Aim of the study:
The paper presents the results of research carried out in the Będkówka stream. The aim of study was to determine the influence of large roughness elements on the change in the coefficient of roughness and resistance coefficients.

Material and methods:
A section of the stream was selected for the study, on which nine measurement cross-sections were determined, including three of them were large roughness elements. The dimensionless resistance coefficient (λ) was calculated from the Colebrook-White equation.

Results and conclusions:
It was stated that in sections with large roughness elements, both water flow velocities as well as resistance and roughness coefficients obtained values higher than in other cross-sections. The coefficient of cross-section cover (ω) and degree of change of roughness coefficient Δn were also calculated and a regression relation Δn = f (ω) was determined. This relationship will allow to determine the change in the hydraulic conditions of the water flow, expressed by the change in the coefficient of roughness.