Experiments on hydraulic characteristics of roll wave for sheet flow with artificial rough bed

In order to investigate hydraulic characteristics of slope shallow flow, changes in hydraulic parameters of slope shallow flow on the bed with uniform roughness (artificial roughness of 0.3850 mm in diameter) at 5 slope gradients and 17 unit width discharges were studied from the viewpoint of fluid mechanics and sediment transport mechanics. Results showed that indexes of flow regime for slope shallow flow varied from 0.33 to 0.43 and the indexes can be used to indicate some hydraulic relationships comprehensively. Velocity of rolling wave flow increased with discharge increase and was affected by gradient slightly. Wave length changed with discharge in the form of single peak, i.e., it increased with discharge increase at first and then decreased after the single peak. The peak was corresponding to the unit width discharge of 0.278 L/(s·m). The frequency of rolling wave decreased with increasing flow path length and the averaged attenuation coefficient of frequency raised with unit width discharge increase.. Under the experiment conditions, the critical Froude number for unstable laminar flow was about 0.64 and the critical Froude number for the unstable turbulent flow was about 2.13.