This paper shows a profile of hydrodynamic conditions present in a Skawa river portion, where fish populations have been found. The river portion surveyed is characterized by a changing gradient and varying morphology, and by a locally diversified velocity and intensity of flow turbulence. The longitudinal and transversal sections of the river bed were geodetically surveyed; the granulometric composition of the fluvial deposits was studied. Using an Acoustic Doppler Velocimeter (ADV), the river flow velocity was measured at three sites: above the riffle, in the riffle, and below it. The measurement results were used to compute shear stresses in the river bed, velocity distributions, and intensity distributions of turbulence. Based on the study, three types of habitats were identified. Using a method known as MEM (Mesohabitat Evaluation Model), the river flow within the zone of the site above and in the riffle was classified as a normal flow, whereas the flow below the riffle was classified as a fast river flow. The fact that the two habitats were classified as zones with normal flow proves that the assumed criterion, i.e. a wide range of shear stress values showing two orders of magnitude does not adequately incorporate changes in hydrodynamic conditions revealed through the survey conducted.

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