurrence (FS ranging from 0.2 to 0.7). The blocks arranged perpendicular to the flow direction are found to be stable compared to those in the inclined conditions which underlines the importance of joint orientation on the erosion process.</p>