Acta Scientiarum Polonorum

Abstract: Investigations of the time and spatial macro-scale of the present paper are based on the measurements of instantaneous velocities in a two-stage trapezoidal channel under three various depth in the channel. These investigations have shown the following: the values of time macro-scale have changed in range since 0.07 to 1.15 s; in all three tests the distributions of the sizes of the eddies reveal stable regularity; the relative length of eddies are bigger on the flood plains and achieve value of 0.1 to 2.5 of the flow depths on the flood plains, whereas in the main channel the sizes of largest eddies do not exceed the value of 1 of the total water depth.