The aim of the study was to analyse the possibility of using dimensionless coordinates in order to determine the typical shape of the overflow stream at the gabion sill, as well as identify the flow zone therein and evaluate the characteristic dimensions of the profile. The analysed weir consists of a permeable part filled with natural stone material, and a solid part in the form of sharp-crested weir on sloping upstream face. The shape of the upper profile of the stream has been determined along with its parameters. Three flow zones at the length of the crest sill were identified: the free flow zone, the inlet wave zone and the sill part, which is free of water. The water flow rate influences the formation of water stream profile flowing over the tested sill. The full correlation dependence of variables was obtained in the analysis. The obtained results can be used in the design of this type of field structures.