As the flow velocity and Reynolds number increase in rockfilled porous media, the flow deviates from Darcy conditions and enters into a new phase known as non-Darcy conditions. Due to a linear relationship between hydraulic gradient and the flow velocity in Darcy formula, the flow can be analyzed with no difficulty. However, as the velocity increases the Darcy law is violated, the flow becomes turbulent, making the analysis more challenging. In this paper a laboratory packed column was built to study high-velocity flow through granular materials and new experimental data have been obtained. The laboratory experiments include application of for six different sizes of rounded aggregates and using different hydraulic gradients to assess the flow behavior. Using new experimental data, the validity of four widely-used head-loss equations were evaluated. The results indicated that the Sidiropoulou et al. (Hydrol Process 21:534-554, 2007) and Ergun's head-loss equations yield satisfactory results comparing to other available relationships.