Abstract
The article contains the analysis of the conditions of water flow through the trapezoidal stone permeable sill with a sharp-crested weir on the upper slope. The aim of the analysis was to develop a nomogram and mathematical relationships to determine the width of the sill covered by the overflow stream. In the implementation of the task, our own model research and results provided in the literature were used. The tests covered a part of the overflow stream at the length of which water inflows into the body of sill. The hydrodynamic similarity principle according to the Froude criterion was used to transform the results into objects in nature. The profile of the stream flowing over the tested sill is influenced by the diameter of the aggregate from which the permeable body is made and the unit water flow rate. The result of the works carried out in the article is a nomogram and regression curves for determining the length of water inflowing to the permeable sill. In the analyses, the good fit of the equations into the introduced variables was obtained. The obtained results can be used in the design of this type of field structures.