Effect of roughness factor on characteristics of hydraulic jump in adverse slopes

In this study, the effect of bed roughness and adverse slope on the characteristics of hydraulic jump in a rectangular channel was experimentally investigated. Experiments were conducted in a laboratory flume with a rectangular cross-section of 0.7 m wide, 0.6 m deep and 15 m long. Initial Froude numbers, adverse slope and roughness factor in the range of 3-6 were considered. Experiments were conducted in five adverse slopes in the range of 0-0.02 with four different roughness factors in the range of 0.0114-0.0191. Characteristics of hydraulic jump including sequent depth ratio, length of jump and the energy dissipation were studied. The results showed that the sequent depth ratio and length of jump decrease by increasing the adverse slope and roughness factor. The main reasons for these changes are effects of the weight as a result of increasing the slope and increase in bed shear stress as a result of bed roughness. Also, results showed that the the energy loss of the hydraulic jump increaseed by increasing adverse slope and roughness factor.